85°E Ridge, India — constraints on its development and architecture

Abstract

The 85°E Ridge is a buried aseismic ridge running parallel to the 85°E meridian in the Bay of Bengal, India. Its origin has been a subject of debate, with opinions ranging from an abandoned spreading centre to a hotspot track. The present study follows the hotspot hypothesis and incorporates gravity, magnetic and seismic data to identify the nature and interpret the origin of the 85°E Ridge. It differs from earlier studies in the integration of deep seismic lines and gravity inversion to identify crustal architecture below the 85°E Ridge. Seismic interpretation along with gravity inversion has been used to determine the crustal structure below the ridge, while sediment thickness maps have been used to infer the uplift during the ridge emplacement. Seismic interpretations together with isostatic residual gravity anomaly map have been used to associate large negative anomalies with hotspot related magmatism. The negative anomaly increases with increasing volcanic load, indicating the presence of a crustal root and magmatic underplating. Typical flexural moat and arch, indicative of hotspot volcanism, is also observed in the seismic profiles. Gravity inversion modeling indicates an "onion-shell" like structure within the volcanic load, inferring the presence of less dense outer layers with a heavier core within the complex. Sediment thickness maps show the presence of dynamic uplift of more than 2000 milliseconds from early Cretaceous onwards. The study concludes that the 85°E Ridge is a result of hotspot volcanism, and proposes a plausible model for the origin of the structure.

Middle to Late Pleistocene Architecture and Stratigraphy of the Lower Bengal Fan—Integrating Multichannel Seismic Data and IODP Expedition 354 Results

“…LM = lower Meghna River; SoNG = Swatch of No Ground. Tectonic features and fan outlines are redrawn after Bastia, Das, et al (), Bastia, Radhakrishna, et al (), Choudhuri et al (), Curray et al (), and McNeill et al ().…”

“…LM = lower Meghna River; SoNG = Swatch of No Ground. Tectonic features and fan outlines are redrawn after , , Choudhuri et al (2014), Curray et al (2003), andMcNeill et al (2017). 10.1029/2019GC008702 have also been described for the Amazon Fan (e.g., Lopez, 2001;Piper et al, 1997), the Congo Fan (Marsset et al, 2009;Savoye et al, 2009), and the Mississippi Fan (Bouma et al, 1989).…”

Overture for the Mandara and Vasuki Plates

“…Left: Small circles (white lines) for an Euler pole ("Centre") at 28.45°S, 25.94°E (calculated for Antarctica in Indian plate reference from Gibbons et al, 2013). Yellow double arrows: relative plate motion azimuths estimated using basement topography contours and fault traces from seismic reflection data (thin yellow lines) along the Indian sheared margin segment and buried strike-slip faults (Choudhuri et al, 2014;Nemčok et al, 2016). Right: Same, for Euler pole at 7.20°N, 1.84°E.…”

A new vision for hydrocarbon trapping of Alam El-Bueib Formation in Aman oil field using Fault seal analysis technique, northern Western Desert, Egypt.

“…Seismic data can be analyzed according to the required investigation. These analyses such as deformed structure can be geometrically analyzed in the hydrocarbon reservoirs [31][32], Crustal architecture analyses [33][34][35][36][37], Strain Analysis [38], and progressive deformation analysis which is important in trapping and sealing of faults reduction analysis as faults reactivate. The timing of the formation of traps vis the timing of hydrocarbon generation is also matched to understand the charging of the reservoir [39][40].…”