Petrogenesis and Sr, Nd and Pb Isotopic Characteristics of Early Palaeozoic Cambrian Kathalguri Granite, Mikir Hills North East (NE) India  

作　　者：Ashokaditya P. Dhurandhar Ashokaditya P. Dhurandhar(Orion Geohytech, Nagpur, India)

机构地区：[1]Orion Geohytech, Nagpur, India

出　　处：《International Journal of Geosciences》2024年第12期967-1019,共53页地球科学国际期刊(英文)

摘　　要：Early Palaeozoic Cambrian A-type Kathalguri Granites in the Mikir Hills of northeastern (NE) India were studied to better understand the geodynamic settings in this region. This research presents new whole-rock geochemical and Sr, Nd, Pb isotopic data for the Cambrian granites in the Kathalguri Granite in Mikir Hills. The Kathalguri Granite shows geochemical characteristics of high SiO2, K2O and low FeOT, MgO, CaO, and P2O5 compositions. They belong to a high K Shoshonite to ultra-potassic series and display a weak metaluminous to peraluminous feature with A/CNK values of 0.83 to 1.02 with corundum and anorthite normative. FeOT/MgO varies from 2.93 - 7.49, is moderately oxidized and belongs to magnetite series. The rocks have a high ΣREE composition of 370.80 - 1353.23 ppm (average 568.55) and are enriched in LREE with flat HREE and (La/Yb)N values of 8.10 - 18.99, and display obvious strong negative Eu anomalies. Trace elements of the studied granites are characterized by enrichment in Rb, Th, U, Pb, Hf, and Sm, and depletion of Ba, Nb, Ta, and Sr. They display geochemical features of high Zr + Y + Nb + Ce values (241 - 934 ppm) and Ga/Al ratios 2.49 - 3.01 consistent with A-Type granites. Based on particular geochemical features, such as high Rb/Nb (3.10 - 19.53) and Low Y/Nb (0.09 - 2.28), Kathalguri Granite can be further classified as an A1-type subgroup. Granites display relatively low Sr (N ratio varying between 0.53 - 0.89 suggesting that the melts generated at greater depths (18 - 40 km), and fractionation at low pressures (−3 and total HGU 98.96 to 214.20. Kathalguri Granite dated by Rb-Sr isotopic isochrone as 489 ± 19 Ma with an initial 87Sr/86Sr 0.7199 ± 0.0017 and MSWD of 4.1, εSr(I) varied between 161.62 - 332.08 suggests that the Kathalguri Granite have originated from partial melting of ancient, evolved continental crustal material. The Sm-Nd Systematics has given a depleted mantle model (TDM) age ranging from 1733 - 2063 Ma with high negative εNd(t) values (−10.39 to −15.18) also hintEarly Palaeozoic Cambrian A-type Kathalguri Granites in the Mikir Hills of northeastern (NE) India were studied to better understand the geodynamic settings in this region. This research presents new whole-rock geochemical and Sr, Nd, Pb isotopic data for the Cambrian granites in the Kathalguri Granite in Mikir Hills. The Kathalguri Granite shows geochemical characteristics of high SiO2, K2O and low FeOT, MgO, CaO, and P2O5 compositions. They belong to a high K Shoshonite to ultra-potassic series and display a weak metaluminous to peraluminous feature with A/CNK values of 0.83 to 1.02 with corundum and anorthite normative. FeOT/MgO varies from 2.93 - 7.49, is moderately oxidized and belongs to magnetite series. The rocks have a high ΣREE composition of 370.80 - 1353.23 ppm (average 568.55) and are enriched in LREE with flat HREE and (La/Yb)N values of 8.10 - 18.99, and display obvious strong negative Eu anomalies. Trace elements of the studied granites are characterized by enrichment in Rb, Th, U, Pb, Hf, and Sm, and depletion of Ba, Nb, Ta, and Sr. They display geochemical features of high Zr + Y + Nb + Ce values (241 - 934 ppm) and Ga/Al ratios 2.49 - 3.01 consistent with A-Type granites. Based on particular geochemical features, such as high Rb/Nb (3.10 - 19.53) and Low Y/Nb (0.09 - 2.28), Kathalguri Granite can be further classified as an A1-type subgroup. Granites display relatively low Sr (N ratio varying between 0.53 - 0.89 suggesting that the melts generated at greater depths (18 - 40 km), and fractionation at low pressures (−3 and total HGU 98.96 to 214.20. Kathalguri Granite dated by Rb-Sr isotopic isochrone as 489 ± 19 Ma with an initial 87Sr/86Sr 0.7199 ± 0.0017 and MSWD of 4.1, εSr(I) varied between 161.62 - 332.08 suggests that the Kathalguri Granite have originated from partial melting of ancient, evolved continental crustal material. The Sm-Nd Systematics has given a depleted mantle model (TDM) age ranging from 1733 - 2063 Ma with high negative εNd(t) values (−10.39 to −15.18) also hint

关 键 词：Kathalguri Granite PETROCHEMISTRY PETROGENESIS Isotopic Age Radiogenic Heat Generation Geodynamic Evolution Mikir Hills 

分 类 号：P58[天文地球—岩石学]