Zhan Wenhuan

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Zhan
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Wenhuan
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  • Article
    Intra- and intertrench variations in flexural bending of the Manila, Mariana and global trenches : implications on plate weakening in controlling trench dynamics
    (Oxford University Press, 2017-11-08) Zhang, Fan ; Lin, Jian ; Zhou, Zhiyuan ; Yang, Hongfeng ; Zhan, Wenhuan
    We conducted detailed analyses of a global array of trenches, revealing systematic intra- and intertrench variations in plate bending characteristics. The intratrench variations of the Manila and Mariana Trenches were analysed in detail as end-member cases of the relatively young (16–36 Ma) and old (140–160 Ma) subducting plates, respectively. Meanwhile, the intertrench variability was investigated for a global array of additional trenches including the Philippine, Kuril, Japan, Izu-Bonin, Aleutian, Tonga-Kermadec, Middle America, Peru, Chile, Sumatra and Java Trenches. Results of the analysis show that the trench relief (W0) and width (X0) of all systems are controlled primarily by the faulting-reduced elastic thickness near the trench axis (Tme) and affected only slightly by the initial unfaulted thickness (TMe) of the incoming plate. The reduction in Te has caused significant deepening and narrowing of trench valleys. For the cases of relatively young or old plates, the plate age could be a dominant factor in controlling the trench bending shape, regardless the variations in axial loadings. Our calculations also show that the axial loading and stresses of old subducting plates can vary significantly along the trench axis. In contrast, the young subducting plates show much smaller values and variations in axial loading and stresses.
  • Preprint
    Variations in oceanic plate bending along the Mariana trench
    ( 2014-05) Zhang, Fan ; Lin, Jian ; Zhan, Wenhuan
    We quantify along-trench variations in plate flexural bending along the Mariana trench in the western Pacific Ocean. A 3-D interpreted flexural deformation surface of the subducting Pacific Plate was obtained by removing from the observed bathymetry the effects of sediment loading, isostatically-compensated topography based on gravity modeling, age-related lithospheric thermal subsidence, and residual short-wavelength features. We analyzed flexural bending of 75 across-trench profile sections and calculated five best-fitting tectonic and plate parameters that control the flexural bending. Results of analysis revealed significant along-trench variations: the trench relief varies from 0.9 to 5.7 km, trench-axis vertical loading (-V0) from -0.73 × 1012 to 3.17 × 1012 N/m, and axial bending moment (-M0) from 0.1 × 1017 to 2.7× 1017 N. The effective elastic plate thickness seaward of the outer-rise region (Te M) ranges from 45 to 52 km, while that trench-ward of the outer-rise (Te m) ranges from 19 to 40 km. This corresponds to a reduction in Te of 21-61%. The transition from Te M to Te m occurs at a breaking distance of 60-125 km from the trench axis, which is near the outer-rise and corresponds to the onset of observed pervasive normal faults. The Challenger Deep area is associated with the greatest trench relief and axial vertical loading, while areas with seamounts at the trench axis are often associated with more subtle trench relief, smaller axial vertical loading, and greater topographic bulge at the outer-rise.