Crustal architecture and rift tectonics across the Visakhapatnam Bay basin, central-east Indian margin: Insights from mu
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Indian Academy of Sciences (0123456789().,-volV)(0123456 789().,-volV)
Crustal architecture and rift tectonics across the Visakhapatnam Bay basin, central-east Indian margin: Insights from multichannel seismic and potential field data PRANAYA SANGVAI1, G SRINIVASA RAO2, K S R MURTHY3 and M RADHAKRISHNA4,* 1 E&P 2
Division, Reliance Industries Ltd., Navi Mumbai, India. Department of Applied Geophysics, Indian Institute of Technology (Indian School of Mines) Dhanabad, Dhanabad 826 004, India. 3 CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam 530 003, India. 4 Department of Earth Sciences, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India. *Corresponding author. e-mail: [email protected] MS received 3 September 2018; revised 16 July 2019; accepted 18 July 2019
The Visakhapatnam Bay (VB) basin is a passive margin rift basin located at the non-basinal segment of the Eastern Continental Margin of India (ECMI) and formed during the rift–drift events associated with the breakup of eastern Gondwanaland. In the present study, integrated analysis of potential field and multi-channel seismic reflection (MCS) data were carried out to understand the rift tectonics, crustal configuration and onshore–offshore structural continuity across this basin. The study revealed the following: (i) crustal models derived through joint gravity-magnetic modelling show limited stretching with 36–40 thick crust below the Eastern Ghat Mobile Belt (EGMB) thinning down to 16–20 km at the Ocean Continent Transition (OCT), (ii) extension of Charnockitic basement associated with the Eastern Ghat Mobile Belt (EGMB) into the offshore region. Comparison of the crustal configuration across the VB basin with that across the adjacent thick sedimentary area of the Krishna–Godavari shows that upper crustal configuration is significantly different in the VB area. The observed limited rift related structuration (horst-graben morphology), the mapped high angle break-away fault with large offset in the seismic data and narrow width (70–90 km) of extended crustal domain in VB basin suggests that this segment acts as transfer zone between Krishna–Godavari and Mahanadi rift zones. Further, long curvelinear trend of magnetic anomalies associated with Pudimadaka Lineament (PKL) demarcate the VB basin from the adjacent Krishna–Godavari rift zone. Keywords. Crustal structure; rift tectonics; Visakhapatnam Bay basin; Eastern Continental Margin of India.
1. Introduction Previous studies have very well established that the development of passive eastern Indian margin is related to the rifting and breakup of India and
East Antarctica during Early Cretaceous (Powell et al. 1988). The pre-existing geology of the East Coast of India (figure 1A), predominantly characterized by the eastern Indian shield crust having high-grade granulite rocks in the south, the
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J. Earth Syst. Sci. (2020)129:28
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A Figure 1. (A) Tectonic map of the East Coast margin of India (after Lal et al. 2009), (B) Topography map of central pa
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