摘要:

AbstractThe geotraverse from Yecheng to Shiquanhe, on the western Qinghai – Tibet Plateau, totalling 1056 km in length, passes the western Kunlun Mountains and the eastern end of the Karakorum Mountains. The Chinese and French scientists made a joint investigation along the line from July to August, 1989. Based on the outcropped ophiolites, palaeontology, sedimentary facies, magmatism, tectonic deformation and metamorphism, the region involved may be divided from north to south into five terranes and four ophiolitic suture zones. The ages of these terranes have a tendency to become increasingly younger from north to sout

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8002001.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractOn the basis of the detailed field work, compositions and contents of plagioclase and K‐feldspar, determination of ordering degree, statistical analysis of plagioclase elongation index, mass‐balance calculation and mineral spatial distribution and geochemistry, it is concluded that the migmatites in the Dabie complex are characterized by the presence of thermocenters. There are regular changes in mineral character in the migmatites from the centers outwards. The dominant genetic mechanism is anatexis and metasomatism, whose intensities decrease from the centers outwards. Finally, according to the simulated experiment on Liesegang' s rings and non‐linear dynamics (dissipative structure theory), the dynamic mechanism of migmatization is profoundly expouded as consisting of the early‐stage metasomatism induced by the thermal anomaly, the cardinal‐stage anatexis induced by the early‐stage matasomatism and finally the last‐stage post‐anatex

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8002002.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractThe northern Guangxi region is an important rare metal, rare earth metal and polymetallic metallogenic province. In the region there exist five metallogenic series and two metallogenic subseries, whose metallogenesis shows features of polycyclic spiral evolution throughout the geological history. As far as various cycles are concerned, mantle‐derived ore substances were reduced while crust‐derived ore substances increased from early to late times; in the whole geological evolutionary history, mantle‐derived substances decreased gradually while crust‐derived ones increased. Meanwhile ore element associations became more and more varied. In terms of space, mineralization migrated from the old basement outwards, i.e. from west to east during the Precambrian, and from north to south during the Phanerozoic, and again from east to west during the Yan

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8002003.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractThis study deals with the first application of the isotope dilution‐inductively coupled plasma mass spectrometry in the rhenium‐osmium geochronometry in China. The chemical separation procedure included decomposition of samples by means of alkali fusion, extraction of rhenium by acetone and extraction of osmium by distillation. The recovery of both elements in the entire process was more than 90% . The blanks of analyses were 0.07 ng for rhenium and 0.01 ng for187Os. The mineralization ages of molybdenites from four molybdenum deposits in China were determined by using this method, with a precision (2σ) of about ±3% . These results agree satisfactorily with their geological backgrounds. The Re‐Os method can directly determine ages of metal deposits and reflect the true ages more reliably than other dating methods that only determine the ages of country rocks from which mineralization ages are inferred. As many hydrothermal sulphide deposits usually contain molybdenites, this method has bright prospects of wide appl

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8002004.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractThe close relationship between the genesis of coal metamorphism and the evolution of the regional tectonic framework is expounded on the basis of an analysis of the geological factors causing the metamorphic zonation of the Late Palaeozoic coals in southern North China; in terms of the mechanism for the formation of palaeogeothermal anomalies, the effects of thermal groundwater on coal metamorphism is highlighted and a geological model for thermal groundwater metamorphism of coal established ; with the concept of the palaeogeotherm‐coal metamorphism system, the genesis of coal metamorphism is analysed according to the distribution pattern of three geological factors: heat source, heat‐carrier and channel, and heat‐coll

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8002005.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractA structural analysis of K of an aquifer system in the study area is presented, and the main direction and degree of the variability of K are found by using the unstationary regionalized variable theory of geostatistics. Optimal estimation of K has been made by universal kriging method (UKM ). Both spatial variability distribution map and division map of K are given.

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8002006.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractBased on a comparison between the oxygen isotope records of benthic and planktonic foraminifers from core 8KL of the South China Sea and sea‐level change records derived from the Huon Peninsula, New Guinea, it is found that both records are very similar from 72 Ka B.P. to the present, especially for the benthic oxygen isotope record. The linear regression shows that δ18O changes (0.9995‰ for benthic foraminifers and 1.022‰ for planktonic foraminifers) are equal to 100 m in sea‐level fluctuation. After making temperature correction in the δ18O record of benthic foraminifers from 72 to 120 Ka B.P., the curve of sea‐level oscillation of the South China Sea since 186 Ka B.P. has been reconstructed. The lowermost sea‐level that occurred in the last glacial maximum and oxygen isotope stage 6 is approxim

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8002007.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper discusses the Cretaceous‐Tertiary magnetic polarity sequence of the the Hengyang Basin on the basis of magnetostratigraphic study. The age of each stratigraphic unit has been determined with the magnetic polarity time scale combined with39Ar/40Ar dating, thus providing evidence for determining the geological ages of different formations. The authors assign the age of the Dongjing Formation of the Hengyang Basin to Early Cretaceous, the Shenhuangshan Formation to Early‐Late Cretaceous, the Daijiaping Formation to Late Cretaceous, and the Dongtang and Xialiushi formations to Palaeoc

ISSN:1000-9515    

DOI:10.1111/j.1755-6724.1995.mp8002008.x

出版商:Geological Publishing House    

年代:1995

数据来源: WILEY