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Li S.,Ocean University of China | Li S.,Key Laboratory of Submarine Geosciences and Prospecting Technique | Zhao G.,University of Hong Kong | Santosh M.,Kochi University | And 6 more authors.
Precambrian Research | Year: 2012

The Paleoproterozoic Jiao-Liao-Ji Belt separates the Eastern Block of the North China Craton into two small sub-blocks: the northern Longgang and the southern Rangrim blocks. However, it still remains unknown or controversial about the subduction polarity, collisional deformation and kinematics between two sub-blocks. The southern segment of the belt consists of the Paleoproterozoic Fenzishan and Jingshan groups, and Paleoproterozoic high pressure mafic granulites and serpentinites blocks which are located in the Jiaodong Complex. All of which are separated from the Jiaodong Complex of Neoarchean TTG gneisses by STZ1 ductile shear zones. Structural analysis in this study indicates that most of the rocks in all the units of the southern segment of the Jiao-Liao-Ji Belt underwent three distinct episodes of folding (D 1 to D 3) and two stage of ductile thrust shearing (STZ 1 coeval to D 1 and D 2, STZ 2 between D 2 and D 3). The D 1 deformation formed penetrative axial planar foliations (S 1), bedding-parallel ductile shear zone, mineral stretching lineations (L 1), and rarely preserved small isoclinal D 1 folds in the Jingshan and Fenzishan groups. In the Jingshan Group, however, penetrative deformational transposition resulted in stacking of sedimentary compositional layers which are separated by bedding-parallel ductile shear zones (STZ 1) at a period of about 1956Ma to 1914Ma. The kinematic indicators of STZ 1 in the Jingshan Group with resultant prograde peak metamorphism up to granulite facies grade and the Fenzishan Group with peak metamorphism up to amphibolite facies grade indicate NW-directed compression. D 2 resulted in crustal thickening with retrograded medium pressure granulite facies grade at about 1914-1893Ma. The D 2 deformation produced NW-verging asymmetric and recumbent folds, interpreted to have resulted from basement-involved thicken-skin structures. The Jiaodong Complex was also involved into the development of WNW-verging asymmetric tight folds associated with D 2 in the Jingshan and the Fenzishan groups. Ongoing collision led to the development of transpressional ductile shearing (STZ 2), forming the transpressional Taipingzhuang dextral ductile shear zone between the Jingshan Group and the southern Archean Complex and the transpressional Tading-Xiadian sinistral ductile shear zone between the Jingshan Group and the northern Archean Complex. All three lithotectonic units were superposed during the late D 3 deformation with amphibolite facies metamorphism. The D 3 deformation developed WNW-trending open to tight upright folds at about 1893-1875Ma. The structural pattern resulting from superimposition of D 2 and D 3 is a composite synform in the Fenzishan and Jingshan groups. The structural events of D 1 and STZ 1, and D 2 and STZ 2 deformation were possibly responsible for fast syn-collisional exhumation of the high pressure mafic granulites. The structural patterns and deformational history of the Fenzishan and Jingshan groups suggest a southeastward-directed oblique subduction beneath the northwestern margin of the Rangrim Block, and that the final scissor-shaped closure of the rift led to collision between the two blocks to form the coherent basement of the Eastern Block of the North China Craton. © 2012 Elsevier B.V.

Li S.,Ocean University of China | Li S.,Key Laboratory of Submarine Geosciences and Prospecting Technique | Geldmacher J.,Leibniz Institute of Marine Science | Hauff F.,Leibniz Institute of Marine Science | And 6 more authors.
Marine Geology | Year: 2014

Numerous calcium carbonate veins were recovered from the igneous basement of the Early Cretaceous Shatsky Rise during Integrated Ocean Drilling Program (IODP) Expedition 324. The chemical (Sr/Ca, Mg/Ca) and isotopic (87Sr/86Sr, 143Nd/144Nd, δ18O, δ13C) compositions of these veins were determined to constrain the timing of vein formation. A dominant control by seawater chemistry on calcite composition is evident for most vein samples with variable contributions from the basaltic basement. Slightly elevated precipitation temperatures (as inferred from oxygen isotope ratios), indicative of hydrothermal vein formation, are only observed at Site U1350 in the central part of Shatsky Rise. The highest 87Sr/86Sr ratios (least basement influence) of vein samples at each drill site range from 0.70726 to 0.70755 and are believed to reflect the contemporaneous seawater composition during the time of calcite precipitation. In principle, age information can be deduced by correlating these ratios with the global seawater Sr isotope evolution. Since the Sr isotopic composition of seawater has fluctuated three times between the early and mid Cretaceous, no unambiguous precipitation ages can be constrained by this method and vein precipitation could have occurred at any time between ~80 and 140Ma. However, based on combined chemical and isotopic data and correlations of vein composition with formation depth and inferred temperature, we argue for a rather early precipitation of the veins shortly after basement formation at each respective drill site. © 2014 Elsevier B.V.

Liu L.,Curtin University Australia | Liu L.,Ocean University of China | Li S.,Ocean University of China | Li S.,Key Laboratory of Submarine Geosciences and Prospecting Technique | And 10 more authors.
Journal of Asian Earth Sciences | Year: 2012

The Xuefeng Tectonic Belt is an important intraplate structural system in the South China Block. Its west margin is up to 1300. km away the present-day continental margin, and the Mesozoic structural trends in this belt are perpendicular to and have no correlation with the Triassic Qinling-Dabie Orogenic Belt. This belt provides important clues for understanding the mechanism of intraplate deformation and the tectonic history of South China. We identified two generations of folding with different strike directions in the Xuefeng Tectonic Belt based on the youngest folding-involved strata and their overprinting relationship. The early one is NE-striking, overprinted by the N-S-striking folds both during Late Jurassic and Late Cretaceous. Thrust faults in the Xuefeng Tectonic Belt mainly show top-to-west thrust movement, which is approximately coeval with the N-S-striking folding. The thrust fault system can be divided into three zones: the root zone with steep thrusts, the middle zone characterized by imbricate thrusts, and the frontal zone with a few shallow thrusts. In addition, two generations of strike-slip faults with different structural trends have been identified: E-W-striking strike-slip faults showing dextral transpression, and NE-striking strike-slip faults with sinistral offset and controlling the upper Cretaceous basins. According to regional geological relationship and structural overprinting, we interpret that the E-W trending strike-slip faults formed in the first stage, whereas the NE-striking strike-slip faults formed later during an E-W-oriented compressional event. Therefore, the principal stress direction varies from NW-SE to E-W. © 2011 Elsevier Ltd.

Liu L.,Key Laboratory of Submarine Geosciences and Prospecting Technique | Liu L.,Ocean University of China | Li S.,Key Laboratory of Submarine Geosciences and Prospecting Technique | Li S.,Ocean University of China | And 8 more authors.
Scientia Geologica Sinica | Year: 2010

The main Mesozoic deformation in the Guizhou Province is Yanshanian three-stage folding, two-stage thrusting and three-stage strike slipping. Three-stage folds of different strikes are divided based on their newest-involved strata in these folds and their superposition relationship. The earliest is nearly EW-striking folds, and the second is NE-striking folds, followed by the N-S-striking folds. The folds formed between Late Jurassic and Late Cretaceous. The thrust fault system consists of the top-to-northwest or top-to-west,NS-striking thrust faults coeval to the NS-striking folds. To the west of west margin of the Xuefeng basement,the thrust belt can be divided into three sections:the root zone,the middle zone and the frontal zone from the east to the west. It underwent two-stage thrusting in root zone. However, there is only one-stage thrusting in the other two zones. Three-stage, differently-oriented strike-slip faults extend spatially parallel to axes of three folds and temporally later than the equivalent folding, respectively. EW-striking strike-slip faults are dextral and transpressional. However,NE-striking strike-slip faults are almost sinistral and transextenional. According to their intersection and confinement among these faults, it is obvious that EW-striking strike-slip faults occurred at the earliest stage, followed by NS- and NE-striking ones in sequence. At last,a possible dynamic model about deformation in Guizhou is proposed.

Dai L.,Key Laboratory of Submarine Geosciences and Prospecting Technique | Dai L.,Ocean University of China | Li S.,Key Laboratory of Submarine Geosciences and Prospecting Technique | Li S.,Ocean University of China | And 7 more authors.
Journal of Asian Earth Sciences | Year: 2014

The East China Sea Shelf Basin is an important oil- and gas-bearing basin in the West Pacific continental margin. This region was affected by subduction of the Pacific Plate and the Philippine Plate in Cenozoic and experienced multi-stage tectonic inversions. This paper presents results from a numerical simulation by finite element method to the Xihu Sag in the East China Sea Shelf Basin and neighboring areas in an attempt to evaluate the WNW-directed compression on the sag during Late Miocene. Based on comprehensive structural analysis of a large number of seismic profiles, we determine the structural geometry of the sag, including the basement of the basin, the sedimentary cover, and 29 major faults in the Xihu Sag. Simulation results show that under continuous WNW-directed compression, tectonic inversion occurred firstly in the Longjing and Yuquan tectonic zones in the sag. Based on quantitative analysis of vertical displacement field of the Xihu Sag and peripheral areas and its stress intensity evolution, we identify a compressional regime in the Longjing Anticline Zone with a gradually propagated uplifting from south to north; whereas the propagation of uplifting in the Yuquan Anticline Zone is from north to south. The inversion intensity decreases from north to south. The formation of the tectonic inversion zone in the Xihu Sag is not only correlated to the direction of compression and fault patterns in the basin, but also closely related to the spatial configuration of fault surfaces of the Xihu-Jilong Fault in the Xihu Sag. © 2013 Elsevier Ltd.

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