摘要:

AbstractThe Taiwan Strait is a part of the continental‐margin rift of eastern China, which can tectonically be divided into the Taiwan Strait basin, southwestern Taiwan basin and Penhu‐Beigang uplift. The basins are structurally semi‐graban down‐faulted ones in character. The Cretaceous‐Cenozoic sedimentary strata in the basins have a maximum thickness of over 10,000 m. The formation and development of the Taiwan Strait rift were not only affected by both the East China Sea basin and South China Sea basin but also closely related to the Central Range collision orogen of Taiwan. In the Cenozoic, the Taiwan Strait area experienced, under the influence of a multiple of tectonic mechanisms, three stages of evolution: poly‐centre downfaulting, downwarping‐faulting and foreland basin formation. The depositional centres of the basins migrated from west to east during the Tertiary, resulting in the thinning of the Palaeogene strata from west to east but that of the Neogene in the reverse direction. All this determined the geological conditions for the oil‐gas generation in th

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8001001.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractWhether there existed the Songpan‐Garzê massif is a controversial problem. This paper expounds and proves that the old basement of the massif is represented by the pre‐Sinian granitic rock series. This massif and the South Qinling fold belt might both be a part of the old Yangtze platform. Rifting generated by the Caledonian orogeny in the terminal Early Palaeozoic caused the massif to be disintegrated from the northwestern part of the Yangtze platform. This disintegration, however, was not thorough, and the rift troughs were later gradually closed and filled up. The Emei taphrogeny that was initiated in the Early Permian Maokou'an Stage involved a second disintegration of this massif from the Yangtze platform. The rift line largely goes along the Muli‐Pingwu line. This rifting belongs to synchronous extensional rifting at peripheries of the Yangtze platform and in its interior, showing that the posterior, lateral and interior extension resulting from rapid northward shift of the Yangtze platform led to isolation of this massif together with South Qinling from their adjacent areas. During the Ladinian Stage, the Songpan‐Garzê massif and southern Qinling sank strongly en masse. This subsidence continued till the end of the Late Triassic when the late Indosinian movement caused the sea trough to be closed and Songpan‐Garzê and southern Qinling to be folded and uplifted and beco

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8001002.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractAlkaline granites (Rb‐Sr ages 276‐286 Ma) occurring in the Bayan U1‐East Ujimqin belt at the southern margin of the Siberian plate originated in a tensional tectonic environment about 60 Ma earlier than the Late Devonian to Early Carboniferous collision between the Siberian and Sino‐Korean plates. They belong to post‐orogenic A ‐ type granites and may be used as an indicator of the end of the orogeny. At the northern margin of the Sino‐Korean plate, however, only late‐orogenic calc‐alkaline granites occurred during the late Caboniferous‐Permian, and alkaline syenites did not appear until the Late Triassic. The asymmetric magmatism at the margins of the two neighbouring plates might be controlled by the differences in size and mas

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8001003.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractPartially migmatized rocks, banded migmatites, augen‐banded migmatites and gneissic migmatites are developed successively from Xindong to Yunlu, Gaozhou, Guangdong Province in the Yunkai Caledonian orogenic belt at the border between Guangdong and Guangxi. Mass‐balance calculations, statistical analysis of the textural relations and mineralogical and geochemical studies of the migmatites and the study of the metamorphic setting of the Yunlu area indicate that the migmatites in the study area were primarily formed by anatexis without remarkable introduction of foreign components such as K, Na and Si and removal of Ca, Fe, Mg,

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8001004.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractThe Bikou Group on the Shaanxi‐Gansu‐Sichuan border is composed of Mid‐Late Proterozoic metamorphosed bimodal volcanic rocks and flysch sediments. Its metamorphism may be divided into the blueschist and greenschist facies. Three metamorphic zones, i.e. zones A, B, and C, may be distinguished on the basis of the field distribution of metamorphic rocks and the variation of b0values of muscovite. Blueschists are characterized by coexistence of sodic amphiboles and epidote and occur as stripes or relict patches in extensive greenschists of zone A. Studies of metamorphic minerals such as amphiboles, chlorite, epidote and muscovite and their textural relationships indicate that blueschists and greenschists were not formed under the same metamorphic physico‐chemical conditions. The blueschist facies was formed at temperatures of 300‐400°C and pressures of 0.5–0.6 GPa. The greenschist facies in zones A and B has similar temperatures but its pressure is only 0.4 GPa or so. The transition from the blueschist to greenschist facies is a nearly isothermal uplift process. The rock and mineral assemblages of the Bikou Group indicate that the blueschist facies metamorphism of the group might be related to crustal thickening or A‐subduction accompanying the closure of an intracontinental sma

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8001005.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractIn the Xinchang‐Yongjia silver (lead‐zinc) ore belt, there mainly occur the large to medium‐sized Haoshi, Bamao, Dalingkou and Wubu silver deposits or silver‐bearing lead‐zinc deposits. On the basis of researches on these typical deposits, the mechanism of leaching‐drawing mineralization of Mesozoic geothermal water and the related model are put forward in this paper in the light of the time interval between rock and formation ages as well as hydrogen, oxygen, sulphur and lead isotope geochemical characteristics. The major metallogenic process occurred in volcanic rock layers. The ore‐forming fluids are geothermal water coming from meteoric water and circulating at shallow layers. This geothermal water leached and absorbed ore‐forming materials from its country rocks during its flowing (such metallogenic elements as silver, lead‐zinc and sulphur mainly came from consolidated volcanic rocks), leading to the formation of meso‐epither

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8001006.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractQuaternary buried ancient river channels are widespread in the shallow‐level sediments of the northern shelf of the South China Sea. The sedimentary sequence mainly of fluvial deposits comprise an important component part of the low‐stand system tract and transgressive system tract in the study region. The plannar variation and spatial association of the sedimentary features such as incised valley fillings, deltaic foreset wedges and block slides of shelf‐marginal fans reflect the palaeogeographic environment during the fall of the regional sea level in the northern part of the South China Sea. Based on the high‐resolution seismic reflection data and gelogical data from boreholes, the present paper makes an integrated interpretation of the Quaternary ancient river channels in the shallow sediments of the study area, studies the sedimentary features of the ancient channels such as their spatial distribution, seismic facies reflection indicators, sedimentary facies and sand‐body types, and discusses their formational setting and evolutionary model, with the main purpose to render a service to the hydrocarbon resources exploration and development and marine engineering in the northern shelf of the South

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8001007.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper studies a large number of Cretaceous‐Eogene ostracod fossils in the Meso‐Cenozoic Nanyang, Zhoukou, Rendian, Luoyang, Lingbao, Tantou and Kaifeng basins of Henan. Eight ostracod assemblages have been recognized. This paper discusses their geographical distribution and geological ages as well as their features and evolutional trends. Besides, it also deals with the palaeoclimate under which the various assemblages lived and the significance in petroleum explorat

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8001008.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractAlthough stolzite was discovered in Yaogangxian, Hunan Province, China, in 1948, no formal report about this mineral has been published. Recently its crystal structure has been refined by means of the Rietveld method. The cell dimensions of the mineral are: a=b=0.544503(3) nm, c=1.20495(1)nm and α=β=γ=90°. The X, Y and Z coordinates of the atom O refined by the authors are 0.2637, 0.1137 and 0.0706, respectively. The length of the W‐O bond is 0.17826 nm and the angle of the O‐W‐O bound are 123° and 103° , r

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8001009.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY