Journal Cover Journal of Applied Geology
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  This is an Open Access Journal Open Access journal
   ISSN (Print) 2086-5104
   Published by Universitas Gadjah Mada Homepage  [27 journals]
  • Groundwater Level Changes in Shallow Aquifer of Yogyakarta City,
           Indonesia: Distribution and Causes

    • Authors: Liliane Manny, Rilo Restu Surya Atmaja, Doni Prakasa Eka Putra
      Pages: 89 - 99
      Abstract: The population in Yogyakarta City, Indonesia has increased since 1970, resulting in high groundwater utilization. This normally results in a decline of groundwater level in shallow aquifer beneath the city. However, expansion of the city and urbanization effects can also have the opposite effect and lead to a rise of groundwater levels due to urban recharge. This study investigates groundwater level changes in Yogyakarta City during a time period of 30 years between 1985 and 2015. Collected data in this research are groundwater level, rainfall, population density, sewer system, and land use. Overlaying various spatial information reveals a pattern of groundwater level rise in some areas of the city by 0–12 m, whilst in other areas a decline of 0–9 m is discovered. Rising groundwater levels are mainly found in areas moderate to high population density where sewer system networks have been installed. The rising of groundwater levels is this expected to be caused by urban recharge and sewers leakage.
      PubDate: 2017-08-18
      Issue No: Vol. 1, No. 2 (2017)
       
  • Geochemistry, Hydrothermal alteration and Ore mineralogy of Skarn
           Mineralization at Wethey-Pheshey area, Thabeikkyin Township, Mandalay
           Region, Myanmar

    • Authors: Toe Naing Oo, Lucas Donny Setijadji, I Wayan Warmada, Than Than Oo
      Pages: 53 - 62
      Abstract: Wethey-Pheshy area is located 80 km north of Mandalay at Thabeikkyin
      Township, Mandalay Region. X-ray Diffraction (XRD) Analysis and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) were applied in this study. Geochemical studies on the host rocks indicate that major and minor oxides compositions of metamorphic
      rocks show some degree of variation. CaO, MgO, FeO, TiO2 and P2O5 concentration of
      the metamorphic rock samples show a coherent negative correlation with SiO2 whereas
      Na2O is positively correlated with SiO2. The metamorphic rocks are strongly enriched
      in light rare earth elements (LREE) and relatively depleted in heavy rare earth element
      (HREE). The depleted Eu-nomalies in the chondrite-normalized REE diagrams indicate a
      plagioclase-depleted Eu crustal source or fractionation during magmatic differentiation.
      Intrusion of granitic rocks in the diopside marble caused the base metal ore mineralization and associated skarn alterations. Granite shows the sub-alkaline nature and peraluminous character. It is identified as I-type granite (magnetite series) developed in the
      volcanic arc setting. Hydrothermal alteration types associated with gold and skarn mineralization in the study area include calc-silicate alteration, propylitization, sericitization
      (argillitization) and hematization. Based on the nature and characteristics of host rocks,
      mineralization and alteration style and geochemical characteristics in the study area is
      identified as intrusion-related skarn mineralization. Common ore minerals include chalcopyrite, galena, sphalerite, pyrite, gold and Fe-oxides.
      PubDate: 2016-07-26
      Issue No: Vol. 1, No. 2 (2016)
       
  • Occurrences and Characteristics of Gold Mineralization in Rampi Block
           Prospect, North Luwu Regency, South Sulawesi Province, Indonesia

    • Authors: Arifudin Idrus, Suaib Mansur, Ahmad ., Rahmayuddin ., Abdul .
      Pages: 63 - 70
      Abstract: This study is aimed to identify the occurences, characterisatics and genetic
      type of gold mineralization, and to elucidate the preliminary gold potential in the study
      area. Research method includes field observation of prospect geology, hydrothermal alteration and ore mineralization. Laboratory analysis consists of petrography, ore microscopy
      and ore chemistry. Geologically, quartz ± gold veins were found in Rampi block prospect,
      which are mainly hosted by metamorphic and metasediment rocks. The quartz veins has
      structurally segmented with massive, brecciated and laminated textures. Orientation and
      distribution of veins is controlled by NW–SE and NE–SW trending structures. Sulfides are
      present with minor abundance (<1 %). Pyrite is obviously observed and partially oxidized.
      Arsenopyrite and stibnite are minor, while basemetal (Pb, Zn) sulfides are very rare. Gold
      mineralization occurred in quartz veins and closely related to silica-clay and silicic alteration. Gold grade varies from 0.1 to 11 ppm Au (29 samples). Quartz veins contained high
      gold grade (>9 ppm) commonly show laminated and brecciated texture and has been undergone a supergene enrichment. According to several characteristics above, gold deposit
      in Rampi block prospect tends to meet the criteria of orogenic/mesothermal gold type (cf.
      Groves et al., 2003). The deposit shares similarities with Awak Mas prospect, which is
      already confirmed to be a mesothermal type in Luwu district (cf. Querubin and Walters,
      2011). Therefore, discoveries of economic mesothermal gold deposits are still open in the
      metamorphic terrains, and thus, it requires a systematic exploration based on the genetic
      model of the deposit.
      PubDate: 2016-07-26
      Issue No: Vol. 1, No. 2 (2016)
       
  • The Effectiveness of Wenner-Schlumberger and Dipole-dipole Array of 2D
           Geoelectrical Survey to Detect The Occurring of Groundwater in the Gunung
           Kidul Karst Aquifer System, Yogyakarta, Indonesia

    • Authors: Oktanius Richard Hermawan, Doni Prakasa Eka Putra
      Pages: 71 - 81
      Abstract: Until today, geoelectrical survey is the most effective method for groundwater exploration. 2D method or known as horizontal profiling is now the most appropriate
      method in the geoelectrical survey compare to vertical electrical sounding method. The 2D
      method of Wenner-Schlumberger and Dipole-dipole configuration proved to be very effective to locate conventional aquifer occurrence on volcanic terrain or sedimentary terrain.
      Karst aquifer system is an unconventional aquifer and acts very differ in contrast with the
      conventional sedimentary aquifer. Heterogeneity and discontinuity of limestones in karst
      terrain will reveal a wide variety of resistivities, hence it is difficult to interpret. This research has important objective to define the effectiveness of the Wenner-Schlumberger and
      Dipole-dipole configuration in the 2D geoelectrical survey to explore groundwater in the
      karst area. Field observation of geology and 2D geoelectrical survey were conducted in
      underground river of Kali Suci Area, Gunung Kidul. In Kali Suci where an endokarst cave
      was occured on the surface, line survey was placed in the top of the cave and across the
      geometry of the cave. Measured stratigraphy in the wall of the cave found four types of
      limestone which consist of packstone, wackestone, grainstone and crystalline limestone.
      The Wenner-Schlumberger and Dipole-dipole method can detect differentiation of limestone types and also the exposed underground river successfully. However, compared to
      Wenner-Schlumberger array, Dipole-dipole array reveals less vertical accuration.. Therefore, on this research, the best method to detect water saturated zone or gourndwater in
      the karst system is the Wenner-Schlumberger method.
      PubDate: 2016-07-26
      Issue No: Vol. 1, No. 2 (2016)
       
  • Lithofacies and Sedimentation of Organic Matter in Fine Grained Rocks of
           Nanggulan Formation in Kulon Progo, Yogyakarta

    • Authors: Hendra Amijaya, Najibatul Adibah, Ahmad Z.A. Ansory
      Pages: 82 - 88
      Abstract: Fine grained rocks especially shale play a significant role in shale hydrocarbon
      system. Research on Eocene Nanggulan shale becomes an interest lately since this shale
      is considered as prospective interval for shale gas source. It potentially contains significant organic matter because coaly sediment is found in this formation as well. Nanggulan
      Formation fine grained rocks was deposited in various depositional environment from
      estuary – shallow marine. This paper integrates the result of lithofacies and depositional
      environment analysis with organic geochemical data to understand the sedimentation process of organic matter. Samples were taken from cores. The result of 14 geochemically
      analysed samples shows Total Organic Carbon (TOC) content between 0.36–1.00 % for
      fin e grained rocks (shales) and 12.80 % for coaly shales. Nine samples are categorized as
      fair and 2 samples are categorized as good source rock. The depositional environment of
      Nanggulan Formation sediment, which was shallow marine at Late Eocene and estuary
      (salt marsh) at Early Eocene, produced sediment with higher TOC. Whereas the deposition of sediment in estuary (tidal flat) at Middle Eocene produced lower content of TOC.
      Vulcanic activity at Middle Eocene also caused less organic material preservation because
      it produced abundant inorganic material.
      PubDate: 2016-07-26
      Issue No: Vol. 1, No. 2 (2016)
       
 
 
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