早前寒武纪变质地层学研究的回顾与思考

主要论述了与早前寒武纪变质地层（学）有关的8个方面的问题：早前寒武纪变质地层的研究概况；早前寒武纪变质地层的复杂性和研究难度；早前寒武纪变质地层研究的思路和工作方法；早前寒武纪变质岩石地层单位岩群、岩组和杂岩的划分问题；重要区域性不整合的研究；鉴定变质地层的原岩类型、岩石性质和恢复古环境；正确区分变质地层和TTG岩系以及其他变质深成岩；变质地层时代的确定。另外，对今后的研究工作提出了3项建议。     

早前寒武纪克拉通问题

早前寒武纪克拉通过去认为是地槽演化的结果。其实不然。本文讨论形成它们变质原岩火山－沉积建造的大地构造条件。现成早前寒武纪克拉通火山沉积盖层的成熟沉积岩丰富了孔兹岩原岩。它们面状展布，经常是很长时期形成的，这改进了识别早前寒武纪克拉通地台式变质原岩建造的标志。这类标志遍及七大洲，高级区和绿岩带。有理由认为，早前寒武纪克拉通是在老克拉通盆地里的地台式火山－沉积建造经变质－混合岩化－塑性流变－硬化的产物。     

略论我国前寒武纪变质作用和地壳演化的某些特征

本文对中国早前寒武纪太古期、早元古期、中晚元古期的变质作用的分布、岩石类型、变质相特点、变质相划分及同位素年龄数据等进行了论述。将中国前寒武纪地壳划分为华北、西北、华南、西南四个变质区、各变质区有自己的不同特点和演化历史。前寒武纪地壳演化是陆壳增长的历史,区域高温和中温变质作用是太古代原始地壳特有的变质作用。     

早前寒琥纪克拉通问题

早前寒武纪克拉通过去认为是地槽演化的结果。其实不然。本文讨论形成它们变质原岩火山－沉积建造的大地构造条件。现成早前寒武纪克拉通火山－沉积盖层的成熟沉积岩丰富了孔兹岩原岩。有理由认为，早前寒武纪克拉通是在老克拉通盆地里的地台式火山－沉积建造经变质－混合岩化－塑性流变－硬化的产物。     

浙西南下元古界八都群的地质年代学

下元古界八都群是中国东南大陆边缘最古老的变质岩系之一，为早前寒武纪浙闽克拉通的主要组成部分。利用单颗粒锆石U-Pb法、常规锆石U-Pb法、锆石蒸发Pb法、Sm-Nd、Rb-Sr等时线法确定八都群的成岩时代为2050-2400Ma，区域变质作用和克拉通化时间为1900±100Ma。     

前寒武纪地质学理论的重要实践─—评《恒山早前寒武纪地壳演化》

前寒武纪地质学理论的重要实践─—评《恒山早前寒武纪地壳演化》田永清（山西省地质科学研究所）李江海、钱样麟合著的《恒山早前寒武纪地壳演化》经《华北地质矿产杂志》编辑部编辑，由山西科学技术出版社以“山西地球科学丛书”出版，这是对山西省前寒武纪及变质地质研...     

燕辽地区太古宇与下元古界间不整合面的发现及其意义

我们经过对冀北东部早前寒武纪变质岩系的岩石，地层，变形变质和同位素年龄以及中间界面的研究，表明上、下部岩系为角膜不整合接触。不整合面的存在，对早前寒武纪地层划分，确定地质时代，研究地壳演化史，开展地质调查及找矿都有一定意义。     

早前寒武纪变质火山-沉积岩系讨论会概况

中国地质学会前寒武纪地质专业委员会和辽宁省地质学会联合召开的“早前寒武纪变质火山-沉积岩系讨论会”,于1981年10月14—19日在沈阳召开。这是第一次规模较大的全国性的早前寒武纪基础地质问题     

黑龙江省东部麻山群黑云斜长片麻岩中锆石的年龄及其地质意义

采自西麻山煤矿附近的麻山群黑云斜长片麻岩中，分离出了较多的锆石。采用单颗粒锆石逐级蒸发沉积法对其进行了定年研究，获得的１０粒锆石的２０７Ｐｂ／２０６Ｐｂ年龄相当一致，平均值为５２７．５±４．４Ｍａ。所测岩样经岩石学和矿物学研究均未发现有显著的后期叠加变质作用，因此，可以认为所测样品的主变质作用发生在寒武纪早－中期，而不是早前寒武纪。麻山群的原岩时代可能也不全是早前寒武纪，而更可能是一个较复杂的岩石构造地层单位，需要将其解体、重新认识和命名。     

燕山地区前寒武纪岩石退变质作用研究报道

华北地台的结晶基底是我国最老的变质岩系.燕山地区是早前寒武纪地层的重要分布区域之一.它西起冀西北,经北京北山,东迄渤海之滨,居于中朝克拉通结晶基底的北缘.近年来,随着变质作用研究的不断深入,也重视了退变质作用.王仁民先生1962年首先在冀东水厂研究退变质作用.从1981年起,由天津地质矿产研究所高凡先生主持退变质作用研究课题,并列入"燕山—阴山地区早前寒武纪地层划分对比研究"项目.1983年单独列题为"燕山地区早前寒武纪岩石退变质作用研究"项目.1987年接受国家自     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

HYDROGEOLOGY

正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level     

METAMORPHIC PETROLOGY

正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),     

SERIALS

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GEOPHYSICAL EXPLORATION

正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci-     

QUATERNARY GEOLOGY & GEOMORPHOLOGY

正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-     

PETROLEUM GEOLOGY

正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)     

GEOCHEMISTRY

正20142002 Wei Hualing(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang065000,China);Zhou Guohua Element Content and Mineral Compositions in Different Sizes of Soil in Tongling Area,Anhui Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(11),2013,p.1861