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- Title
Geochemical characteristics of Tukureswari and Barbhita granitoid in Goalpara district, Assam.
- Authors
Bhagabaty, B.; Mazumdar, M.; Mazumdar, A.; Borah, P.
- Abstract
Late intrusive Tukureswari granitoids (TKG) and the Barbhita granitoids (BBG) of Goalpara district in western Assam constitute an important component of the continental crust of the Shillong Plateau. Thus, the geochemical study of these two granitoids involving their origin, classification and petrogenetic significance would be a contribution towards a better understanding of the evolution of continental crust of the Shillong Plateau. The major oxide and trace element geochemistry reveals several genetic issues on these two granitoids. The I-type affinity of the TKG is indicated from the geochemical features such as high TiO, PO and KO contents, low normative corundum (< 1%), high NaO/KO ratios, and low concentrations of Ni, Co and Cr. Further, enriched LREE-LILE and HFSE depletion, as well as the normal calc-alkaline nature of arc affinity (e.g., enhanced LILE abundance and low HFSE/LILE ratios) of the TKG indicate subduction-related magmatism. TheTKG are also categorized as a deep-level pluton, being enriched in LREE and depleted in total REE and HFSE (Y, Nb, Ta, Zr, Hf). The high La/Nb ratio (1.9-8.6), negative Nb and Ti anomalies also suggest orogenic related magmatism. On the other hand, the geochemistry of the BBG reveal a high Niggli Si and Mg values, slightly high normative corundum values (2.16-3.41), high Th/Ta, Y/Nb, La/Nb, KO/NaO, and Rb/Sr ratios. It also shows ASI, K, Rb, and U contents, prominent depletion of Nb, Sr and Ti on the primitive mantle-normalized multi-element spider diagrams and a low concentrations of Cu, Cr, V and NaO (> 3.2%). All these geochemical characteristics provide strong evidences in support of a sedimentary parentage for Barbhita granitoids (BBG) and are dominantly of S-type.
- Subjects
ASSAM (India); GEOCHEMISTRY; PETROGENESIS; MAGMATISM; IGNEOUS intrusions
- Publication
Journal of the Geological Society of India, 2017, Vol 89, Issue 5, p532
- ISSN
0016-7622
- Publication type
Article
- DOI
10.1007/s12594-017-0641-8