Depositional history, processes and mechanism of early Miocene sediments of Upper Assam Basin

Abstract

A detailed analysis of depositional history of Miocene sediments and various effects which are governed for creation of accommodation space as well as the processes of sedimentation inherent to the depositional system at that period is described in this work. The early Miocene clastic sediments are deposited in prograding environment where sediment supply exceeds the accommodation space available. The accommodation space created due to basin subsidence and source area upliftment due to local and regional tectonic activity in the basin. In the early Miocene time, the Assam shelf major transgression occurred and several minor transgression followed. There was wide spread deposition of the fluvial Tipam sandstones. In Miocene time due to thrust loading and flexure subsidence, accommodation space was created for deposition of the sediments. The Tipam Sandstone is deposited by cyclic deposition of fining upward sequence in a fluvial to brackish water environment of braided river processes. The mechanism of braided rivers is also discussed in which it laterally expanded, leaving sheet like or wedge -shaped deposits of channel and bar complexes preserving only minor amounts of flood plain material.

Deciphering relationships between the Nicobar and Bengal submarine fans, Indian Ocean

“…At ~5 Ma, a drop in MARs is observed in both the Nicobar Fan and Bengal fans. Also, at ~5 Ma, there was a change in river drainage to west of uplifting Shillong Plateau, but as seen in the provenance (Tipam Formation; Shrivastava et al, 1974;Sahoo and Gogoi, 2009;Sarma and Chutia, 2013). Drainage remained open to the east of the Shillong Plateau.…”

Delineation of oil–water contact within Tipam reservoir: A study from Upper Assam Basin, North‐East India

“…The Upper Assam Basin is a foreland basin located between the foothills of North‐East Himalaya and Assam–Arakan thrust belt (Mandal & Dasgupta, 2013; Murty, 1984; Naidu & Panda, 1997; Nandy, 2017; Sahoo & Gogoi, 2011). Structurally, the basin is located on a regional triangle zone created between the Himalayan Frontal Thrust (HFT) and the Naga Thrust.…”

“…The basin configuration was strongly influenced by the tectonic interplay of Himalayan orogeny in the north, Mishmi Thrust in the east and Assam–Arakan ranges in the south (Figure 1). It is configured as an asymmetric slope dipping towards the Himalayan foothills in the north and the Naga Hills in the south (Corps, 1949; Mandal & Dasgupta, 2013; Pahari et al, 2008; Sahoo & Gogoi, 2011). Towards NE, the basin is terminated by the blocks of Mishmi Thrust (Figure 1), and to the SW, it is partially disrupted by the Shillong plateau basement uplift (Figure 1).…”

Seismic Lithofacies Distribution Modeling Using the Single Normal Equation Simulation (SNESIM) Algorithm of Multiple-Point Geostatistics in Upper Assam Basin, India

“…It is part of the Assam-Arakan Basin, and extend up to the Arakan range, Myanmar. The basin limits are defined by the Naga Hills along the south-eastern boundary, the Eastern Himalayas in the north, and the Mikir Hills in the southwest (Sahoo and Gogoi, 2009). The Basin lies between two convergent margins and is categorized by a central NE-SW trending buried "basement ridge," which is a continuation of the exposed Precambrian basement of the Mikir Hills.…”

“…The geological study suggests that the study area is a part of basin hinge lines with normal faults transacted by reverse faults that preceded the major thrust. The geological interpretation has suggested that the area of study is the vast sedimentation of the Brahmaputra River, having large, braided channels with many meandering channels (Sahoo and Gogoi, 2009). A Ti can be generated with three facies representing shale, water-bearing sand, hydrocarbon-bearing sand based on geological knowledge of the study area, and proportions of lithofacies from the cross-plot analysis.…”