Lake Lop Nur is located in the eastern part of the Tarim Basin in Xinjiang,northwestern China.A 220-cm-long sediment core was collected from the center of the ear-shaped depression forming the basin and dated with AMS...Lake Lop Nur is located in the eastern part of the Tarim Basin in Xinjiang,northwestern China.A 220-cm-long sediment core was collected from the center of the ear-shaped depression forming the basin and dated with AMS^(14)C.Grain size,total organic matter(TOC),total nitrogen(TN),and TOC/TN(C/N)analyses were used to reconstruct climatic conditions from 13.0 to 5.6 cal ka BP.The results showed fi ve main climatic stages.Zone I(13.0–11.3 cal ka BP)was a wet–dry environment,whereas Zone II(11.3–8.9 cal ka BP)consisted of a primarily wet environment.Zone III(8.9–7.7 cal ka BP)was subdivided into Zone IIIa(8.9–8.2 cal ka BP)that indicated lake constriction and dry climate,and Zone IIIb(8.2–7.7 cal ka BP)in which the proxies indicated wet conditions.In Zone IV(7.7–6.6 cal ka BP),the climate presented a bit wet conditions.In Zone V(6.6–5.6 cal ka BP),abundant glauberite is present in the sediment and silt dominates the lithology;these results indicate the lake shrank and the overall climate was dry.Abrupt environmental events were also identifi ed,including six dry events at 11.0,10.5,9.3,8.6,8.2,and 7.6 cal ka BP and one fl ood event from 7.8 to 7.7 cal ka BP in the Early–Middle Holocene.展开更多
This paper briefly introduces the Seismotectonic Map of Xinjiang and its neighborhood in the scale of 1∶2500000.The map is amended,supplemented and expanded based of the newly compiled Seismotectonic Map of Xinjiang ...This paper briefly introduces the Seismotectonic Map of Xinjiang and its neighborhood in the scale of 1∶2500000.The map is amended,supplemented and expanded based of the newly compiled Seismotectonic Map of Xinjiang in scale 1∶1000000.The base map of this seismotectonic map is the geologic map of western China and its neighborhood compiled by Li Tingdong.The abundant new materials from related research,referential literatures and the analyses on remote sensing data were used in the compiling work.A database and relevant documents are built for nearly 300 active faults and 150 active folds.The basic information of the major active faults,especially those near the border areas in this map are introduced in this paper.展开更多
The Permian Lucaogou Formation is an important hydrocarbon source rock in the Junggar, Turpan, and Santanghu basins in Xinjiang, NW China. For the first time, dolostones associated with mantle-originated exhalative hy...The Permian Lucaogou Formation is an important hydrocarbon source rock in the Junggar, Turpan, and Santanghu basins in Xinjiang, NW China. For the first time, dolostones associated with mantle-originated exhalative hydrothermal fluid flows are discovered in Yuejingou section in the Santanghu Basin area. They include dolomicrite, doloarenite, and a small amount of dolorudite, and are finely (0.05-0.15 cm thick) interlaminated with lime micrite and dolomicritic analcime laminites. Alkali feldspar and analcime grains are common in doloarenite and are interpreted as having been derived from analcime phonolites and peralkaline magmatic rocks. These magmatic fragments were brought up from subsurface by hydrothermal fluid flow and had experienced exhalative brecciation, transport, and deposition on the lake floor. The matrix consists dominantly of dolomite and ankerite smaller than 0.01 mm. The dolostones can be subdivided into four types on the basis of mineral composition and content. The detrital analcime and alkaline feldspar grains and tuff lithics are interpreted as intraclasts, which were deposited in an under-filled starved lake basin. The δ18OPDB values of dolostones are -5‰ to -21.1‰, and -11.9‰ on average; the 87Sr/86Sr ratios of dolostones are 0.70457 to 0.706194, and 0.705005 on average. These values, in combination with evidence of multi-episodes of peralkaline extrusion, suggest a mantle origin of the hydrothermal fluids, which may have promoted primary dolomite formation. The fluid from the upper mantle caused serpentinization of ultramafic rocks that intruded into the lower crust to obtain Mg2+ and Fe2+, and injected the ions into the lake water as the Mg and Fe sources for dolomite and ankerite. Hydro- thermal fluids associated with peralkaline magmatic rocks also provided Ca2+, Mg2+, Fe2+, and CO32-. Explosive breccias formed and dolostones were convoluted near the vent of hydrothermal fluid exhalation, whereas laminated dolostones formed farther away from the vent. The dolostones are primary dolomite deposition in an intracontinental rift basin and associated with mantle-originated hydrothermal fluids. They provide an insight into the origin of dolomite formation in the geologic history and clues to understand the sedimentary environments and tectonic conditions in northern Xinjiang during the late Paleozoic.展开更多
基金Supported by the National Natural Science Foundation of China(No.41271205)the PhD Research Startup Foundation of Heibei GEO Univerity(No.BQ201604)
文摘Lake Lop Nur is located in the eastern part of the Tarim Basin in Xinjiang,northwestern China.A 220-cm-long sediment core was collected from the center of the ear-shaped depression forming the basin and dated with AMS^(14)C.Grain size,total organic matter(TOC),total nitrogen(TN),and TOC/TN(C/N)analyses were used to reconstruct climatic conditions from 13.0 to 5.6 cal ka BP.The results showed fi ve main climatic stages.Zone I(13.0–11.3 cal ka BP)was a wet–dry environment,whereas Zone II(11.3–8.9 cal ka BP)consisted of a primarily wet environment.Zone III(8.9–7.7 cal ka BP)was subdivided into Zone IIIa(8.9–8.2 cal ka BP)that indicated lake constriction and dry climate,and Zone IIIb(8.2–7.7 cal ka BP)in which the proxies indicated wet conditions.In Zone IV(7.7–6.6 cal ka BP),the climate presented a bit wet conditions.In Zone V(6.6–5.6 cal ka BP),abundant glauberite is present in the sediment and silt dominates the lithology;these results indicate the lake shrank and the overall climate was dry.Abrupt environmental events were also identifi ed,including six dry events at 11.0,10.5,9.3,8.6,8.2,and 7.6 cal ka BP and one fl ood event from 7.8 to 7.7 cal ka BP in the Early–Middle Holocene.
基金Funded by the State Special Project for International Cooperation on Science and Technology(2012DFR20440K02)the 973 Program(2008CB4257)
文摘This paper briefly introduces the Seismotectonic Map of Xinjiang and its neighborhood in the scale of 1∶2500000.The map is amended,supplemented and expanded based of the newly compiled Seismotectonic Map of Xinjiang in scale 1∶1000000.The base map of this seismotectonic map is the geologic map of western China and its neighborhood compiled by Li Tingdong.The abundant new materials from related research,referential literatures and the analyses on remote sensing data were used in the compiling work.A database and relevant documents are built for nearly 300 active faults and 150 active folds.The basic information of the major active faults,especially those near the border areas in this map are introduced in this paper.
基金supported by National Natural Science Fundation of China (Grant No. 40802024)Sinopec Project "Study and Map Compilation for Structure, Lithofacies, and Paleogeography in Northwestern China (Grant No. YPH08103)"State Key Laboratory of Continental Dynamics (Grant No. BJ091358)
文摘The Permian Lucaogou Formation is an important hydrocarbon source rock in the Junggar, Turpan, and Santanghu basins in Xinjiang, NW China. For the first time, dolostones associated with mantle-originated exhalative hydrothermal fluid flows are discovered in Yuejingou section in the Santanghu Basin area. They include dolomicrite, doloarenite, and a small amount of dolorudite, and are finely (0.05-0.15 cm thick) interlaminated with lime micrite and dolomicritic analcime laminites. Alkali feldspar and analcime grains are common in doloarenite and are interpreted as having been derived from analcime phonolites and peralkaline magmatic rocks. These magmatic fragments were brought up from subsurface by hydrothermal fluid flow and had experienced exhalative brecciation, transport, and deposition on the lake floor. The matrix consists dominantly of dolomite and ankerite smaller than 0.01 mm. The dolostones can be subdivided into four types on the basis of mineral composition and content. The detrital analcime and alkaline feldspar grains and tuff lithics are interpreted as intraclasts, which were deposited in an under-filled starved lake basin. The δ18OPDB values of dolostones are -5‰ to -21.1‰, and -11.9‰ on average; the 87Sr/86Sr ratios of dolostones are 0.70457 to 0.706194, and 0.705005 on average. These values, in combination with evidence of multi-episodes of peralkaline extrusion, suggest a mantle origin of the hydrothermal fluids, which may have promoted primary dolomite formation. The fluid from the upper mantle caused serpentinization of ultramafic rocks that intruded into the lower crust to obtain Mg2+ and Fe2+, and injected the ions into the lake water as the Mg and Fe sources for dolomite and ankerite. Hydro- thermal fluids associated with peralkaline magmatic rocks also provided Ca2+, Mg2+, Fe2+, and CO32-. Explosive breccias formed and dolostones were convoluted near the vent of hydrothermal fluid exhalation, whereas laminated dolostones formed farther away from the vent. The dolostones are primary dolomite deposition in an intracontinental rift basin and associated with mantle-originated hydrothermal fluids. They provide an insight into the origin of dolomite formation in the geologic history and clues to understand the sedimentary environments and tectonic conditions in northern Xinjiang during the late Paleozoic.
