摘要:

AbstractThe apparent polar wander (APW) path from the Tarim block consists of palaeo‐ magnetic poles of Devonian (λ = 16 ° N, φ= 165 ° E, A95= 4 °), Late Carboniferous (A = 41 ° N, φ= 160 ° E, A95 = 4 °), Permian u = 61 ° N, φ=177° E, A95 = 9°), Early Triassic U = 69° N, φ=183° E, A95=ll °) and Jurassic/ Cretaceous (A = 65 ° N, (A = 214 ° E, A95= 6 °) times. On the basis of this APW path, it is concluded that the Tarim block was subducted beneath the Kazakstan plate between Devonian and Permian times. The Tarim, North China and South China blocks were sutured between the Early Triassic and Early Cretaceous. Tarim had moved eastward some 2000 km relative to Siberia

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3001001.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractThe Nadanhada terrane, a Jurassic disrupted terrane in Heilongjiang Province of China, is principally composed of Permo‐ Carboniferous limestone and greenstone, Triassic bedded chert and middle Jurassic siliceous shale, all enclosed within younger (presumably Late Jurassic‐ Early Cretaceous) clastics. Palaeontological and lithological characteristics and structural features of these formations are entirely identical to those of the Mino terrane of the Japanese Islands. Prior to opening of the Sea of Japan, these terranes formed a single superterrane together with the Western Sikhote‐Alin terrane. Tectono‐stratigraphic terranes very similar to the Nadanhada and Mino terranes are also found in the Ryukyu are, the Philippines and probably in Borneo. All these terranes constituted a belt of accretionary complexes during Late Jurassic and / or Early Cretaceous time along the eastern continental margin of Asia after completion of the Triassic collage of the Chinese co

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3001003.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractMost chrysotile deposits occur in ultramafic rocks of the ophiolite suite. The chrysotile deposits discussed in the present paper were formed through metasomatism and infilling‐crystallization in a continental serpentinization environment after plate convergence, where ultramafic rocks were replaced by hydrothermal solutions consisting mainly of deep‐circulating heated water derived from atmospheric precipitation. The critical state for the formation of asbestos in ultramafic rock bodies might be reached by superposition of multiple stages of serpentinization. Favourable fracture systems and relatively stable geological environment are important conditions for forming chrysotile deposits. Three subtypes of chrysotile deposits could be formed in different tectonic settings and under different minerogenic geochemical conditi

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3001004.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractSystematical Sr, Nd and O isotopic studies were made on the Huashan granite complex in Guangxi. In combination with the studies of geological, petrological and geochemical data, it is believed that the complex consists of granites of three stages, with different geneses and different source materials. They are not the products of differentiation and evolution of one single consanguineous magma. Granites of the 1st stage are of the Indosinian syntectic type or I type, also derived from a mixed mantle‐crustal source. Those of the 2nd stage are of the early Yanshanian syntectic type or I type, also derived from a mixed mantle‐crustal source, and those of the 3rd stage are of the late Yanshanian transformed type or S type, derived from a crustal sou

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3001005.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractThe granitioids in question are located in the geosynclinal fold belt of the Northern Tianshan Mountains. The magmas are intruded into a Carboniferous marine volcanic‐sedimentary rock series, forming a contemporaneous, intermediate‐basic to acid, composite intrusion. With a whole‐rock Rb‐Sr isochron age of 315.7 Ma, it is considered to be of middle Hercynian age. The granitoids have a SiO2content of 48–78%, a calc‐alkali index of 60 and silica‐alkali indices ρ = 2.2–2.4 and σ= 1.5–2. From basic to acid compositions, the total REE content increases from 38 to 143 ppm. δEu ranges from 0.47 to 0.86 and the Eu anomalies are negative. The normalized curves of REE of various rock types are very similar. These coupled with the characteristics of trace element geochemistry show that the intrusion is an island arc‐continental margin, calc‐alkaline one. The δ18O values range from 5.8 to 8.9% and the87Sr /86Sr initial ratio is 0.705. The materials of the intrusion are composed of a mixture of the magmas at the top of the upper mantle and in the lower crust. This indicates that the rocks might be consanguineous, differentiated and evolved products and possess the characteri

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3001006.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper presents a comprehensive evaluation on the Devonian‐Carboniferous Boundary (DCB) section in Nanbiancun, Guilin, Guangxi on the basis of Palaeontological, biostratigraphical and sedimentary petrological studies as well as microfacies analysis, REE and trace element analysis and isotopic dating.The DCB at this section conforms to the definition of this boundary and essentially measure up the criteria and conditions for selection of the boundary stratotype. Up to 14 fossil groups are contained in the section. The section presents a general biostratigraphical framework with multispecies fossils zones, assemblage zones and multiple groups of fossils and has latent preponderant conditions for magnetostratigraphic and chronostratigraphic studies. The boundary and point occur in a persistent and continuous monofacial carbonate succession, and the section is located in a tourist city with convenient communication, where various facies of DCB sections are developed, allowing the correlation within a small area. So it is an ideal candidate boundary stratotyp

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3001007.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractThe abundance distributions of more than 40 elements in the No. 502 Ordovician‐Silurian (O/S) boundary section at Fenxiang, Yichang have been studied by RNAA and INAA. The results show that in the boundary bed, there is a distinctive Ir anomaly because the Ir concentration abruptly increases to 0.64 ppb. Furthermore, the Ir is positively correlated in abundance variation with some siderophile and sulphophile elements. In the same bed of the O/S boundary section at Huanghuachang, Yichang, there is also a δ13C excursion. These geochemical signs support the hypothesis that the terminal Ordovician mass extinction was probably related to extraterrestrial event, and provide new evidence for defining the O / S boundary between theHirnantia‐KinnellaandG. persculptusZ

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3001008.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractThe calculations of unsteady flow to a multiple well system with the application of boundary element method (BEM) are discussed. The mathematical model of unsteady well flow is a boundary value problem of parabolic differential equation. It is changed into an elliptic one by Laplace transform to eliminate time variable. The image function of water headHcan be solved by BEM. We derived the boundary integral equation of the transformed variableHand the discretization form of it, so that there is no need to discretize the boundaries of well walls and it becomes easier to solve the groundwater headHby numerical inversion.

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3001009.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY

摘要:

AbstractOn the basis of the temperature variation, the glaucophane‐schist facies can be classified into two facies groups, the glaucophane‐lawsonite facies group and the glaucophane‐greenschist facies group, and forms various facies series with other metamorphic facies. Glaucophane‐schist belts of China are of different types with regard to their average T‐ P gradients and tectonic environments. They are: (1) Proterozoic intracratonic glaucophane‐ schist belts, (2) Caledonian intracratonic glaucophane‐ schist belts, (3) Palaeozoic pericratonic glaucophane‐ schist belts along the northern margin of the Chinese Platform, and (4) Meso‐ Cenozoic glaucophane‐schist belts related to subduction.The initiation and evolution of glaucophane‐schist metamorphism are related to their tectonic environments. Most glaucophane‐schist belts of China were formed in sialic environments. First the crust began to break up and eventually oceanic crust was formed. It seems that a non‐uniformitarian mechanism may be involved as this evolution is related to the change of the configuration of the h

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1990.mp3001002.x

出版商:Geological Publishing House    

年代:1990

数据来源: WILEY