检索条件"作者=DENG Xiguang, DING Lin, LIU Xiaohan & ZHOU YongLaboratory of Lithospheric Tectonic Evolution, Institute of geology and geophysics,{2.,{3., China"
The petrology and mineral assemblages of blueschists in the Gangmar, central Qiangtang, northern Tibet were examined, which indicates that the metamorphic condition is high-pressure low-temperature. In this note, we r...
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The petrology and mineral assemblages of blueschists in the Gangmar, central Qiangtang, northern Tibet were examined, which indicates that the metamorphic condition is high-pressure low-temperature. In this note, we reported the 40Ar/3.Ar dating results of glaucophane from two blueschist samples. Their apparent ages are (2.5.0±1.3. Ma and (2.7.6±2.3. Ma and similar isochron ages are (2.5.0±0.9) Ma and (2.2.4±0.8) Ma, respectively. These iso-topic datings show the high-pressure metamorphism occurring in Lower Permian. The ages also coincide with the evolution of Palaeo-Tethys ocean in Late Palaeozoic.
The uplift history of south-eastern Tibet is crucial to understanding processes driving the tectonic {2. of the Tibetan Plateau and surrounding areas. Underpinning existing palaeoaltimetric studies has been regi...
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The uplift history of south-eastern Tibet is crucial to understanding processes driving the tectonic {2. of the Tibetan Plateau and surrounding areas. Underpinning existing palaeoaltimetric studies has been regional mapping based in large part on biostratigraphy that assumes a Neogene modernization of the highly diverse, but threatened, Asian biota. Here, with new radiometric dating and newly collected plant-fossil archives, we quantify the surface height of part of the south-eastern margin of Tibet in the latest Eocene(~3. Ma) to be ~3.km and rising, possibly attaining its present elevation(3.9 km) in the early Oligocene. We also find that the Eocene–Oligocene transition in south-eastern Tibet witnessed leaf-size diminution and a floral composition change from sub-tropical/warm temperate to cool temperate, likely reflective of both uplift and secular climate change, and that, by the latest Eocene, floral modernization on Tibet had already taken place, implying modernization was deeply rooted in the Palaeogene.
The Xuhuai fold thrust belt(XHTB)is a curved structure in the southeastern margin of the North china Craton(NCC)that has attracted great attentions due to its tectonic and petrological ***,few geophysical studies have...
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The Xuhuai fold thrust belt(XHTB)is a curved structure in the southeastern margin of the North china Craton(NCC)that has attracted great attentions due to its tectonic and petrological ***,few geophysical studies have focused on the deep structure of this *** this study,we carry out a systematic demonstration of the main geophysical features that characterize the XHTB and surroun{2. *** results reveal small negative gravity and magnetic anomalies,thin crust and lithosphere,lower shear velocity and shallower earthquake epicenters relative to other areas of the NCC,collectively indicating a {3.-scale rheological anomaly at this *** magnetic alignments show a trend similar to that of geological units in southeastern NCC and adjacent areas,although they differ from the SKS-splitting fast polarization directions,except in the Qinling-Dabie orogen where a vertical coherent deformation of the crust and mantle may be involved *** on the geophysical data,we propose a detachment-controlled model,which was caused by the different detachment depth/strength,for the formation of XHTB to explain its arcuate shape as well as the magnetic alignments,thus provi{2. new insight into the deep processes of southeastern NCC.
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