• Volume 62,Issue 1,1988 Table of Contents
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    • Mass Extinction——A Fundamental Indicator for Major Natural Divisions of Geological History

      1988, 62(1).

      Abstract (1687) HTML (0) PDF 0.00 Byte (84) Comment (0) Favorites

      Abstract:In 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 stronglysuggest that they have the following similar features: mass extinctions of many taxa, positive anomalies ofplatinum-group metals, and abrupt changes of stable isotopes (δ~(13)C). It is quite probable that these were theconsequences of some rare catastrophic events of extraterrestrial origin. Hence, the three above-mentionedmass extinction events may be regarded as key indicators for the division of the geological history of thePhanerozoic.

    • The Marine Cretaceous in the Western Part of the Tarim Basin of Xinjiang and Its Depositional Environments

      1988, 62(1).

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      Abstract:The western part of the Tarim Basin in Xinjiang is one of the main areas in China where the marineCretaceous is well developed. The Upper Cretaceous Yingjisha Group represented mainly by sediments of lit-toral, near-shore neritic and estuarine facies is divided in ascending order into the Kukebai Formation, theOytak 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 lowermostmarine horizon of the Cretaceous in the western part of the Tarim Basin, which represents the earliest trans-gression of the Cretaceous Sea into this region. Recently. marine trace fossils, Ophiomorpha nodosa, O.tuberosa and Thalassinoides? spp. were found in abundance and fine preservation from the upper subcycle andupper part of the lower subcycle of the Kezlesu Group underlying the Kukebai Formation. The fact indicatesthat 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 pe-riod from the late Early Cretaceous to the end of the Cretaceous is also discussed in this paper.

    • Relationship between the Malan Loess and the Salawusu Formation in the Salawusu River Area,Ordos,and Their Geological Ages

      1988, 62(1).

      Abstract (1846) HTML (0) PDF 0.00 Byte (61) Comment (0) Favorites

      Abstract:In the middle and lower reaches of the Salawusu River. the Salawusu Formation regarded traditionallyas fluvio-lacustrine deposits actually includes a series of strata which mainly consist of eolian sandy depositsnamed as "Chengchuan Formation" by the authors. The eolian sand of the Chengchuan Formation and theMalan loess distributed in the upper reaches of the Salawusu River are deposits of sand and loess faciesformed by wind action during the same period. The relationship of the Chengchuan Formation and theMalan Loess with the Salawusu Formation which is really of fluvio-lacustrine deposits is that the formertwo superpose the latter. This can be demonstrated by the difference of the extinct species proportion of thefaunas 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 LatePleistocene.

    • The Neotectonic Movements of the Changle-Zhao''''an Fault Belt in Fujian

      1988, 62(1).

      Abstract (1759) HTML (0) PDF 0.00 Byte (79) Comment (0) Favorites

      Abstract:The Changle-Zhao' an fault belt is an important belt bordering the southeast coast of China. It wasformed in pre-Mesozoic time and has undergone polyphase activities of different modes ever since. Through astudy of the data concerning the Cenozoic strata, volcanism. seismicity, hydrothermal activity and crustaldeformation, 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 invarious structural basins along the fault zone were compared. Besides, this paper also discusses the main causefor the origin of the Quanzhou-Shantou strong earthquake tectonic zone.

    • Metamorphic Characteristics of Granulite Facies Rocks in the Laixi-Pingdu Area in Eastern Shandong Provincc

      1988, 62(1).

      Abstract (1828) HTML (0) PDF 0.00 Byte (76) Comment (0) Favorites

      Abstract:Granulite in eastern Shandong is mainly exposed in Laixi. Pingdu, Changyi and Anqiu, and the diagnosticmineral assemblage is Opx+Cpx+Hb+PI±Q±Sca. The appearance of orthopyroxene and Its coexistence withhornblende indicate that the reaction Hb+Q=Opx+Cpx+PI+H_2O did not proceed completely and thereforethese rocks belong to the amphibolite-granulite transition facies. i.e., belonging to hornblende-granulitesubfacics. According to the data obtained from such geothermometers and geobarometers as Opx-Cpx,Opx-Hb. Cpx-Hb, Hb-PI. Sca-PI and Fe-Ti oxides, it has been determined that the temperature of the mainmetamorphic stage was 720-810℃, the pressure 0.5 GPa and fo_210~(-15.5), showing a geothermal gradient of41-46℃/km, and thus the rocks belong to "low-temperature" and low-pressure granulite facies.

    • Physico-chemical Conditions and Ore-forming Process of the Zhilingtou Au-Ag Deposit, Zhejiang

      1988, 62(1).

      Abstract (1857) HTML (0) PDF 0.00 Byte (76) Comment (0) Favorites

      Abstract:The mineralization of the Zhilingtou Au-Ag deposit occurred in a heated circulation system of infiltratedmeteoric water during the Indosinian and early Yanshanian, at a temperature ranging from 350 to 160℃ andat a depth of less than 2 km. The ore-forming solution was acidic, strongly oxidized. and poor in sulfur, withmoderate Cl~- activity and salinity. Au and Ag migrated in the forms of AuCl_2~- and AgCl_2~-, and then wereconcentrated 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 fluidwas injected intermittently, and its boiling was characterized by pulsation. The presence of high-valence man-ganese might represent the auxiliary mechanism for remobilization of Au and Ag in the Chencai Group and fortheir entering into the hydrothermal fluid.

    • A Comprehensive Study of Buried Structures in the Beijing Plain Using Multi-Temporal Remote Sensing Data Processing And Multiple Information Sources

      1988, 62(1).

      Abstract (1885) HTML (0) PDF 0.00 Byte (63) Comment (0) Favorites

      Abstract:Proceeding from gaining a knowledge of the structural settings in this area, the authors applied remotesensing techniques and selected multi-temporal image processing to extract information of buried structures inthe Beijing plain area. Good results have been achieved. Through an integrated analysis of remote-sensing, geo-logical, seismic and aeromagnetic data, it is pointed out that there exist two sets of buried fractures of differingtrends and orders-the northeast set and the northwest set. forming a rhombic framework in the images. Thetwo sets of fractures have still been active since the Quaternary. which is of practical signifcance for geologicalstudy, earthquake prevention and planning of urban construction in the area. The results demonstrate that theselection of multi-temporal processing of remote sensing images and the integrated analytic method are impor-tant in the study of buried structures.

    • Applications of Remote-Sensing Techniques in Peat Resource Investigations in Zoig■

      1988, 62(1).

      Abstract (1814) HTML (0) PDF 0.00 Byte (78) Comment (0) Favorites

      Abstract:The paper presents an example of the application of remote-sensing techniques in peat resource investiga-tions. The study was carried out in the Zoige region. The optimal imagery time (during October) and theoptimal band (MSS_7) of Landsat data were selected. The preferred images were processed optically and bycomputer and interpreted in a comprehensive way. And in-situ spectrum measurements and drilling verificationwere carried out.The identification signature of the peat bogs in Zoige was defined. The feature of the identifi-cation signature for peat was that the peat bog area showed a dark tone with lower reflectance in images of thefour MSS bands. The distribution range of peat bogs in the region was exactly located. The types of peat bogswere distinguished. The total peat area of 4038 km~(2) was defined with a total reserve of 5 billion m~3. The resultof the study indicates that the large-area, small-scale investigation of peat resources by use of satelliteremote-sensing data is an advanced method. by which the work efficiency can increase by about 20 times.

Chief Editor:HOU Zengqian

Governing Body:China Association for Science and Technology

Organizer:Geological Society of China

start publication :1922

ISSN:ISSN 1000-9515

CN:CN 11-2001/P

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