Repeated large-scale mass-transport deposits and consequent rapid sedimentation in the western part of the bay of bengal, india

Yuzuru Yamamoto, Shun Chiyonobu, Toshiya Kanamatsu, Naokazu Ahagon, K. A.N. Aoike, Nana Kamiya, Takanori Ojima, Takehiro Hirose, Takamitsu Sugihara, Saneatsu Saito, Masataka Kinoshita, Yusuke Kubo, Yasuhiro Yamada

Research output: Contribution to journalArticlepeer-review

Abstract

The National Gas Hydrate Program Expedition 02 was conducted in early 2015 using the Drilling Vessel Chikyu in the western part of the Bay of Bengal, India. During drilling off Vishakhapatnam, NE India, some bottom-simulating reflectors were penetrated, and numerous mass-transport deposits (MTDs) were identified. The recovered cores were composed of post-late Miocene muddy slope deposits containing the late Miocene–Pliocene hiatus that is widespread in that region. Based on detailed visual core descriptions and calcareous nannofossil biostratigraphy, two major MTD-rich intervals were identified: the Pleistocene interval above the hiatus, and the middle–late Miocene interval below it. Although the MTDs in both intervals are composed of variously coloured clay–silt blocks in an olive-black or olive-grey silty clay matrix (muddy MTDs), the Pleistocene MTDs consist of larger-sized blocks (mostly less than a few metres but with some >10 m) without clear shear fabrics, whereas the Miocene MTDs contain smaller blocks (<0.1 m) with asymmetrical shear fabrics. The muddy blocks are composed of older components (Pliocene–Cretaceous) compared with the depositional ages of the MTDs. The high abundance of MTDs above the hiatus and the depositional ages of the interbedded coherent layers indicate that large-scale MTDs occurred repeatedly during the Pleistocene. Such repeated MTDs contributed to maintaining the high sedimentation rate in this area and potentially provided stable pressure and temperature conditions for the formation of gas hydrates.

Original languageEnglish
Pages (from-to)183-193
Number of pages11
JournalGeological Society Special Publication
Volume477
Issue number1
DOIs
Publication statusPublished - 2019
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Water Science and Technology
  • Ocean Engineering
  • Geology

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