New seismic images of the Central Indian Suture Zone and their tectonic implications

Abstract

[1] The Central Indian Suture (CIS), a mega shear zone, located in the central part of the Indian shield exhibits a complex structure with compositional heterogeneity. Multifold deep seismic reflection data acquired across the shear zone have been previously processed using the conventional common midpoint (CMP) method. In this study, we show results from imaging this shear zone using the common reflection surface (CRS) stack method, an alternative to the CMP stack. Our new images reveal geological features that are either poorly resolved or entirely absent in the earlier CMP stack section. Our major findings include a well-imaged Moho throughout the study area, existence of different crustal blocks each with distinct dipping reflection fabrics on the northern and southern sides of the CIS, a well-defined 8 km of Moho offset beneath the CIS, and a high-amplitude reflective zone representing the CIS. The Moho located at a depth of 48 km in the Bastar craton, to the south of the CIS, is also clearly resolved in our CRS stack, as well as in the time-migrated section. A deeply penetrating crustal-scale imbricated structure imaged up to a depth of 16.0 s two-way time (TWT), to the south of the CIS, suggests that the Bastar craton is subducting toward north. An oppositely dipping reflection fabric, a Moho offset, a positive-negative gravity anomaly pair, and the geological data indicate that the CIS represents a collision zone developed due to the interaction of the Bastar and Bundelkhand cratons with the evolution of the Sausar orogeny at~1000 Ma. This orogeny is contemporaneous with the Grenvillian orogeny and Rodinia assembly. Another thrust fault extending from 4 to 14 s TWT observed to the north of the CIS may represent the earlier, pre-Sausar orogenic activity at 1.6-1.5 Ga. The available seismic characteristics suggest that the CIS, the collisional suture, is also likely to represent a strike-slip fault.

The current status of orogenesis in the Central Indian Tectonic Zone: A view from its Southern Margin

“…This tectonic interpretation when combined with new geophysical (Mandal, Sen, & Vijaya Rao, ) and zircon Hf‐isotopic data (Bhowmik et al, ) confirms previous predictions that the CIS marks an Early Mesoproterozoic suture. The suture, which is traditionally considered to represent the boundary between North and South Indian blocks, has been placed at the southern margin of the BBG belt, separating it from the South Indian Block (Figure ; e.g., Jain et al, ; Yedekar et al, ).…”

Mega‐scale Moho relief and the structure of the lithosphere on the eastern flank of the Viking Graben, offshore southwestern Norway

“…Here south dipping segments of high reflectivity are separated by zones of lower reflectivity. Similar structures are known from the Protoproterozoic Trans‐Hudson Orogen [ Lucas et al ., ] and the Mesoprotrozoic and Neoprotrozoic parts of the Central Indian Suture Zone of the Himalayan Orogen [ Burg et al ., ; Mandal et al ., ]. There, the structures are taken as indications of contractional shear, consistent with a strong lower crust [ Burg et al ., ; Mandal et al ., ].…”

“…Similar structures are known from the Protoproterozoic Trans-Hudson Orogen [Lucas et al, 1993] and the Mesoprotrozoic and Neoprotrozoic parts of the Central Indian Suture Zone of the Himalayan Orogen [Burg et al, 1994;Mandal et al, 2013]. There, the structures are taken as indications of contractional shear, consistent with a strong lower crust Tectonics 10.1002/2014TC003778 [Burg et al, 2002;Mandal et al, 2013]. Also, Meissner [1996] emphasized that contraction structures in the lower crust has a better potential for preservation than do extension structures and cited the Wind River Thrust in Wyoming [Smithson et al, 1979[Smithson et al, , 1980, the Grenville front in North America [Green et al, 1988;Milkreit et al, 1990], and the Appalachians as examples of this.…”

“…Detailed interpretation of the lower crust and the upper mantle from deep reflection seismic data is commonly difficult and controversial due to limited seismic resolution and the uncertainty of geological constraints [ Burg et al ., ; Brittan and Warner , ; Meissner , ; Culshaw et al ., ; Anahnah , ; Anahnah et al ., ; Jones et al ., ; Mandal et al ., ]. Still, hard data for describing the lower crust and the upper mantle can sometimes be derived from outcrops of rocks that have been brought to the surface by tectonic and erosional processes [ Wernicke , , ; Miller et al ., ; Allmendinger et al ., ; Block and Royden , ; Whitney et al ., ; Platt et al ., ] together with potential field geophysical data [e.g., Fichler and Hospers , ; Holliger and Klemperer , ; Fichler et al ., ], teleseismicity, and refraction or reflection seismic data [ Holliger and Klemperer , ; Marsden et al ., ; Christiansson et al ., ; Odinsen et al ., ].…”

Common Reflection Surface Stack Imaging of the Proterozoic Chambal Valley Vindhyan Basin and Its Boundary Fault in the Northwest India: Constraints on Crustal Evolution and Basin Formation

“…However, only a few applications are also found in the crustal structure and tectonics studies (e.g. Mandal et al, 2014, Mandal et al, 2013, Menyoli et al, 2004, Yoon et al, 2009).…”