Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/151580
Title: Subduction initiation and the rise of the Shillong Plateau
Authors: Mallick, Rishav
Hubbard, Judith
Lindsey, Eric Ostrom
Bradley, Kyle
Moore, James Daniel Paul
Ahsan, Aktarul
Alam, A. K. M. Khorshed
Hill, Emma M.
Keywords: Science::Geology::Structural geology
Issue Date: 2020
Source: Mallick, R., Hubbard, J., Lindsey, E. O., Bradley, K., Moore, J. D. P., Ahsan, A., Alam, A. K. M. K. & Hill, E. M. (2020). Subduction initiation and the rise of the Shillong Plateau. Earth and Planetary Science Letters, 543, 116351-. https://dx.doi.org/10.1016/j.epsl.2020.116351
Project: NRF2018NRF-NRFI001-21 
Journal: Earth and Planetary Science Letters 
Abstract: Discrepancies between geodetically and geologically estimated thrust fault slip rates are generally viewed as a methodological problem. Even when slip rate is steady over geological time, a discrepancy may exist because each method is sensitive to different deformation processes. However, this offers a tool to estimate the partitioning of convergence between footwall and hanging wall deformation, and therefore a way to discriminate among orogenic styles. Here we investigate one such discrepancy for the Shillong Plateau, a basement-cored contractional orogen within the Himalayan foreland basin. Using a regional block model to explain the modern geodetic velocity field and explicit uncertainty analysis of the geologic rates, we show that this discrepancy cannot be reconciled simply by invoking uncertainties in individual methods. Our results indicate that the Shillong Plateau is not an ongoing forward break of the Bhutan Himalayas, as was believed until recently. Instead, the observed inter-plate convergence and plateau uplift in this region may be driven primarily by an attempt of the negatively buoyant Indian passive margin lithosphere (the Surma Basin), south of the plateau, to initiate subduction. As a result, the uplift history of the plateau, which constrains the geologic rate, is significantly lower than expected given the geodetic convergence rate. We propose that this convergence is largely accommodated by the transport of the footwall into the mantle. This geodynamic scenario has important regional seismotectonic implications: (1) the cold and brittle sinking passive margin may have enabled the deep extent (∼30 km) and therefore large magnitude of the MW 8+ Shillong Earthquake of 1897; (2) the collapse of the Indian lithosphere into the mantle may have created the anomalously deep (∼20 km) Surma Basin; and (3) this subsidence may also drive accelerated post-Miocene westward propagation of the Indo-Burman Wedge. We propose that the Shillong Plateau is the only modern example of passive margin collapse, and can serve as a natural laboratory to study the earliest phase of subduction.
URI: https://hdl.handle.net/10356/151580
ISSN: 0012-821X
DOI: 10.1016/j.epsl.2020.116351
DOI (Related Dataset): https://researchdata.ntu.edu.sg/dataverse/shillongmibb
Rights: © 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:ASE Journal Articles
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