摘要:

AbstractThere occurred rifting on Hainan Island in the Late Palaeozoic. Bimodal volcanic rocks composed of basalt and rhyolite developed in the Carboniferous. Widespread in the Late Palaeozoic formations are several layers of fluvial intermontane conglomerates whose distribution is controlled by rift faults. The Late Palaeozoic deposits dominated by clastic rocks are, for a major part, of marine facies and of continental facies in the lower and upper parts. Lithological and lithochemical studies indicate that the detrital rocks were formed in a tectonic setting of continental rifting. The evolution of the rifting terminated at the stage of transition form an intra continental rift to an intercontinental one and the rift basin was a bay opening westward to the sea.

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1991.mp4004001.x

出版商:Geological Publishing House    

年代:1991

数据来源: WILEY

摘要:

AbstractActive faults have special electromagnetic effect and remote sensing characteristics, and exhibit unique imagery marks in satellite images. A comprehensive comparison of images of active faults in eastern China and an analysis of geologic and geomorphic data can tell us some characteristics of fault activity in the area during the neotectonic period: 1) The fault activities of the north‐south tectonic zone, North China and Taiwan were stronger than those of southeastern and northeastern China; 2) the faulting in the north‐ south tectonic zone, North China and Taiwan has continued up to now, and most of the fault activites in southeastern and north‐eastern China have become weaker since the Middle Pleistocene; 3) the activity is unsteady in time, most being intermittent, or episodic, i.e. alternately strong and weak; 4) most active faults of a definite size can be divided into several segments which somewhat differ from each other in the characteristics of the act

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1991.mp4004002.x

出版商:Geological Publishing House    

年代:1991

数据来源: WILEY

摘要:

AbstractThe deposit under study is a hydrothermal filling‐metasomatic vein type lead‐zinc‐silver deposit, in which gold and silver can be recovered as by‐products. These metals mainly occur as microgranular native gold, electrum, stephanite, acanthite, pyraragyrite, freibergite, and native silver. Gold minerals tend to be associated with galenobismutite, native bismuth and unnamed Bi2Te. They are either enclosed in pyrite, marmatite, iron‐bearing sphalerite and galens or fill the microfissures of these minerals. Silver minerals usually occur in cleavages or fissures of galena, marmatite and pyrite, but are not associated with gold and bismuth minerals. Gold and silver mineralizations occurred later than lead and zinc, while the silver mineralization was preceded by tha

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1991.mp4004003.x

出版商:Geological Publishing House    

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper mainly discusses the origin and depositional features of fan‐deltas and braid deltas. Fan‐deltas are storm discharge‐dominated, while braid deltas are usually flashy flood‐dominated. The two types of delta, like common deltas, were reworked by marine processes. Delta systems are classified into nine delta types on the.basis of. the subaerial depositional processes and the nature of marine reworking.Fan‐ deltas and braid deltas are of great significance for petroleum exploration. In divergent‐ margin foreland and intraplate rift‐subsided basin settings fan‐deltas often form combination traps for petrole

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1991.mp4004004.x

出版商:Geological Publishing House    

年代:1991

数据来源: WILEY

摘要:

AbstractMost of the hinterland of the North China platform is devoid of Late Ordovician strata. The Baiyanhua Mountain section at Shetai Town is a standard section of the Upper Ordovician newly established in recent years at the northernmost margin of the platform. This establishment directly involved the determination of the north boundary of the platform and the understanding of its evolutionary history. The area is quite different from the hinterland of the platform in Middle Ordovician rock types and sedimentary environments, with the former characterized by frequent slope deposits and the latter consisting almost entirely of platform deposits. The present paper focuses on the petrographic features and sedimentary environments of the Middle‐Upper Ordovician strata in the area, providing further theoretical support to the establishment of the section and filling the gap in this respec

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1991.mp4004005.x

出版商:Geological Publishing House    

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper deals with a simulated test of biogenic mineralization made with a blue‐ green alga species,Spirulina platensis. The data in the experiment were recorded by a computerized surveying system. The influence of algae on the accumulation of phosphorus by changing their microenvironment to promote the formation and deposition of phosphate was studied.The results show that the pH value of cultural liquor rose up to 10 and the redox potential (Eh) may drop by 100‐200 mV during the algal logarithmic growth stage, and the cultrual liquor was changed into a medium with a weakly reducing condition. At the end of the logarithmic growth stage white deposits of Na2Ca(CO3)2· 5H2O and Ca2Mg (PO4)2· 2H2O were formed on the floor of cultural containers. The test presented a valuable evidence for the theory of biogenic mineraliz

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1991.mp4004006.x

出版商:Geological Publishing House    

年代:1991

数据来源: WILEY

摘要:

AbstractA marine stratigraphic sequence across the Pliocene / Pleistocene boundary has been found in the northern continental shelf of the South China Sea. The marine Quaternary deposits in the Yinggehai Basin may exceed 2,000 m in thickness, probably providing the best section for studying the lower boundary of the marine Pleistocene in South China. The vertical succession with planktonic foraminifers and nannofossils revealed in boreholes in the basin has been well correlated with that in the international stratotype section of the Pliocene / Pleistocene boundary at Vrica, Italy, resulting in the acquirement of a biostratigraphic boundary at 1,64 Ma. This boundary, however, does not coincide with any prominent lithological palaeoenvironmental changes in the study area and can hardly be used in geological practice. There are, in contrast, significant changes at the level of LAD ofGloborotalia multicamerata sensu latolocated below the above‐ mentioned boundary. The percentage of planktonic foraminifers in the total population and preservation of foraminiferal tests display great changes at this level corresponding to a clear onlap on the seismic profiles and indicating a depositional hiatus at ca. 2.0‐2.5 Ma. Since the level can be widely traced in the Pearl River Mouth Basin and the Beibu Gulf Basin and well corresponds with the marked depositional environmental changes recorded in the west Pacific and other regions, it is recommended that the Plio / Pleistocene boundary be drawn at the level ofGr. multicamerata sensu latoLAD, roughly concurrent with the Gauss / Matuyama t

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1991.mp4004007.x

出版商:Geological Publishing House    

年代:1991

数据来源: WILEY

摘要:

AbstractIn this paper, it is demonstrated that there exist marine horizons in the upper part of the lower subcycle and the upper subcycle of the Kizilsu Group in Xinjiang, based on new evidence of authigenic glauconite, boron content, carbon and oxygen stable isotopic analyses, and lithological and sedimentary features. The upper part of the lower subcycle is the lowermost marine horizon of the Cretaceous in the western Tarim Basin, which is inferred to be of Barremian age.

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1991.mp4004008.x

出版商:Geological Publishing House    

年代:1991

数据来源: WILEY