摘要:

AbstractIn the Phanerozoic, there are three major geological boundaries: Precambrian / Cambrian, Permian / Triassic and Cretaceous / Tertiary. Studies of these boundaries in China and over the world strongly suggest that they have the following similar features: mass extinctions of many, taxa, positive anomalies of platinum‐group metals, and abrupt changes of stable isotopes (δ13C). It is quite probable that these were the consequences of some rare catastrophic events of extraterrestrial origin. Hence, the three above‐mentioned mass extinction events may be regarded as key indicators for the division of the geological history of the Phanero

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1988.mp1001001.x

出版商:Geological Publishing House    

年代:1988

数据来源: WILEY

摘要:

AbstractThe western part of the Tarim Basin in Xinjiang is one of the main areas in China where the marine Cretaceous is well developed. The Upper Cretaceous Yingjisha Group represented mainly by sediments of littoral, near‐shore neritic and estuarine facies is divided in ascending order into the Kukebai Formation, the Oytak Formation, the Ygezya Formation and the Tuylouk Formation.For about thirty years, the basal beds of the Kukebai Formation had been considered to be the lowermost marine horizon of the Cretaceous in the western part of the Tarim Basin, which represents the earliest transgression of the Cretaceous Sea into this region. Recently, marine trace fossils,Ophiomorpha nodosa,O. tuberosaandThalassinoides? spp. were found in abundance and fine preservation from the upper subcycle and upper part of the lower subcycle of the Kezlesu Group underlying the Kukebai Formation. The fact indicates that the marine transgression there took place earlier than the Kukebaian.Process of transgression and regression and change of environment in the West Tarim Basin during the period from the late Early Cretaceous to the end of the Cretaceous is also discussed in this pape

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1988.mp1001002.x

出版商:Geological Publishing House    

年代:1988

数据来源: WILEY

摘要:

AbstractIn the middle and lower reaches of the Salawusu River, the Salawusu Formation regarded traditionally as fluvio‐lacustrine deposits actually includes a series of strata which mainly consist of eolian sandy deposits named as “Chengchuan Formation” by the authors. The eolian sand of the Chengchuan Formation and the Malan loess distributed in the upper reaches of the Salawusu River are deposits of sand and loess facies formed by wind action during the same period. The relationship of the Chengchuan Formation and the Malan Loess with the Salawusu Formation which is really of fluvio‐lacustrine deposits is that the former two superpose the latter. This can be demonstrated by the difference of the extinct species proportion of the faunas in different strata. In this area, the Salawusu formed during the early period of Late Pleistocene, while the Malan Loess and the Chengchuan Formation deposited during the late period of the Late Plei

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1988.mp1001003.x

出版商:Geological Publishing House    

年代:1988

数据来源: WILEY

摘要:

AbstractThe Changle‐Zhao' an fault belt is an important belt bordering the southeast coast of China. It was formed in pre‐Mesozoic time and has undergone polyphase activities of different modes ever since. Through a study of the data concerning the Cenozoic strata, volcanism, seismicity, hydrothermal activity and crustal deformation, the characteristics of the neotectonic movement of this fault belt were preliminarily ascertained, the amplitudes and rates of recent faulting in some places were calculated, and the intensities of the activities in various structural basins along the fault zone were compared. Besides, this paper also discusses the main cause for the origin of the Quanzhou‐Shantou strong earthquake tectonic

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1988.mp1001004.x

出版商:Geological Publishing House    

年代:1988

数据来源: WILEY

摘要:

AbstractGranulite in eastern Shandong is mainly exposed in Laixi, Pingdu, Changyi and Anqiu, and the diagnostic mineral assemblage is Opx+Cpx+Hb+Pl ± Q ± Sea. The appearance of orthopyroxene and its coexistence with hornblende indicate that the reaction Hb+Q = Opx+Cpx+Pl+H2O did not proceed completely and therefore these rocks belong to the amphibolite‐ granulite transition facies, i.e., belonging to hornblende‐granulite subfacies. According to the data obtained from such geothermometers and geobarometers as Opx‐ Cpx, Opx‐ Hb, Cpx‐ Hb, Hb‐ PI, Sca‐ Pl and Fe‐ Ti oxides, it has been determined that the temperature of the main metamorphic stage was 720° – 810°C, the pressure 0.5 GPa and fo210−15.5, showing a geothermal gradient of 41–46°C / km, and thus the rocks belong to “low‐temperature” a

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1988.mp1001005.x

出版商:Geological Publishing House    

年代:1988

数据来源: WILEY

摘要:

AbstractThe mineralization of the Zhilingtou Au‐Ag deposit occurred in a heated circulation system of infiltrated meteoric water during the Indosinian and early Yanshanian, at a temperature ranging from 350 to 160°°C and at a depth of less than 2 km. The ore‐forming solution was acidic, strongly oxidized, and poor in sulfur, with moderate Cl−activity and salinity. Au and Ag migrated in the forms of AuCl−2and AgCl−2, and then were concentrated and precipitated in a pressure‐relief, dilatant zone—a tenso‐shear fracture.Pressure relief and boiling were the major mechanism for unloading of the fluid. The hydrothermal fluid was injected intermittently, and its boiling was characterized by pulsation. The presence of high‐valence manganese might represent the auxiliary mechanism for remobilization of Au and Ag in the Chencai Group and for their entering into the

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1988.mp1001006.x

出版商:Geological Publishing House    

年代:1988

数据来源: WILEY

摘要:

AbstractProceeding from gaining a knowledge of the structural settings in this area, the authors applied remote sensing techniques and selected multi‐temporal image processing to extract information of buried structures in the Beijing plain area. Good results have been achieved. Through an integrated analysis of remote‐sensing, geological, seismic and aeromagnetic data, it is pointed out that there exist two sets of buried fractures of differing trends and orders—the northeast set and the northwest set, forming a rhombic framework in the images. The two sets of fractures have still been active since the Quaternary, which is of practical signifcance for geological study, earthquake prevention and planning of urban construction in the area. The results demonstrate that the selection of multi‐temporal processing of remote sensing images and the integrated analytic method are important in the study of buried str

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1988.mp1001007.x

出版商:Geological Publishing House    

年代:1988

数据来源: WILEY

摘要:

AbstractThe paper presents an example of the application of remote‐sensing techniques in peat resource investigations. The study was carried out in the Zoigê region. The optimal imagery time ( during October) and the optimal band (MSS7) of Landsat data were selected. The preferred images were processed optically and by computer and interpreted in a comprehensive way. And in‐situ spectrum measurements and drilling verification were carried out. The identification signature of the peat bogs in Zoigê was defined. The feature of the identification signature for peat was that the peat bog area showed a dark tone with lower reflectance in images of the four MSS bands. The distribution range of peat bogs in the region was exactly located. The types of peat bogs were distinguished. The total peat area of 4038 km2was defined with a total reserve of 5 billion m3. The result of the study indicates that the large‐area, small‐scale investigation of peat resources by use of satellite remote‐sensing data is an advanced method, by which the work efficiency can increase by abo

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1988.mp1001008.x

出版商:Geological Publishing House    

年代:1988

数据来源: WILEY