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EARTH SCIENCES (469 journals)                  1 2 3 | Last

Showing 1 - 200 of 371 Journals sorted alphabetically
Acta Geochimica     Hybrid Journal   (Followers: 3)
Acta Geodaetica et Geophysica     Hybrid Journal   (Followers: 1)
Acta Geodaetica et Geophysica Hungarica     Full-text available via subscription   (Followers: 2)
Acta Geophysica     Open Access   (Followers: 6)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3)
Advances in High Energy Physics     Open Access   (Followers: 18)
Advances In Physics     Hybrid Journal   (Followers: 15)
Aeolian Research     Hybrid Journal   (Followers: 5)
African Journal of Aquatic Science     Hybrid Journal   (Followers: 12)
Algological Studies     Full-text available via subscription   (Followers: 2)
Alpine Botany     Hybrid Journal   (Followers: 3)
AMBIO     Hybrid Journal   (Followers: 13)
Anadolu University Journal of Science and Technology     Open Access  
Anales del Instituto de la Patagonia     Open Access   (Followers: 1)
Andean geology     Open Access   (Followers: 4)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3)
Annales UMCS, Geographia, Geologia, Mineralogia et Petrographia     Open Access  
Annals of Geophysics     Full-text available via subscription   (Followers: 12)
Annals of GIS     Hybrid Journal   (Followers: 19)
Annals of Glaciology     Full-text available via subscription   (Followers: 2)
Annual Review of Marine Science     Full-text available via subscription   (Followers: 10)
Anthropocene     Hybrid Journal   (Followers: 3)
Anthropocene Review     Hybrid Journal   (Followers: 4)
Applied Clay Science     Hybrid Journal   (Followers: 4)
Applied Geochemistry     Hybrid Journal   (Followers: 11)
Applied Geomatics     Hybrid Journal   (Followers: 3)
Applied Geophysics     Hybrid Journal   (Followers: 7)
Applied Ocean Research     Hybrid Journal   (Followers: 4)
Applied Petrochemical Research     Open Access   (Followers: 2)
Applied Remote Sensing Journal     Open Access   (Followers: 33)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 34)
Arctic Science     Open Access   (Followers: 6)
Arctic, Antarctic, and Alpine Research     Full-text available via subscription   (Followers: 10)
Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences     Open Access   (Followers: 16)
Asia-Pacific Journal of Atmospheric Sciences     Hybrid Journal   (Followers: 20)
Asian Journal of Earth Sciences     Open Access   (Followers: 20)
Asian Review of Environmental and Earth Sciences     Open Access   (Followers: 1)
Atlantic Geology : Journal of the Atlantic Geoscience Society / Atlantic Geology : revue de la Société Géoscientifique de l'Atlantique     Full-text available via subscription   (Followers: 3)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 12)
Atmospheric and Climate Sciences     Open Access   (Followers: 25)
Australian Journal of Earth Sciences: An International Geoscience Journal of the Geological Society of Australia     Hybrid Journal   (Followers: 11)
Boletim de Ciências Geodésicas     Open Access  
Boreas: An International Journal of Quaternary Research     Hybrid Journal   (Followers: 10)
Bragantia     Open Access   (Followers: 2)
Bulletin of Earthquake Engineering     Hybrid Journal   (Followers: 10)
Bulletin of Geosciences     Open Access   (Followers: 8)
Bulletin of the Lebedev Physics Institute     Hybrid Journal   (Followers: 1)
Bulletin of the Seismological Society of America     Full-text available via subscription   (Followers: 20)
Bulletin of Volcanology     Hybrid Journal   (Followers: 17)
Cadernos de Geociências     Open Access  
Canadian Journal of Plant Science     Full-text available via subscription   (Followers: 15)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 20)
Carbonates and Evaporites     Hybrid Journal   (Followers: 3)
CATENA     Hybrid Journal   (Followers: 4)
Chemical Geology     Hybrid Journal   (Followers: 14)
Chemie der Erde - Geochemistry     Hybrid Journal   (Followers: 4)
Chinese Geographical Science     Hybrid Journal   (Followers: 5)
Chinese Journal of Oceanology and Limnology     Hybrid Journal   (Followers: 3)
Ciencias Espaciales     Open Access  
Climate and Development     Hybrid Journal   (Followers: 12)
Coastal Management     Hybrid Journal   (Followers: 24)
Cogent Geoscience     Open Access  
Comptes Rendus Geoscience     Full-text available via subscription   (Followers: 8)
Computational Geosciences     Hybrid Journal   (Followers: 12)
Computational Mathematics and Mathematical Physics     Hybrid Journal   (Followers: 1)
Computers and Geotechnics     Hybrid Journal   (Followers: 8)
Contemporary Trends in Geoscience     Open Access   (Followers: 2)
Continental Shelf Research     Hybrid Journal   (Followers: 8)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 9)
Contributions to Plasma Physics     Hybrid Journal   (Followers: 3)
Coral Reefs     Hybrid Journal   (Followers: 16)
Cretaceous Research     Hybrid Journal   (Followers: 6)
Cybergeo : European Journal of Geography     Open Access   (Followers: 4)
Depositional Record     Open Access  
Developments in Geotectonics     Full-text available via subscription   (Followers: 3)
Developments in Quaternary Science     Full-text available via subscription   (Followers: 3)
Développement durable et territoires     Open Access   (Followers: 3)
Diatom Research     Hybrid Journal  
Doklady Physics     Hybrid Journal   (Followers: 1)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 10)
E&S Engineering and Science     Open Access  
E3S Web of Conferences     Open Access  
Earth and Planetary Science Letters     Hybrid Journal   (Followers: 68)
Earth and Space Science     Open Access   (Followers: 10)
Earth Interactions     Full-text available via subscription   (Followers: 11)
Earth Science Research     Open Access   (Followers: 6)
Earth Surface Dynamics (ESurf)     Open Access   (Followers: 4)
Earth Surface Processes and Landforms     Hybrid Journal   (Followers: 19)
Earth System Dynamics     Open Access   (Followers: 6)
Earth System Dynamics Discussions     Open Access   (Followers: 4)
Earth's Future     Open Access   (Followers: 1)
Earth, Planets and Space     Open Access   (Followers: 90)
Earthquake Engineering and Engineering Vibration     Hybrid Journal   (Followers: 6)
Earthquake Science     Hybrid Journal   (Followers: 9)
Earthquake Spectra     Full-text available via subscription   (Followers: 17)
Ecohydrology     Hybrid Journal   (Followers: 9)
Ecological Questions     Open Access   (Followers: 7)
Electromagnetics     Hybrid Journal   (Followers: 4)
Energy Efficiency     Hybrid Journal   (Followers: 11)
Energy Exploration & Exploitation     Full-text available via subscription   (Followers: 4)
Environmental Earth Sciences     Hybrid Journal   (Followers: 23)
Environmental Geology     Hybrid Journal   (Followers: 10)
Environmental Geosciences     Full-text available via subscription   (Followers: 4)
Environmental Geotechnics     Hybrid Journal   (Followers: 3)
Erwerbs-Obstbau     Hybrid Journal  
Estuaries and Coasts     Hybrid Journal   (Followers: 17)
Estuarine, Coastal and Shelf Science     Hybrid Journal   (Followers: 34)
Estudios Geográficos     Open Access  
European Journal of Mineralogy     Full-text available via subscription   (Followers: 11)
Exploration Geophysics     Hybrid Journal   (Followers: 4)
Facies     Hybrid Journal   (Followers: 9)
Fieldiana Life and Earth Sciences     Full-text available via subscription   (Followers: 1)
Física de la Tierra     Open Access  
Folia Musei rerum naturalium Bohemiae occidentalis. Geologica et Paleobiologica     Open Access  
Folia Quaternaria     Open Access  
Forestry Chronicle     Full-text available via subscription   (Followers: 10)
Frontiers in Earth Science     Open Access   (Followers: 5)
Frontiers in Geotechnical Engineering     Open Access   (Followers: 2)
Frontiers of Earth Science     Hybrid Journal   (Followers: 8)
Fundamental and Applied Limnology / Archiv für Hydrobiologie     Full-text available via subscription   (Followers: 4)
GEM - International Journal on Geomathematics     Hybrid Journal   (Followers: 1)
Geo-Marine Letters     Hybrid Journal   (Followers: 7)
Geoacta     Open Access   (Followers: 4)
Geobiology     Hybrid Journal   (Followers: 7)
Geocarto International     Hybrid Journal   (Followers: 18)
Geochemical Perspectives     Hybrid Journal  
Geochemistry : Exploration, Environment, Analysis     Hybrid Journal   (Followers: 7)
Geochemistry, Geophysics, Geosystems     Full-text available via subscription   (Followers: 24)
Geochimica et Cosmochimica Acta     Hybrid Journal   (Followers: 26)
Geochronometria     Hybrid Journal   (Followers: 3)
Geoderma Regional : The International Journal for Regional Soil Research     Full-text available via subscription   (Followers: 3)
Geodinamica Acta     Hybrid Journal   (Followers: 3)
Geodynamics & Tectonophysics     Open Access   (Followers: 1)
Geoenvironmental Disasters     Open Access   (Followers: 3)
Geofluids     Hybrid Journal   (Followers: 4)
Geoforum     Hybrid Journal   (Followers: 20)
Géographie physique et Quaternaire     Full-text available via subscription   (Followers: 1)
Geography and Natural Resources     Hybrid Journal   (Followers: 5)
Geoheritage     Hybrid Journal   (Followers: 1)
Geoinformatica Polonica : The Journal of Polish Academy of Arts and Sciences     Open Access  
Geoinformatics & Geostatistics     Hybrid Journal   (Followers: 8)
Geological Journal     Hybrid Journal   (Followers: 14)
Geology Today     Hybrid Journal   (Followers: 20)
Geomagnetism and Aeronomy     Hybrid Journal   (Followers: 3)
Geomatics, Natural Hazards and Risk     Hybrid Journal   (Followers: 9)
Geomechanics for Energy and the Environment     Full-text available via subscription  
GEOmedia     Open Access   (Followers: 1)
Geomorphology     Hybrid Journal   (Followers: 25)
Geophysical & Astrophysical Fluid Dynamics     Hybrid Journal   (Followers: 2)
Geophysical Journal International     Hybrid Journal   (Followers: 30)
Geophysical Prospecting     Hybrid Journal   (Followers: 7)
Geophysics     Full-text available via subscription   (Followers: 18)
GeoResJ     Hybrid Journal  
Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards     Hybrid Journal   (Followers: 8)
Geoscience Canada : Journal of the Geological Association of Canada / Geoscience Canada : journal de l'Association Géologique du Canada     Full-text available via subscription   (Followers: 3)
Geoscience Data Journal     Open Access   (Followers: 2)
Geoscience Frontiers     Open Access   (Followers: 9)
Geoscience Letters     Open Access  
Geoscience Records     Open Access  
Geosciences     Open Access   (Followers: 2)
Geosciences Journal     Hybrid Journal   (Followers: 9)
Geoscientific Instrumentation, Methods and Data Systems     Open Access   (Followers: 4)
Geoscientific Model Development     Open Access   (Followers: 2)
Geostandards and Geoanalytical Research     Hybrid Journal   (Followers: 2)
Geosystem Engineering     Hybrid Journal   (Followers: 1)
Geotectonic Research     Full-text available via subscription   (Followers: 4)
Geotectonics     Hybrid Journal   (Followers: 7)
GISAP : Earth and Space Sciences     Open Access   (Followers: 2)
Glass Physics and Chemistry     Hybrid Journal   (Followers: 3)
Global and Planetary Change     Hybrid Journal   (Followers: 12)
Global Biogeochemical Cycles     Full-text available via subscription   (Followers: 12)
Gondwana Research     Hybrid Journal   (Followers: 6)
Grassland Science     Hybrid Journal   (Followers: 1)
Ground Water     Hybrid Journal   (Followers: 26)
Ground Water Monitoring & Remediation     Hybrid Journal   (Followers: 17)
Groundwater for Sustainable Development     Full-text available via subscription  
GSA Today     Partially Free  
Helgoland Marine Research     Open Access   (Followers: 3)
History of Geo- and Space Sciences     Open Access   (Followers: 4)
Hydrobiologia     Hybrid Journal   (Followers: 18)
Hydrogeology Journal     Hybrid Journal   (Followers: 16)
Hydrological Processes     Hybrid Journal   (Followers: 23)
Hydrology and Earth System Sciences     Open Access   (Followers: 26)
ICES Journal of Marine Science: Journal du Conseil     Hybrid Journal   (Followers: 53)
IEEE Journal of Oceanic Engineering     Hybrid Journal   (Followers: 11)
Indian Geotechnical Journal     Hybrid Journal   (Followers: 2)
Indonesian Journal on Geoscience     Open Access   (Followers: 2)
Interdisciplinary Environmental Review     Hybrid Journal   (Followers: 3)
International Geology Review     Hybrid Journal   (Followers: 5)
International Journal of Advanced Geosciences     Open Access  
International Journal of Advanced Remote Sensing and GIS     Open Access   (Followers: 33)
International Journal of Advancement in Earth and Enviromental Sciences     Open Access   (Followers: 3)
International Journal of Advancement in Remote Sensing, GIS, and Geography     Open Access   (Followers: 27)
International Journal of Applied Earth Observation and Geoinformation     Hybrid Journal   (Followers: 34)
International Journal of Coal Geology     Hybrid Journal   (Followers: 2)
International Journal of Disaster Risk Reduction     Hybrid Journal   (Followers: 10)
International Journal of Earth Sciences     Hybrid Journal   (Followers: 30)
International Journal of Forest, Soil and Erosion     Open Access   (Followers: 4)

        1 2 3 | Last

Journal Cover Chemie der Erde - Geochemistry
  [SJR: 0.881]   [H-I: 34]   [4 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0009-2819
   Published by Elsevier Homepage  [3038 journals]
  • Preservation of coal-waste geochemical markers in vegetation and soil on
           self-heating coal-waste dumps in Silesia, Poland
    • Authors: Monika J. Fabiańska; Justyna Ciesielczuk; Magdalena Misz-Kennan; Łukasz Kruszewski; Adam Kowalski
      Pages: 211 - 226
      Abstract: Publication date: Available online 8 April 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Monika J. Fabiańska, Justyna Ciesielczuk, Magdalena Misz-Kennan, Łukasz Kruszewski, Adam Kowalski
      Occurrence and distributions of geochemical markers on vegetation and in soils covering two self-heating coal waste dumps were investigated with gas chromatography-mass spectrometry (GC–MS) and compared with those of bitumen expelled on the coal waste dump surface. Presence of biomarkers, alkyl aromatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and such polar compounds as phenols indicate that components of self-heating coal wastes indeed migrate to soils and plants surface and their characteristic fingerprints can be applied in passive monitoring to investigate migration of contaminants from self-heating coal wastes. Moreover, results allow to discriminate between the Upper- and Lower Silesian coal basins, notwithstanding value shifts caused by heating. Mechanisms enabling the migration of geochemical compounds into soils include mixing with weathered coal-waste material, transport in gases emitted due to self-heating and, indirectly, by deposition of biomass containing geochemical substances. Transport in gases involves mostly lighter compounds such as phenols, methylnaphthalenes, methylbiphenyls, etc. Distributions and values of geochemical ratios are related to differences in their boiling temperatures in the case of lighter compounds but preserve geochemical features in the case of heavier compounds such as pentacyclic trierpanes.

      PubDate: 2016-04-09T14:20:28Z
      DOI: 10.1016/j.chemer.2016.04.001
      Issue No: Vol. 76, No. 2 (2016)
  • Assessment of groundwater quantity and quality and saltwater intrusion in
           the Damghan basin, Iran
    • Authors: Milad Ebrahimi; Hamidreza Kazemi; Majid Ehtashemi; Thomas D. Rockaway
      Pages: 227 - 241
      Abstract: Publication date: Available online 25 April 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Milad Ebrahimi, Hamidreza Kazemi, Majid Ehtashemi, Thomas D. Rockaway
      This study describes the groundwater quantity and quality conditions in the Damghan aquifer in Iran. The quantitative analysis of data obtained from observation wells indicates overexploitation of groundwater during recent years, which has resulted in deterioration of water quality. The mean water level has declined about 7.4m between years of 1966 and 2010. The hydrochemical facies of water collected from sampling wells were investigated though Piper and Chadha diagrams, and the general dominant type of water in the study area was determined as Na-Cl. The quality assessment examined the suitability of groundwater for drinking and irrigation purposes. Compared to the World Health Organization (WHO) guidelines for drinking water, all regions were found to have unpotable groundwater. Furthermore, unsuitability of groundwater for agricultural applications due to high salinity was observed through analysis of major quality indicators. The saltwater intrusion was investigated by ionic ratio analyses and was determined to be the main factor contributing to high salinity and deterioration of the groundwater quality in the Damghan basin.

      PubDate: 2016-06-13T12:09:56Z
      DOI: 10.1016/j.chemer.2016.04.003
      Issue No: Vol. 76, No. 2 (2016)
  • Isotopic and geochemical identifications of groundwater salinisation
           processes in Salalah coastal plain, Sultanate of Oman
    • Authors: Brahim Askri; Abdelkader T. Ahmed; Razan Ali Al-Shanfari; Rachida Bouhlila; Khater Ben Khamis Al-Farisi
      Pages: 243 - 255
      Abstract: Publication date: Available online 9 May 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Brahim Askri, Abdelkader T. Ahmed, Razan Ali Al-Shanfari, Rachida Bouhlila, Khater Ben Khamis Al-Farisi
      A detail investigation was carried out to improve the current knowledge of groundwater salinisation processes in coastal aquifers using hydrochemical and isotopic parameters. Data of major ions for 40 wells located in the Salalah plain aquifer, Sultanate of Oman, were collected during pre-monsoon 2004 and analysed. The groundwater changes along the general flow path towards the coast from fresh (EC<1500μS/cm), brackish (EC: 1500–3000μS/cm) and saline (EC>3000μS/cm). Results of inverse modeling simulations using PHREEQC show that dissolution of halite may be the main source of Cl and Na in the study area. Ionic delta calculation indicates that the depletion of Na and K and enrichment of Ca and Mg in groundwater were probably attributed to reverse ion exchange reactions. During a sampling campaign conducted in October 2015, 11 groundwater samples were collected for Cl, Br and isotopic analysis (2H/18O). Molar Cl/Br ratios in fresh groundwater were higher than those of seawater, indicating the impact of halite dissolution on the groundwater quality. For saline groundwater, these ratios were less than those of seawater, showing the influence of anthropogenic input from agriculture on the same. Relatively depleted isotopic signature of all groundwater samples show that the monsoon precipitation is the main source of groundwater recharge in the study area.

      PubDate: 2016-06-13T12:09:56Z
      DOI: 10.1016/j.chemer.2015.12.002
      Issue No: Vol. 76, No. 2 (2016)
  • Geochronology and geochemistry of the major host rock of the Dong’an
           gold deposit, Lesser Khingan Range: Implications for petrogenesis and
           metallogenic setting during the Early–Middle Jurassic in northeast China
    • Authors: Yubo Zhi; Bile Li; Aihua Xi; Qinglin Xu; Liang Zhang; Yonggang Sun; Jingjuan Chang; Bo Peng
      Pages: 257 - 274
      Abstract: Publication date: Available online 25 March 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Yubo Zhi, Bile Li, Aihua Xi, Qinglin Xu, Liang Zhang, Yonggang Sun, Jingjuan Chang, Bo Peng
      The Dong’an gold deposit is a large-sized epithermal gold deposit recently discovered in the Lesser Khingan Range, NE China. Here, we present a detailed study of the petrogenesis, magma source, and tectonic setting of a medium–coarse grained alkali-feldspar granite, the major host rock of the Dong’an gold deposit. The LA–ICP–MS zircon U–Pb dating of the medium–coarse grained alkali-feldspar granite yields an early Jurassic age of 176.3±1.1Ma (MSWD=0.62). The whole-rock geochemical data indicate that the samples are felsic, ferroan, alkali-calcic and peraluminous with relatively high alkali (K2O+Na2O) content. They are enriched in LREEs and LILEs (e.g., Rb, Ba, K), but are depleted in HFSEs (e.g., Nb, Ta, P, Ti), especially in P and Ti, showing characteristics of volcanic arc magmas and similarities with the Early–Middle Jurassic granitic rocks in Xing’an Mongolian orogenic belt. Meanwhile, the negative Eu, Nb, Ta, Ti, and P anomalies are consistent with fractional crystallization of plagioclase, Ti-bearing phases (rutile, ilmenite, titanite, etc.) and apatite during magma evolution. The samples have low Nb/Ta ratios (8.65–14.91) and low Mg# values (18–36), which are indicative of crustal derived magmas and no interaction between source magmas and the mantle. In-situ Hf isotopic analyses of the zircons from the medium–coarse grained alkali-feldspar granite yield εHf(t) values of +3.38–+5.68 and two-stage model ages (TDM2) of 772–900 Ma, indicating the magmas formed this intrusion were generated by partial melting of Neoproterozoic basaltic materials in the young lower crust, and the magma source could be derived from a depleted mantle. The medium–coarse grained alkali-feldspar granite most likely formed in the late stage of Toarcian subduction of the Pacific plate, which can be identified on the tectonic setting discrimination diagrams, and the formation of this intrusion was associated with underplating of mantle-derived magmas, which provided heat for crustal partial melting. Similar to the medium–coarse grained alkali-feldspar granite, large amounts of granitic rocks and a series of nonferrous metal hydrothermal deposits (Mo, Cu, Au) formed in northeast China as results of magmatic activities triggered by subduction of the Pacific plate during the Early–Middle Jurassic.

      PubDate: 2016-03-26T07:09:44Z
      DOI: 10.1016/j.chemer.2016.03.001
      Issue No: Vol. 76, No. 2 (2016)
  • Chemical, isotopic and mineralogical characteristics of volcanogenic
           epithermal fluorite deposits on the Permo-Mesozoic foreland of the Andean
           volcanic arc in Patagonia (Argentina)
    • Authors: Harald G. Dill; Liliana I. Luna; Nicole Nolte; Bent T. Hansen
      Pages: 275 - 297
      Abstract: Publication date: Available online 7 April 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Harald G. Dill, Liliana I. Luna, Nicole Nolte, Bent T. Hansen
      Epithermal deposits mined for fluorite in Patagonia, Argentina, are closely related to late Triassic through Jurassic magmatic activity which brought about felsic to intermediate magmatic rocks. The fluorite mineralization in the Patagonian epithermal system resulted from gaseous F-and CO2-enriched magmas which lead to an explosive phreatomagmatic volcanism, when getting in contact with groundwater near the surface. As a result of these hydrothermal processes, rapid cooling took place in the epithermal mineralization. Changes in the viscosity along with the cooling down of mineralizing fluids caused mottled mineral colors blurring the boundaries between the stages and ore textures. The fluids accountable for the main constituents fluorite, quartz, barite and silica were operative over a vertical extension of roughly 600m. Their temperature of formation dropped from 379°C through 64°C, while the pH decreased from the heat center towards the paleosurface under oxidizing conditions. This steep temperature gradient conducive to the telescoping of mineral associations into each other was accompanied by a rapid loss in CO2, and a mixing of meteoric and magmatic fluids. Even the boundary between the hypogene and supergene alteration cannot be drawn precisely within the assemblage of Mn oxides, which bridge the gap between hypogene and supergen mineralization. The physical-chemical parameters of the fluids, particularly, the redox conditions did not allow sulfides to be preserved. A classification of the epithermal system as to its degree of sulfidation is based on K-feldspar and kaolinite which are present in significant amounts, whereas APS (aluminum-phosphate-sulfate) minerals are absent. Therefore a categorization as an epithermal fluorite deposit of low- to intermediate sulfidation is justified, because the only mineral of economic interest in the system is fluorite. The data obtained during this joint study render the Patagonian fluorite district a reference type of fluorite in an epithermal system of low- to intermediate sulfidation which are widespread in Argentina, e.g., Sierras Pampeanas, and evolved on part of the stable craton, called Gondwana and which grade into epithermal Au, Ag, In, Pb and Zn deposits.

      PubDate: 2016-04-08T14:20:10Z
      DOI: 10.1016/j.chemer.2016.03.002
      Issue No: Vol. 76, No. 2 (2016)
  • Melt impregnation phases in the mantle section of the Ślęża
           ophiolite (SW Poland)
    • Authors: Piotr Marian Wojtulek; Jacek Puziewicz; Theodoros Ntaflos
      Pages: 299 - 308
      Abstract: Publication date: Available online 3 April 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Piotr Marian Wojtulek, Jacek Puziewicz, Theodoros Ntaflos
      The ultramafic member of the Variscan Ślęża Ophiolite (SW Poland) consists of heavily serpentinised, refractory harzburgites. Those located down to 1.5km below paleo-Moho contain scarce grains or aggregates of olivine, clinopyroxene and spinel. Non-serpentine phases occur in various assemblages: M1—olivine (Fo 90.2–91.0%, NiO 0.38–0.47wt.%) and rounded or amaeboidal aluminous chromite, rimmed by Al poor chromite and magnetite; M2—olivine (Fo 90.5–91.5, NiO 0.32–0.44wt.%), olivine with magnetite inclusions (Fo 87.1–92.5, NiO 0.01–0.68wt.%), rounded, cleavaged clinopyroxene I (Mg# 91.1–93.2, Al2O3 3.00–4.00wt.%, Cr2O3 1.00–1.40wt.%) and elongated clinopyroxene II and clinopyroxene from symplectites with magnetite (Mg#=92.2–94.1, Al2O3 2.20–3.20wt.% and Cr2O3 0.80–1.20wt.%). Clinopyroxene is depleted in REEs relative to chondrite. The M3 assemblage consists of intergrown olivine (Fo 90.8–92.7, NiO 0.20–0.38wt.%) and clinopyroxene (Mg#=96.0–98.1, Al2O3 0.00–1.00wt.% and Cr2O3 0.20–0.60wt.%). The M1 assemblage contains chromite which records greenschist-facies metamorphism. Textural relationships and chemical composition of clinopyroxene occurring in the M2 assemblage are similar to those formed in oceanic spreading centres by LREE depleted basaltic melt percolation. Olivine occurring in M1 assemblage and part of that from M2 have composition typical of residual olivine from the abyssal harzburgites and of olivine formed in those rocks by melt percolation. The olivine with magnetite inclusions (M2 assemblage) and that from M3 record later deserpentinization event, which supposedly produced also M3 clinopyroxene. The non-serpentine phases from the Ślęża ophiolite mantle member, albeit very poorly preserved, document depleted basaltic melt percolation in the Variscan oceanic spreading centre.

      PubDate: 2016-04-04T07:30:04Z
      DOI: 10.1016/j.chemer.2016.03.004
      Issue No: Vol. 76, No. 2 (2016)
  • Geochemistry and U-Pb zircon dating constraints of some plutonic rocks
           along Bir Tawilah shear zone, central Saudi Arabia: Implication for magma
           peterogenesis and age of gold mineralization
    • Authors: Hesham M. Harbi; Kamal A. Ali; Abdelmonem A. Eldougdoug; Nasir S. Al-Jahdli
      Pages: 309 - 324
      Abstract: Publication date: Available online 5 May 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Hesham M. Harbi, Kamal A. Ali, Abdelmonem A. Eldougdoug, Nasir S. Al-Jahdli
      The study area covered by this work is located along the Bir Tawilah fault zone which encompasses the Arabian Shield between Afif terrane and western oceanic terranes. The rocks are dominantly ophiolite assemblages, island arc metavolcanic and metasedimentary rocks, and dioritic to granitic intrusions. The diorite and granodiorite rocks are I-type granitoids, calk-alkaline, metaluminous to peraluminous, formed in a volcanic arc setting, whereas the monzogranite is classified as A-type granite, alkaline and highly fractionated calc-alkaline, generated in within-plate tectonic setting. Nb and Y relationships indicated that the diorites and granodiorites were generated by a mafic parental magma contaminated with crustal materials, and controlled by fractional crystallization, whereas the monzogranites were generated from a magma characterized by an enriched mantle (EM) source. Mineralization including gold is hosted by the carbonatized serpentinite (listvenite) and the syn-tectonic granodiorite along Bir Tawilah thrust zone. U-Pb zircon geochronology indicates that the granodiorite at Jabal Ghadarah is emplaced at ca. 630±12Ma, probably suggests that the metallic minerals associated with the granodiorite along Bir Tawilah thurst zone are the result of remobilization of pre-existing gold mineralization associated with listevenite that is related to arc accretion.

      PubDate: 2016-06-13T12:09:56Z
      DOI: 10.1016/j.chemer.2016.04.004
      Issue No: Vol. 76, No. 2 (2016)
  • Geochemical mapping based on geological units: A case study from the
           Marnoso-arenacea formation (Northern Apennines, Italy)
    • Authors: Valerio Lancianese; Enrico Dinelli
      Pages: 49 - 62
      Abstract: Publication date: Available online 4 February 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Valerio Lancianese, Enrico Dinelli
      Geochemical maps can provide us with much information on geology, earth surface processes and anthropogenic pressure and are valuable tools for ore prospecting and land management. Stream sediments represent an integral of the various possible sources of sediments upstream from the sampling point therefore there can be multiple signal sources but generally the prevailing signal source is the one related to bedrock geology. Stream sediments collected from active second-order channels including singular geological units, were selected in order to determine the geochemical characteristics of each unit. The aim of this study was to analyse their potential for using them to integrate geological interpretation and produce a geologically-oriented geochemical map. From the 770 samples collected for a regional geochemical mapping program, we selected 149 samples whose catchment basin included only one of the members recognized within the Marnoso–Arenacea formation. This Middle-Upper Miocene (Langhian–Tortonian) turbiditic unit forms the backbone of the Romagna Apennines and has been subdivided into 14 members according to age and lithostratigraphic criteria. The results indicate that there are marked differences in the composition of the members of the Marnoso Arenecea formation which indicate the provenance of the sediment and the palaeogeographic evolution of the units. By means of univariate and multivariate statistical analyses (Factor analyses) two main types of sediment compositions are identified: Tortonian members are characterized by sialic coarse grain- sediments while the Langhian–Serravallian members are richer in carbonate fraction, slightly enriched in a mafic contribution. This study elaborated the geochemical data from a geological point of view by integrating the information available in literature to spatially extend the interpretation based on limited site observation as for petrographic studies. In general, the geochemical map based on a geological unit could be a useful tool for carrying out the geological reconstruction of a complex area.

      PubDate: 2016-02-12T07:21:53Z
      DOI: 10.1016/j.chemer.2015.12.001
      Issue No: Vol. 76, No. 1 (2016)
  • U–Pb dating of zircons from tuff layer, sandstone and tillite samples in
           the uppermost Liantuo Formation and the lowermost Nantuo Formation in
           Three Gorges area, South China
    • Authors: Dao-Hui Pi; Shao-Yong Jiang
      Pages: 103 - 109
      Abstract: Publication date: Available online 21 January 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Dao-Hui Pi, Shao-Yong Jiang
      Uranium-lead (U–Pb) dating was conducted on zircons in tuff layers and sandstone samples from the uppermost Liantuo Formation and in a tillite sample from the lowermost Nantuo Formation in Three Gorges area, South China, using SHRIMP and LA-ICP-MS techniques. Zircons from these samples yielded age spectrum (within 1000Ma) of ∼890, ∼830, ∼780, ∼730, and 646Ma. Zircons from the Liantuo tuffs have a weighted mean 206Pb/238U age of 734.1±8.1Ma (2σ, n =7, MSWD=0.48), which was regarded as the best estimation of the upper boundary age of the Liantuo Formation. Combining with previous geochronologic data, the Liantuo Formation was proposed to be a pre-Chang′an glaciation unit, and it is comparable to the middle-upper Banxi/Danzhou Group in South China.

      PubDate: 2016-01-22T11:54:03Z
      DOI: 10.1016/j.chemer.2015.12.003
      Issue No: Vol. 76, No. 1 (2016)
  • Petrography and classification of NWA 7402: A new sulfide-rich
           unequilibrated ordinary chondrite
    • Authors: Christine E. Jilly-Rehak; Gary R. Huss; Lydie Bonal; Eric Twelker
      Pages: 111 - 116
      Abstract: Publication date: Available online 23 January 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Christine E. Jilly-Rehak, Gary R. Huss, Lydie Bonal, Eric Twelker
      We classify a new chondritic find Northwest Africa (NWA) 7402. This meteorite is highly unequilibrated, and is therefore potentially significant for the study of primitive Solar System materials. Mineralogy, mineral chemistry, and modal abundances of minerals indicate that NWA 7402 is most likely an L chondrite. However, the specimen contains a higher abundance of sulfide than commonly seen in ordinary chondrites. The structural order of organic matter in the matrix and the chromium content of Fe-rich olivine grains indicate a petrologic type of 3.1. NWA 7402 largely escaped thermal metamorphism, and secondary phases formed by aqueous alteration are rare to absent. Minor planar fractures and undulatory extinction of olivine grains suggest that NWA 7402 experienced shock up to stage 2 or 3. Terrestrial weathering is heterogeneous in the specimen; much of the stone's exterior shows substantial Fe oxidation (weathering grade 2), while some parts of the interior remain relatively fresh (weathering grade 1). NWA 7402 has some unusual features that should be investigated further. The sulfide abundance is higher than reported sulfide contents for other L chondrites, and the chromium content of the olivines does not fall on the trend established for unequilibrated ordinary chondrites by Grossman and Brearley (2005).

      PubDate: 2016-01-28T05:45:05Z
      DOI: 10.1016/j.chemer.2016.01.001
      Issue No: Vol. 76, No. 1 (2016)
  • Elemental and organic geochemistry of Gondwana sediments from the
           Krishna–Godavari Basin, India
    • Authors: Devleena Mani; B. Ratnam; M.S. Kalpana; D.J. Patil; A.M. Dayal
      Pages: 117 - 131
      Abstract: Publication date: Available online 22 January 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Devleena Mani, B. Ratnam, M.S. Kalpana, D.J. Patil, A.M. Dayal
      Elemental and organic geochemical studies have been carried out on the Gondwana sediments, collected from the outcrops of Permian and Jurassic–Cretaceous rocks in the Krishna–Godavari basin on the eastern coast of India, to understand their paleo and depositional environment and its implications for hydrocarbon generation in the basin. Amongst the studied formations, the Raghavapuram, Gollapalli and Tirupati form a dominant Cretaceous Petroleum System in the west of the basin. Raghavapuram shales and its stratigraphic equivalents are the source rock and Gollapalli and Tirupati sandstones form the reservoirs, along with basaltic Razole formation as the caprock. Major element systematics and X-ray diffraction study of the sandstones indicate them to be variably enriched with SiO2 relative to Al2O3 and CaO, which is associated, inherently with the deposition and diagenesis of the Gondwana sediments. Post-Archean Average Shale normalized rare earth elements in shales show enrichment in most of the samples due to the increasing clay mineral and organic matter assemblage. A negative europium and cerium anomaly is exhibited by the REE's in majority of rocks. Composed primarily of quartz grains and silica cement, the Gollapalli and Tirupati sandstones have characteristics of high quality reservoirs. The shales show a significant increase in the concentration of redox sensitive trace elements, Ni, V, Cr, Ba and Zn. The total organic carbon content of the shales ranges between 0.1 and 0.5wt%. Programmed pyrolysis of selected samples show the Tmax values to range between 352–497°C and that of hydrogen index to be between 57–460mgHC/gTOC. The organic matter is characterized by, mainly, gas prone Type III kerogen. The n-alkane composition is dominated by n-C11–C18 and acyclic isoprenoid, phytane. The aromatic fraction shows the presence of naphthalene, anthracene, phenanthrene, chrysene and their derivatives, resulting largely from the diagenetic alteration of precursor terpenoids. The organic geochemical proxies indicate the input of organic matter from near-shore terrestrial sources and its deposition in strongly reducing, low oxygen conditions. The organic matter richness and maturity derived from a favorable depositional setting has its bearing upon the Gondwana sediments globally, and also provides promising exploration opportunities, particularly in the Raghavapuram sequence of the KG basin.

      PubDate: 2016-01-22T11:54:03Z
      DOI: 10.1016/j.chemer.2016.01.002
      Issue No: Vol. 76, No. 1 (2016)
  • Cycling of calcite and hydrous metal oxides and chemical changes of major
           element and REE chemistry in monomictic hardwater lake: Impact on
    • Authors: Peter Möller; Christian Siebert
      Pages: 133 - 148
      Abstract: Publication date: Available online 9 February 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Peter Möller, Christian Siebert
      The variation of major and rare earth elements and yttrium (REY) in the monomictic hardwater Lake Tiberias during the wet and dry seasons of the hydrological year was studied in two profiles. The average volume and Cl concentration of the known and unknown saline inflows of 1.6×107 m3 and 1.2×109 mol are derived by closing both balances. This brine corresponds to a mixture of 83% of groundwater from Cretaceous aquifers and 17% of very saline deep brine. Taking cycling of calcite in the hypolimnion into account, the settling rate of authigenic calcite is estimated to be 3.3molm−2 a−1. In the stratified lake of the dry season dissolved inorganic carbon increases by 490μM at the thermo-/chemocline due to microbial reduction of SO4 2−, NO3 −, chemical reduction of Fe(III) and MnO2 colloids, and cycling of calcite in the hypolimnion. REY distribution in the stratified water column is dominantly controlled by coprecipitation with calcite, hydrous ferric oxides and MnO2 in the epilimnion and cycling of these compounds in the hypolimnion. The positive Ce anomaly in the hypolimnetic water is produced by cycling of MnO2. The simulation of the increase of REY in the hypolimnion reveals that hydrous ferric and manganese oxides only play a negligible role except Ce. Only about 10% of REY from cycled matter enhance REY in solution. Most of the released REY are adsorbed by particular matter and thus settling on the floor of the lake. Different from Na, U, SO4 2− and SiO2, the other elements, in particular REY, increase in the mixed water column from the top to the lower third and mostly decrease thereafter toward the bottom in the mixed lake during the wet season. The behavior of REY is caused by some cycling of calcite and pH-dependent re-equilibration of REY bound to hydrous ferric and manganese oxides adsorbed by particular matter.

      PubDate: 2016-02-12T07:21:53Z
      DOI: 10.1016/j.chemer.2016.01.003
      Issue No: Vol. 76, No. 1 (2016)
  • Chlorine isotopes in sediments of the Qarhan Playa of China and their
           paleoclimatic significance
    • Authors: Chongguang Luo; Hanjie Wen; Yingkai Xiao; Haizhou Ma; Qishun Fan; Yunqi Ma; Yanling Zhang; Xiuqun Yang; Maoyong He
      Pages: 149 - 156
      Abstract: Publication date: Available online 12 February 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Chongguang Luo, Hanjie Wen, Yingkai Xiao, Haizhou Ma, Qishun Fan, Yunqi Ma, Yanling Zhang, Xiuqun Yang, Maoyong He
      This study presents chlorine isotopic composition of salt deposits recovered in a core from the Qarhan Saline Lake in the Qinghai Province of China. The δ 37Cl trend has three stages, and they correspond to the upper, middle, and lower salt-bearing groups of the entire evaporite system. The δ 37Cl values are between −0.22‰ and 0.13‰ with an average value of −0.02‰ in the lower salt-bearing group. It ranges between 0.14‰ and 0.76‰ ( x ¯ =0.36‰) in the middle salt-bearing group, and varies between −0.35‰ to 0.35‰ ( x ¯ =−0.04‰) in the upper salt-bearing group. This work indicates that stratification of δ 37Cl values is accompanied by stratigraphic variations in Mg/Cl and K/Cl in halite. We suggest a “evaporation cycles model” and it indicates the potential of Cl isotope as a geochemical tracer in order to understand paleoclimatic conditions during different stages of evaporite deposition.

      PubDate: 2016-02-16T07:40:42Z
      DOI: 10.1016/j.chemer.2016.01.004
      Issue No: Vol. 76, No. 1 (2016)
  • Sedimentological, mineralogical and geochemical characteristics of the
           ooids in Cleopatra (Sedir Island, Gökova Bay, SW Turkey) and Alexandria
           (NW Egypt) Beach sediments: A comparison and reality of myth of the love
    • Authors: Muhsin Eren; Cüneyt Güler; Selahattin Kadir; Hamdalla Wanas
      Pages: 157 - 169
      Abstract: Publication date: Available online 10 March 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Muhsin Eren, Cüneyt Güler, Selahattin Kadir, Hamdalla Wanas
      According to the myth, ooid-rich sediments in Cleopatra Beach (Sedir Island, Turkey) were brought by ships from Alexandria Beach (Egypt) by the Roman leader, Marcus Antonius, for his lover Cleopatra. Ooids of both beaches have been compared in terms of sedimentology, mineralogy and geochemistry to determine reality of the myth of love. Sieve analyses exhibit that sediments of Cleopatra Beach are slightly better sorted than Alexandria Beach sediments, and have relatively smaller sized ooids, interpreted to represent a relatively less agitated environment. All ooids are composed mainly of aragonite characterized by high Sr contents (>8600mg/kg). Hierarchical Cluster Analysis, the cross-plot of δ18Oaragonite versus δ13Caragonite values of ooids, and the presence of detrital grains such as gneiss and schist hint on two distinct groups of samples that correspond to the Cleopatra and Alexandria Beach ooids. These results suggest that the myth may not be realistic, and the ooids on the shore of Sedir Island were formed in-situ, e.g., during the Late Holocene.

      PubDate: 2016-03-13T05:18:55Z
      DOI: 10.1016/j.chemer.2016.02.001
      Issue No: Vol. 76, No. 1 (2016)
  • Spatial distribution, environmental assessment and source identification
           of metals content in surface sediments of freshwater reservoir, Pakistan
    • Authors: Javed Iqbal; Muhammad Saleem; Munir H. Shah
      Pages: 171 - 177
      Abstract: Publication date: Available online 23 February 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Javed Iqbal, Muhammad Saleem, Munir H. Shah
      Surface sediments were collected from different sites of a freshwater reservoir, Pakistan, and analyzed for eight metals (Cd, Co, Cr, Cu, Fe, Mn, Pb and Zn) using flame atomic absorption spectrometry. The estimated metals levels were found higher than other reported studies. The environmental indices including geoaccumulation index, enrichment factor and contamination factor identified Cd, Co, Pb and Zn as the priority pollutants of concern. Chromium, Cu and Mn were also found to be enriched in some areas. The pollution load index (≥1) indicated progressive deterioration of the sediments quality. Principal component and cluster analyses revealed that Cd, Co, Pb and Zn were mainly originated from agricultural activities, domestic wastes, road runoffs and recreational activities. Chromium, Cu, Fe and Mn were mainly derived from natural sources though Cr, Cu and Mn were partially contributed by human inputs. Based on spatial distribution, inlet and middle sites of the reservoir were found more contaminated. This study would drive urgent attention to develop preventive actions and remediation processes for aquatic system protection and future restoration of the reservoir.

      PubDate: 2016-02-25T09:25:33Z
      DOI: 10.1016/j.chemer.2016.02.002
      Issue No: Vol. 76, No. 1 (2016)
  • Dissolution kinetics of selected natural minerals relevant to potential
           CO2-injection sites – Part 2: Dissolution and alteration of carbonates
           and feldspars in CO2-bearing brines
    • Abstract: Publication date: Available online 13 October 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Astrid Holzheid
      Chemical interaction processes among injected CO2, saline fluids and potential reservoir materials are experimentally simulated to derive dissolution rates of natural materials (minerals) that can be used as input parameters for modeling of CO2 storage in deep saline formations and risk analyses. In order to study dissolution processes, mineral aliquots were exposed to CO2-bearing brines at elevated temperature (60, 100, 150°C) and pressure (85bar) and at various run durations. Several potential reservoir rocks include carbonates as cement. Calcite and dolomite grains were therefore mainly used as solid starting material. Experiments with the two feldspar varieties alkali feldspar and almost pure anorthite were performed in addition. Grain sizes of the mineral starting materials varied between <63μm and 500μm with most experiments performed at grain size fractions of 160 – 250μm and 250 – 500μm. All experiments run with a complex synthetic brine (total dissolved solids: ∼156g/l) according to a natural upper cretaceous formation water. Dry ice was used as CO2-source. All experiments were done in closed batch reactors. These reactors allow mimicking reservoir conditions far from the injection site as well as reservoir conditions after finishing the CO2 injection. The concentration changes during the experiment were monitored by ICP-OES measurements of the initial and the post-run fluids. Dissolution rates were derived based on the concentration changes of the brine. Most of the studied experimental variables and parameters (temperature, run duration, grain size, brine composition – expressed as pH-value and ionic strength) impact alteration of the reacting agents, i.e. they change the chemical composition of the brine, change the surfaces of the mineral aliquots exposed to the CO2-bearing brine, and induce formation of secondary minerals. Hence, all influencing parameters on dissolution processes have to be considered and time-resolved changes of the dissolution behavior have to be implemented in numerical simulations of processes at CO2 injection sites and CO2 storage reservoirs.

      PubDate: 2016-10-16T10:09:22Z
  • Editorial board members
    • Abstract: Publication date: October 2016
      Source:Chemie der Erde - Geochemistry, Volume 76, Issue 3

      PubDate: 2016-10-11T09:21:47Z
  • Alteration processes of cement induced by CO2-saturated water and its
           effect on physical properties: Experimental and geochemical modeling study
    • Authors: Byoung-Young Choi; Hikweon Lee; Gi-Tak Chae; Taehee Kim; Jeong-Chan Kim
      Abstract: Publication date: Available online 4 October 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Byoung-Young Choi, Hikweon Lee, Gi-Tak Chae, Taehee Kim, Jeong-Chan Kim
      The objective of this study is to understand cement alteration processes with the evolution of porosity and hardness under geologic CO2 storage conditions. For this study, the cylindrical cement cores (class G) were reacted with CO2–saturated water in a vessel (40°C and 8MPa) for 10 and 100 days. After the experiment, the CO2 concentration and Vickers hardness were measured in the hydrated cement core to estimate the carbonation depth and to identify the change in hardness, respectively. Diffusive-reactive transport modeling was also performed to trace the alteration processes and subsequent porosity changes. The results show that cement alteration mainly results from carbonation. With alteration processes, four different reaction zones are developed: degradation zone, carbonation zone, portlandite depletion zone, and unreacted zone. In the degradation zone, the re-dissolution of calcite formed in the carbonation zone leads to the increase of porosity. In contrast, the carbonation zone is characterized by calcite formation resulting mainly from the dissolution of portlandite. The carbonation zone acts as a barrier to CO2 intrusion by consuming dissolved CO2. Especially in this zone, although the porosity decreases, the Vickers hardness increases. Our results show that cement alteration processes can affect the physical and hydrological properties of the hydrated cement under CO2-saturated conditions. Further long-term observation is required to confirm our results under in-situ fluid chemistry of a CO2 storage reservoir. Nonetheless, this study would be helpful to understand alteration processes of wellbore cements under CO2 storage conditions.

      PubDate: 2016-10-11T09:21:47Z
      DOI: 10.1016/j.chemer.2016.10.001
  • Dissolution kinetics of selected natural minerals relevant to potential
           CO2-injection sites − Part 1: A review
    • Authors: Astrid Holzheid
      Abstract: Publication date: Available online 7 October 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Astrid Holzheid
      This publication provides a literature review on experimental studies of dissolution kinetics of mainly carbonates and feldspar group minerals, i.e. most common minerals at potential CO2-injection and/or storage sites. Geochemical interaction processes between injected CO2 and coexisting phases, namely reservoir and cap rock minerals and formation fluids close to the CO2-injection site can be simulated by flow-through or mixed flow reactors, while processes far from the injection site and long-term processes after termination actual CO2-injection can be mimicked by batch reactors. At sufficient small stirring rates or fluid flow rates as well as low solute concentrations flow-through reactors are also able to simulate processes far from the injection site. The experimental parameter temperature not only intensifies the dissolution process, the dominant dissolution mechanisms are also influenced by temperature. The dissolution mechanisms change from incongruent and surface controlled mechanisms at lower temperatures to congruent and transport controlled mechanisms at higher temperatures. The CO2 partial pressure has only a second order influence on dissolution behavior compared to the influence of pH-value and ionic strength of the CO2-bearing brine. Minerals exposed to CO2-bearing brines at elevated temperatures and pressures are subject of alteration, leading to severe changes of reactive surfaces and potential precipitation of secondary minerals. Computational simulations of mineral reactions at potential CO2 storage sites have therefore to include not only the time-resolved changes of dissolution behavior and hence kinetics of mineral dissolution, but also the influence of secondary minerals on the interaction of the minerals with CO2-enriched brines.

      PubDate: 2016-10-11T09:21:47Z
      DOI: 10.1016/j.chemer.2016.09.007
  • Data analysis of a revisited exploration geochemical dataset of quartz
           porphyrites from SW Jordan using GIS techniques
    • Authors: Ghazi Saffarini; Ghaleb Jarrar Harald. Dill Hind Ghanem Najel Yaseen
      Abstract: Publication date: Available online 19 September 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Ghazi Saffarini, Ghaleb H. Jarrar, Harald. G. Dill, Hind Ghanem, Najel Yaseen
      The spatial distribution of Cu and its pathfinder elements in quartz porphyrites along Wadi Araba was studied in order to gain an insight about the geologic framework of Cu mineralization in the area. A geochemical exploration data set of 242 samples was revisited. Multivariate statistical and geostatistical analysis were performed on the data set. The objectives of the study were to define Cu relationships with its possible pathfinder elements and to figure out whether geostatistical treatment of exploration data would help telescoping already existing Cu mineralization in Wadi Araba, SW Jordan. Factor analysis and hierarchical cluster analysis were performed on the data set. The results of which indicate that seven elements, namely, Ba, Cr, Mn, Ni, Sc, Sr and V can be considered as pathfinder elements for Cu. Significant correlations do exist between Cu and these elements. The encountered experimental semivariograms of the defined pathfinders were fit to exponential models with varying nugget effects with the exception of Mn which was fit to the spherical model. Ordinary kriging was found to be most appropriate to generate geochemical exploration maps. The applied methods succeeded in deriving valuable information and visualizing the already existing Cu mineralization in Wadi Abu Khusheiba area.

      PubDate: 2016-09-23T17:54:08Z
  • Evidence of Mid-ocean ridge and shallow subduction forearc magmatism in
           the Nagaland-Manipur ophiolites, northeast India: constraints from
           mineralogy and geochemistry of gabbros and associated mafic dykes
    • Authors: Krishnakanta Singh; Khogenkumar Romendro Singh R.K. Bikramaditya Ch. Mangi Khuman
      Abstract: Publication date: Available online 19 September 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): A. Krishnakanta Singh, S. Khogenkumar, L. Romendro Singh, R.K. Bikramaditya, Ch. Mangi Khuman, S.S. Thakur
      We discuss here the mineralogical and geochemical characteristics of mafic intrusive rocks from the Nagaland-Manipur Ophiolites (NMO) of Indo-Myanmar Orogenic Belt, northeast India to define their mantle source and tectonic environment. Mafic intrusive sequence in the NMO is characterized by hornblende-free (type-I) and hornblende-bearing (type-II) rocks. The type-I is further categorized as mafic dykes (type-Ia) of tholeiitic N-MORB composition, having TiO2 (0.72–1.93wt.%) and flat REE patterns (LaN/YbN =0.76–1.51) and as massive gabbros (type-Ib) that show alkaline E-MORB affinity, having moderate to high Ti content (TiO2 =1.18 to 1.45wt.%) with strong LREE-HREE fractionations (LaN/YbN =4.54–7.47). Such geochemical enrichment from N-MORB to E-MORB composition indicates mixing of melts derived from a depleted mantle and a fertile mantle/plume source at the spreading center. On the other hand, type-II mafic intrusives are hornblende bearing gabbros of SSZ-type tholeiitic composition with low Ti content (TiO2 =0.54wt.%–0.86wt.%) and depleted LREE pattern with respect to HREE (LaN/YbN =0.37–0.49). They also have high Ba/Zr (1.13–2.82), Ba/Nb (45.56–151.66) and Ba/Th (84.58–744.19) and U/Th ratios (0.37–0.67) relative to the primitive mantle, which strongly represents the melt composition generated by partial melting of depleted lithospheric mantle wedge contaminated by hydrous fluids derived from subducting oceanic lithosphere in a forearc setting. Their subduction related origin is also supported by presence of calcium-rich plagioclase (An16.6–32.3). Geothermometry calculation shows that the hornblende bearing (type-II) mafic rocks crystallized at temperature in range of 565°–625°C±50 (at 10kbar). Based on these available mineralogical and geochemical evidences, we conclude that mid ocean ridge (MOR) type mafic intrusive rocks from the NMO represent the section of older oceanic crust which was generated during the divergent process of the Indian plate from the Australian plate during Cretaceous period. Conversely, the hornblende-bearing gabbros (type-II) represent the younger oceanic crust which was formed at the forearc region by partial melting of the depleted mantle wedge slightly modified by the hydrous fluids released from the subducting oceanic slab during the initial stage of subduction of Indian plate beneath the Myanmar plate.

      PubDate: 2016-09-23T17:54:08Z
  • Separation of a geochemical anomaly from background by fractal and
           U-statistic methods, a case study: Khooni district, Central Iran
    • Authors: Neda Mahvash Mohammadi; Ardeshir Hezarkhani; Bashir Shokouh Saljooghi
      Abstract: Publication date: Available online 16 September 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Neda Mahvash Mohammadi, Ardeshir Hezarkhani, Bashir Shokouh Saljooghi
      Separation of geochemical anomalies from background are one of the important steps in mineral exploration. The Khooni mineral district (Central Iran) has complex geochemical surface expression due to a complex geological background. This region was chosen as a study area for recognition of the spatial distribution of geochemical elements and separating anomalies from background using stream sediment geochemical data. In the past decades, geochemical anomalies have been identified by means of various methods. Some of these separation methods include: statistical analysis methods, spatial statistical methods and fractal and multi-fractal methods. In this article, two efficient methods, i.e. U-statistics and the fractal concentration-area for separation and detection of anomalous areas of the background were used. The U spatial statistic method is a weighted mean, which considers sampling point positions and their spatial relation in the estimation of anomaly location. Also, fractal and multi-fractal models have also been applied to separate anomalies from background values. In this paper, the concentration–area model (C–A) was suggested to separate the anomaly of background. For this purpose, about 256 stream sediment samples were collected and analyzed. Then anomaly maps of elements were generated based on U spatial statistics and the C-A fractal methods for Au, As and Sb elements. According to obtained results, the U-statistics method performed better than C-A method. Because the comparisons of the known deposits and occurrences against the anomalous area created using thresholds from U-statistics and C-A method show that the spatial U-statistics method hits all of 3 known deposits and occurrences, the C-A fractal method hits 1 and fails 2. In addition, the results showed that these methods with regard to spatial distribution and variability within neighboring samples, in addition to concentration value frequency distributions and correlation coefficients, have more accurate results than the traditional approaches.

      PubDate: 2016-09-18T17:27:53Z
      DOI: 10.1016/j.chemer.2016.09.001
  • Petrogenesis and geodynamic evolution of the Kajan Neogene subvolcanic
           rocks, Nain, Central Iran
    • Authors: Shirin Golkaram; Nematollah Rashidnejad–Omran; Hossein Azizi; Yoshihiro Asahara; David M. Buchs; Iain McDonald; José Francisco Santos
      Abstract: Publication date: Available online 3 September 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Shirin Golkaram, Nematollah Rashidnejad–Omran, Hossein Azizi, Yoshihiro Asahara, David M. Buchs, Iain McDonald, José Francisco Santos
      Kajan subvolcanic rocks in the Urumieh–Dokhtar magmatic arc (UDMA), Central Iran, form a Late Miocene-Pliocene shallow-level intrusion. These subvolcanics correspond to a variety of intermediate and felsic rocks, comprising quartz diorite, quartz monzodiorite, tonalite and granite. These lithologies are medium-K calc-alkaline, with SiO2 (wt.%) varying from 52% (wt.%) to 75 (wt.%). The major element chemical data also show that MgO, CaO, TiO2, P2O5, MnO, Al2O3 and Fe2O3 define linear trends with negative slopes against SiO2, whilst Na2O and K2O are positively correlated with silica. Contents of incompatible trace elements (e.g. Ba, Rb, Nb, La and Zr) become higher with increasing SiO2, whereas Sr shows an opposite behaviour. Chondrite-normalized multi-element patterns show enrichment in LILE relative to HFSE and troughs in Nb, P and Ti. These observations are typical of subduction related magmas that formed in an active continental margin. The Kajan rocks show a strong affinity with calc-alkaline arc magmas, confirmed by REE fractionation (LaN/YbN =4.5–6.4) with moderate HREE fractionation (SmN/YbN =1.08–1.57). The negative Eu anomaly (Eu/Eu* <1), the low to moderate Sr content (<400ppm) and the Dy/Yb values reflect plagioclase and hornblende (+- clinopyroxene) fractionation from a calc-alkaline melt Whole–rock Sr and Nd isotope analyses show that the 87Sr/86Sr initial ratios vary from 0.704432 to 0.705989, and the 143Nd/144Nd initial ratios go from 0.512722 to 0.512813. All the studied samples have similar Sr-Nd isotopes, indicating an origin from a similar source, with granite samples that has more radiogenic Sr and low radiogenic Nd isotopes, suggesting a minor interaction with upper crust during magma ascent. The Kajan subvolcanic rocks plot within the depleted mantle quadrant of the conventional Sr-Nd isotope diagram, a compositional region corresponding to mantle-derived igneous rocks.

      PubDate: 2016-09-06T15:53:49Z
      DOI: 10.1016/j.chemer.2016.08.007
  • Strongly peraluminous leucogranite (Ebrahim-Attar granite) as evidence for
           extensional tectonic regime in the Cretaceous, Sanandaj Sirjan zone,
           northwest Iran
    • Authors: Hossein Azizi; Keivan Mohammadi; Yoshihiro Asahara; Motohiro Tsuboi; Narges Daneshvar; Behzad Mehrabi
      Abstract: Publication date: Available online 1 September 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Hossein Azizi, Keivan Mohammadi, Yoshihiro Asahara, Motohiro Tsuboi, Narges Daneshvar, Behzad Mehrabi
      The Ebrahim-Attar (EBAT) leucogranite body is intruded within the Jurassic metamorphic complex of the Ghorveh area, located in the northern part of the Sanandaj Sirjan zone (SaSZ) of northwest Iran. The granite comprises alkali feldspar, quartz, Na-rich plagioclase and to a lesser extent, muscovite and biotite. Garnet and beryl are also observed as accessory minerals. Additionally, high SiO2 (71.4–81.0wt%) and Rb (145–440ppm) content; low MgO (<0.12wt%), Fe2O3 (<0.68wt.%), Sr (mainly<20ppm), Ba (<57ppm), Zr (10–53ppm) and rare earth elements (REEs) low content (3.88–94.9ppm with an average=21.2ppm); and flat REE patterns with a negative Eu anomaly characterize these rocks. The chemical composition and mineral paragenesis indicate that the rocks were formed by the partial melting of siliciclastic to pelitic rocks and can be classified as per-aluminous leucogranite or strongly per-aluminous (SP) granite. The Rb-Sr whole rock and mineral isochrons confirm that crystallization of the body occurred at 102.5±6.1 Ma in Albian. The 87Sr/86Sr(i) and 143Nd/144Nd(i) ratios are 0.7081±0.009 and 0.51220±0.00005, respectively, and εNd(t) values range from −5.8 to −1.6. These values verify that the source of this body is continental crust. The Nd model ages (TDM2) vary between 1.0 and 1.3 Ga and are more consistent with the juvenile basement of Pan African crust. Based on these results, we suggest that the upwelling of the hot asthenospheric mantle in the SaSZ (likely during the Neo-Tethys rollback activity) occurred after the late Cimmerian orogeny. Consequently, we suggest that this process was responsible for a thinning and heating of the continental crust, from which the SP granite was produced by the partial melting of muscovite rich in pelitic or felsic-metapelitic rocks in the northern SaSZ.

      PubDate: 2016-09-06T15:53:49Z
      DOI: 10.1016/j.chemer.2016.08.006
  • Combination of single and sequential chemical extractions to study the
           mobility and host phases of potentially toxic elements in airborne
           particulate matter
    • Authors: Péter Sipos; Chung Choi; Zoltán May
      Abstract: Publication date: Available online 30 August 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Péter Sipos, Chung Choi, Zoltán May
      Risk assessment of metals associated to airborne particulate matter (PM) has usually been based on the analysis of their total concentrations, which is a poor indicator of metal mobility. Chemical fractionation processes may provide an additional level of information, however, chemical complexity and small sample sizes do not allow to combine several extraction methods. Additionally, analysing the metal concentrations during the extractions exceptionally provides restricted information about metals’ speciation. To overcome these limitations we collected total suspended particulate matter (TSP) samples from the air filters placed in the air supply channel of methane-heated turbines of thermal power stations which allows collecting large amounts of TSP materials. Additionally, we combined single and sequential chemical extractions in which not only the concentrations of potentially toxic elements (PTE) (Cd, Cr, Cu, Ni, Pb, Zn) but also that of the major chemical components (Al, Ca, Fe, K, Mg, Mn, Na, P, S, Ti) were analysed. Our aims were to study these metals’ mobility and speciation through the study of their association to major chemical components. Accumulation of the studied PTEs in the TSP material suggests moderate contamination for Ni, Cd and Cr whereas a heavy one for Cu, Zn and Pb. Three groups of these PTEs could be distinguished based on their mobility. The highly mobile Zn and Cd (large ratios of water and weak acid soluble fractions) can be considered as especially harmful elements to environment. The moderately mobile Pb and Cu (large ratios of reducible and oxidizable fractions, respectively) may potentially have a negative effect on the environment, whereas the immobile Cr and Ni cannot be expected to pose a serious risk. Based on the statistical evaluation of extraction data, the potential phases for Zn and Cu are presented by metal-sulphates, -nitrates, -chlorides, -carbonates and -hydroxides, as well as sorbed forms. Lead primarily hosted by metal-carbonates and sorbed forms, as well as by -hydroxides, whereas Cu by organic matter. Finally, Cr and Ni are mostly incorporated into very resistant phases, most probably by magnetite or other resistant metal-oxides. Combination of single and sequential extractions, as well as that of the analysis of not only the target elements but also the major chemical components were found to be a very effective tool to study the host phases of PTEs in the TSP material. The necessity for relatively large sample amounts for such analyses could be fulfilled using special sampling methodology; however, obvious disadvantages of this kind of sampling must be taken into account when resulted data are evaluated.

      PubDate: 2016-09-01T15:42:10Z
      DOI: 10.1016/j.chemer.2016.08.005
  • Spatial variability of soils and stream sediments and the remediation
           effects in a Portuguese uranium mine area
    • Authors: Ana Margarida Ribeiro Neiva; Paula Cristina Simões de Carvalho; Isabel Margarida Horta Ribeiro Antunes; Marina Marques da Silva Cabral Pinto; António Carlos Tavares dos Santos; Pedro P. Cunha; Maria Mafalda Costa
      Abstract: Publication date: Available online 28 August 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Ana Margarida Ribeiro Neiva, Paula Cristina Simões de Carvalho, Isabel Margarida Horta Ribeiro Antunes, Marina Marques da Silva Cabral Pinto, António Carlos Tavares dos Santos, Pedro P. Cunha, Maria Mafalda Costa
      The old Senhora das Fontes uranium mine, located in central Portugal, was closed down in 1971. The treatment of ores from this mine and other mines by heap-leach ended in 1982. Seven dumps partially covered by vegetation were left in the area. Soil and stream sediment samples were collected in December 2009. The remediation was carried out from May 2010 to January 2011. Stream sediment samples were collected again in October 2013. Before the remediation, soils from inside the mine influence area have higher Al, As, Co, Cr, Cu, Fe, Ni, Sr, Th, U and Zn concentrations than soils from outside this area, due to radionuclides, metals and metalloid released from the mine dumps. The principal component analysis (PCA) shows a distinction between soils from inside and outside the mine influence area. The U(VI), As(V) and metals from soils can be adsorbed to Fe-oxyhydroxides and the humic acid can increase the U uptake. Soils must not be used for public or private green and residential areas, because they are contaminated in U, As, Co, Cd and Ni. Before the remediation, downstream sediments have higher Al, As, Cu, Mn, Ni, Pb, U and Zn than upstream sediments, due to erosion and percolation of water through the mine dumps. The PCA shows a distinction between downstream and upstream sediments. The U(VI), Th and As(V) can be adsorbed to Fe-oxyhydroxides. The stream sediments are contaminated in As, Mn, Th and U. Downstream sediments are the most contaminated in U and As. After the remediation, upstream and downstream sediments have generally higher Al, Fe, As, Cr, Ni, Th, U and Zn concentrations than before the remediation, attributed to the relocation of dumps. Radionuclides, metals and metalloids were transported by surface water. Consequently downstream sediments have higher Al, As, Cu, Mn, Ni, Th, U and Zn concentrations than upstream sediments. The U(VI), Th and As(V) can be adsorbed to Fe-oxyhydroxides. Stream sediments became more contaminated in U, Th and As than before the remediation, but more intensively downstream.

      PubDate: 2016-08-28T15:10:18Z
      DOI: 10.1016/j.chemer.2016.08.003
  • Assessment of trace metal and rare earth elements contamination in rivers
           around abandoned and active mine areas. The case of Lubumbashi River and
           Tshamilemba Canal, Katanga, Democratic Republic of the Congo
    • Authors: Emmanuel K. Atibu; Naresh Devarajan; Amandine Laffite; Gregory Giuliani; Joseph A. Salumu; Richard C. Muteb; Crispin K. Mulaji; Jean-Paul Otamonga; Vicky Elongo; Pius T. Mpiana; John Poté
      Abstract: Publication date: Available online 25 August 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Emmanuel K. Atibu, Naresh Devarajan, Amandine Laffite, Gregory Giuliani, Joseph A. Salumu, Richard C. Muteb, Crispin K. Mulaji, Jean-Paul Otamonga, Vicky Elongo, Pius T. Mpiana, John Poté
      Active and abandoned mine activities constitute the sources of deterioration of water and soil quality in many parts of the world, particularly in the African Copperbelt regions. The accumulation in soils and the release of toxic substances into the aquatic ecosystem can lead to water resources pollution and may place aquatic organisms and human health at risk. In this study, the impact of past mining activity (i.e., abandoned mine) on aquatic ecosystems has been studied using ICP-MS analysis for trace metals and Rare Earth Elements (REE) in sediment samples from Lubumbashi River (RL) and Tshamilemba Canal (CT), Katanga, Democratic Republic of the Congo (DRC). Soil samples from surrounding CT were collected to evaluate trace metal and REE concentrations and their spatial distribution. The extent of trace metal contamination compared to the background area was assessed by Enrichment Factor (EF) and Geoaccumulation Index (Igeo ). Additionally, the trace metal concentrations probable effect levels (PELs) for their potential environmental impact was achieved by comparing the trace metal concentrations in the sediment/soil samples with the Sediment Quality Guidelines (SQGs). Spearman's Rank-order correlation was used to identify the source and origin of contaminants. The results highlighted high concentrations of trace metals in surface sediments of CT reaching the values of 40152, 15586, 610, 10322, 60704 and 15152mgkg−1 for Cu, Co, Zn, Pb, Fe and Mn, respectively. In the RL, the concentrations reached the values of 24093, 2046, 5463, 3340, 68290 and 769mgkg−1 for Cu, Co, Zn, Pb, Fe and Mn, respectively. The ΣREE varied from 66 to 218 and 142–331mgkg−1 for CT and RL, respectively. The soil samples are characterized by variable levels of trace metals. The EF analysis showed “extremely severe enrichment” for Cu and Co. However, no enrichment was observed for REE. Except for Mo, Th, U, Eu, Mo, Ho and Tm for which Igeo is classified as “moderately polluted and/or unpolluted”, all elements in different sites are classified in the class 6, “extremely polluted”. The trace metal concentrations in all sampling sites largely exceeded the SQGs and the PELs for the Protection of Aquatic Life recommendation. Cu and Co had positive correlation coefficient values (r=0.741, P<0.05, n=14). This research presents useful tools for the evaluation of water contamination in abandoned and active mining areas.

      PubDate: 2016-08-28T15:10:18Z
      DOI: 10.1016/j.chemer.2016.08.004
  • The synorogenic pegmatitic quartz veins of the Guacha Corral Shear zone
           (Sierra de Comechingones, Argentina): A textural, chemical, isotopic,
           cathodoluminescence and fluid inclusion study
    • Authors: G. Morteani; F. Eichinger; A. Tarantola; A. Müller; J. Götze; J.A. Sfragulla
      Abstract: Publication date: Available online 13 August 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): G. Morteani, F. Eichinger, A. Tarantola, A. Müller, J. Götze, J.A. Sfragulla
      The quartz veins and pegmatites of the Sierra de Comechingones (Sierras de Córdoba, NE Argentina) belong to the Comechingones Pegmatite field (CPF). For the quartz veins and the zoned pegmatites related parental granites are missing. The country rock of the quartz veins are mylonitic augengneisses in granulite to upper amphibolite facies. Field relations, microscopy, cathodoluminescence, radiometric age data, fluid inclusion, chemical and isotopic composition and literature define the quartz veins as synorogenic formed during the high-temperature phase of the Famatinian (480–460Ma) event. During the Famatinian up to the Achalian (382–366Ma) event the synorogenic quartz veins were subjected to high temperature ductile deformation documented by folding, boudinage and finally brittle shearing. K-Ar ages of illite from the shear zones of about 166Ma document the final cooling of the Sierras Pampeanas below 100°C. The long lasting thermal and deformational history of the study area is reflected by very different populations of fluid inclusions in vein quartz with remarkably high contents of thermogenic hydrocarbons in the early-formed fluid inclusions. LA–ICP–MS analysis reveals very low lattice-bound trace element contents, i.e. high purity quartz.

      PubDate: 2016-08-14T21:11:28Z
      DOI: 10.1016/j.chemer.2015.09.001
  • Sediment characteristics and mineralogy of salt mounds linked to
           underground spring activity in the Lop Nor playa, Western China
    • Authors: Lichun Ma; Qingfeng Tang; Baoguo Li; Yufei Hu; Wenjun Shang
      Abstract: Publication date: Available online 8 August 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Lichun Ma, Qingfeng Tang, Baoguo Li, Yufei Hu, Wenjun Shang
      Salt mounds are commonly distributed along playa margins and typically comprise alternating layers of loose fine sand and slightly hard halite-rich sediments as a result of long-term underground spring activity. A model of salt mound development was constructed for this study. It suggests that wind-blown sand supply and upward recharge of underground springs are two important factors in salt mound construction. Furthermore, it proposes that salt mound height is mainly controlled by the vertical transport range of underground springs and the thickness of the capillary fringe. A 1.5m representative profile dug from the center of salt mound LP1 in the Lop Nor playa revealed a fairly complicated mineral assemblage including halite, gypsum, anhydrite, glauberite, epsomite, anhydrite, calcite, bischofite, polyhalite, schoenite, kieserite and carnallite. This matches closely with the assemblage predicted by the EQL/EVP model. The groundwater in the area is highly concentrated brine rich in Cl− and Na+ and poor in Ca2+, displaying low alkalinity, and containing considerable amounts of SO4 2−, Mg2+ and K+. Chemical analysis of groundwater revealed considerable variation in the salinity and chemical composition of groundwater over time. The Cs-137 technique was used to measure the accumulated ages of the salt mounds. This method may prove useful in the research of relatively young playa environments where carbon dating techniques are unworkable because of an absence of carbon-rich materials in recent saline sediments.

      PubDate: 2016-08-11T21:03:40Z
      DOI: 10.1016/j.chemer.2016.08.001
  • Geology, mineralogy, and geochemistry of low grade Ni-lateritic soil (Oman
           Mountains, Oman)
    • Authors: Salah A. Al-Khirbash
      Abstract: Publication date: Available online 7 August 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Salah A. Al-Khirbash
      The laterite profiles investigated in the present study developed after the emplacement of a slab of oceanic crust and upper mantle sequence (the Semail ophiolite) onto the East Arabian margin during the late Cretaceous. The laterites formed as a result of prolonged weathering of the ophiolite assemblage under tropical to subtropical conditions. Nine laterite profiles have been examined for their Ni potential along a NW-SE segment of the Oman Mountains. The preserved laterite profile shows variations in thickness, mineralogy, and chemical composition. The profiles show a vertical succession from bedrock protolith through saprolite, oxide laterite, to clay laterite. The laterite profiles are unconformably capped either by clastics rocks of the Late Cretaceous Qahlah Formation or by Palaeogene carbonates of the Jafnayn or Abat Formations. The protolith corresponds either to a fine-grained, blackish to greenish serpentinized peridotite or to a coarse-grained dark green altered layered gabbro. The bulk geochemistry of the studied profiles indicates a typical low Ni-laterite pattern in which magnesium (Mg) and silica (Si) become depleted towards the top of the profile, whereas iron (Fe) and aluminum (Al) increase. A significant enrichment in Ni and Co occurred as a result of the laterization process. Ni concentrations average 0.63% (Ibra), 0.72% (East Ibra), 0.67% (Al-Russayl), and 0.33% (Tiwi). Other elements such as Cr, V, Pb, TiO2, Zr, Ba, and Zn were also remobilized across the profiles during the laterization processes.

      PubDate: 2016-08-07T20:34:50Z
      DOI: 10.1016/j.chemer.2016.08.002
  • Geochronology and magma oxygen fugacity of Ehu S-type granitic pluton in
           Zhe-Gan-Wan region, SE China
    • Authors: Jun-Ting Qiu; Liang Qiu
      Abstract: Publication date: Available online 25 July 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Jun-Ting Qiu, Liang Qiu
      In this paper, we determined the U-Pb isotopic and trace element compositions of zircons from the Ehu S-type granite in the Zhe-Gan-Wan region, SE China, using in-situ laser ablation (LA) ICP-MS. The weighted mean 206Pb/238U age of 132.0±0.6Ma for the Ehu granite indicates that the pluton was formed in the Early Cretaceous and during the Late Mesozoic Cu-Mo mineralization quiescence in Zhe-Gan-Wan region. The calculated logarithmic magma oxygen fugacities for Ehu granite range from −19.19 to −11.43 with an average magma oxidation state of FMQ-0.29, which is much lower than those of Cu-Mo bearing granites in the Zhe-Gan-Wan region. Since Ehu granite was derived from partial melting of metasedimentary basement without fractional crystallization and mantle-derived magma contamination, the low oxidation state of this granite suggests that the assimilation of metasedimentary basement component may not significantly increase the oxidation state of reduced melts from asthenospheric mantle and could not generate oxidized magmas that are favorable for Cu-Mo mineralization.

      PubDate: 2016-07-28T18:35:30Z
      DOI: 10.1016/j.chemer.2016.06.004
  • Natural iron oxalates and their analogous synthetic counterparts: A review
    • Authors: Enrique J. Baran
      Abstract: Publication date: Available online 14 July 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Enrique J. Baran
      Four iron-containing natural oxalates, usually classified as organic minerals, are known (humboldtine, minguzzite, stepanovite and zhemchuzhnikovite). Their occurrences and general properties are presented and briefly discussed. The subsequent part of the review is devoted to the discussion of synthetic oxalato-complexes, analogous to these natural species, including usual synthetic procedures and a thorough analysis of their crystallographic and structural peculiarities. The thermal, spectroscopic and magnetic properties of these complexes are also analyzed in detail and comparisons with other closely related complexes are also included in the discussions.

      PubDate: 2016-07-17T16:54:14Z
      DOI: 10.1016/j.chemer.2016.06.005
  • Do lunar and meteoritic archives record temporal variations in the
           composition of solar wind noble gases and nitrogen? A reassessment in the
           light of Genesis data
    • Authors: Rainer Wieler
      Abstract: Publication date: Available online 12 July 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Rainer Wieler
      Since about half a century samples from the lunar and asteroidal regoliths been used to derive information about elemental and isotopic composition and other properties of the present and past solar wind, predominantly for the noble gases and nitrogen. Secular changes of several important compositional parameters in the solar wind were proposed, as was a likely secular decrease of the solar wind flux. In 2004 NASA’s Genesis mission returned samples which had been exposed to the solar wind for almost 2.5 years. Their analyses resulted in an unprecendented accuracy for the isotopic and elemental composition of several elements in the solar wind, including noble gases, O and N. The Genesis data therefore also allow to re-evaluate the lunar and meteorite data, which is done here. In particular, claims for long-term changes of solar wind composition are reviewed. Outermost grain layers from relatively recently irradiated lunar regolith samples conserve the true isotopic ratios of implanted solar wind species. This conclusion had been made before Genesis based on the agreement of He and Ne isotopic data measured in the aluminum foils exposed to the solar wind on the Moon during the Apollo missions with data obtained in the first gas release fractions of stepwise in-vacuo etch experiments. Genesis data allowed to strengthen this conclusion and to extend it to all five noble gases. Minor variations in the isotopic compositions of implanted solar noble gases between relatively recently irradiated samples (<100Ma) and samples irradiated billions of years ago are very likely the result of isotopic fractionation processes that happened after trapping of the gases rather than indicative of true secular changes in the solar wind composition. This is particularly important for the 3He/4He ratio, whose constancy over billions of years indicates that hardly any 3He produced as transient product of the pp-chains has been mixed from the solar interior into its outer convective zone. The He isotopic composition measured in the present-day solar wind therefore is identical to the (D+ 3He)/4He ratio at the start of the suns’s main sequence phase and hence can be used to determine the protosolar D/H ratio. Genesis settled the long-standing controversy on the isotopic composition of nitrogen in lunar regolith samples. The 15N/14N ratio in the solar wind as measured by Genesis is lower than in any lunar sample. This proves that nitrogen in regolith samples is dominated by non-solar sources. A postulated secular increase of 15N/14N by some 30% over the past few Ga is not tenable any longer. Genesis also provided accurate data on the isotopic composition of oxygen in the solar wind, invaluable for cosmochemisty. These data superseded but essentially confirmed one value – and disproved a second one – derived from lunar regolith samples shortly prior to Genesis. Genesis also confirmed prior conclusions that lunar regolith samples essentially conserve the true elemental ratios of the heavy noble gases in the solar wind (Ar/Kr, Kr/Xe). Several secular changes of elemental abundances of noble gases in the solar wind had been proposed based on lunar and meteoritic data. I argue here that lunar data – in concert with Genesis – provide convincing evidence only for a long-term decrease of the Kr/Xe ratio by almost a factor of two over the past several Ga. It appears that the enhancement of abundances of elements with a low first ionisation potential in the solar wind (FIP effect) changed with time. Finally, Genesis allows a somewhat improved comparison of the present-day flux of solar wind Kr and Xe with the total amount of heavy solar wind noble gases in the lunar regolith. It remains unclear whether the past solar wind flux has been several times higher on average than it is today.

      PubDate: 2016-07-17T16:54:14Z
      DOI: 10.1016/j.chemer.2016.06.001
  • Editorial board members
    • Abstract: Publication date: June 2016
      Source:Chemie der Erde - Geochemistry, Volume 76, Issue 2

      PubDate: 2016-07-01T12:42:24Z
  • Petrogenesis of a late-Variscan rhyodacite at the Ossa Morena-Central
           Iberian zones boundary, Iberian Massif, Central Portugal: Evidence for the
           involvement of lithospheric mantle and meta-igneous lower crust
    • Authors: S.B.A. Henriques; A.M.R. Neiva; G.R. Dunning
      Abstract: Publication date: Available online 23 June 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): S.B.A. Henriques, A.M.R. Neiva, G.R. Dunning
      A late-Variscan rhyodacite is exposed at the contact between the Ossa Morena Zone and the Central Iberian Zone of the Iberian Massif, Central Portugal. Dykes of rhyodacite intruded the Série Negra Unit and the Sardoal Complex that are part of the Cadomian basement. The igneous crystallization age of the rhyodacite (308±1 Ma) was obtained on igneous monazite by the ID-TIMS U-Pb method. It is broadly coeval with the emplacement of late-Variscan granitoids during the last deformation phase of the Variscan Orogeny (ca. 304–314 Ma) and with the development of the large late-Variscan strike-slip shear zones (ca. 307 Ma). The rhyodacite samples are calc-alkaline, show identical composition and belong to the same magmatic sequence. The rhyodacite isotopic signatures (Sm-Nd and δ18O) are consistent with depleted-mantle juvenile sources and the contribution of the meta-igneous lower crust. The input of mantle juvenile sources is related to Variscan reactivation of lithospheric fractures. The inherited Neoproterozoic (ca. 619 Ma) and Mesoproterozoic (ca. 1054 Ma) zircon ages, are similar to those of the Central Iberian Zone. This suggests that lower crust of the Central Iberian Zone was involved in the magma generation of the rhyodacite. Coeval late-Variscan magmatic rocks display a larger contribution from ancient crustal components, which may be attributed to the smaller volume and faster cooling rate of the rhyodacite and consequent lower melting of the crust. Mixing of juvenile mantle-derived melts with melts from the lower continental crust was followed by fractional crystallization of garnet and amphibole that remained in the source. Fractional crystallization of plagioclase, biotite, quartz and zircon occurred in shallower magma chambers. Fractional crystallization of zircon was not significant.

      PubDate: 2016-07-01T12:42:24Z
      DOI: 10.1016/j.chemer.2016.06.003
  • A comparison of black claystones, lignites and dump materials from the
           Maritsa Iztok Coal Basin, Bulgaria, using organic geochemical proxies
    • Authors: K. Markova; M. Stefanova; Z. Milakovska; S.P. Marinov
      Abstract: Publication date: Available online 24 June 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): K. Markova, M. Stefanova, Z. Milakovska, S.P. Marinov
      Geochemical analysis of dump materials from the opencast Maritsa Iztok mines, Bulgaria, was carried out based on biomarker assemblages of hydrocarbon fractions. Organic matter (OM) and secondary transformations in three representative samples (massive black claystones and materials from the Iztok and Staroselets dump sites) were studied using geochemical proxies. A number of differences were recognised in the respective OM compositions of the samples compared to both published data and between the individual dump samples themselves. The ОM of the studied samples was found to be polar, but also contains some apolar compounds. It consists mainly of resins and asphalthenes. Claystone OM is of the dispersed type, with intense oxidative-reductive interactions in a lacustrine environment resulting in its transformation into an inert material. Dump sample kerogen is of Type II and mixed Type II/III. In all samples, “odd” numbered n-alkanes are found in higher amounts. Diterpenoids (С19, С20) with pimarane, abietane and phyllocladane skeletons are preponderant. Tri- and tetracyclic terpenoids and steranes have been identified in the black claystones OM only. Hopanes are present in low amounts in extractable OM from all three samples. Biomarkers indicate that black claystone OM is formed from aqueous flora, with a minor supply of gymnosperms (mainly G. Sequoia). Iztok Dump OM is structured by higher plants with an aqueous vegetation input. The Staroselets Dump OM formation is assigned to an active microbial reworking of aqueous vegetation and bacteria with a minor coniferous supply. Different geochemical parameters admit anoxic stratified bottom waters for the black claystones with an addition of deep water stagnation for Staroselets sample in a Maritsa Iztok Basin (MIB) aqueous environment. An attempt was also made to track the effect of secondary processes (oxidation, destruction, dearomatisation), temperature, water drainage and wash-out on dump materials. Leaching and weak degradation processes in the MIB dump environment are likely for a time span of ca. 40–50 years, considering the low percentage of short-chain n-alkanes, long-chain prevalence and low Pr/nC17 and Ph/nC18 ratios, with the Iztok Dump sample experiencing more advanced transformations.

      PubDate: 2016-07-01T12:42:24Z
      DOI: 10.1016/j.chemer.2016.06.002
  • Thermodynamic properties of tooeleite, Fe63+(As3+O3)4(SO4)(OH)4·4H2O
    • Authors: Juraj Majzlan; Edgar Dachs; Artur Benisek; Christian Bender Koch; Ralph Bolanz; Jörg Göttlicher; Ralph Steininger
      Abstract: Publication date: Available online 13 June 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Juraj Majzlan, Edgar Dachs, Artur Benisek, Christian Bender Koch, Ralph Bolanz, Jörg Göttlicher, Ralph Steininger
      Tooeleite, nominally Fe6 3+(As3+O3)4(SO4)(OH)4·4H2O, is a relatively uncommon mineral of some acid-mine drainage systems. Yet, if it does occur, it does so in large quantities, indicating that some specific conditions favor the formation of this mineral in the system Fe-As-S-O-H. In this contribution, we report the thermodynamic properties of synthetic tooeleite. The sample was characterized by powder X-ray diffraction, scanning electron microscopy, extended X-ray absorption fine-structure spectroscopy, and Mössbauer spectroscopy. These methods confirmed that the sample is pure, devoid of amorphous impurities of iron oxides, and that the oxidation state of arsenic is 3+. Using acid-solution calorimetry, the enthalpy of formation of this mineral from the elements at the standard conditions was determined as −6196.6±8.6kJmol−1. The entropy of tooeleite, calculated from low-temperature heat capacity data measured by relaxation calorimetry, is 899.0±10.8Jmol−1 K−1. The calculated standard Gibbs free energy of formation is −5396.3±9.3kJmol−1. The log K sp value, calculated for the reaction Fe6(AsO3)4(SO4)(OH)4·4H2O+16H+ =6Fe3+ +4H3AsO3 +SO4 2− +8H2O, is −17.25±1.80. Tooeleite has stability field only at very high activities of aqueous sulfate and arsenate. As such, it does not appear to be a good candidate for arsenic immobilization at polluted sites. An inspection of speciation diagrams shows that the predominance field of Fe3+ and As3+ overlap only at strongly basic conditions. The formation of tooeleite, therefore, requires strictly selective oxidation of Fe2+ to Fe3+ and, at the same time, firm conservation of the trivalent oxidation state of arsenic. Such conditions can be realized only by biological systems (microorganisms) which can selectively oxidize one redox-active element but leave the other ones untouched. Hence, tooeleite is the first example of an “obligatory” biomineral under the conditions prevailing at or near the Earth's surface because its formation under these conditions necessitates the action of microorganisms.

      PubDate: 2016-06-17T18:10:13Z
      DOI: 10.1016/j.chemer.2016.05.001
  • Greenhouse gas emissions from soils—A review
    • Authors: Cornelius Oertel; Jörg Matschullat; Kamal Zurba; Frank Zimmermann; Stefan Erasmi
      Abstract: Publication date: Available online 26 April 2016
      Source:Chemie der Erde - Geochemistry
      Author(s): Cornelius Oertel, Jörg Matschullat, Kamal Zurba, Frank Zimmermann, Stefan Erasmi
      Soils act as sources and sinks for greenhouse gases (GHG) such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Since both storage and emission capacities may be large, precise quantifications are needed to obtain reliable global budgets that are necessary for land-use management (agriculture, forestry), global change and for climate research. This paper discusses exclusively the soil emission-related processes and their influencing parameters. It reviews soil emission studies involving the most important land-cover types and climate zones and introduces important measuring systems for soil emissions. It addresses current shortcomings and the obvious bias towards northern hemispheric data. When using a conservative average of 300mg CO2e m−2 h−1 (based on our literature review), this leads to global annual net soil emissions of ≥350Pg CO2e (CO2e=CO2 equivalents=total effect of all GHG normalized to CO2). This corresponds to roughly 21% of the global soil C and N pools. For comparison, 33.4 Pg CO2 are being emitted annually by fossil fuel combustion and the cement industry.

      PubDate: 2016-06-13T12:09:56Z
      DOI: 10.1016/j.chemer.2016.04.002
  • Editorial board members
    • Abstract: Publication date: March 2016
      Source:Chemie der Erde - Geochemistry, Volume 76, Issue 1

      PubDate: 2016-06-13T12:09:56Z
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