Tectonic appraisal of the Mid-Thane Creek of Mumbai, India: An integrated geophysical approach
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Indian Academy of Sciences (0123456789().,-volV)(0123456789( ).,-volV)
Tectonic appraisal of the Mid-Thane Creek of Mumbai, India: An integrated geophysical approach J JACOB1,2,* , V K PITCHIKA1, K M DUBEY1,3 , A MISHRA1,4 , P KUMAR1,4, S KUMAR1,5, V P MAHALE2 and A K CHAUBEY1 1
CSIR-National Institute of Oceanography, Regional Center, Lokhandwala Road, Andheri (West), Mumbai, Maharashtra 400 053, India. 2 CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004, India. 3 Department of Marine Sciences, Goa University, Taleigao Plateau, Goa 403 206, India. 4 Academy of ScientiBc and Innovative Research, CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004, India. 5 Department of Geophysics, Banaras Hindu University, Varanasi 221 005, India. *Corresponding author. e-mail: [email protected] [email protected] MS received 10 January 2020; revised 5 June 2020; accepted 24 June 2020
Integrated geophysical surveys, comprising marine magnetic, high resolution shallow seismic and single-beam bathymetry were conducted to assess subsurface tectonics of the Mid-Thane Creek (MTC) of Mumbai. The bathymetry in the intertidal zone of MTC varies drastically due to periodic dredging, with maximum depth up to 6.4 m and a minimum of *1.6 m. High resolution shallow seismic sections up to the depth of *35 m from the sea-Coor are generated to analyze the neotectonic activity of the creek. Imprints of deep-seated lineaments are recognized from magnetic anomaly map of the MTC. To delimit lateral extent of the lineaments/faults, results of several derivative methods including tilt derivative and standard Euler deconvolution are merged with the selected crest value of the horizontal derivative. To estimate depth to the source, Euler deconvolution, tilt derivative, analytic signal, and source parameter imaging method have been used. However, the depth estimation for the lineaments/faults is highly discrepant for this region, because of the complex tectonics associated with the periodic emplacements of Deccan Cood basalt. To conBne the top and bottom boundary of this highly magnetized basaltic layer, we have carried out spectral analysis considering 18 windows of 2000 9 2000 m with an overlap of 500 m. The average depth to the top and bottom of the source body estimated using spectral analysis is consistent with the depth estimated from the derivative Blters. This conBrms that the lineaments identiBed by the derivative Blters may embed in the basaltic layer of MTC. The most prominent lineament interpreted from the seismic and magnetic data, in the central region of MTC is inferred as the marine analogue of Alibagh–Uran Fault passing through the mainland of Alibagh and Uran close to Mumbai city. Keywords. Thane creek; marine magnetic; high resolution shallow seismic; single beam bathymetry; source depth; Cood basalt thickness; spectral analysis.
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1. Introduction The commercial prominence of Thane creek has been emphasized over centuries as the creek serves as navigational channel for Mumbai harb
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