The Qilian Shan lies along the northeastern edge of the Tibetan Plateau. To constrain its deformation history, we conducted integrated research on Mesozoic-Cenozoic stratigraphic sections in the Jiuxi Basin immediatel...The Qilian Shan lies along the northeastern edge of the Tibetan Plateau. To constrain its deformation history, we conducted integrated research on Mesozoic-Cenozoic stratigraphic sections in the Jiuxi Basin immediately north of the mountain range. Paleocurrent measurements, sandstone compositional data, and facies analysis of Cenozoic stratigraphic sections suggest that the Jiuxi Basin received sediments from the Altyn Tagh Range in the northwest, initially in the Oligocene （-33 Ma）, depositing the Huoshaogou Formation in the northern part of the basin. Later, the source area of the Jiuxi Basin changed to the Qilian Shan in the south during Late Oligocene （-27 Ma）, which led to the deposition of the Baiyanghe Formation. We suggest that uplift of the northern Qilian Shan induced by thrusting began no later than the Late Oligocene. Fission-track analysis of apatite from the Qilian Shan yields further information about the deformation history of the northern Qilain Shan and the Jiuxi Basin. It shows that a period of rapid cooling, interpreted as exhumation, initiated in the Oligocene. We suggest that this exhumation marked the initial uplift of the Qilian Shan resulting from the India-Asia collision.展开更多
The widely distributed thick gravel deposits along the rim of the Tibetan Plateau have been long thought to be the product of rapid tectonic uplift of the plateau. However, this has been challenged by recent works tha...The widely distributed thick gravel deposits along the rim of the Tibetan Plateau have been long thought to be the product of rapid tectonic uplift of the plateau. However, this has been challenged by recent works that suggest these thick gravels may be the result of climate change. In this paper we carried out a detailed field measurement of gravel grain sizes from the Jiuquan and Gobi Gravel Beds in the top of the Laojunmiao section in the Jiuxi Basin in the northern margin of Qilian Mts. (northern Tibetan Plateau). The results suggest that the grain sizes of the Jiuquan and Gobi Gravel Beds over the last 0.8 Ma are characterized by nine coarse-fine cycles having strong 100-ka and 41-ka periodicities that correlate well with the loess-paleosol monsoon record and isotopic global climatic record from deep sea sediments as well as by a long trend of coarsening in gravel grain size. The coarse gravel layers were formed during the warm-humid interglaciations while the fine layers correspond to the cold-dry glaciations. Because the paleoclimate in NW China began to get dramatically drier after the mid-Pleistocene, we think the persistent coarsening of gravel grain size was most probably caused by the rapid uplift of the northern Tibetan Plateau, and that the orbital scale cyclic variations in gravel grain size were driven by orbital forcing factors that were superimposed on the tectonically-forced long-term coarsening trend in gravel size. These findings also shed new light on the interaction results of climate and tectonics in relation to the uplift of the Tibetan Plateau.展开更多
Whether the Altyn Tagh fault (ATF) had been extended beyond its current northeastern tip and linked with strike-slip faults in East Asia is a key to understanding the timing and mechanisms of crustal deformation in th...Whether the Altyn Tagh fault (ATF) had been extended beyond its current northeastern tip and linked with strike-slip faults in East Asia is a key to understanding the timing and mechanisms of crustal deformation in the northern Tibetan Plateau. We present Late Cretaceous dextral movement affected by Okhotomorsk Block-East Asia collision and a larger sinistral offset since Late Eocene along the ATF based on the provenance analysis of western Jiuxi Basin. Moreover, currently available estimates of offset based on displaced Paleozoic and Jurassic rocks could not represent the maximum offset due to late Cretaceous dextral offset.展开更多
The age and evolutional history of the Altyn Tagh fault and its role in the formation and uplift of the Qinghai—Tibetan plateau have been focused for years. Many geologists believe that the formation of the fault is ...The age and evolutional history of the Altyn Tagh fault and its role in the formation and uplift of the Qinghai—Tibetan plateau have been focused for years. Many geologists believe that the formation of the fault is a result of the collision between India and Asia. Some people thought that it should have formed earlier than Cenozoic but have no critical evidence. Here we report a preliminary result from our recent investigation on the volcanic rocks at the north end of the Altyn Tagh fault.1 The volcanic rocks on the north end of the Altyn Tagh fault The volcanic rocks are located on the north end of the Altyn Tagh fault, northern Qinghai—Tibetan plateau. The investigated volcano occurs in the Jiuxi basin, a Cretaceous and Tertiary depositional basin. It is about 300m×100m in size and form about a 100m high cliff above the folded Cretaceous strata. It likes relic neck of a volcano rather than a kind of widely distributed lava flow commonly seen in the northern Tibet. The country rocks are Cretaceous sandstone, silt and fine\|grained conglomerate. The cliff formed most likely due to the differing erosion between the hard volcanic rocks and soft rocks.展开更多
It is an inevitable trend to replace the traditional agriculture with modern agricultural science and technology park, but the excessively unified development mode, similar functions and feature loss of modern science...It is an inevitable trend to replace the traditional agriculture with modern agricultural science and technology park, but the excessively unified development mode, similar functions and feature loss of modern science and technology park have become the obstacles to its development. As a kind of structure view element with the highest life attributes, plants can make the modern agricultural science and technology park have more vitality. Therefore, combined with the case study of Jiuxi Agricultural Science and Technology Park, the modern agricultural science and technology park planning was analyzed based on the perspective of plant experience, with the aim to provide bases for the planning of featured modern leisure science and technology park.展开更多
Carbonate contourite drift at Jiuxi. Taoyuan, northern Hunan, was developed in a deepwater area ofnorthern Hunan on the margin of the Early Ordovician South China palcocontinent. The Lower Ordoviciansequence in the ar...Carbonate contourite drift at Jiuxi. Taoyuan, northern Hunan, was developed in a deepwater area ofnorthern Hunan on the margin of the Early Ordovician South China palcocontinent. The Lower Ordoviciansequence in the area is more than 350 m thick and contains well-developed contourites that can be groupedinto the following five types: the calcilutitic, the arenitic, the siltitic. the fine ruditic and the bioclastic. Thefirst three often constitute a complete or incomplete contourite succession. The arenitic contourite is nearlyuniformly distributed as interlayers throughout the succession, creating a monotonously rhythmic texture inthe contourite drift. The pattern of spatial distribution of the succession shows that the contourite drift is ahuge ridge-like sedimentary body extending along the trend of paleoslope. Numerous marks of flow direc-tion have pointed to an eastward paleoflow direction along the slope.展开更多
基金supported by theNational Key Basic Research Program(MOST grants2007411305 to Z J Guo)
文摘The Qilian Shan lies along the northeastern edge of the Tibetan Plateau. To constrain its deformation history, we conducted integrated research on Mesozoic-Cenozoic stratigraphic sections in the Jiuxi Basin immediately north of the mountain range. Paleocurrent measurements, sandstone compositional data, and facies analysis of Cenozoic stratigraphic sections suggest that the Jiuxi Basin received sediments from the Altyn Tagh Range in the northwest, initially in the Oligocene （-33 Ma）, depositing the Huoshaogou Formation in the northern part of the basin. Later, the source area of the Jiuxi Basin changed to the Qilian Shan in the south during Late Oligocene （-27 Ma）, which led to the deposition of the Baiyanghe Formation. We suggest that uplift of the northern Qilian Shan induced by thrusting began no later than the Late Oligocene. Fission-track analysis of apatite from the Qilian Shan yields further information about the deformation history of the northern Qilain Shan and the Jiuxi Basin. It shows that a period of rapid cooling, interpreted as exhumation, initiated in the Oligocene. We suggest that this exhumation marked the initial uplift of the Qilian Shan resulting from the India-Asia collision.
基金Supported by NSFC (Grant Nos. 40334038 and 40421001)the National Basic Research Program of China (Grant No. 2005CB422000)the President Fund Program of Chinese Academy of Sciences
文摘The widely distributed thick gravel deposits along the rim of the Tibetan Plateau have been long thought to be the product of rapid tectonic uplift of the plateau. However, this has been challenged by recent works that suggest these thick gravels may be the result of climate change. In this paper we carried out a detailed field measurement of gravel grain sizes from the Jiuquan and Gobi Gravel Beds in the top of the Laojunmiao section in the Jiuxi Basin in the northern margin of Qilian Mts. (northern Tibetan Plateau). The results suggest that the grain sizes of the Jiuquan and Gobi Gravel Beds over the last 0.8 Ma are characterized by nine coarse-fine cycles having strong 100-ka and 41-ka periodicities that correlate well with the loess-paleosol monsoon record and isotopic global climatic record from deep sea sediments as well as by a long trend of coarsening in gravel grain size. The coarse gravel layers were formed during the warm-humid interglaciations while the fine layers correspond to the cold-dry glaciations. Because the paleoclimate in NW China began to get dramatically drier after the mid-Pleistocene, we think the persistent coarsening of gravel grain size was most probably caused by the rapid uplift of the northern Tibetan Plateau, and that the orbital scale cyclic variations in gravel grain size were driven by orbital forcing factors that were superimposed on the tectonically-forced long-term coarsening trend in gravel size. These findings also shed new light on the interaction results of climate and tectonics in relation to the uplift of the Tibetan Plateau.
文摘Whether the Altyn Tagh fault (ATF) had been extended beyond its current northeastern tip and linked with strike-slip faults in East Asia is a key to understanding the timing and mechanisms of crustal deformation in the northern Tibetan Plateau. We present Late Cretaceous dextral movement affected by Okhotomorsk Block-East Asia collision and a larger sinistral offset since Late Eocene along the ATF based on the provenance analysis of western Jiuxi Basin. Moreover, currently available estimates of offset based on displaced Paleozoic and Jurassic rocks could not represent the maximum offset due to late Cretaceous dextral offset.
文摘The age and evolutional history of the Altyn Tagh fault and its role in the formation and uplift of the Qinghai—Tibetan plateau have been focused for years. Many geologists believe that the formation of the fault is a result of the collision between India and Asia. Some people thought that it should have formed earlier than Cenozoic but have no critical evidence. Here we report a preliminary result from our recent investigation on the volcanic rocks at the north end of the Altyn Tagh fault.1 The volcanic rocks on the north end of the Altyn Tagh fault The volcanic rocks are located on the north end of the Altyn Tagh fault, northern Qinghai—Tibetan plateau. The investigated volcano occurs in the Jiuxi basin, a Cretaceous and Tertiary depositional basin. It is about 300m×100m in size and form about a 100m high cliff above the folded Cretaceous strata. It likes relic neck of a volcano rather than a kind of widely distributed lava flow commonly seen in the northern Tibet. The country rocks are Cretaceous sandstone, silt and fine\|grained conglomerate. The cliff formed most likely due to the differing erosion between the hard volcanic rocks and soft rocks.
文摘It is an inevitable trend to replace the traditional agriculture with modern agricultural science and technology park, but the excessively unified development mode, similar functions and feature loss of modern science and technology park have become the obstacles to its development. As a kind of structure view element with the highest life attributes, plants can make the modern agricultural science and technology park have more vitality. Therefore, combined with the case study of Jiuxi Agricultural Science and Technology Park, the modern agricultural science and technology park planning was analyzed based on the perspective of plant experience, with the aim to provide bases for the planning of featured modern leisure science and technology park.
文摘Carbonate contourite drift at Jiuxi. Taoyuan, northern Hunan, was developed in a deepwater area ofnorthern Hunan on the margin of the Early Ordovician South China palcocontinent. The Lower Ordoviciansequence in the area is more than 350 m thick and contains well-developed contourites that can be groupedinto the following five types: the calcilutitic, the arenitic, the siltitic. the fine ruditic and the bioclastic. Thefirst three often constitute a complete or incomplete contourite succession. The arenitic contourite is nearlyuniformly distributed as interlayers throughout the succession, creating a monotonously rhythmic texture inthe contourite drift. The pattern of spatial distribution of the succession shows that the contourite drift is ahuge ridge-like sedimentary body extending along the trend of paleoslope. Numerous marks of flow direc-tion have pointed to an eastward paleoflow direction along the slope.
