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Geosciences Journal
Journal Prestige (SJR): 0.381
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Number of Followers: 11  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1598-7477 - ISSN (Online) 1226-4806
Published by Springer-Verlag Homepage  [2467 journals]
  • Optimum interval of artificial groundwater recharge wells, considering
           injection rate and economic feasibility

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      Abstract: Abstract Artificial recharge of groundwater increases the water level in an aquifer, which can be used for water security in a drought-prone region. This study was conducted to identify the interval of injection wells in a small basin upstream of a watershed. For the pilot test, 11 injection wells were installed, in which individual and simultaneous injections were performed. The rates of the individual and simultaneous injections ranged from 0.49–38.13 and 0.04–11.48 m3/d, respectively. Simultaneous injection resulted in a reduced injection rate of approximately 4.4–95.4% compared to that of individual injection owing to the interference effect of the injection wells. Moreover, the hydraulic conductivity of each well and the radius of influence were used to analyze the interference effect during injection using the Thiem-Dupuit equation. The interference effect between injection wells was evaluated by increasing the space from 2 to 15 m at four recharge lines (total length: 340 m) within the study area, and the expected injection rate was calculated as the rates of 220.85–58.95 m3/d. On the other hand, construction cost for installing injection wells became higher at 2 m interval than at 15 m. Therefore, there was no significant increase in construction cost per 1-m3 injection volume as well as decrease in total injection rate if the well interval was > 5 m and the optimum interval of injection well was suggested to be at least 5 m. Drought-prone areas are generally excluded from water-welfare benefits and are economically fragile; consequently, when developing an artificial recharge facility, injection wells should be designed considering the security of suitable amount of water with economic feasibility.
      PubDate: 2023-02-01
       
  • Seismo-tectonic and morphological study of the north-east Himalaya

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      Abstract: Abstract The study of the spatial distribution of strain and stress accumulation in a continent-continent convergent system is significant for seismic hazard assessment. The Indian Plate is moving towards the north-east at a pace of 5cm/year, according to GPS velocity vectors. Since the Main Central Thrust (MCT) was active from 23 Ma to 12 Ma, when the Eurasian and Indian Plates collided for the first time, The Main Boundary Thrust (MBT) was formed by continuous collision to the south of the MCT, which continued until 3 Ma. The Main Frontal Thrust (MFT) is newly formed in the Himalayan Orogeny and is still tectonically active. This tectonically active area has been divided into four regions according to the computed ‘b’ value distribution. Regions 2 and 3 represent the inverse relationship between magnitude and frequency distribution. The magnitude range is greater than the frequency in Region 2, while the frequency distribution is greater than the magnitude in Region 3. In an overview of such alteration, two selected watersheds, namely Kameng from R-3 (Region 3) and Dibang from R-2 (Region 2), display the different values of the index of active tectonics (IAT), considering the sub-basins. Here parameters like the basin shape index (Bs), the compactness coefficient (Cc), the form ratio (Rf), the circularity ratio (Rc), the leminscate coefficient (k), the hypsometric integral (HI), the stream gradient index (SL), and the sinuosity index (SI) have been considered to compute the IAT. According to the overall average range of the IAT of the two watersheds, Kameng is more active (2.198) than Dibang (2.272). The VP and VS anomalies at 20 km, 40 km and 60 km indicate that the Kameng watershed is more active than Dibang as the higher range of VP and VS at a depth of 20 km lies near the foredeep section and it is also supported by the location of active sub-basins between the MBT (Main Boundary Thrust) and the MFT (Main Frontal Trust). The active crustal shortening across the southern part of the Kameng River, around the Main Frontal Thrust Décollement Zone, intensifies the plate movement by 10 mm/year along the section of R-3.
      PubDate: 2023-02-01
       
  • Metallogenesis and hydrothermal evolution of the Saibo copper deposit in
           the western Tianshan: evidence from fluid inclusions, H−O−S isotopes,
           and Re−Os geochronology

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      Abstract: Abstract The Saibo copper polymetallic deposit, located in the West Tianshan Sailimu-Sitaihaiquan copper lead and zinc ore belt, is a new breakthrough in medium-large copper mine. Through the thin section authentication and the thermometric analysis of fluid inclusion, it is concluded that skarnization was developed in this deposit, the mineralization stage can be divided into retrograde skarn stage (S1), quartz-sulfide stage (S2) and quartz-carbonate stage (S3). Fluid inclusions (FIs) were distinguished as liquid-rich aqueous FIs (LV-type), vapor-rich aqueous FIs (VL-type), and NaCl daughter mineral-bearing three phase FIs (S-type). The mineralization fluids indicate that the initial stage (S1 stage) is of high temperature and high salinity, with a handful of metallic matters. During the main metallogenic stage (S2 stage), the meteoric water is mixed, the temperature and salinity gradually decrease, the fluid is distinctly boiling, and a large amount of metallic matters are precipitated, and then to the S3 stage, when the temperature and salinity decrease along with the carbonation. Chalcopyrite Re−Os dating yielded a mineralization age of 379.2 ± 7.7 Ma, which corresponds well with the zircon U−Pb age (385.9 ± 1.3 Ma) of the granite porphyry. The C−H−O isotopes indicate that the ore-forming fluid was dominated by initial mixed magmatic water in the early stage and by meteoric water in the late stage, and C is derived from limestone strata metasomatized by magmatic fluids. The S and Pb isotopes indicate that the ore-forming materials are derived from the mixed crust-mantle source, of which S is almost entirely derived from the mantle, while Pb is mainly derived from the crustal material of the orogenic belt. On the whole, the Saibo copper deposit is a typical calcium skarn type deposit, which formed in the shallower setting at active continental margin in the Late Devonian period.
      PubDate: 2023-02-01
       
  • Mineralogical and geochemical study of hydrothermal dolomite from the
           Daliang zinc deposit in Guizhou, Southwest China: new evidence for the
           genesis

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      Abstract: Abstract The Daliang zinc deposit occurs in the southwestern Xiangxi-Qiandong Zn-Pb metallogenic belt and is located on the southeastern margin of the upper Yangtze block. In this study, we present results from petrographic observations, rare earth elements, C-H-O isotopes, and fluid inclusions. The zinc deposit is hosted by middle Cambrian dolomite. The ore-forming process is divided into three stages from early to late: pyrite-galena, sphalerite-pyrite-dolomite, and dolomite. The characteristics of the REEs suggest that multiple fluids were involved in hydrothermal dolomite precipitation under low-temperature conditions. Two types of hydrothermal dolomite fluid inclusions were identified: pure liquid phase inclusions and liquid-rich phase inclusions. The fluid inclusions of hydrothermal dolomite yield homogenization temperatures of 108–192 °C (average 153 °C), with salinities of 12.3–26.4 wt% (average 23.0 wt%) NaCl equiv. The δ13Cfluid, δDfluid and δ18Ofluid values for ore-forming fluids range from −4.2 to −3.5‰ (mean −3.8‰), −38.8 to −34.3‰ (mean −36.0‰), and 6.2–6.4‰ (mean 6.3‰), respectively. This study demonstrates that ore-forming fluid was sourced from a moderate- to high-salinity basinal brine and leached metals from metasedimentary rocks of the basement in the Yangtze block. The main transportation of ore-forming fluid occurred in the form of chlorine complexes along well-developed faults, and sulfides precipitated with decreases in pressure and temperature, as well as pH changes. Studies of the Daliang zinc deposit suggest that it is a medium- to low-temperature MVT-like deposit.
      PubDate: 2023-01-19
       
  • Petrogenesis of lavas from Mokolo-Kosséhone region, northernmost segment
           of the Cameroon Volcanic Line: constraints from major/trace elements and
           Sr-Nd-Pb isotopic data

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      Abstract: Abstract This study presents major and trace elements, and Sr-Nd-Pb isotope data of the Mokolo-Kosséhone volcanic rock (basanite, trachybasalt, trachyte, and rhyolite) from the northernmost segment of the Cameroon Volcanic Line (CVL). The basanite sample exhibits primitive character (MgO: 12–14 wt%; Mg#: 69–72; Ni: 327–427 ppm; Cr: 524–599 ppm; Co: 57–60 ppm). Trace element and isotopic signatures of the mafic lavas are similar to those of OIB. The trends observed in the major oxides and compatible trace elements against SiO2 from basanite to rhyolite are attributed to the fractionation of different mineral phases such as Fe-Ti oxides, olivine, clinopyroxene, feldspar, and quartz. The enrichment in LREEs and depletion in HREEs associated with (La/Yb)N > 5 (12.39–32.65), (Tb/Yb)N > 1.7 (1.71–2.89), and Dy/Yb > 2 (2.16–3.63), suggest the presence of a garnet phase in a mantle source. The lavas were produced at varying depths by low degrees of partial melting (< 4%) of a source containing less than 5% of garnet peridotite. The 206Pb/204Pb values of basanite (19.69630–19.79122) are similar to those of FOZO (206Pb/204Pb > 19.5). The trachybasalt samples with 206Pb/204Pb values of 19.25 and 19.37 suggest the probable enrichment of magma with a high-μ (HIMU) signature (206Pb/204Pb < 19.5) by a crustal component. Trace elements and isotopic compositions (87Sr/86Sr: 0.70308–0.70378, 143Nd/144Nd: 0.51287–0.51296, 206Pb/204Pb: 19.24652–19.79122) of the Mokolo-Kosséhone lavas are consistent with a mixture of different source material from the sub-continental lithospheric mantle (SCLM) and the asthenosphere with minor crustal contamination. The composition of the source is analogous to those described in the northern portion of the CVL and other volcanic massifs along the CVL.
      PubDate: 2022-12-21
       
  • Geochronology, geochemistry, Hf isotope, and electron probe analysis of
           the diorite in the Jianhei Mountain, East Kunlun Orogenic Belt, China, and
           their geological significance

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      Abstract: Abstract The Eastern Kunlun orogenic belt (EKOB) is located in southern margin of the Qaidam Basin. After the evolution of the Proto-Tethys Ocean and the Paleo-Tethys Ocean, the geological structure is complex and diverse in the EKOB. Herein, the results of geochronological, geochemical, Hf isotope, and electron probe analyses are presented for the Jianhei Mountain diorite in the EKOB. The results of the geochemical studies show that the rock is enriched in Al, Ca, and Fe, depleted in Ni and Cr, and contains moderate amounts of Mg. The samples exhibit a high degree of fractionation of light and heavy rare earth elements (REEs), with the light REEs being enriched, and the heavy REEs being depleted. Furthermore, the samples are enriched in the large ion lithophile elements, and depleted in the high field strength elements. The Jianhei Mountain diorite yields a weighted mean zircon U-Pb dating age of 251.3 ±1.8 Ma, which is in the Early Triassic. The Zircon Hf isotope analysis gives a zircon (Eu/Eu⋆)N value that ranges from −5.2 to −3.3, and the two-stage model age is 1244–1342 Ma. Combined with other geochemical characteristics, it can be concluded that the source area of the Jianhei Mountain diorite is dominated by Mesoproterozoic crustal materials, with a small amount of mantle material involved in the petrogenetic process. In addition, the results of electron probe micro-analysis show that the MgO content of the hornblende is 9.57–10.40%, the Mg/(Mg + Fe2+) ratio is 0.49–0.52, the Mg content is 2.15–2.31, the Ca content is 1.71–1.80, and the total of Fe3+ + Fe2+ is 2.04–2.17. The MgO content of the biotite is 8.47–9.31%, and the Fe2+/(Mg + Fe2+) ratio is 0.50–0.52. In accordance with previous studies, the mineral compositions of the hornblende and biotite are closely related to their genesis. It can be concluded that the hornblende and biotite of the Jianhei Mountain diorite have the characteristics of a crust-mantle mixed source. Overall, the present authors believe that the Jianhei Mountain diorite is the product of partial melting of the lower crust in the tectonic background of the northward subduction of the Paleo-Tethys Ocean, with a small amount of mantle material involved in the petrogenetic process.
      PubDate: 2022-12-01
      DOI: 10.1007/s12303-022-0013-2
       
  • Surface sediment geochemistry for understanding the recent sedimentary
           environment in northwestern Karnataka, south India

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      Abstract: Abstract Geochemical study of 195 stream sediment samples (in less than 75 µm grain size) distributed in parts of Belgaum, Dharwad, and Uttar Kanada districts (bounded by latitudes from 15°15′00″ to 15°30′00″ and longitudes from 74°30′00″ to 74°45′00″) were studied for the major oxide, trace and rare earth element content. The objective of this study is to understand the recent sedimentary environment by establishing the generalized climatic conditions, chemical weathering, sediment sorting and recycling, sediment sources, and the tectonic setting of the study area. Geochemical signatures of the sediments indicate a semi-arid to the moist climate in the study area. Geochemical proxies show that annual rainfall in the study area varies from 378 to 692 mm, higher in the western part compared to that in the eastern side. The chemical index of alteration (67.70–94.01) and chemical index of weathering (76.24–97.37) collectively suggest moderate to high chemical weathering. Studied samples show a wide variation in major oxides and trace elements. Fe2O3, MnO, K2O, P2O5, Rb, Zr, and Sc display a positive correlation with Al2O3 confirming their possible hydraulic fractionation. Zr/Sc vs. Th/Sc plot and correlation between CIA vs. Al2O3 indicate strong sediment recycling and sorting. Bulk geochemistry data suggests the involvement of granite and other felsic rocks, intermediate and mafic rocks as the sources of surface sediments. Our observations are very well matching with the geology of the area. Major and trace element set of discrimination diagrams demarcates the passive margin settings for the studied samples, except for a few samples plotting into an active continental margin tectonic settings.
      PubDate: 2022-12-01
      DOI: 10.1007/s12303-022-0011-4
       
  • Formation of talc fault gouge analog using high-energy ball mill

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      Abstract: Abstract Fault gouge, located in highly deformed fault cores, shows substantial particle size reduction and loss of crystallinity, which could affect the physicochemical properties and thus control the slip behavior and earthquake stability of a fault. To systematically investigate the effect of deformed fault gouge on fault slip behavior in laboratory-scale experiments, a fault gouge analog with variable particle size and crystallinity is required. However, the systematic study for formation of a fault gouge analog (i.e., controlling the particle size and crystallinity) was not performed well. In this study, we investigated the effect of the rotation speed of a high-energy ball mill on particle size reduction rate and degree of amorphization. As the rotation speed increased from 500 to 2000 rpm, the comminution rate linearly increased, and reached a reduced particle size limit. The degree of amorphization and its rate also increased with increasing rotation speed. Upon grinding, the X-ray diffraction (XRD) peaks markedly decreased and reached critical amorphization points within 120 min, except for the case of grinding with a rotation speed of 500 rpm. Talc ground with a rotation speed of 500 rpm did not reach steady-state in mechanical amorphization after 360 min of grinding, thus necessitating prolonged grinding for further amorphization. A comparison of talc powders having similar specific surface areas, but ground at different rotation speeds, shows that grinding with a higher rotation speed for a shorter duration preserves the crystalline structure relatively well compared with grinding at a lower rotation speed for a longer duration. These results indicate that optimizing the grinding rotation speed facilitates the formation of talc fault gouge analogs with systematically varying particle size and crystallinity. The specific surface area of talc increased from 6.1 to 365 m2/g, and the degree of crystallinity decreased from approximately 75% to 11%. Our results indicate that an artificial talc fault gouge can be prepared by varying the particle size and crystallinity using a high-energy ball mill.
      PubDate: 2022-12-01
      DOI: 10.1007/s12303-022-0012-3
       
  • A machine learning algorithm with random forest for recognizing hidden
           control factors from seismic fault distribution

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      Abstract: Abstract Stress interaction among many faults in earthquake prone region is strongly affected by the spatial distribution of faults. To build a robust Machine Learning (ML) algorithm for finding hidden relationships between fault distribution and its controlling factors, the performance of ML in dependence of various parameters, such as the complexity and data size of the fault distribution, needs to be investigated. We have, therefore, developed an ML algorithm by combining Principal Component Analysis (PCA) with a Random Forest (RF) to unveil the controlling factors on seismic fault distribution. We synthesized fault images for training of RF classifier ND (> 10,000) fault images, which scattered the faults in a square with R km R km. R, ranging from 200 km to 600 km, is a controlling factor of fault distribution. PCA extracts the dominant features of the seismic fault images to supply the refined training data to the RF. This leads to a dimensional reduction of the data. We tested the influence of the number of principal components (NP) on PCA performance in retaining the information. Larger and more variable R values (i.e., a more complicated fault distribution) with larger amounts of training data required more principal components for a full preservation of the original data. We quantified the optimized NP/ND ratio for an efficient RF classifier, which was about ∼0.1 for the evaluating efficacy of the PCA. This showed that the RF classifiers is effective in predicting R values depending on the fault zone with R km R km and not on specific fault locations. We propose that a small NP, equivalent to ∼10% of the training data, suffices for training accurately RF classifier for fault distributions, which can reduce the complexity of fault distribution to understand stress interaction among many faults.
      PubDate: 2022-11-19
      DOI: 10.1007/s12303-022-0029-7
       
  • Evolution process of W−Pb−Zn mineralizing fluid: implication from the
           carbonate-hosted Subok deposit in the Hwanggangri mineralized district,
           South Korea

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      Abstract: Abstract The evolutionary process and spatiotemporal variation of W and Pb−Zn mineralizing fluids was investigated for the Subok deposit, a representative W−Pb−Zn deposit in the Hwanggangri mineralized district (HMD) in South Korea. The deposit was emplaced in Paleozoic carbonate rocks, which were intruded by Cretaceous Muamsa granite. The paragenetic sequence is characterized by early pyrrhotite-scheelite-arsenopyrite and late arsenopyrite-sphalerite-galena assemblages. In terms of spatial distribution, pyrrhotite and scheelite were dominant in the lower part, whereas arsenopyrite mainly occurred in the upper part. The upward increasing δ34SH2S values of ore-bearing fluids range from 1.0 to 5.9‰, corresponding to a magmatic origin. In this deposit, according to As content of arsenopyrite, fluid inclusion, and sulfur stable isotope, the early W and late Pb−Zn mineralization was controlled by decreasing temperature (425–590 to 380–450 °C), pressure (0.54–5.13 to 0.38–3.99 kbar), and sulfur fugacity of the uprising ore-bearing fluids. In the HMD, wolframite and molybdenite mainly occur in the granitic rock, whereas scheelite is precipitated in the carbonate host rock under decreasing oxygen fugacity, salinity, and pH, and the input of Ca from the host rock in the distal area. Late Pb−Zn mineralization was achieved by decreasing temperature and pressure of ore-bearing fluids and mixing with meteoric water in the distal area. The mineral zonation and physicochemical variation of W and Pb−Zn mineralizations can be applicable as indicators for the exploration of ore deposits.
      PubDate: 2022-11-17
      DOI: 10.1007/s12303-022-0028-8
       
  • Non-invasive mineral analysis of pigments of wall paintings in the
           Sungseonjeon Hall

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      Abstract: Abstract Non-destructive investigations were conducted by applying various analysis methods to investigate the production period of six wall paintings of the Sungseonjeon Hall in the royal tomb of King Suro, Historic Site No. 73 in Gimhae, South Korea. Portable microscopy and portable X-ray fluorescence analysis were performed in situ, and Raman spectroscopy and X-ray diffraction were applied to small fragments of painting layers. From microscopic observations, the size and arrangement of the mineral pigment particles used in the wall paintings were confirmed to be suitable for non-destructive analysis. Among the major elements and mineral phases detected in the wall paintings that are regarded to be earlier works (late 17th century), talc, minium with cinnabar, atacamite with botallackite, and lazurite have been detected in white, red, green, and blue specimens, respectively, confirming the use of traditional mineral pigments employed since ancient times. In contrast, in wall paintings added later (after the 19th century), anatase, minium, lavendulan with cornwallite, and lazurite were detected, along with crocoite in yellow specimens. These results indicate the existence of modern traces through synthetic pigments such as titanium white, emerald green, and chrome yellow, which were introduced by the West with the passage of time.
      PubDate: 2022-11-17
      DOI: 10.1007/s12303-022-0027-9
       
  • A method of determining optimum sections suitable for the simultaneous
           extraction of coalbed methane from 3# and 15# coal seams in the
           Wangcun-Xiadian Block and its application

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      Abstract: Abstract In addition to reservoir geological factors, economic benefits are another important factor that determines the feasibility of co-layer drainage. In view of this, this paper takes the 3# and 15# coal seams in the Wangcun-Xiadian block of the Qinshui Basin (Shanxi Province, China) as the research object, adopts the step-by-step method to summarize the geological influencing factors and thresholds of the drainage of the total combined seam, and eliminates the unsuitable geological conditions blocks for layer development. Using the productivity numerical simulation software combined with the constructed economic evaluation model, the suitable blocks for co-production in this zone were identified. The one-sidedness of the evaluation results caused by only considering the geological reservoir conditions is avoided, and the practicability of the evaluation results is guaranteed. The results indicate that the difference of formation liquid supply capacity between the two layers of coal is the key factor affecting combined layer drainage. When the gas content of 3# coal seam is 8,15m3/t and the post-fracturing permeability exceeds 5.17 × 10−3 µm2 and 1.13 × 10−3 µm2 respectively, it is suitable for single development of 3# coal seam. When the geological conditions for commingled production are met, it is suitable for simultaneous development of 3# and 15# when the permeability after fracturing exceeds 6.27 × 10−3 µm2 and 1.31 × 10−3 µm2 respectively under the same gas content. The study methodology considers both geological reservoirs and economic benefits, which can more objectively and accurately evaluate the suitable development blocks.
      PubDate: 2022-11-17
      DOI: 10.1007/s12303-022-0026-x
       
  • The use of magnetic and geoelectrical methods to locate buried ancient
           artificial canals and wells around the cultural heritage of Indrapatra
           Fort, Aceh, Indonesia

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      Abstract: Abstract The application of magnetic and geoelectrical methods for archaeological study is presented in this paper. The study was intended to map near-surface structures around the Indrapatra Fort, the 16th-century fortification built during the Early Aceh Sultanate in the north of Sumatra. Some of the structures around the fort have been buried after the 2004 Indian Ocean Tsunami or even by previous paleotsunami deposits. The ground magnetic measurements were performed over an area of 6 750 m2 using a high-resolution Proton Precession Magnetometer G-19 Geometric. Total magnetic field data were acquired as a 3-m grid station along survey lines spaced 3-m apart. Total magnetic field anomalies were calculated by diurnal and International Geomagnetic Reference Field corrections. To clarify the position of objects causing the anomalies, analytical signals and tilt derivative filters have been applied to the total magnetic field anomalies. The method found several structures with contrasting physical properties to those of the surrounding material. Both filters were able to identify the presence of circular, elongated, and square anomalies around the Indrapatra site. The archaeological interpretation of such structures is in terms of wells, canals, and road floors. The structures are made of limestone boulders buried within the uppermost sand layer. The burning process to cement the boulders causes their magnetic properties to be different in contrast to the layer of sand that covers them. Based on magnetic interpretation, three geoelectrical profiles were measured crossing the targeted objects using Supersting R8/IP 56 Electrode Electric Resistivity. Wenner configuration with 1-meter electrodes spacing was applied for a better model resolution. The inverted models of apparent resistivity data show an agreement with magnetic interpretation at shallow depth. The models also imaged the depth and geometry of the objects based on the electrical resistivity properties of subsurface materials. It is expected that the structures preserved tsunamigenic deposits, so the discovery of the structures will be able to contribute to further research on paleotsunami in Aceh.
      PubDate: 2022-11-07
      DOI: 10.1007/s12303-022-0025-y
       
  • Impact of road embankment construction on groundwater system in alluvial
           aquifers

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      Abstract: Abstract This study aims to evaluate the impact of road embankment construction on the groundwater system in alluvial aquifers that have excessively used groundwater. A road embankment was constructed across extensive flat alluvial deposits. Laboratory permeability tests demonstrated that the loading by road embankment significantly reduced the permeability of alluvial sediments, creating an impermeable boundary in the groundwater system. The numerical modeling results showed that road embankment acting as an impermeable boundary caused groundwater levels to rise in the upstream area but decline in the downstream area. However, unlike in other upstream areas, there was no noticeable rise in the groundwater level after the embankment construction in the area where the groundwater was in extensive use. The long-term water level monitoring also confirmed no meaningful change in water level during the road embankment construction. This is because the additional decline of the water level due to the decrease in the influence radius of groundwater pumping by the impermeable boundary offsets the increase in the upstream water level. The flow modeling and the water level monitoring showed that the overall impact of the road embankment construction on the groundwater supplies could be insignificant. However, the numerical modeling indicates that the degree of impact varies with the distance from the road embankment. This study implies that the impact of the road embankment construction on the groundwater supplies in the upstream area will depend on the geological and hydraulic settings, which determine the radius of influence, such as the hydraulic property of the alluvial aquifer, pumping rate, the number and location of pumps, etc.
      PubDate: 2022-11-02
      DOI: 10.1007/s12303-022-0024-z
       
  • Study on pore evolution characteristics of gas adsorption and desorption
           in coal under the action of liquid nitrogen

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      Abstract: Abstract CBM (Coalbed methane) belongs to unconventional natural gas mineral resources. The development and utilization of CBM can greatly reduce the occurrence of mine gas accidents, and how to improve the desorption capacity of CBM has always been a hot issue for researchers. Liquid nitrogen has obvious effect on coal seam cracking and permeability improvement. The purpose of this paper is to study the cracking mechanism of liquid nitrogen on coal, and provide a theoretical basis for using liquid nitrogen freezing and thawing to treat coal so as to improve the production of coalbed methane. Coal samples from Yangquan County, Shanxi Province were pretreated. The pore structure test, microscopic observation test and methane isothermal adsorption test were carried out after the coal samples with different particle sizes were treated with different liquid nitrogen freeze-thaw cycles. According to the experimental data, the evolution law of pores of coal before and after freezing and thawing with liquid nitrogen, the cracking mechanism of coal treated with freezing and thawing with liquid nitrogen, and the optimal number of freezing and thawing cycles with liquid nitrogen are analyzed. The results show that: 1) the evolution characteristics of pore structure of lower coal after liquid nitrogen freezing and thawing are that micropores in coal are promoted to develop into transition pores and mesopores, and mesopores and transition pores develop into macropores and fractures. 2) Through the observation of a metallographic microscope, the expansion degree of coal surface crack is positively correlated with the times of liquid nitrogen freeze-thaw. 3) Liquid nitrogen freeze-thaw treatment has an optimal number of cycles for the cracking degree of coal. With the increase of freeze-thaw cycles, the final adsorption capacity of coal pillar increases first and then decreases; The adsorption capacity of granular coal first increases and then decreases. After reaching freeze-thaw saturation, continued freeze-thaw is not conducive to the increase of adsorption capacity. These research results provide theoretical support for the implementation of liquid nitrogen fracturing and permeability enhancement technology in coal reservoirs.
      PubDate: 2022-11-02
      DOI: 10.1007/s12303-022-0022-1
       
  • Controls on sediment storage in wide mountain valleys — a case study
           from Srinagar (Garhwal) valley, NW Himalaya

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      Abstract: Abstract The valley-fill deposits in a tectonically active setting play a key role in understanding a river’s response to climatic/tectonic shifts. These deposits are a result of the interaction between the regional and the local processes, which in turn are controlled by tectonics and climate. In this study, valley-fill deposits in the widest reach of the Alaknanda River (a headwater tributary of the Ganga River)—the Srinagar valley—in the northwest Himalaya is investigated for the interaction between, 1) the axial channel (representing regional processes) and local tributary (representing local processes) and 2) axial channel and hillslope (representing local processes). We identified eight levels of terraces and five levels of debris flow surfaces in the Srinagar valley. The terraces are composed of axial river deposits and local stream deposits, whereas debris flow surfaces mainly consist of hillslope deposits. Strath terraces are also present towards the western part of the valley. The 1D resistivity survey and field data show that thick sedimentary cover caps the bedrock in the eastern part of the Srinagar valley. Geochronology data based on optically stimulated luminescence (OSL) dating suggests that some of the sediments in the Alaknanda valley are older than 80 ± 5 ka. Integration of results shows that the width of the Srinagar valley is controlled structurally by the presence of the North Almora Thrust (NAT), a regional structure present in the Alaknanda River basin. The valley width increases around the central part of the Srinagar valley; this increase in width has provided accommodation space and resulted in thick sedimentation. Major filling and evacuation of the Srinagar valley occurred between 80 ± 5 ka and 8 ± 1 ka. The study demonstrates that the long-term interaction of the axial river, tributaries, and the hillslope processes can often be masked by the younger sediments to give a deceptive morphology and evolution history, if not thoroughly investigated.
      PubDate: 2022-11-02
      DOI: 10.1007/s12303-022-0023-0
       
  • Measurement of surface deformation related to the December 2018 Mt. Etna
           eruption using time-series interferometry and magma modeling for hazard
           zone mapping

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      Abstract: Abstract Mount Etna has erupted several times since it was first formed. Recently, Mount Etna began erupting again over 24–27 December 2018. Because it erupts frequently, Mount Etna should be observed on a frequent basis. From June 2018 to October 2019, 34 and 56 synthetic aperture radar (SAR) images were acquired from the ascending and descending tracks of the Sentinel-1 satellite, respectively. We employed the Stanford Method for Persistent Scatterers (StaMPS) and a refined small baseline subset (SBAS) InSAR method to produce a surface deformation time-series map. In the time-series analysis, the phase signal remained unaltered with time. The Okada model was then applied to the result to generate a modeled interferogram, and the Q-LavHA program was run to generate a lava flow prediction model. A direct comparison of the results showed that Persistent Scatterers Interferometry (PSI)-StaMPS and the refined SBAS technique were comparable in terms of the displacement pattern, with slightly different velocity values obtained for individual points. In particular, a velocity range of −25 to 21 cm/yr was obtained from PSI-StaMPS, whereas a range of −30 to 25 cm/yr was obtained from the refined SBAS method. Upon computation of the vertical and east-west displacement components based on ascending and descending track data using both methods, deformation velocities of 51.5 and 52.5 cm/yr in the westerly direction on the western flank of Mount Etna were obtained from PSI-StaMPS and the refined SBAS method, respectively, whereas on the eastern flank, deformation toward the east was estimated to occur at a velocity of 50.1 or 54.2 cm/yr, respectively. PSI-StaMPS estimated a vertical deformation velocity of −5.3 to 18.3 cm/yr, whereas the refined SBAS method produced a velocity range of approximately −7 to 19 cm/yr. The interferogram obtained via Okada modeling showed two fault sources in the 2018 Mount Etna eruption and a total volume change of approximately 12.39 × 106 m3. From the modeling results, a lava flow prediction model was generated using the Q-LavHA program. The approaches described in this study can be used by government officials, authorities, and other decision-makers to monitor and assess the risk of volcanic activity in the region.
      PubDate: 2022-10-17
      DOI: 10.1007/s12303-022-0021-2
       
  • Improvement of fluid penetration in soil by plasma blasting

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      Abstract: Abstract Plasma blasting by high-voltage arc discharge was performed in laboratory-scale soil samples to investigate fluid penetration. A plasma blasting device with a large-capacity capacitor and columnar soil samples with a diameter of 80 cm and a height of 60 cm were prepared. The columnar soil samples were made of sand and silt mixed in a 7:3 ratio (the A samples) or a 9:1 ratio (the B samples). When fluid was injected by pressure without plasma blasting, fluid penetrated into the soil only near the borehole, and the penetration area ratio was less than 10%. In further tests, fluid was injected by plasma blasting with different discharge energies of 1–27 kJ. When plasma blasting was performed once in the A samples, the penetration area ratios of the fluid were 16–25%; after five consecutive blasts, the penetration area ratios were 30–48%. When five consecutive plasma blasts were carried out on the B samples, the fluid penetration area ratios were 33–72%. This difference indicates that the fluid penetration area increases with higher discharge energy of plasma blasting and with a greater number of blasts. The fluid penetration radius was calculated to assess the fluid penetration volume. When the fluid was injected by hydraulic pressure only, the penetration radius was 9–12.4 cm, whereas the penetration radius was 27–33.2 cm when blasting was performed five times. The radius was increased by up to 200% by plasma blasting. In the field tests, the fluid injection in the test hole subjected to plasma blasting was greater by about 170% compared with the control test hole, in which the fluid was injected only by hydraulic pressure. In addition, the electrical resistivity around the test hole subjected to plasma blasting was markedly lower, and fluid diffused from this test hole to a minimum radius of 2 m. These results indicate that a cleaning agent will penetrate further and the remediation efficiency of contaminated soil will be improved if plasma blasting is applied for in situ cleaning of low-permeability contaminated soil.
      PubDate: 2022-10-11
      DOI: 10.1007/s12303-022-0020-3
       
  • Confirmation of the Floian-Darriwilian (Lower to Middle Ordovician) hiatus
           in the Taebaek Group, Korea: integration of conodont biostratigraphy and
           sedimentology

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      Abstract: Abstract An Ordovician depositional hiatus spanning the middle Floian to lower Darriwilian, estimated to represent a period of at least 3 Myr, is confirmed for the first time in the Taebaek Group, Korea, based on integrated conodont biostratigraphic and sedimentologic data. The conodont biozones of the uppermost Dumugol and lower Makgol formations are revised and redefined with presentation of a new biozonal framework, which contains, the Serratognathus bilobatus Biozone, the Serratognathus extensus Biozone, the Paraserratognathus obesus Biozone, and the Tangshanodus tangshanensis Biozone in ascending order. The hiatus lies within the barren interval between the middle Floian Paraserratognathus obesus Biozone and the early Darriwilian Tangshanodus tangshanensis Biozone. The unconformity surface is located at the boundary between the basal and lower members of the Makgol Formation, 1.5 meters above the base of the barren interval, on the basis of sedimentary evidence such as differences in the depositional and diagenetic features as well as a sharp contact between the two members with subaerial exposure feature including vuggy to channel pore and dolostone breccia. The barren interval above the hiatus is considered due to environmental factor: the peritidal condition is regarded unfavorable for inhabitation of conodont animals. The newly established Floian and Darriwilian conodont biozones and depositional hiatus within the lower Makgol Formation indicate that the Ordovician succession of the Taebaek Group is essentially an extension of that of the North China Block.
      PubDate: 2022-09-07
      DOI: 10.1007/s12303-022-0018-x
       
  • Crack initiation and propagation thresholds of Hwangdeung granite under
           elevated temperature

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      Abstract: Abstract In this study, we investigated the effect of high temperature on the mechanical behavior of Hwangdeung granite in Korea. Uniaxial compression and Brazilian tests were performed under temperatures ranging from 20 °C to 250 °C. The development of the thermally induced microcracks was observed utilizing a scanning electron microscope (SEM). The target temperature was chosen for rock engineering projects, such as high-level radioactive waste disposal, enhanced geothermal energy, and thermal energy storage. Considering the long-term strength and fracture process associated with crack development, we examined the temperature dependence of crack initiation and propagation thresholds and conventional strength and deformation parameters, as well as the stress-strain relation under high temperature. Compressive strength, tensile strength, and Young’s modulus decreased with increasing temperature, particularly at temperatures above 100 °C, and Poisson’s ratio decreased linearly. The changes in the tensile strength and elastic constants were more pronounced than those in uniaxial compressive strength. The stress-strain curves revealed that the thermal effect on deformation, rather than strength, was evident. Microscopic observations of the heated rock samples have revealed that high temperature promoted the interaction and networking of pre-existing and thermally induced cracks, resulting in microstructural damage before loading. We determined the crack closure stress, crack initiation stress, and crack damage stress under the respective temperatures by analyzing the stress-strain curves. An increase in temperature increased the crack closure stress and reduced the crack initiation stress, resulting in a decreased elastic range; the former increased by 12.1 MPa as the temperature increased from 20 °C to 250 °C, and the latter significantly reduced by 25.1 MPa. This finding suggests that the mechanical behavior of rocks or rock masses under high-temperature conditions, particularly at low-stress levels, is uncertain and cannot be approximated with standard material properties. No systemic relation was detected between temperature and crack damage stress; however, the volumetric strain at the crack damage stress increased consistently with temperature.
      PubDate: 2022-08-13
      DOI: 10.1007/s12303-022-0015-0
       
 
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