The early drift of the Indian plate

Wilfried Jokat,Graeme Eagles,Tabea Altenbernd,Wolfram H Geissler

doi:10.1038/s41598-021-90172-z

Abstract

Plate kinematic models propose that India and Sri Lanka (INDSRI) separated from Antarctica by extremely slow seafloor spreading that started in early Cretaceous times, and that a long-distance ridge jump left a continental fragment stranded off the Antarctic margin under the Southern Kerguelen Plateau 1-3. Here, we present newly acquired magnetic and deep wide-angle seismic data that require a fundamental re-evaluation of these concepts. The new data clearly define the onset of oceanic crust in the Enderby Basin and off southern Sri Lanka, and date its formation with unprecedented confidence. The revised timing indicates that India and Sri Lanka detached from Antarctica earlier in the east than in the west. Furthermore, no compelling evidence for an extinct spreading axis is found in the Enderby Basin. A refined plate motion model indicates that India and Sri Lanka departed from Antarctica without major rift jumps, but by the action of three spreading ridges with different timings and velocities that must have been accommodated by significant intracontinental deformation.

Highlights

Plate kinematic models propose that India and Sri Lanka (INDSRI) separated from Antarctica by extremely slow seafloor spreading that started in early Cretaceous times, and that a long-distance ridge jump left a continental fragment stranded off the Antarctic margin under the Southern Kerguelen Plateau 1-3
A refined plate motion model indicates that India and Sri Lanka departed from Antarctica without major rift jumps, but by the action of three spreading ridges with different timings and velocities that must have been accommodated by significant intracontinental deformation
According to these two-phase models[1,2,3], at least two microcontinents or continental fragments (Elan Bank and southern Kerguelen Plateau (SKP)) lie embedded in the ocean floor that formed by the divergence of the Indian and Antarctic plates

Summary

Introduction

Plate kinematic models propose that India and Sri Lanka (INDSRI) separated from Antarctica by extremely slow seafloor spreading that started in early Cretaceous times, and that a long-distance ridge jump left a continental fragment stranded off the Antarctic margin under the Southern Kerguelen Plateau 1-3. The principal evidence for the northward ridge jump is the discovery of felsic clasts in a polymict gravel cored during ODP Leg 183, at site 1137 on Elan Bank to the west of the northern Kerguelen Plateau[7] (Fig. 1, NKP) This gravel is the main reason why Elan Bank is interpreted as a continental sliver that became detached from India by the action of the new mid-ocean ridge along the continent’s eastern m argin[2,8]. The Mesozoic seafloor spreading isochrons on which the two-phase model is based are derived from widely spaced and unevenly distributed ship-borne data[2] Another set of constraints, the locations of the onset of oceanic crust off INDSRI and East Antarctica, are controversial because they are not constrained by any deep seismic data.

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Conclusion