The terrace like feature in the mid-continental slope region off Trivandrum and a plausible model for India–Madagascar juxtaposition in immediate pre-drift scenario

Morphotectonic architecture of an India–Madagascar breakup related anomalous submarine terrace complex on the southwest continental margin of India

“…If this CKE and Vishnu FZ correspondence is correct, then the CKE will appear as the conjugate of the Mauritius FZ since separation of India and Madagascar. However, contrary to this situation, the w 83 Ma reconstruction (Yatheesh et al, 2006) of IndiaeMadagascar with the same Norton and Sclater (1979) rotation parameters or with the much more recent rotation parameters of Müller et al (2008) suggest the CKE region as aligned with the Mahanoro FZ of the Mascarene Basin. These observations cast doubt about the possibility of the CKE as the northwards continuation of the Vishnu FZ.…”

“…Dyment (1991) suggested that the eastern part of northern Madagascar Ridge and the bathymetric high regions of the ATTC are conjugate with respect to Mascarene Basin spreading center. Yatheesh et al (2006) specifically shown that southern part of the ATTC (TT in Fig. 1) fits well in shape and size, with a bathymetric notch located in the northern Madagascar Ridge, as a conjugate feature representing scars related to IndiaeMadagascar break-up.…”

“…This little studied bathymetric protrusion of large areal extent (area > 35,000 sq km) have been postulated (Yatheesh et al, 2006) to represent a scar related to IndiaeMadagascar separation, where its conjugate feature is proposed to be a conspicuous bathymetric notch in the northern Madagascar Ridge. This conjugate association, once unambiguously established, can provide a distinct 'piercing point' to constrain the IndiaeMadagascar juxtaposition in their immediate pre-drift scenario.…”

“…We denote those two features as terraces because their morphological characteristics match well with the definition of an undersea terrace as stipulated by the International Hydrographic Organization (IHO-IOC, 1989). The larger of these two terraces, denoted by Yatheesh et al (2006) as 'Terrace off Trivandrum (TOT)', lies approximately south of the latitude of Trivandrum (Fig. 2) and a smaller terrace, referred as 'Alleppey Platform' (Singh et al, 1999) or 'Terrace off Quilon' (Rao and Bhattacharya, 1975), lies approximately between latitudes of Alleppey and Quilon.…”

A relook into the crustal architecture of Laxmi Ridge, northeastern Arabian Sea from geopotential data

“…If underplating is a necessary pre-requisite for any rifting mechanism, then we infer that Seychelles was attached only to the NW-SE segment of the Laxmi Ridge which was later separated forming the present Arabian Basin. We speculate that the initial rifting of India from Madagascar-Seychelles-Laxmi RidgeLaccadive Ridge took place prior to the passage of Indian plate over the Reunion hotspot, possibly related to the Marion hotspot activity during 85 Ma (Yatheesh et al 2006). But due to some reasons, the rifting got aborted after a given time interval, forming a failed rift, thereby forming a platform for the accumulation of sediments in these failed rift grabens.…”