合肥盆地基底构造属性

根据合肥盆地及周边地表地质、地震剖面、同位素测年及MT等新资料的综合研究,提出中-新生代合肥盆地的基底是一个不同构造类型基底的叠合与复合.上古生界以前的基底以六安断裂为界,其北为华北板块陆壳型-过渡壳型结晶基底及其上的华北克拉通-被动大陆边缘盆地沉积的上元古-下古生界基底;其南为大别型结晶基底及其上的北淮阳弧后盆地沉积的上元古-下古生界变质基底,而上古生界基底属于弧后前陆盆地型沉积.六安断裂是合肥盆地部位北大别弧、北淮阳晚元古-早古生代弧后盆地在早古生代晚期-晚古生代早期与华北板块的弧-陆碰撞缝合线.     

东北及内蒙古东部地区显生宙构造演化的有关问题

以国家油气资源战略选区项目研究成果为基础,结合近年来该区积累的大量区域地质调查资料和已发表的数据,对东北及内蒙古东部地区早古生代以来的大地构造性质及其演化进行综合对比分析。东北地区晚古生代以来的构造演化以稳定的大陆地块为主体,而非两大板块间多岛洋演化形成的造山带。东北地区的各地块均具有前寒武纪—早前寒武纪、甚至是太古宙的古老基底,它们在早古生代早期(490～510Ma)同时遭受了区域变质作用和花岗质岩浆侵入。350～450Ma,各地块均处于相对稳定的构造环境,以普遍缺失这一时期的花岗质岩浆活动记录为标志。从早古生代晚期开始,东北及内蒙古东部地区至少已存在2个早古生代早期固结的微陆块,即额尔古纳—兴安微陆块和松嫩—佳木斯微陆块,这2个微陆块向北分别与俄罗斯境内的额尔古纳微陆块和布列亚微陆块相连。二者在早石炭世沿北北东向展布的开鲁—嫩江—黑河—诺拉—索霍提(Nora-Soukhotin)一线碰撞拼合,形成统一的东北亚晚古生代大陆板块。西拉沐伦河断裂西端被北北东向构造所截,向东延至开鲁—嫩江断裂,并没有延伸到松辽盆地内,说明西拉沐伦河断裂可能与开鲁—嫩江碰撞带的形成有关。从晚石炭世开始,东北亚大陆板块整体处于伸展构造背景,至少在中国境内具有北陆南海的构造-沉积古地理格局,早期发育以火山岩为主的断陷盆地,到中二叠世演化成一个规模巨大的海相沉积盆地。中生代以来,东北地区的构造体制转换及物质成分演化不仅仅是古亚洲洋构造域和西太平洋构造域叠加转换的结果,蒙古—鄂霍茨克构造域的演化对该区现今构造体制的形成也具有重要影响。地质和地球物理综合证据显示,大兴安岭北部的得尔布干断裂、内蒙古中部的贺根山断裂和黑龙江省东部的跃进山断裂可能并不是具有一定深度规模的构造分区断裂。东北地区的中、新生代盆地之下并非都是变质结晶基底,而是存在一个规模巨大的晚古生代海相沉积盆地。     

中国中西部小型克拉通盆地群的叠合复合性质及其含油气系统

中国中西部盆地油气资源潜力巨大,是晚古生代一早中生代一新生代大型造山带环绕的小型克拉通盆地,盆地核心为构造相对稳定的小型克拉通,边缘环绕构造活跃的前陆冲断带。与北美、欧洲等大型含油气盆地相比,中国含油气盆地规模小、构造活动性强。盆地普遍经历：（1）寒武—志留纪,各自漂离于大洋中的小型克拉通盆地;（2）泥盆—二叠纪,亚欧板块南缘地体增生;（3）三叠—古近纪,特提斯洋关闭,陆相断（坳）陷盆地;（4）新近纪以来,再生前陆盆地等四个构造演化阶段。从下而上叠合了早古生代海相克拉通盆地、晚古生代海陆交互相克拉通盆地、早中生代陆相断（坳）陷盆地和新生代再生前陆盆地四个构造层序。古生界克拉通盆地构造相对稳定,古生代发育多期不整合界面和大型古隆起;中新生代前陆盆地叠置复合在其边缘,发育成排成带的构造。中国含油气盆地的叠合-复合性质决定了其叠合-复合含油气系统的特征：具有多油气系统、多源多阶段生烃、多期成藏、多层系含油气。中国中西部盆地的油气勘探主要包括古生界小型克拉通层序和中新生代前陆层序两大领域,其中早古生代克拉通层序以古隆起及其斜坡、晚古生代克拉通层序以大面积岩性储集体、中新生代前陆盆地以大型冲断带控制着油气的成藏与富集。     

地块—海槽边缘带成油成气新概念

对准噶尔，塔里木等盆地沉积环境的研究表明，古生代时，中国西北区海相沉积，沉积盆地的基底是一些离散的古老结晶地块，其上海水侵浸，地块之间为大洋或窄大洋的海槽，地块之间的海槽或地块与海槽过渡的边缘带盆地是油气形成的有利地带。     

地块—海槽边缘带的油气形成

对准噶尔，塔里木等盆地沉积环境的研究成因，在古生代，中国西北区为海相沉积，沉积盆地的基底是一些离散的古老结晶地块、其上海水侵漫，基间为大洋或窄大洋的海槽。地块蝗海或地块与海槽过渡的边缘带盆地是油气形成的有利地带。     

我国东北地区晚侏罗世聚煤规律

我国东北地区在地史上晚侏罗世是一个极为重要的聚煤期,并形成了一系列重大煤田,其煤的储量约占全区煤总储量的89.8%。1.盆地基底结构我图东北地区的晚侏罗世煤盆地主要分布于建平—铁岭东西向古隆起带,大兴安岭西坡与黑龙江东部。盆地基底结构复杂。建平—铁岭古隆起带上的平庄、(?)新、铁法等煤田盆地的基底为太古界、大兴安岭西坡的海拉尔、白音华等盆地群的基底,一般为石炭二叠系低变质岩及中侏罗统陆相碎屑岩。黑龙江东部的三江—穆棱一带的基底较为复杂,有元古界变质岩系及其花岗岩、古生界低变质碎屑岩、碳酸岩与海西期花岗岩,上三叠统—中侏罗统海相硅质岩、陆相碎屑岩与燕山期侵入岩与火山岩。     

佳木斯地块东缘南双鸭山组碎屑锆石年代学及其大地构造意义

正佳木斯地块位于我国黑龙江省东部,大地构造上处于华北和西伯利亚两大古板块所夹持的中亚构造带最东端,东邻西太平洋大陆边缘中生代增生杂岩带。该地块以广泛出露有麻粒岩相高级变质表壳岩系,东缘发育晚古生代大陆边缘沉积层系和早中生代海相沉积地层为特征。早期的研究普遍认为,东北地区以佳木斯地块等为代表的诸变质构造单元是卷入到东亚晚古生代地槽褶皱带或古亚洲     

松辽地块大地构造属性: 古生界碎屑锆石年代学的制约

对松辽地块南部上古生界哲斯组的碎屑锆石应用LA--ICP --MS U --Pb 测试的结果显示了4 个主要的年龄段: 263 ～ 378 Ma ( 峰值年龄274 Ma) ; 405 ～ 547 Ma ( 峰值515 Ma) ; 660 ～ 974 Ma ( 峰值为 923 Ma) ; 其余均为中元古代年龄1 165 Ma、1 369 Ma、1 476 Ma、1 517 Ma。其中最年轻一组锆石年龄263 ± 2 Ma 代表了哲斯组主体沉积的下限年龄; ～ 274 Ma 的峰期年龄与附近地区的大石寨组火山岩和岛弧岩浆岩的年龄一致; ～ 515 Ma 的峰期年龄与东北地区泛非期基底变质杂岩的年龄一致; 其余的古老年龄均反映了松辽地块基底的信息。结合松辽地块的北部上古生界土门岭组、西部本巴图组和东缘黑龙宫组的碎屑锆石年龄,显示松辽地块应存在太古代和元古代的变质基底,为古生界地层提供了丰富的物源。松辽地块应为一个稳定的微地块,而不是长期活动的造山带。     

藏北羌塘盆地基底变质岩的锆石SHRIMP年龄及其地质意义

羌塘盆地经受了青藏高原隆升事件等强烈的构造作用,盆地是否具有刚性结晶基底,对于油气的保存至关重要。长期以来对于该盆地是否具有前古生代的结晶基底,分歧较大。笔者新近在羌塘盆地中央隆起带北缘俄久卖发现的含夕线石和蓝晶石的片麻岩以及其附近发现的极浅变质的奥陶系地层,证实羌塘盆地具有变质结晶基底。本文进一步开展了片麻岩中锆石的SHRIMP年龄分析,获得了7组锆石年龄：2498~2374Ma 、1780 ~1666Ma、645~522Ma、465~420Ma、402~369Ma、270~233Ma和223~198Ma。通过CL图象对各组年龄锆石进行成因分析,并结合区域地质特征,认为1780 ~1666Ma为该片麻岩的主期变质年龄,羌塘盆地具有前寒武纪结晶基底,并对其余年龄组反映的构造热事件及其地质意义进行了讨论。     

东北及邻区晚古生代大地构造属性新认识

哲斯腕足动物群是一个凉水型腕足动物群,土著种含量在75%以上,古生物地理区划属于北方生物地理大区的内蒙古区。自成一个地理区说明其北有重要地理隔绝:暗示存在一个较大地块(佳—蒙地块);凉水型性质则说明中二叠世这个稳定地块与华北板块之间存在一个足够宽的深海洋盆——古亚洲洋南支。在佳—蒙地块上,晚古生代地层发育较佳,保存较好。这些晚古生代地层围绕佳—蒙地块核心呈环带状分布,明显构成佳—蒙地块的大陆边缘沉积。在我国东北地区,出露的晚古生代海相地层主要为佳—蒙地块的南缘和北缘沉积。根据目前已有资料统计,中生代为东北及邻区花岗岩侵位的峰期,志留纪—泥盆纪为花岗岩浆活动相对沉寂的时期,花岗岩的这种侵位时代特征支持晚古生代存在一个稳定地块的设想。东北地区晚古生代地层主体未见遭受低绿片岩相区域变质的迹象,说明这一地区晚古生代地层主体未曾发生过强烈的褶皱造山、普遍的区域变质的地槽发展过程。东北及邻区为天然地震弱震区,其周缘被锡霍特—珲春、蒙古—鄂霍次克、阿尔泰—华北北缘强地震带所围,似乎可以得出这是一个构造相对稳定的区域、其间不曾存在晚古生代以来的板块构造缝合线的结论。东北地区中、新生代发生的大规模拆离—走滑使得原本较为完整的、稳定的块体发生了分割与位移。如此,一个完整的地块被切割成多个块体(即所称的众多"微板块")。东北及邻区晚古生代构成了一个巨大地块:佳—蒙地块。佳—蒙地块是北由蒙古—鄂霍次克缝合带、南由西拉木伦河—延吉缝合带、东由中锡霍特俯冲带所围限的一个晚古生代稳定的大地构造单元。     

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