The eastern margin of the Qaidam Basin lies in the key tectonic location connecting the Qinling, Qilian and East Kunlun orogens. The paper presents an investigation and analysis of the geologic structures of the area ...The eastern margin of the Qaidam Basin lies in the key tectonic location connecting the Qinling, Qilian and East Kunlun orogens. The paper presents an investigation and analysis of the geologic structures of the area and LA-ICP MS zircon U-Pb dating of Paleozoic and Mesozoic magmatisms of granitoids in the basement of the eastern Qaidam Basin on the basis of 16 granitoid samples collected from the South Qilian Mountains, the Qaidam Basin basement and the East Kunlun Mountains. According to the results in this paper, the basement of the basin, from the northern margin of the Qaidam Basin to the East Kunlun Mountains, has experienced at least three periods of intrusive activities of granitoids since the Early Paleozoic, i.e. the magmatisms occurring in the Late Cambrian （493.1±4.9 Ma）, the Silurian （422.9±8.0 Ma-420.4±4.6 Ma） and the Late Permian-Middle Triassic （257.8±4.0 Ma-228.8＋1.5 Ma）, respectively. Among them, the Late Permian - Middle Triassic granitoids form the main components of the basement of the basin. The statistics of dated zircons in this paper shows the intrusive magmatic activities in the basement of the basin have three peak ages of 244 Ma （main）, 418 Ma, and 493 Ma respectively. The dating results reveal that the Early Paleozoic magmatism of granitoids mainly occurred on the northern margin of the Qaidam Basin and the southern margin of the Qilian Mountains, with only weak indications in the East Kunlun Mountains. However, the distribution of Permo-Triassic （P-T） granitoids occupied across the whole basement of the eastern Qaidam Basin from the southern margin of the Qilian Mountains to the East Kunlun Mountains. An integrated analysis of the age distribution of P-T granitoids in the Qaidam Basin and its surrounding mountains shows that the earliest P-T magmatism （293.6-270 Ma） occurred in the northwestern part of the basin and expanded eastwards and southwards, resulting in the P-T intrusive magmatism that ran through the whole basin basement. As the Cenozoic basem展开更多
Recent mapping and seismic survey reveal that intensive compression during the Early Cenozoic in the Qiangtang block of the central Tibetan Plateau formed an extensive complex of thrust sheets that moved relatively so...Recent mapping and seismic survey reveal that intensive compression during the Early Cenozoic in the Qiangtang block of the central Tibetan Plateau formed an extensive complex of thrust sheets that moved relatively southward along several generally north-dipping great thrust systems. Those at the borders of the ~450 km wide block show it overrides the Lhasa block to the south and is overridden by the Hohxil-Bayanhar block to the north. The systems are mostly thin-skinned imbricate thrusts with associated folding. The thrust sheets are chiefly floored by Jurassic limestone that apparently slid over Triassic sandstone and shale, which is locally included, and ramped upward and over Paleocene-Eocene red-beds. Some central thrusts scooped deeper and carried up Paleozoic metamorphic rock, Permian carbonate and granite to form a central uplift that divides the Qiangtang block into two parts. These systems and their associated structures are unconformably overlain by little deformed Late Eocene-Oligocene volcanic rock or capped by Miocene lake beds. A thrust system in the northern part of the block, as well as one in the northern part of the adjacent Lhasa block, dip to the south and appear to be due to secondary adjustments within the thrust sheets. The relative southward displacement across this Early Cenozoic mega thrust system is in excess of 150 km in the Qiangtang block, and the average southward slip-rate of the southern Qiangtang thrusts ranged from 5.6 mm to 7.4 mm/a during the Late Eocene-Oligocene. This Early Cenozoic thrusting ended before the Early Miocene and was followed by Late Cenozoic crustal extension and strike-slip faulting within the Qiangtang block. The revelation and understanding of these thrust systems are very important for the evaluation of the petroleum resources of the region.展开更多
越南东北部-海南岛-粤西南构造带整体上呈NW-SE走向展布于华南板块的南缘,是理解华南构造演化的关键地区。作为印支运动代表性地区的越南东北部地区Song Chay构造带上,下古生界浅变质沉积岩、上古生界至早-中三叠世未变质的沉积盖层中...越南东北部-海南岛-粤西南构造带整体上呈NW-SE走向展布于华南板块的南缘,是理解华南构造演化的关键地区。作为印支运动代表性地区的越南东北部地区Song Chay构造带上,下古生界浅变质沉积岩、上古生界至早-中三叠世未变质的沉积盖层中都发育向北东逆冲推覆,韧性变形域表现为NE-SW向的矿物拉伸线理和上部指NE的剪切变形,而脆性变形域则记录了大量NE极性的褶皱和冲断构造。两广交界的云开地体和海南岛地区存在着相同样式的构造变形。关于这期变形的时间,本文通过对野外地层以及所出露不同时期岩体变形特征的综合研究,并结合高质量的锆石U-Pb年代学数据,在越南的东北部厘定为237～228Ma。这期广泛分布于华南板块南缘构造事件的动力学机制同Day Nui Con Voi(大象山)微陆块与华南板块在早中生代的构造拼合事件相关。本文认为华南板块在早三叠世开始沿着越南东北部的Song Chay缝合带俯冲拼合于Day Nui Con Voi微陆块之下,因此在早-中三叠世时期,在作为俯冲盘的华南板块南缘发育一系列的褶皱和逆冲推覆构造,晚三叠世印支造山作用结束。因此,华南板块南缘的越南东北部-海南岛-粤西南构造带被一同卷入早-中三叠世同印支板块的碰撞造山体系之中。展开更多
基金supports by the Basic Research Foundation of the Institute of Geomechanics,CAGS,China (DZLXJK200703)the National Natural Science Foundation of China(40342015)+1 种基金SinoProbe-Deep Exploration in China(SinoProbe-08)the National Science Foundation(USA) Instrumentation and Facilities Program (EAR-0443387)
文摘The eastern margin of the Qaidam Basin lies in the key tectonic location connecting the Qinling, Qilian and East Kunlun orogens. The paper presents an investigation and analysis of the geologic structures of the area and LA-ICP MS zircon U-Pb dating of Paleozoic and Mesozoic magmatisms of granitoids in the basement of the eastern Qaidam Basin on the basis of 16 granitoid samples collected from the South Qilian Mountains, the Qaidam Basin basement and the East Kunlun Mountains. According to the results in this paper, the basement of the basin, from the northern margin of the Qaidam Basin to the East Kunlun Mountains, has experienced at least three periods of intrusive activities of granitoids since the Early Paleozoic, i.e. the magmatisms occurring in the Late Cambrian （493.1±4.9 Ma）, the Silurian （422.9±8.0 Ma-420.4±4.6 Ma） and the Late Permian-Middle Triassic （257.8±4.0 Ma-228.8＋1.5 Ma）, respectively. Among them, the Late Permian - Middle Triassic granitoids form the main components of the basement of the basin. The statistics of dated zircons in this paper shows the intrusive magmatic activities in the basement of the basin have three peak ages of 244 Ma （main）, 418 Ma, and 493 Ma respectively. The dating results reveal that the Early Paleozoic magmatism of granitoids mainly occurred on the northern margin of the Qaidam Basin and the southern margin of the Qilian Mountains, with only weak indications in the East Kunlun Mountains. However, the distribution of Permo-Triassic （P-T） granitoids occupied across the whole basement of the eastern Qaidam Basin from the southern margin of the Qilian Mountains to the East Kunlun Mountains. An integrated analysis of the age distribution of P-T granitoids in the Qaidam Basin and its surrounding mountains shows that the earliest P-T magmatism （293.6-270 Ma） occurred in the northwestern part of the basin and expanded eastwards and southwards, resulting in the P-T intrusive magmatism that ran through the whole basin basement. As the Cenozoic basem
基金financially supporting the research under grants No.1212011221111,Sinoprobe-02-01 and 2006DFB21330 respectively
文摘Recent mapping and seismic survey reveal that intensive compression during the Early Cenozoic in the Qiangtang block of the central Tibetan Plateau formed an extensive complex of thrust sheets that moved relatively southward along several generally north-dipping great thrust systems. Those at the borders of the ~450 km wide block show it overrides the Lhasa block to the south and is overridden by the Hohxil-Bayanhar block to the north. The systems are mostly thin-skinned imbricate thrusts with associated folding. The thrust sheets are chiefly floored by Jurassic limestone that apparently slid over Triassic sandstone and shale, which is locally included, and ramped upward and over Paleocene-Eocene red-beds. Some central thrusts scooped deeper and carried up Paleozoic metamorphic rock, Permian carbonate and granite to form a central uplift that divides the Qiangtang block into two parts. These systems and their associated structures are unconformably overlain by little deformed Late Eocene-Oligocene volcanic rock or capped by Miocene lake beds. A thrust system in the northern part of the block, as well as one in the northern part of the adjacent Lhasa block, dip to the south and appear to be due to secondary adjustments within the thrust sheets. The relative southward displacement across this Early Cenozoic mega thrust system is in excess of 150 km in the Qiangtang block, and the average southward slip-rate of the southern Qiangtang thrusts ranged from 5.6 mm to 7.4 mm/a during the Late Eocene-Oligocene. This Early Cenozoic thrusting ended before the Early Miocene and was followed by Late Cenozoic crustal extension and strike-slip faulting within the Qiangtang block. The revelation and understanding of these thrust systems are very important for the evaluation of the petroleum resources of the region.
文摘越南东北部-海南岛-粤西南构造带整体上呈NW-SE走向展布于华南板块的南缘,是理解华南构造演化的关键地区。作为印支运动代表性地区的越南东北部地区Song Chay构造带上,下古生界浅变质沉积岩、上古生界至早-中三叠世未变质的沉积盖层中都发育向北东逆冲推覆,韧性变形域表现为NE-SW向的矿物拉伸线理和上部指NE的剪切变形,而脆性变形域则记录了大量NE极性的褶皱和冲断构造。两广交界的云开地体和海南岛地区存在着相同样式的构造变形。关于这期变形的时间,本文通过对野外地层以及所出露不同时期岩体变形特征的综合研究,并结合高质量的锆石U-Pb年代学数据,在越南的东北部厘定为237～228Ma。这期广泛分布于华南板块南缘构造事件的动力学机制同Day Nui Con Voi(大象山)微陆块与华南板块在早中生代的构造拼合事件相关。本文认为华南板块在早三叠世开始沿着越南东北部的Song Chay缝合带俯冲拼合于Day Nui Con Voi微陆块之下,因此在早-中三叠世时期,在作为俯冲盘的华南板块南缘发育一系列的褶皱和逆冲推覆构造,晚三叠世印支造山作用结束。因此,华南板块南缘的越南东北部-海南岛-粤西南构造带被一同卷入早-中三叠世同印支板块的碰撞造山体系之中。
