30The oblique collision of Taiwan orogen led to a progressive southward uplift and 31 emergence of a submarine accretionary wedge. The Hengchun Peninsula located at 32 the southernmost tip of Taiwan island represents the most recently emerged 33 landform of an antecedent submarine surface. In this study we examine the 34 geomorphic evolution of this newly emerged and uplifted landscape.
Taiwan is an archetypal example of continental accretionary wedges. Yet the generally poor knowledge of three-dimensional strain distribution over time and role of architecture of the rifted margin shed doubt on the cylindrical two-dimensional kinematic models of Taiwan collision. Here we provide new field-based constraints on strain distribution, new Raman Spectroscopy on Carbonaceous Materials temperatures and apply mica-chlorite multiequilibrium approach to determine pressure-temperature in the Central Range of Taiwan. We identify three distinct structural domains that define zones of orthogonal shortening in the western Backbone Range and left-lateral ductile shearing overprinted by left-lateral transtensional brittle deformation in eastern Central Range. Field surveys show the lack of nappe stacking in the Backbone Range. Combining new temperature estimates with existing thermochronological constraints we emphasize that western Taiwan mostly inherited preorogenic thermal history. We show that metamorphic peak conditions of 5-6 kbar and 330-400°C in the eastern Backbone Range and HP rocks of the Yuli Belt exhumed along the P-T paths related to transcurrent deformation. We propose a three-dimensional kinematic model of Taiwan accounting for the oblique motion of the Philippine Sea Plate relative to the plate boundary and the reactivation of a NS striking transform fault in the South China Sea rifted margin. Recent and ongoing strain partitioning in the Taiwan accretionary wedge is reflected by the coexistence of brittle left-lateral shear, oblique extension, and contraction. Our results have impact on orogen-based plate kinematic reconstructions that consider two-dimensional kinematic evolution of orogens.
<p>The warming in the Arctic has induced accelerated changes in coastal topography, such as the retreat of glaciers, thaw of permafrost, and increase of erosion and sedimentation along the coastline. A majority of Svalbard territory has been designated as natural reserves for numerous wildlife, especially on the west coast of Spitsbergen, which has seven locations listed as Ramsar Sites. Therefore, monitoring coastal dynamics is crucial for assessments of the climatic impact on those habitats. This study aims to utilize multiple satellite data, including Sentinel-1, Sentinel-2, and Landsat series to reconstruct time-varying digital elevation models (DEMs) over the intertidal zone of west Spitsbergen. The method includes the following steps: (1) classifying water in an image; (2) stacking images for inundation frequency; (3) converting frequency to elevation via a tide model; (4) repeating the workflow in a five-year temporal window. The latest DEM is verified by ICESat-2 spaceborne LiDAR ATL03 photons. Our preliminary results show that the accuracy of DEM, in terms of standard deviation, achieves 0.5 m level. Slight changes in coastal topography have been observed near Longyearbyen and other outlet glaciers.</p>
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