Paleogene plate tectonic evolution of the Arabian and Eastern Somali basins

Abstract

We review previous models for the Paleogene tectonic evolution of the Arabian and Eastern Somali basins and present a model based on a new compilation of magnetic and gravity data. Using plate reconstructions, we derive a self-consistent set of isochrons for Chron 27 to Chron 21 (61–46 Ma). The new isochrons account for the development of successive ridge propagation events along the Carlsberg Ridge, leading to an important spreading asymmetry between the conjugate basins. Our model predicts the growth of the outer and inner pseudofaults associated with the ridge propagation events. The location of outer pseudo-faults appears to remain very stable despite a drastic change in the direction of ridge propagation before Chron 24 (c. 54 Ma). The motion of the Indian plate relative to the Somalian plate is stable in direction through Paleogene time; spreading velocities decrease from 6 to 3 cm a−1. Our reconstructions also confirm that the Arabia-India plate boundary was located west of the Owen Ridge along the Oman margin during Paleogene time; some compression is predicted at about Chron 21 (47 Ma) between the Indian and Arabian plates.

Early oceanic opening off Western India–Pakistan margin: The Gop Basin revisited

“…Widely observed highly reliable imprints of large scale ridge propagation in the area (Miles and Roest, 1993;Chaubey et al, 1998Chaubey et al, , 2002Dyment, 1998;Miles et al, 1998;Royer et al, 2002) indeed strengthen this inference.…”

“…Additional time constraints come from the adjacent Arabian Basin, where the seafloor spreading history is well established (e.g., Chaubey et al, 1998Chaubey et al, , 2002Dyment, 1998;Royer et al, 2002). Fig.…”

“…The conjugate Arabian and Eastern Somali basins (Northwestern Indian Ocean) have been formed by seafloor spreading along the Carlsberg Ridge since early Tertiary time; the Laxmi and Laccadive ridges mark the landward boundary of this oceanic crust in the Arabian Basin (McKenzie and Sclater, 1971;Norton and Sclater, 1979;Naini and Talwani, 1982;Schlich, 1982;Bhattacharya et al, 1992;Chaubey et al, 1993Chaubey et al, , 1998Chaubey et al, , 2002Miles and Roest, 1993;Miles et al, 1998;Dyment, 1998;Royer et al, 2002). However, between the Laxmi Ridge and the India-Pakistan continental shelf is a wide region of deep offshore, whose genesis and evolution still remains to be confidently established.…”

Geoelectric structure of northern Cambay rift basin from magnetotelluric data

“…The eruption of the DVP by the Reunion hotspot has been inferred as late syn-rift-tobreakup volcanism contemporaneous with the separation of the Seychelles and India ~ 65 Ma ago. As the Indian plate started moving northward, the adjacent offshore areas were influenced by the Reunion hotspot, resulting in various magmatic intrusions within the stretched continental crust of the WCMI (Bhattacharya and Chaubey 2001;Chaubey et al 2002;Royer et al 2002). The region was uplifted around the impingement location of the hot mantle plume and developed a four-way radially deviating mega-fracture pattern.…”

Guest editorial for the special issue “Tectonics of Bay of Bengal and Arabian Sea with special emphasis on coastal and marine geohazards”

“…Subsequent geophysical studies during the period from 1970 to this date, mainly by the National Institute of Oceanography, India, and also by other academic institutes and organizations led to the generation of several new concepts on the structure, tectonics, and geodynamic evolution of the Bay of Bengal and Arabian Sea region. Satellite altimetry derived free-air gravity data along with ship-borne gravity and magnetic data sets, integrated with multichannel seismic data during the last two decades, added significant new information on the breakup and spreading history of the Indian Ocean Radha Krishna et al 2002;Royer et al 2002;Ramana et al 2003;Krishna et al 2009;Ajay et al 2010). In contrast, studies related to marine geohazards are relatively sparse in the northern Indian Ocean.…”