Petrogenesis of the late Archean Pillow Basalts from the Chitradurga greenstone belt, Western Dharwar Craton (southern India)

Ruksana Rose, Ria Mukherjee*, Robert Frei, Sisir K. Mondal, M. Lingadevaru

*Corresponding author af dette arbejde

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Abstract

The well-preserved exposures of pillow basalts from the late Archean (2.7 Ga) Chitradurga greenstone belt (Western Dharwar Craton) have been studied in detail using petrological, bulk-rock geochemical and isotope data. The pillows are compositionally basalts to basaltic andesites, and constituted of actinolite and plagioclase. The pillows show slight to moderately depleted LREE (La/SmN = 0.6−1.03), and nearly flat HREE patterns (Gd/YbN = 1.03−1.17) that are comparable with MORBs, but have an overall depletion in REEs relative to the latter. The trace-element patterns of the pillows on an N-MORB normalized multi-element diagram, however, are broadly comparable with that of Island Arc Basalts. The pillows were perhaps generated during the initiation of an intra-oceanic subduction zone where a depleted upper mantle (MORB-source) was metasomatized with slab-derived aqueous fluids. The pillows show a whole-rock Sm–Nd errorchron age of 2433 ± 400 Ma, which is within error of the previously reported Sm–Nd age of 2747 ± 15 Ma. The Pb–Pb isochron age (2627 ± 82 Ma) of the pillows is much closer to the previously reported Sm–Nd age, and it may also indicate the 2.62 Ga thermal event associated with felsic magmatism in the Western Dharwar Craton.

OriginalsprogEngelsk
Artikelnummer95
TidsskriftJournal of Earth System Science
Vol/bind131
Udgave nummer2
Antal sider26
ISSN2347-4327
DOI
StatusUdgivet - 2022

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© 2022, Indian Academy of Sciences.

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