| 1 | Polyphase Tectonic Events and Cenozoic Basin-Range Coupling in the Tianshan Belt,Northwestern China显示文摘Studies show that the Tianshan orogenic belt was built in the late stage of the Paleozoic, as evidenced by thePermian red molasses and foreland basins, which are distributed in parallel with the Tianshan belt, indicating that anintense folding and uplifting event took place. During the Triassic, this orogenic belt was strongly eroded, and basins werefurther developed. Starting from the Jurassic, a within-plate regional extension occurred, forming a series of Jurassic-Paleogene extensional basins in the peneplaned Tianshan region. Since the Neogene, a collision event between the Indianand the Eurasian plates that took place on the southern side of the Tianshan belt has caused a strong intra-continentalorogeny, which is characterized by thrusting and folding. Extremely thick coarse conglomerate and sandy conglomerate ofthe Xiyu Formation of Neogene System were accumulated unconformably on the Tianshan piedmont. Studies haverevealed that the strong compression caused by the Indian-Eurasian collision had a profound influence over the orogenicbelt in the hinterland, and Mesozoic-Cenozoic brittle deformed structures superposed on the ductile deformed Paleozoicrocks. The Mesozoic extensional basins were converted into Cenozoic compressional basins. The deformation in thebasins is featured by step thrusts and fault-related folds. Statistics of joints show that the principal compressive stress sincethe Neogene is in a N-S direction. Meanwhile, owing to the underthrusting of the basin toward the orogenic belt, thePaleozoic strata were thrust on the Meso-Cenozoic rocks as tectonic slices, revealing distinct kinematic features indifferent geologic units. The basin-range coupling zones are characterized by intensive compression, folding and thrusting,accompanied by local sub-E-W-trending strike-slip faults. In the Tianshan region, Cenozoic thrusting is the most commonbasin-range coupling mode. The folding and faulting of Mesozoic sedimentary rocks, spontaneous combustion of Jurassiccoal layers and formation of sintered rocks, the Cenozoic earthquakes and active faulting, and the unique mosaic pattern ofbasin-range framework of Xinjiang are all products of tectonism since the Neogene. | SHULiangshu WANGBo YANGFan LUHuafu J.CHARVET S.LAURENT-CHARVET | 2003 | Acta Geologica Sinica(English Edition)2003，77，4： | 20 |
| 2 | The Discovery of Diamond from the Zhimafang Pyrope Peridotite of the Sulu UHP Metamorphic Zone, East China, and Its Geological Implications显示文摘From Donghai County of Jiangsu Province to Rongcheng County of Shandong Province on the southern border of the Sulu orogen, there exposes an ultramafic belt, accompanied with an ultrahigh-pressure metamorphic zone. It can be further divided into the Xugou belt (the northern belt), and the Maobei-Gangshang belt (the southern belt). One grain of diamond has been discovered from the Zhimafang pyrope peridotite in the southern belt using the heavy mineral method. The diamond grain is 2.13 mm×1.42 mm ×0.83 mm in size and weighs 9.4 mg. The occurrence of the diamond suggests that the Zhimafang pyrope peridotite xenolith is derived from the lithospheric upper mantle. The tectonic emplacement mechanism of the pyrope peridotite xenoliths in granite-gneisses is obviously different from those in kimberlite. The Sulu orogen was located on the active continental margin of the Sino-Korean craton in the Neoproterozoic. The relatively cold and water-bearing oceanic crustal tholeiite slab subducted beneath the lithospheric mantle of the Sino-Korean craton, and partly melted to produce granitic magma and water-bearing fluids. The magma and fluids pierced through and fractured the overlying lithospheric mantle, and ascended to the crustal level together with the ultramafic mantle fragments as xenoliths. | PANMingbao ZHANGQinglong LUHuafu CHENHuogen CHENShouju ZHUShipeng | 2003 | Acta Geologica Sinica(English Edition)2003，77，3： | 3 |
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