{"title":"Geothermobarometry of granitic pegmatites of Nagamalai - Pudukottai area, Madurai Block, South India","authors":"Raj R. Manu, S. N. Kumar","doi":"10.31870/ESI.11.3.2018.11","DOIUrl":"https://doi.org/10.31870/ESI.11.3.2018.11","url":null,"abstract":"The pegmatites in the Neoproterozoic A-type granites of NagamalaiPudukottai area are of two typesgray and pink. These pegmatites contain hornblende. In this work an attempt is made to understand the nature of magma, the process of crystallisation and the Pressure-Temperature (P-T) conditions of formation of the rock with the help of the Electron microprobe (EPMA) study of hornblende from both varieties of pegmatites. The EPMA of the hornblende from the granitic pegmatites indicate their calcic nature. The structural formula of these calcic amphiboles corresponds to hastingsite. The Al pressure calibration suggests the formation of the gray and pink pegmatites to be 5 kilobar (average). Based on the amphibole-plagioclase thermometer the magmatic temperature deduced for gray and pink pegmatites is 760C and 745C respectively. These temperature values suggest the later formation of pink pegmatites. The study reveals the formation of the granites and associated pegmatites from a less evolved, hydrous, and less viscous calcic melt in the upper crust.","PeriodicalId":129224,"journal":{"name":"Earth Science India","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121064526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Assessment of shallow groundwater quality for irrigation in parts of Agra District, Uttar Pradesh, India","authors":"P. Singh, S. Atal, S. K. Dubey","doi":"10.31870/ESI.11.3.2018.09","DOIUrl":"https://doi.org/10.31870/ESI.11.3.2018.09","url":null,"abstract":"","PeriodicalId":129224,"journal":{"name":"Earth Science India","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122857520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Geochemical and petrographic interpretation of Sandhan Formation: An insight into provenance, tectonics and paleoclimatic conditions","authors":"Shubhendu Shekhar, Avinash Shukla, Pramod Kumar","doi":"10.31870/ESI.11.3.2018.10","DOIUrl":"https://doi.org/10.31870/ESI.11.3.2018.10","url":null,"abstract":"The relative sea-level fall in terminal Cenozoic exposed continental shelf of Kutch provided opportunity to develop a fluvial system of braided nature. The terminal Cenozoic formation of Kutch, the Sandhan Formation provides a rare opportunity where a clear transition from a marine to fluvial succession can be identified in the field. The occurrence of fluvial deposits in the rock record suggest an abrupt and considerable fall in the base level. The ~157 m thick upper part of the Sandhan Formation is deposited in the fluvial environment. The fluvial succession of the Sandhan Formation has not been studied for their sediment geochemistry. Provenance, tectonic setting, paleo-weathering, and paleoclimate of the upper part of the Sandhan Formation is interpreted on the basis of extensive geochemical and petrographic analysis of sandstone samples by using XRF, the bivariate diagram Log (SiO2/Al2O3) versus Log (Na2O/K2O) diagram, QFL diagram, Provenance Discrimination Plot, SiO2/Al2O3 ratio with K2O/Na2O ratio, Chemical Index of Alteration (CIA) weathering indices, Plagioclase Index of Alteration (PIA), Chemical index of Weathering (CIW), A-CN-K Diagram, SiO2/Al2O3 ratio and binary SiO2 wt.% versus (Al2O3 + K2O + Na2O) wt.% diagram. These provided the detailed geological origin of the upper part of the Sandhan Formation as, it originated from a mixed provenance (quartzose sedimentary and mafic igneous), with arkose to subarkose nature. The upper part of Sandhan Formation is formed in an arid paleoclimate, both Active Continental Margin (ACM) and Passive Margin (PM) tectonic setting and moderate to intense paleo-weathering conditions.","PeriodicalId":129224,"journal":{"name":"Earth Science India","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129769571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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