Title

Large-scale mass wasting on the miocene continental margin of Western India

Authors

Sarah K. Dailey, Louisiana State University
Peter D. Clift, Louisiana State University
Denise K. Kulhanek, Texas A&M University
Jerzy Blusztajn, Woods Hole Oceanographic Institution
Claire M. Routledge, University College London
GérÔme Calvès, Universite Paul Sabatier Toulouse III
Paul O'Sullivan, GeoSep Services
Tara N. Jonell, The University of Queensland
Dhananjai K. Pandey, National Centre for Polar and Ocean Research
Sergio Andò, University of Milano - Bicocca
Giovanni Coletti, University of Milano - Bicocca
Peng Zhou, Louisiana State University
Yuting Li, College of Science
Nikki E. Neubeck, Louisiana State University
James A.P. Bendle, University of Birmingham
Sophia Aharonovich, Macquarie University
Elizabeth M. Griffith, The Ohio State University
Gundiga P. Gurumurthy, Birbal Sahni Institute of Palaeobotany
Annette Hahn, University of Bremen
Masao Iwai, Kochi University
Boo Keun Khim, Pusan National University
Anil Kumar, Wadia Institute of Himalayan Geology
A. Ganesh Kumar, National Institute of Oceanography India
Hannah M. Liddy, Center for Climate Systems Research
Huayu Lu, Nanjing University
Mitchell W. Lyle, Oregon State University
Ravi Mishra, National Centre for Polar and Ocean Research
Tallavajhala Radhakrishna, Centre for Earth Science Studies India
Rajeev Saraswat, National Institute of Oceanography India
Rakesh Saxena, Oil and Natural Gas Corporation Limited
Giancarlo Scardia, UNESP-Universidade Estadual Paulista
Girish K. Sharma, Kumaun University India
Arun D. Singh, Banaras Hindu University

Document Type

Article

Publication Date

1-1-2020

Abstract

© 2019 Geological Society of America. A giant mass-transport complex was recently discovered in the eastern Arabian Sea, exceeding in volume all but one other known complex on passive margins worldwide. The complex, named the Nataraja Slide, was drilled by International Ocean Discovery Program (IODP) Expedition 355 in two locations where it is ~300 m (Site U1456) and ~200 m thick (Site U1457). The top of this mass-transport complex is defined by the presence of both reworked microfossil assemblages and deformation structures, such as folding and faulting. The deposit consists of two main phases of mass wasting, each consisting of smaller pulses, with generally fining-upward cycles, all emplaced just prior to 10.8 Ma based on biostratigraphy. The base of the deposit at each site is composed largely of matrix-supported carbonate breccia that is interpreted as the product of debris-flows. In the first phase, these breccias alternate with wellsorted calcarenites deposited from a high-energy current, coherent limestone blocks that are derived directly from the Indian continental margin, and a few clastic mudstone beds. In the second phase, at the top of the deposit, muddy turbidites dominate and become increasingly more siliciclastic. At Site U1456, where both phases are seen, a 20-m section of hemipelagic mudstone is present, overlain by a ~40-m-thick section of calcarenite and slumped interbedded mud and siltstone. Bulk sediment geochemistry, heavy-mineral analysis, clay mineralogy, isotope geochemistry, and detrital zircon U-Pb ages constrain the provenance of the clastic, muddy material to being reworked, Indus-derived sediment, with input from western Indian rivers (e.g., Narmada and Tapti rivers), and some material from the Deccan Traps. The carbonate blocks found within the breccias are shallow-water limestones from the outer western Indian continental shelf, which was oversteepened from enhanced clastic sediment delivery during the mid-Miocene. The final emplacement of the material was likely related to seismicity as there are modern intraplate earthquakes close to the source of the slide. Although we hypothesize that this area is at low risk for future mass wasting events, it should be noted that other oversteepened continental margins around the world could be at risk for mass failure as large as the Nataraja Slide.

Publication Source (Journal or Book title)

Bulletin of the Geological Society of America

First Page

85

Last Page

112

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