Crustal velocity structure of the Neoarchean convergence zone between the eastern and western blocks of Dharwar Craton, India from seismic wide-angle studies
“…This boundary shear zone has also been central to a recent experiment of deep-seismic wide-angle refraction and coincident reflection profile between Chickmagalur and Perur (Fig. 1, Vijaya Rao et al, 2015b;Mandal et al, 2018). This data offers a new insight into the assembly of EDC and WDC together with recent results from modelling of gravity, magnetic and magnetotellurics data along the profile Pratap et al, 2018).…”
Section: Post 30 Ga Crust: the Neoarchean Orogenysupporting
“…This boundary shear zone has also been central to a recent experiment of deep-seismic wide-angle refraction and coincident reflection profile between Chickmagalur and Perur (Fig. 1, Vijaya Rao et al, 2015b;Mandal et al, 2018). This data offers a new insight into the assembly of EDC and WDC together with recent results from modelling of gravity, magnetic and magnetotellurics data along the profile Pratap et al, 2018).…”
Section: Post 30 Ga Crust: the Neoarchean Orogenysupporting
“…The CRS-stack section is time-migrated and presented in depth using the velocity information from the coincident refraction data 11 . The conventional CMP and relatively new CRS stacking images are presented in Fig.…”
Section: Seismic Reflection Datamentioning
confidence: 99%
“… Figure 1 Geological map of Archean Dharwar craton, southern India, along with the Perur-Chikmagalur main and Parasurampura-Sira cross-profiles marked over it. (modified after Vijaya Rao et al 11 ). EDC-Eastern Dharwar Craton; WDC-Western Dharwar Craton; CEBSZ-Chitradurga Eastern Boundary Shear Zone.…”
Section: Introductionmentioning
confidence: 99%
“…A DHARSEIS experiment was conducted to understand the structure, dynamics, and tectonic evolution of the Dharwar craton and to delineate the accretionary boundary between the WDC and EDC 11 . Further, it is designed to understand the mechanism of the plateau uplift in the region.…”
Section: Introductionmentioning
confidence: 99%
“…Deep crustal seismic studies along the main profile provided the subsurface crustal structure and velocity-depth model 11 , 20 , 21 . These studies suggested accretion of the WDC and EDC during the Neoarchean convergence based on the differences in crustal structure, the Moho geometry, and crustal thickness between them.…”
Plateaus, located far away from the plate boundaries, play an important role in understanding the deep-rooted geological processes responsible for the epeirogenic uplift and dynamics of the plate interior. The Karnataka plateau located in the Dharwar craton, southern India, is a classic example for the plateau uplift. It is explored using orthogonal deep crustal seismic reflection studies, and a mechanism for the epeirogenic uplift is suggested. A pseudo three-dimensional crustal structure derived from these studies suggests a regionally extensive 10 km thick magmatic underplating in the region. It is further constrained from active-source refraction and passive-source seismological data. We interpret the Marion and Reunion mantle plume activities during 88 Ma and 65 Ma on the western part of Dharwar craton are responsible for the magmatic underplating, which caused epeirogenic uplift. Flexural isostasy related to the onshore denudational unloading and offshore sediment loading is also responsible for the persisting uplift in the region. Plate boundary forces are found to be contributing to the plateau uplift. The present study provides a relationship between the mantle plumes, rifting, development of continental margins, plateau uplift, and denudational isostasy. Combination of exogenic and endogenic processes are responsible for the plateau uplift in the region.
The Indian subcontinent comprises geological terranes of varied age and structural character. In this study, we provide new constraints to existing crustal models by inverting the P‐to‐s receiver functions (RFs) at 317 broadband seismic stations. Inversion results fill crucial gaps in existing velocity models (CRUST1.0 and SEAPS) by capturing regions which are less represented. The final model produced is much more heterogeneous and is able to capture the structural variations between closely spaced seismic stations. In comparison to the global models, major differences are seen for seismic stations located over various rift zones (e.g., Godavari, Narmada, and Cambay) and those close to the coastal regions where transition from oceanic to continental crust is expected to create drastic changes in the crustal configuration. Seismic images are produced along various profiles using 49,682 individual RFs recorded at 442 seismic stations. Lateral variations captured using migrated images across the Himalayan collisional front revealed the hitherto elusive southern extent of the Moho and intracrustal features south of the Main Central Thrust (MCT). Poisson's ratio and crustal thickness estimates obtained using H‐k stacking technique and inversion of RFs are grossly similar lending credence to the robustness of inversions. An updated crustal thickness map produced using 1,525 individual data points from controlled source seismics and RFs reveals a (a) thickened crust (>55 km) at the boundary of Dharwar Craton and Southern Granulite Terrain, (b) clear difference in crustal thickness estimates between Eastern Dharwar Craton and Western Dharwar Craton, (c) thinner crust beneath Cambay Basin between southwest Deccan Volcanic Province and Delhi‐Aravalli Fold Belt, (d) thinner crust (<35 km) beneath Bengal Basin, (e) thicker crust (>40 km) beneath paleorift zones like Narmada Son Lineament and Godavari Graben, and (f) very thick crust beneath central Tibet (>65 km) with maximum lateral variations along the Himalayan collision front.
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