摘要:

AbstractA new type of vortex structure—binucleus‐type vortex structure—is presented in this paper. It is characterized by two nuclear columns which distinguish it from uninucleus‐type vortex structure. The vortical surfaces of the structure are commonly s‐ shaped and reversed s‐ shaped and subordinately of elliptic and hyperbolic shape, and sometimes turbine‐like surfaces are observed.On the basis of field structural studies, a mechanical model of rotation around a binuclear column of crustal materials is presented in the paper. Burgers viscoelastic solutions of the stress field and deformation field of this structural type have been obtained using the principle and method of rheology, and simulation experiments have been performed. The results of the theoretical calculation and experiments indicate that the proposed mechanical model

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3004001.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractIt is clarified in this paper that the Lower Yangtze depression is a Meso‐Cenozoic rift zone formed on the basement of the Hercynian‐Indosinian foreland basins. The rift zone is divided into eastern and western sectors and is different in northern and southern parts. The rift zone in plane combination comprises parallel, trifurcate or splitting rifts. The North Jiangsu‐South Yellow Sea region represents a.“drift‐type” rift basin whose deposition center migrates gradually eastward. The formation mechanism and dynamic evolution of the rift basin are discussed from a viewpoint of the crustal fine‐structure, with evidence in geology and geophysics and analysis results of dynamic

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3004002.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractA series of ductile shear zones of the overthrust and strike‐slip types and related ductile shear metamorphic rocks, including tectonic melange and mylonites, were formed in the core of the Qinling orogenic belt in the course of the Caledonian‐Indosinian ductile and brittle‐ductile reworking. The study on their petrography, variations in composition and conditions of formation is conducive to revealing the metamorphism‐deformation history of the core of the Qinling orogenic belt and further to understanding the dynamic mechanism of its ev

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3004003.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractCarbonate contourite drift at Jiuxi, Taoyuan, northern Hunan, was developed in a deep‐water area of northern Hunan on the margin of the Early Ordovician South China paleocontinent. The Lower Ordovician sequence in the area is more than 350 m thick and contains well‐developed contourites that can be grouped into the following five types: the calcilutitic, the arenitic, the siltitic, the fine ruditic and the bioclastic. The first three often constitute a complete or incomplete contourite succession. The arenitic contourite is nearly uniformly distributed as interlayers throughout the succession, creating a monotonously rhythmic texture in the contourite drift. The pattern of spatial distribution of the succession shows that the contourite drift is a huge ridge‐like sedimentary body extending along the trend of paleoslope. Numerous marks of flow direction have pointed to an eastward paleoflow direction along the

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3004004.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractThe formation of the Tongyu gold deposit, controlled by regional polyphase deformation‐metamorphism, is closely related to the regional composite antiform‐shear slip fracture zone. Late‐stage reworking of the Taihua Group accounts for the enrichment of ore substances. It is a typical syntectonic gold deposit.The formation and evolution of the deposit involved four stages: ( I ) the stage of preparation of ore substances, in which primary source beds originated; (II ) the stage of remobilization of ore substances, in which regional progressive metamorphism and migmatization and thermodynamic‐chemical differentiation led to remobilization of gold and its initial local concentration; (III) the stage of gold deposit formation, in which regional folding produced concordant and cross shear‐slip fractures and under the dynamic action gold was separated and migrated in a certain direction and concentrated to form a gold deposit; (IV ) the stage of superpositon, reworking and exposure of orebodies, in which the block uplifted and the deposit again underwent reworking through faulting and mechanical differentiation. Thermodynamic mineralization played a dominant role in the formation of th

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3004005.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractGeological and penological studies indicate that three phases of metabasic dykes are present in the Taipingzhai‐ Jinchangyu area within the high‐ grade metamorphic terrane of eastern Hebei. Garnet and hornblende in metabasic dykes of the second and third phases occur separately, forming two mineral aggregate areas gt+cpx+pl± hy and hb+cpx+pl± hy. PH2Oin the rocks appears to be the main factor controlling the formation of the two aggregate areas. Both were formed simultaneously at the same metamorphic temperature.The second‐phase basic dykes underwent metamorphism of pyroxene‐granulite facies at a temperature pf some 825°C ; later the dykes, together with the third‐ phase basic dykes experienced metamorphism of amphibole‐granulite facies at a temperature of about 750°C under pre

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3004006.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractIn the Inner Mongolia axis and Jiaoliao anteclise along the northern margin of the North China Platform, it has been found that the strata formerly considered as Archaean and Proterozoic are in fact an ophiolite suite similar to the Early Palaeozoic Ondor Sum Group in the Northern Geosyncline region of China. The strata have been named in northern Liaoning as the Qinghezhen Group. The emphasis of this paper is on the discussion of the small shelly fossils found in the siliceous rocks in the upper part of the Qinghezhen Group. This ophiolite suite stretches in an E‐W direction for about 1000 km along the northern margin of the North China Platform, in which 15 fossil localities with stable stratigraphic horizons have been discovered. In this paper. 4 types. 7 genera (including 5 new ones) and 10 species (including 8 new ones and 1 new subspecies) are described, which are collectively referred to as the Qinghezhen Fauna. The characteristics of these fossils are: shell form simple, the maximum length not exceeding 4 mm, with obvious shell wall and wall ornaments. The Qinghezhen Fauna is comparable in shell structure of some genera and species with the Meishucun Fauna in South China, but differs from the latter in having only monotonous fossil groups developed in a distinctly varied ecological environment. The two faunas may belong to the same evolutionary stage of the Early Cambrian but have developed parallelly in different regions. The existence of the Qinghezhen Fauna represents an important biological event in the Early Cambrian in the Northern Geosyncline region of China. The discovery of the Qinghezhen Fauna will bring new knowledge and profound influence to a series of problems on basic geology and mineral deposit prospecting such as the Cambrian faunas, biogeographical povincialism in China and the geotectonic features of the northern margin of the North China Platfor

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3004007.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY