DOI: 10.1016/j.epsl.2020.116351
论文题名: Subduction initiation and the rise of the Shillong Plateau
作者: Mallick R. ; Hubbard J.A. ; Lindsey E.O. ; Bradley K.E. ; Moore J.D.P. ; Ahsan A. ; Khorshed Alam A.K.M. ; Hill E.M.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 543 语种: 英语
中文关键词: active tectonics
; geodesy geology
; mountain building
; Shillong Plateau
; subduction initiation
; Surma Basin
英文关键词: Deformation
; Earthquakes
; Fault slips
; Geodesy
; Geodynamics
; Velocity
; Convergence rates
; Deformation process
; Hanging-wall deformations
; Methodological problems
; Natural laboratories
; Plate convergence
; Seismotectonics
; Subduction initiation
; Uncertainty analysis
; deformation
; foreland basin
; orogeny
; plate convergence
; slip rate
; subduction
; uncertainty analysis
; uplift
; India
; Shillong Plateau
英文摘要: 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. © 2020 The Author(s) Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165146
Appears in Collections: 气候变化与战略
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作者单位: Asian School of the Environment, Nanyang Technological University, Singapore; Earth Observatory of Singapore, Nanyang Technological University, Singapore; Geological Survey of Bangladesh, Dhaka, Bangladesh
Recommended Citation:
Mallick R.,Hubbard J.A.,Lindsey E.O.,et al. Subduction initiation and the rise of the Shillong Plateau[J]. Earth and Planetary Science Letters,2020-01-01,543