Flexural Rigidity of the Lithosphere as a Powerful Tool for the Continental Correlation: A study on the Paleo-fit of India and Madagascar

Monday, 15 December 2014
R.T Ratheesh Kumar, Indian Institute of Science, Bangalore, India
The temporal evolution and spatial configuration of continents can be analyzed through their response to long-term forces, as a function of the elastic property of the lithosphere, which is parameterized as effective elastic thickness (Te). The Te method has been widely used as a key proxy to examine the long-term strength/rigidity structure of the lithosphere. The present study employs the gravity inversion and flexure inversion techniques that operate in spatial domain in order to estimate the spatial variation of Te as well as the Moho configuration along the western continental margins of India (WCMI) and eastern continental margin of Madagascar (ECMM). The main objective of the present study is to understand the nature of isostasy and structure of the lithosphere along these conjugate passive margins. The results correlate well with the continental and oceanic regional-scale structures including ridges and basins in the WCMI and ECMM that reveal their mode of evolution. This study obtained comparable results from both the passive margins such as a linear zone of anomalously low-Te (1–5 km) along the WCMI (~1680 km long), which exactly correlates with the low-Te patterns obtained all along the ECMM. These low-Te zones along the passive margins are attributed as paleo-rift inception points of lithosphere thermally and mechanically weakened by the combined effects of the Marion hotspot and lithospheric extension due to rifting. When these conjugate passive margins were correlated by matching the mirrored low-Te linear zones, obtained a best fit position of Madagascar against India during the Gondwana Rifting time. The hence derived India-Madagascar paleo-fit model is well justified by the best close-fit of the crustal geometry and bathymetry of the continental shelf margins, and also by the matching of tectonic lineaments, lithology and geochronological belts along the margins of both the continents.