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Formation of the Yazi Spring Stream and its significance on tectonics-climate on the northern slope of Kunlun Mountains 被引量:3
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作者 CHANG Hong ZHANG Peizhen +3 位作者 AN Zhishen WANG Xulong QIANG Xiaoke FU Chaofeng 《Chinese Science Bulletin》 SCIE EI CAS 2005年第18期2063-2068,共6页
The sequences of fluvial terraces in the Yazi Spring Stream are signs of the stepwise uplift of the Kunlun Mountains in the northern part of the Tibetan Plateau since the Late Pleistocene. Geomorphic and sedimentary f... The sequences of fluvial terraces in the Yazi Spring Stream are signs of the stepwise uplift of the Kunlun Mountains in the northern part of the Tibetan Plateau since the Late Pleistocene. Geomorphic and sedimentary features of the terraces reveal that they have resulted from the phased tectonic uplift and the consequent river incision in the northern plateau. Using the method of Single-aliquot Regenerative-dose (SAR) Protocol and Radiocarbon 14C dating, the deposit ages of three-grade terraces were ob- tained, which are 57.5, 12.8 and 5.7 kaBP, respectively. The features and ages of terraces reveal that the incision rate of the stream accelerated at the beginning of the Holocene. The incision rate changed suddenly at 12.8 KaBP, from 0.43±0.07 mm/a to 1.59±0.55 mm/a. This implicates that uplift of the Kunlun Mountains is intensive at the first onset of the Holo- cene, corresponding to the obvious change of slip-rate on the Altyn Tagh Fault. But its uplift rate is much lower than that of the latter, which suggests that growth of the northern mar- gin of the Tibetan Plateau is stronger than its interior. 展开更多
关键词 青藏高原 昆仑山脉 激励发光 沉淀特征 地球科学
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Differences in both the structure and interaction of the crust and mantle on the eastern and western sides of the Ordos Block
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作者 Yong CHEN Yifang CHEN +3 位作者 Jiuhui CHEN Biao GUO Yu LI Panpan ZHAO 《Science China Earth Sciences》 SCIE EI CAS 2024年第12期3900-3913,共14页
The Ordos Block,the western part of the North China Craton(NCC),has preserved most of its cratonic lithospheric roots during the destruction and modification of the NCC,and nowconnects two distinctly different tectoni... The Ordos Block,the western part of the North China Craton(NCC),has preserved most of its cratonic lithospheric roots during the destruction and modification of the NCC,and nowconnects two distinctly different tectonic units,i.e.,the Tibetan Plateau(TP)to the west and the North China Plain to the east.It is important to studythe detailed crust-mantle structure of the Ordos Block and surroundings to understand the interactions between the Ordos and adjacent regions and the dynamics of the NCC evolution.In this study,the S-wave velocity structure at depths of 0–100 km along an E-W profile at around 36.5°N from the Qilian orogen(QLO)to the Trans-North China Orogen(TNCO)within the NCC was investigated by joint inversion of the receiver functions(RFs)and surface wave dispersion data from 104 broadband seismic stations deployed in the region under the ChinArray project(PhaseⅡand PhaseⅢ).The image of discontinuity structures along the profile was further constructed by common conversion point stacking of RFs.The main results are as follows:(1)The depth of the Moho in the study region gradually decreases from west to east,being the deepest in the QLO,the second in the Ordos Block,and the shallowest in the TNCO.Local depression and uplift of the Moho are also identified beneath the Haiyuan fault zone and the Shanxi-Shaanxi rift system(SSR),respectively.(2)The crust-mantle structure displays obvious lateral heterogeneities among tectonic regions.A pronounced low-velocity anomaly is observed at depths of 20–40 km beneath the QLO and becomes weakened and thinned to the east,indicating that thickening of the mid-to-lower crust probably occurred in the QLO during the growth and lateral extrusion of the northeastern TP under the resistance of the NCC.The lithosphere-asthenosphere boundary beneath the TNCO is imaged at~90 km depth,which is significantly shallower than that beneath the Ordos Block.This observation suggests that the lithosphere of the TNCO may have experienced a notable thinning,possibly by thermal erosion and modification due to the mantle upwelling associated with the western Pacific subduction in the Mesozoic.(3)The uplifted Moho under the SSR and its neighboring areas is spatially coincident with the thinned lithosphere in the TNCO,indicating a close relationship between the development of the SSR and the lithospheric thinning and modification in this region. 展开更多
关键词 Ordos Block Qilian orogen Shanxi-Shaanxi rift system Mid-to-lower crustal thickening Mantle upwelling
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