| 项目编号: | 1345096
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| 项目名称: | Adjoint tomography of the crustal and upper-mantle seismic structure beneath Continental China |
| 作者: | Min Chen
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| 承担单位: | William Marsh Rice University
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| 批准年: | 2013
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| 开始日期: | 2014-08-01
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| 结束日期: | 2017-07-31
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| 资助金额: | USD250000
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| 资助来源: | US-NSF
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| 项目类别: | Standard Grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Geosciences - Earth Sciences
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| 英文关键词: | china
; east asia
; seismic structure
; fabric structure
; adjoint tomography
; east china
; upper-mantle structure
; widespread intracontinental rifting
; lithosphere
; ancient continental root
; south china
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| 英文摘要: | East Asia has drawn much attention of geoscientists due to its complicated zoo of tectonic activities: unique continent-continent collision of India and Asia, different styles of plate subduction, various types of hydrocarbon-bearing basin formation, widespread intracontinental rifting, intraplate volcanism and magamatism. Tracing the driving forces behind these tectonic activities is vital to understand how the ancient continental roots, continental and oceanic plates at the plate margins, and mantle flows underlying lithosphere interact amongst each other in a dynamic earth framework. It?s essential to obtain high-definition multi-parameter seismic images of the earth?s interior to test different hypotheses of the tectonic driving forces, such as crustal shortening or/and Indian plate underthrusting causing the uplift of ?the world?s roof?, the Tibetan Plateau, lower-mantle plume or/and dehydration from the stagnant slab in the mantle transition zone (410 ? 650 km depths) inducing hot mantle upwelling contributing to the intraplate volcano Changbaishan along the border of China and North Korea, and the Pacific slab subduction and rollback producing extension, transtension, and thinning of the lithosphere beneath the East China and opening of the marginal seas of Japan and South China. Seismic imaging in this study will map full waveforms of seismic records to render more realistic models representing the earth?s interior properties. The outcome will not only provide the independent and robust seismological constrains to test the end members of tectonic formation mechanism, but also shed new light on the composition, thermal state, flow and fabric structure of the lithosphere and upper mantle, which are complementary to geological, geochemical, petrological, and geodetic observations of East Asia.
An unprecedented seismic waveform dataset recorded by very dense array stations in China and its surrounding regions will be used to image the crust and upper-mantle structure beneath the East Asia. This dataset is comprised of seismic records from the CEArray, the NECESSArray, the INDEPTH-IV Array, F-net and other global and regional seismic networks. Contrary to traditional ray-theory based seismic imaging, adjoint tomography of this study takes into account full 3D wave propagation effects and off-ray-path sensitivity. In this implementation, it utilizes a spectral-element method for precise wave propagation simulations. The tomographic method starts with a 3D initial model that combines the smooth radially anisotropic mantle model S362ANI with 3D crustal model Crust2.0 (potentially recently released Crust1.0 can be used for more accurate and higher resolution model refinement). Traveltime and amplitude misfits are minimized iteratively based on a conjugate gradient method, harnessing 3D finite-frequency kernels computed for each updated 3D model. The massively parallel simulations are carried out on XSEDE supercomputers available to the team via an existing XSEDE research allocation. The final models will allow close examination of seismic structures beneath different tectonic units of East Asia, and better understanding of how sub-surface processes shaping surface geology and tectonic features. The preliminary results already show strong correlations between heterogeneities in the crust and upper mantle with surface tectonic units, such as the Himalaya Block, the Tibetan Plateau, the Tarim Basin, the Ordos Block, and the Sichuan Basin. Narrow slab features emerge from the smooth initial model above the transition zone. 3D wavespeed variations in the preliminary model are either comparable to or sharper than high-frequency P- and S-wave tomographic images from previous studies. Additional iterations will be carried out to refine the 3D radially anisotropic models, and to resolve 3D azimuthal anisotropy and attenuation, which are closely related to mantle rheology and crustal and lithospheric strain rates and flow. This proposal will support one graduate student and one research scientist. The outcome of this research will also have a broader impact on understanding the linkage between 3D wavespeed heterogeneities and seismogenic processes. The more realistic high-definition models will help assess seismic hazard by providing more accurate ground motion maps, more robust slip predictions and rupture estimations on finite fault surfaces for future catastrophic earthquakes. The final models will be archived and distributed for quantitative studies in other fields of geoscience, such as geology, geochemistry, petrology, geodynamics and volcanology. With the existing 3D visualization lab facility at Rice, the earth models can be readily displayed to the public to promote earth science. Finally the results will enhance scientific communication between US and China and broaden future potential collaborations.
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| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/96056
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| Appears in Collections: | 影响、适应和脆弱性
气候减缓与适应
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| Recommended Citation: | |
Min Chen. Adjoint tomography of the crustal and upper-mantle seismic structure beneath Continental China. 2013-01-01.
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