Mechanism of rift flank uplift and escarpment formation evidenced by Western Ghats, India.

This paper presents new petrological, geological and palaeomagnetic data from samples of the Deccan basalt within a continuous drill core section(s) of the Continental Scientific Deep Drilling Project in the Western Ghats, India.The Western Ghats is one of the excellent example to probe epeirogenic uplift, extension and subsidence in volcanic continental margins. A continuous unbiased stratigraphic section of basalt of 1250 m drill hole of the Continental Scientific Deep Drilling Project is considered to investigate the above aspects. These results, combined with existing geological and geophysical data, constitute a multi-method approach that demonstrates (a) igneous underplating caused uplift prior to frequently suggested flexural isostasy (b) plume impact and eruption are near-simultaneous and extension/rifting essentially followed soon after volcanism and (c) lithosphere beneath the continental margin, while returning to normal temperatures following the Seychelles-India breakup, experienced thermal collapse and subsidence causing slumping of basalt basement below sea level for about ~300 m. The flows across the entire drill core clealy display more evolved compositions from primary melts of mantle in terms of petrology and a single geomagnetic polarity transition in palaeomagnetic data.

Figure Caption: Zr vs Ni (left) and Cr (right) variations of KBH-7 drill core samples along with Batch melting model partial melting curves and Rayleigh fractionation modelled trends. It is seen that the KBH-7 Deccan samples are the variants between picrite-gabbro fractionated partial melts and direct picrite (with different proportions of mineral phases) fractionated partial melts.


Figure Caption: Characteristic magnetization inclinations of Deccan basalt down to basement interface along three drill holes (KBH-7, KBH-8 and KBH-5A) against the mean sea level elevation.



Radhakrishna T, Asanulla R. Mohamed, Venkateshwarlu M, Soumya G. S & Prachiti P. K. 2019. Mechanism of rift flank uplift and escarpment formation evidenced by Western Ghats, India, Scientific Reports, 9:10511., published online on 19th July, 2019.