Sandstones from the Neoproterozoic Jinshanzhai Formation in northern Anhui Province, China, were analyzed for major oxides and trace elements to infer their provenance, the intensity of paleo-weathering of their sourc...Sandstones from the Neoproterozoic Jinshanzhai Formation in northern Anhui Province, China, were analyzed for major oxides and trace elements to infer their provenance, the intensity of paleo-weathering of their source rocks and the depositional tectonic setting. Diagrams of (SiO2/20)-(Na2O+K2O)-(MgO+TiO2+FeO*), TiO2-Ni, Th-Hf-Co, Hf-La/Th and some ratios of elements indicate that felsic rocks constitute the source rocks in the provenance. The values of Chemical Index of Alteration (CIA) are low, which are considered to be affected by K-metasomatism. Whereas the high CIW (Chemical Index of Weathering) values indicate intensive weathering of the source material. Plots of sandstones on bivariate and triangle discriminant diagrams, as well as ICV (Index of Compositional Variation) values revealed that they were deposited on a passive continental margin or in an intra-plate basin. Our recent study, in combination with previous studies and the research progress of the Rodinia super continent, demonstrated that the convergence and extension of the Rodinia super continent were preserved by twice extension as expressed by petrological variation of the southeastern margin of the North China Craton (NCC) during the Neoproterozoic.展开更多
The timing of the "Yanshanian Movement" and the tectonic setting that controlled the Yanshan fold-and-thrust belt during Jurassic time in China are still matters of controversy. Sediments that filled the int...The timing of the "Yanshanian Movement" and the tectonic setting that controlled the Yanshan fold-and-thrust belt during Jurassic time in China are still matters of controversy. Sediments that filled the intramontane basins in the Yanshan belt perfectly record the history of "Yanshanian Movement" and the tectonic background of these basins. Recognizing syn-tectonic sedimentation, clarifying its relationship with structures, and accurately defining strata ages to build up a correct chronostratigraphic framework are the key points to further reveal the timing and kinematics of tectonic deformation in the Yanshan belt from the Jurassic to the Early Cretaceous. This paper applies both tectonic and sedimentary methods on the fold-and-thrust belt and intramontane basins in the Zhangjiakou area, which is located at the intersection between the western Yanshan and northern Taihangshan. Our work suggests that the pre-defined "Jurassic strata" should be re-dated and sub-divided into three strata units: a Late Triassic to Early Jurassic unit, a Middle Jurassic unit, and a Late Jurassic to early Early Cretaceous unit. Under the control of growth fold-and-thrust structures, five types of growth strata developed in different growth structures: fold-belt foredeep type,thrust-belt foredeep type, fault-propagation fold-thrust structure type, fault-bend fold-thrust structure type, and fault-bend foldthrust plus fault-propagation fold composite type. The reconstructed "source-to-sink" systems of Late Triassic to Early Jurassic,Middle Jurassic and Late Jurassic to early Early Cretaceous times, which are composed of a fold-and-thrust belt and flexure basins, imply that the "Yanshanian Movement" in our study area started in the Middle Jurassic. During Middle Jurassic to early Early Cretaceous times, there have been at least three stages of fold-thrust events that developed "Laramide-type" basementinvolved fold-thrust structures and small-scale intramontane broken "axial basins". The westward migration of a "pair" of basement-involved fold-thrust belt and flexure basins might have been controlled by flat subduction of the western Paleo-Pacific slab from the Jurassic to the Early Cretaceous.展开更多
基金financially supported jointly by the National Natural Science Foundation of China(41173106)the Outstanding Young Talent Foundation of Colleges and Universities in Anhui Province(2010SQRL190)the Foundation of Scientific Platform in Suzhou University(2010YKF30)
文摘Sandstones from the Neoproterozoic Jinshanzhai Formation in northern Anhui Province, China, were analyzed for major oxides and trace elements to infer their provenance, the intensity of paleo-weathering of their source rocks and the depositional tectonic setting. Diagrams of (SiO2/20)-(Na2O+K2O)-(MgO+TiO2+FeO*), TiO2-Ni, Th-Hf-Co, Hf-La/Th and some ratios of elements indicate that felsic rocks constitute the source rocks in the provenance. The values of Chemical Index of Alteration (CIA) are low, which are considered to be affected by K-metasomatism. Whereas the high CIW (Chemical Index of Weathering) values indicate intensive weathering of the source material. Plots of sandstones on bivariate and triangle discriminant diagrams, as well as ICV (Index of Compositional Variation) values revealed that they were deposited on a passive continental margin or in an intra-plate basin. Our recent study, in combination with previous studies and the research progress of the Rodinia super continent, demonstrated that the convergence and extension of the Rodinia super continent were preserved by twice extension as expressed by petrological variation of the southeastern margin of the North China Craton (NCC) during the Neoproterozoic.
基金supported by National Natural Science Foundation of China(Grant Nos.41572189&91114203)National Key R&D Plan(Grant No.2017YFC0601405)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB18000000)
文摘The timing of the "Yanshanian Movement" and the tectonic setting that controlled the Yanshan fold-and-thrust belt during Jurassic time in China are still matters of controversy. Sediments that filled the intramontane basins in the Yanshan belt perfectly record the history of "Yanshanian Movement" and the tectonic background of these basins. Recognizing syn-tectonic sedimentation, clarifying its relationship with structures, and accurately defining strata ages to build up a correct chronostratigraphic framework are the key points to further reveal the timing and kinematics of tectonic deformation in the Yanshan belt from the Jurassic to the Early Cretaceous. This paper applies both tectonic and sedimentary methods on the fold-and-thrust belt and intramontane basins in the Zhangjiakou area, which is located at the intersection between the western Yanshan and northern Taihangshan. Our work suggests that the pre-defined "Jurassic strata" should be re-dated and sub-divided into three strata units: a Late Triassic to Early Jurassic unit, a Middle Jurassic unit, and a Late Jurassic to early Early Cretaceous unit. Under the control of growth fold-and-thrust structures, five types of growth strata developed in different growth structures: fold-belt foredeep type,thrust-belt foredeep type, fault-propagation fold-thrust structure type, fault-bend fold-thrust structure type, and fault-bend foldthrust plus fault-propagation fold composite type. The reconstructed "source-to-sink" systems of Late Triassic to Early Jurassic,Middle Jurassic and Late Jurassic to early Early Cretaceous times, which are composed of a fold-and-thrust belt and flexure basins, imply that the "Yanshanian Movement" in our study area started in the Middle Jurassic. During Middle Jurassic to early Early Cretaceous times, there have been at least three stages of fold-thrust events that developed "Laramide-type" basementinvolved fold-thrust structures and small-scale intramontane broken "axial basins". The westward migration of a "pair" of basement-involved fold-thrust belt and flexure basins might have been controlled by flat subduction of the western Paleo-Pacific slab from the Jurassic to the Early Cretaceous.
