Precambrian Acid Volcanism in Central India - Geochemistry and Origin |
| |
Authors: | V Divakara Rao BL Narayana P Rama Rao NN Murthy MV Subba Rao J Mallikharjuna Rao GLN Reddy |
| |
Institution: | 1. University of Bucharest, Faculty of Geology and Geophysics, Lithos Research Center, 1 Nicolae B?lcescu Avenue, RO-01041 Bucharest, Romania;2. OMV Petrom, 22 Coralilor Street, RO-13329 Bucharest, Romania;3. National Institute of Marine Geology and Geo-ecology (GEOECOMAR), 23-25 Dimitrie Onciul Street, RO-024053 Bucharest, Romania |
| |
Abstract: | The Early Proterozoic Bijli rhyolites (2180 ± 25 Ma) constitute an important part of the Nandgaon group in the Central Indian craton, a tectonically active block sandwiched between the Dharwar craton in the south and the Bundelkhand craton in the north. The rhyolites are chemically heterogeneous. They have high SiO2 (74.4%), K2O (4.41%), Ba (834 ppm), and low MgO (0.22%), CaO (1.0%), iron (2.8%) V, Cr and Ni (5, 6 and 1 ppm respectively). They contain moderate Sr (88 ppm), Rb (140 ppm), Th (27 ppm) and U (6 ppm). Total REE ranges from 223 ppm to 453 ppm with high LREE (ΣLREE = 307) and all the rhyolites have low to high negative europium anomalies (Eu/Eu* 0.03 to 0.77). The overall chemical signatures support a crustal anatectic origin for the rhyolites from a source of intermediate composition. Basalt pooling below the crust and associated rifting most likely initiated anatexis. |
| |
Keywords: | Acid volcanism Central India Precambrian REEs Bijli rhyolites |
本文献已被 ScienceDirect 等数据库收录! |
|