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Elasto-plastic deformation and plate weakening due to normal faulting in the subducting plate along the Mariana Trench
Zhou, ZY; Lin, J; jlin@whoi.edu
2018
Source PublicationTECTONOPHYSICS
Volume734Pages:59-68
AbstractWe investigated variations in the elasto-plastic deformation of the subducting plate along the Mariana Trench through an analysis of flexural bending and normal fault characteristics together with geodynamic modeling. Most normal faults were initiated at the outer-rise region and grew toward the trench axis with strikes mostly subparallel to the local trench axis. The average trench relief and maximum fault throws were measured to be significantly greater in the southern region (5 km and 320 m, respectively) than the northern and central regions (2 km and 200 m). The subducting plate was modeled as an elasto-plastic slab subjected to tectonic loading at the trench axis. The calculated strain rates and velocities revealed an array of normal fault-like shear zones in the upper plate, resulting in significant faulting-induced reduction in the deviatoric stresses. We then inverted for solutions that best fit the observed flexural bending and normal faulting characteristics, revealing normal fault penetration to depths of 21,20, and 32 km beneath the seafloor for the northern, central, and southern regions, respectively, which is consistent with the observed depths of the relocated normal faulting earthquakes in the central Mariana Trench. The calculated deeper normal faults of the southern region might lead to about twice as much water being carried into the mantle per unit trench length than the northern and central regions. We further calculated that normal faulting has reduced the effective elastic plate thickness L by up to 52% locally in the southern region and 33% in both the northern and central regions. The best-fitting solutions revealed a greater apparent angle of the pulling force in the southern region (51-64 degrees) than in the northern (22-35 degrees) and central (20-34 degrees) regions, which correlates with a general southward increase in the seismically-determined dip angle of the subducting slab along the Mariana Trench.
Department[Zhou, Zhiyuan; Lin, Jian] Chinese Acad Sci, South China Sea Inst Oceanol, Key Lab Ocean & Marginal Sea Geol, Guangzhou 510301, Guangdong, Peoples R China; [Lin, Jian] Woods Hole Oceanog Inst, Dept Geol & Geophys, Woods Hole, MA 02543 USA
Subject AreaGeochemistry & Geophysics
WOS KeywordMariana Trench ; Normal fault ; Elasto-plastic deformation ; Plate weakening ; Geodynamic modeling
Funding ProjectMSG
Document Type期刊论文
Identifierhttp://ir.scsio.ac.cn/handle/344004/17132
Collection中科院边缘海地质重点实验室
Corresponding Authorjlin@whoi.edu
Recommended Citation
GB/T 7714
Zhou, ZY,Lin, J,jlin@whoi.edu. Elasto-plastic deformation and plate weakening due to normal faulting in the subducting plate along the Mariana Trench[J]. TECTONOPHYSICS,2018,734:59-68.
APA Zhou, ZY,Lin, J,&jlin@whoi.edu.(2018).Elasto-plastic deformation and plate weakening due to normal faulting in the subducting plate along the Mariana Trench.TECTONOPHYSICS,734,59-68.
MLA Zhou, ZY,et al."Elasto-plastic deformation and plate weakening due to normal faulting in the subducting plate along the Mariana Trench".TECTONOPHYSICS 734(2018):59-68.
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