摘要:

AbstractThe Dabie Mountains are believed to be a collisional orogenic belt between the Yangtze amd Sino‐Korean continental plates. It is composed of the foreland fold‐thrust zone, the subducting cover and basement of the Yangtze continental plate, the coesite‐ and diamond‐bearing ultra‐high pressure métamorphic zone and the meta‐ophiolitic mèlange zone in the subducting basement, the fore‐arc flysch nappe and the back thrust zone occurring respectively on the southern and northern margins of the Sino‐Korean continental plate and the inherited basin with molassic deposits on the northern margin. When the palaeo‐Dabie oceanic plate subducted northward in the Early Palaeozoic, volcanic arc and back arc basin probably formed on the southern margin of the Sino‐Korean continental plate. The Sm / Nd isotopic dating of the strata and eclogite which were drawn into the foreland fold‐thrust zone indicates that the intense collision of the two continental plates took plac

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1992.mp5003001.x

出版商:Geological Publishing House    

年代:1992

数据来源: WILEY

摘要:

AbstractHigh in sodium and low in potassium (Na2O/K2O>1), the charnockitic gneiss series in the Santunying‐ Taipingzhai area, eastern Hebei province, consists of hypersthene‐ quartz‐ diorite, hypersthene‐granodiorite and hypersthene‐plagioclase‐granite. Geological, petrological and large ion lithophile element (LILE), high field strength element (HFSE) and REE geochemical studies suggest that the medium‐coarse‐grained hypersthene‐granodiorite is the product of crystallization of anatectic magmas of the same composition. Under granulite facies conditions, the equilibrium crystallization differentiation of the magmas yielded the early crystallization phase—high‐ SiO2, LILE‐depleted, low‐ΣREE, positive Eu anomaly and REE‐ saturated hypersthene‐ plagioclase‐ granite. The residual phase, coarse‐ grained to pegmatitic hypersthene‐granodiorite, is marked by low SiO2, LILE‐enrichment, high ΣREE and REE‐undersaturation. These rocks and hypersthene‐quartz‐diorite enclaves constitute the sodium‐charnockitic gneiss series in eastern Hebei province. Model calculation for trace elements in the granitoids was applied. On the basis of a systematic geological study, the equation for calculation was chosen, the source magma was determined and the partition coefficients were obtained. The resulting curves are entirely consistent with those observed in the patterns of actual rocks. The study indicates that whole‐rock REE patterns can not be used directly in the co

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1992.mp5003002.x

出版商:Geological Publishing House    

年代:1992

数据来源: WILEY

摘要:

AbstractThe author studied the grain size, shape, colour, altered coat, mineral species, chemical composition, end‐ member components and infrared spectra of clinopyroxenes occurring as megacryst, macrocryst and groundmass minerals, intergrowths with pyrope and ilmenite and minerals in deep‐seated xenoliths and inclusions in diamonds in kimberlites of China. The clinopyroxenes under study were compared with megacryst clinopyroxenes in basalts and minerals in their deep‐seated xenoliths and clinopyroxenes in lamproites and minettes. The coexisting clinopyroxene‐pyrope pair was studied. Besides the author also studied the origin of clinopyroxenes in kimberlites, P‐T conditions for their formation and their reflected tectonic environments of the kimberlite formation. He suggests that this mineral is an indicator for diamond ex

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1992.mp5003003.x

出版商:Geological Publishing House    

年代:1992

数据来源: WILEY

摘要:

AbstractExperiments for oxygen isotope exchange between ferberite and water were carried out and the following equation on oxygen isotope fractionation between ferberite and water against temperature was obtained: 10001nα FeWO4−H2O = 1.04 × 106T−2− 2.5Combining this equation with the equation of Clayton et al. (1972) on oxygen isotope fractionation between quartz and water, an equation on oxygen isotope fractionation between quartz and ferberite was obtained: 10001nαSiO2− FeWO4= 2.34 × 106T−2− 0.4The Bigeleison‐Mayer function method was used to calculate the oxygen isotope fractionation between quartz and ferberite. The theoretical curve obtained agrees with the experimental calibration results quite well in the temperature range of study.The above calibrated equation has been used in 5 world famous tungsten deposits to determine their temperatures of formation. The results show that the temperature range for an idividual deposit determined by this geothermometer agrees with those obtained from fluid inclusion determination and other isotop

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1992.mp5003004.x

出版商:Geological Publishing House    

年代:1992

数据来源: WILEY

摘要:

AbstractThe newly obtained Sm‐Nd isochron ages are 1034 Ma and 935 Ma for ophiolites from northeastern Jiangxi and Fuchuan, southern Anhui respectively. There exist two unconformity surfaces under the initial Late Proterozoic volcanics as well as the Sinian rocks. The Xiuning intrusive body which was intruded into the Shangxi Group in southern Anhui yields a whole‐rock Rb‐Sr isochron age of 963 Ma. There occurs a belt of Late Proterozoic calc‐alkali volcanic rocks extending from northeastern Jiangxi to northwestern Zhejiang. In the light of the above facts, the authors consider that the southeastern margin of Jiangnania is an ancient island arc. At about 1000 Ma ago, the Huanan (South China) oceanic crust was subducted along the line linking Dexing and Hangzhou, thus starting the accretion of the island arc system to Jiangnania. At 800 Ma ago Cathaysia and Jiangnania converged together along the Jiangshan‐Shaoxing line, marking the end of the

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1992.mp5003005.x

出版商:Geological Publishing House    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper describes the fossil charophytes collected from the Late Triassic Xujiahe Formation in Dazu and Early Jurassic Lower Yimen Formation in Xichang, Sichuan Province, and their significance. Up to now, papers dealing with fossil charophytes of the Late Triassic, especially of the Early Jurassic, have been rarely published. The description of the two new species ofPorochara, P. dazuensisandP. xichangensis, and their fossil assemblage not only provides an important basis for classification and correlation of red beds in southwestern China but reveals for the first time the features of the charophyte flora of the Late Triassic‐Early Jurassic in the area, thus offering valuable data for the establishment of Triassic and Jurassic charophyte fossil zones in Chin

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1992.mp5003006.x

出版商:Geological Publishing House    

年代:1992

数据来源: WILEY

摘要:

AbstractThis Paper discusses the origin of the Coastal Zone Loess on the Liaodong Peninsula, Liaoning Province. The loess is composed mainly of proximal materials transported by low‐altitude air flow and less commonly of inland distal materials carried by high‐altitude air flow. The main provenance is the Liaodong Bay. When the sea level declined during glacial period, the bottoms of the Liaodong Bay and Bohai Sea emerged, where desertization occurred. As a result, submarine sediments were transported by strong northwesterly winds to the eastern coastal zone of the peninsula and deposited there. These materials mixed with the windblown dust carried by atmospheric circulation from the interior of the continent, forming the loess. Key words: Liaodong Peninsula, coastal zone, lo

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1992.mp5003007.x

出版商:Geological Publishing House    

年代:1992

数据来源: WILEY