The characteristics of Late Cenozoic tectonic uplift of the southern margin of the Qinghai- Tibet Plateau may be inferred from fluvio-lacustrine strata in the Zanda basin, Ngari, Tibet. Magnetostratigraphic study show...The characteristics of Late Cenozoic tectonic uplift of the southern margin of the Qinghai- Tibet Plateau may be inferred from fluvio-lacustrine strata in the Zanda basin, Ngari, Tibet. Magnetostratigraphic study shows that the very thick fluvio-lacustrine strata in the basin are 5.89- 0.78 Ma old and that their deposition persisted for 5.11 Ma, i.e. starting at the end of the Miocene and ending at the end of the early Pleistocene, with the Quaternary glacial stage starting in the area no later than 1.58 Ma. Analysis of the sedimentary environment indicates that the Zanda basin on the southern Qinghai-Tibet Plateau began uplift at -5.89 Ma, later than the northern Qinghai-Tibet Plateau. Presence of gravel beds in the Guge and Qangze Formations reflects that strong uplift took place at -5.15 and -2.71 Ma, with the uplift peaking at -2.71 Ma.展开更多
Based on field geological survey, stratigraphic section measurement and indoor comprehensive investigation, the Zanda Basin＇s tectonic location in the Himalaya Plate was ascertained, and the formation and evolution o...Based on field geological survey, stratigraphic section measurement and indoor comprehensive investigation, the Zanda Basin＇s tectonic location in the Himalaya Plate was ascertained, and the formation and evolution of the Zanda Basin during the Pliocene to Early Pleistocene was classified as six stages： （a） primary rift-faulting stage, （b） quick rift-faulting Stage, （c） intensive rift-faulting stage, （d） stasis stage, （e） secondary rift-faulting stage, and （f） secondary quick rift-faulting stage. Based on this six-staged formation-evolution theory of the Zanda Basin, the upwelling process of the Western Himalaya Mountains from the Pliocene to Early Pleistocene was classified as the following five stages： （a） slow upwelling stage （5.4-4.4 Ma）, （b） mid-velocity upwelling stage （4.4-3.5 Ma）, （c） quick upwelling stage （3.5-3.2 Ma）, （d） upwelling-ceasing stage （3.2-2.7 Ma）, and （e） quick upwelling stage （2.7 Ma）. Research has shown that in the duration from the Early Pliocene （4.7 Ma） to the End of Pliocene （2.67 Ma）, which lasted 2.03 million years, the Himalaya Mountains had uplifted 1500 m at a velocity of 0.74 mm/a; this belongs to a mid-velocity upwening. During the 1.31 million years in the Early Stage of the Early Pleistocene, the Himalaya Mountains had risen up another 1500 m at a velocity of 1.15 mm/a; this is a rather quick upwelling. All of these data have shown that the upwelling of the Western Himalaya Mountains is along a complicated process with multi-stages, multi-velocities, and non-uniformitarian features.展开更多
The Zanda basin is one of the very important basins at the north slope of the Himalaya Range. Thus the study of the basin strata will provide critical information about the tectonic evolution of the Himalayan Orogenic...The Zanda basin is one of the very important basins at the north slope of the Himalaya Range. Thus the study of the basin strata will provide critical information about the tectonic evolution of the Himalayan Orogenic Belt. 268 oriented block samples were collected in the 750-m-thick sections of the Zanda ba- sin. The characteristic remanent magnetization (ChRM) was isolated that decays linearly to the origin between 500oC and 690oC for most studied samples. An age range of 9.5―2.6 Ma was estimated from the correlation between our observed polarity column and the Geomagnetic Polarity Time Scale (GPTS). The age of the Zanda basin does not support the models that the South Tibetan Detach system (STDS) is one of the basin controlling faults. Given the sedimentological features in the basin and the tectonic features at the north edge of the basin, the Zanda basin was a half graben that was possibly controlled by the Karakorum fault on the northeast.展开更多
基金This study was supported jointly by the National Natural Science Foundation grant 40572134 the Land and Resources Survey project ＂Environmental Evolution Sequence of Tertiary Major Paleolakes on the Qinghai- Tibet Plateau＂ （Ke[2003]007-02）.
文摘The characteristics of Late Cenozoic tectonic uplift of the southern margin of the Qinghai- Tibet Plateau may be inferred from fluvio-lacustrine strata in the Zanda basin, Ngari, Tibet. Magnetostratigraphic study shows that the very thick fluvio-lacustrine strata in the basin are 5.89- 0.78 Ma old and that their deposition persisted for 5.11 Ma, i.e. starting at the end of the Miocene and ending at the end of the early Pleistocene, with the Quaternary glacial stage starting in the area no later than 1.58 Ma. Analysis of the sedimentary environment indicates that the Zanda basin on the southern Qinghai-Tibet Plateau began uplift at -5.89 Ma, later than the northern Qinghai-Tibet Plateau. Presence of gravel beds in the Guge and Qangze Formations reflects that strong uplift took place at -5.15 and -2.71 Ma, with the uplift peaking at -2.71 Ma.
基金supported by the National Natural Science Foundation Project(Grant No.40572134)the China Geological Survey Projects"The Key Tertiary Ancient Lakes Environmental Evolution Series of China's Qinghai-Tibet Plateau"(Grant No.Science[2005]005-02+2 种基金1212010511902)"The Study of Neotectonics and Late Cenozoic Gigantic Ancient Lakes of China's Qinghai-Tibet Plateau"(Grant No.Basic[2008]Tibet 21-18Grant No. 1212010610108)
文摘Based on field geological survey, stratigraphic section measurement and indoor comprehensive investigation, the Zanda Basin＇s tectonic location in the Himalaya Plate was ascertained, and the formation and evolution of the Zanda Basin during the Pliocene to Early Pleistocene was classified as six stages： （a） primary rift-faulting stage, （b） quick rift-faulting Stage, （c） intensive rift-faulting stage, （d） stasis stage, （e） secondary rift-faulting stage, and （f） secondary quick rift-faulting stage. Based on this six-staged formation-evolution theory of the Zanda Basin, the upwelling process of the Western Himalaya Mountains from the Pliocene to Early Pleistocene was classified as the following five stages： （a） slow upwelling stage （5.4-4.4 Ma）, （b） mid-velocity upwelling stage （4.4-3.5 Ma）, （c） quick upwelling stage （3.5-3.2 Ma）, （d） upwelling-ceasing stage （3.2-2.7 Ma）, and （e） quick upwelling stage （2.7 Ma）. Research has shown that in the duration from the Early Pliocene （4.7 Ma） to the End of Pliocene （2.67 Ma）, which lasted 2.03 million years, the Himalaya Mountains had uplifted 1500 m at a velocity of 0.74 mm/a; this belongs to a mid-velocity upwening. During the 1.31 million years in the Early Stage of the Early Pleistocene, the Himalaya Mountains had risen up another 1500 m at a velocity of 1.15 mm/a; this is a rather quick upwelling. All of these data have shown that the upwelling of the Western Himalaya Mountains is along a complicated process with multi-stages, multi-velocities, and non-uniformitarian features.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40672142 and 40334038)China National Key Project (Grant Nos. 2005CB422000 and 2002CB412601)
文摘The Zanda basin is one of the very important basins at the north slope of the Himalaya Range. Thus the study of the basin strata will provide critical information about the tectonic evolution of the Himalayan Orogenic Belt. 268 oriented block samples were collected in the 750-m-thick sections of the Zanda ba- sin. The characteristic remanent magnetization (ChRM) was isolated that decays linearly to the origin between 500oC and 690oC for most studied samples. An age range of 9.5―2.6 Ma was estimated from the correlation between our observed polarity column and the Geomagnetic Polarity Time Scale (GPTS). The age of the Zanda basin does not support the models that the South Tibetan Detach system (STDS) is one of the basin controlling faults. Given the sedimentological features in the basin and the tectonic features at the north edge of the basin, the Zanda basin was a half graben that was possibly controlled by the Karakorum fault on the northeast.
