北澜沧江带的性质——是冈瓦纳板块与扬子板块的界线吗?

藏东地区冈瓦纳板块与扬子板块的界线是不能回避的关键问题。借助前人已有的区域地质资料和研究成果,对北澜沧江带两侧的基底岩系、古生代沉积建造、地层古生物、火山岩浆弧、变质岩、变质作用、高压变质带、吉塘岩群、酉西群、构造运动分期等进行剖析,并与邻区进行了简单对比。在此基础上初步得出北澜沧江带是藏东地区连接滇西澜沧江缝合带与龙木错－双湖缝合带的纽带,是藏东地区冈瓦纳板块与扬子板块界线的倾向性意见,还有待于深入研究的验证。     

汇聚造山带变质矿物冠状反应边及生长环带

哀牢山、澜沧江、高黎贡山、念青唐古拉山等汇聚造山带变质岩中,发现一些标型或特征变质矿物间形成冠状反应边或生长环带。它们是变质过程的真实记录,反映了变形变质环境条件的不断变化,完整或直观地表现了不同地体或构造带PTt轨迹特征。可帮助恢复汇聚造山带中不同地体构造属性,为研究造山带PTtD轨迹和PTDX轨迹,提供准确资料。可从另一侧面了解汇聚造山带的演化史。     

从冰川剥蚀作用看念青唐古拉山脉(中段)的隆升

通过对念青唐古拉山主峰地区第四纪冰碛地层划分与同位素测年,发现主峰地区的第四纪冰川分别形成于700～600kaBP、200～140kaBP和70～30kaBP三个时段,指示了自中更新世以来念青唐古拉山中段开始大规模隆升,冰川活动加剧,并堆积了相应的冰碛物。根据念青唐古拉山主峰地区基岩地层与岩性的空间分布、不同火成岩和变质岩组合的形成深度和不同冰期冰碛物砾石成分统计研究,发现冰川对基岩剥蚀与念青唐古拉山中段隆升过程有着明显的对应关系。本文从念青唐古拉山主峰地区的基岩地层的岩石成分和分布的研究,及其对山脉隆升与冰碛物成分的关系等方面,分析了念青唐古拉山脉的切割及其对山脉隆升的反映。念青唐古拉山主峰地区的隆升过程可较好地与青藏高原的隆起相对比,它应是青藏高原隆升的响应。     

澜沧江构造带南段变质岩系锆石U-Pb年代学及构造涵义

澜沧江构造带南段的古老变质岩系因临沧花岗岩基的大面积出露而呈零星分散状出露,该地区是否存在前寒武纪结晶基底和变质岩系的精确时代以及澜沧江构造带变质岩系的变质时限等问题还不是很清楚。本文以变质岩系为研究对象,挑选出锆石颗粒进行U-Pb SHRIMP定年,获得锆石核部U-Pb年龄是1802Ma、1404Ma、1092Ma、906~961Ma、812Ma和727~623Ma,时代为古元古代、中元古代和新元古代,揭示研究区存在前寒武纪的结晶基底,三叠纪(~230Ma)发育区域性岩浆作用事件,破坏改造了其结晶基底;昌宁-耈街剖面近澜沧江岸边花岗质片麻岩的锆石U-Pb谐和年龄为73.9±1.8Ma(MSWD=1.3,N=6),记录澜沧江构造带变质岩经历了晚白垩世变质事件。综合研究认为澜沧江构造带南段存在区域性前寒武纪结晶基底,构造带中昌宁段之变质岩系的变质时间为晚白垩世(85~74Ma),并一直持续到36Ma,约32Ma之后构造带发生走滑运动,变质事件明显早于走滑运动事件。     

唐古拉山上新世至第四纪古地理环境的演变(以山口地区为例)

唐古拉山横亘于青藏高原腹部地区,是世界著名大河—长江、怒江和澜沧江发源之地。笔者几年来通过该地区实地考察,对山地由于晚新生代期间强烈隆起而导致古地理环境的深刻演变获得了难忘的印象。本文拟以唐古拉山口地区为例,对山地自上新世以来自然环境的变迁作一初步探索和讨论,这或将有助于对整个青藏高原第四纪古地理环境演变的认识。     

念青唐古拉山深部构造特征研究

本文利用INDEPTH项目深反射地震资料和大地电磁测深资料对念青唐古拉山地壳构造特征进行了深入细致的研究,通过对深反射地震资料的地震相分析及与大地电磁资料的比较得到：①16～22km深度的部分熔融体是多个不连通的独立的穹隆;②在羊八井一当雄北地区,深45～58km以下的下地壳深度存在NE走向的向形构造,该向形构造向北延伸、逐渐变深;③当雄北20km附近,中下地壳在深29～58km范围内存在大型的正断层,断距达6km。     

鄂尔多斯盆地本溪组沉积物物源探讨及其构造意义

鄂尔多斯盆地在经历了古生代抬升剥蚀之后,在晚古生代晚期开始沉降并沉积了海陆过渡相本溪组碎屑岩。为阐明该套碎屑岩的物源体系特征,基于露头、岩芯、分析化验等多种分析测试手段,分析了本溪组砾岩分布、轻矿物碎屑组分、石英阴极发光、重矿物特征及碎屑锆石U-Pb年龄分布特征,识别了本溪组平面上不同物源体系,继而确定了不同物源体系的母岩类型及本溪组沉积时期盆地南部构造演化特征;研究表明本溪组沉积时期,鄂尔多斯盆地整体南北双向供源,其中北部物源供给相对较强,进一步划分为四个子物源体系,西北物源母岩主要为变质岩和少量火山岩,东北部地区母岩主要为酸性侵入岩,西南部地区物源主要为高级变质岩、部分岩浆岩和少量沉积岩,东南部地区主要为高级变质岩。同时在本溪组沉积时期,南部物源影响范围可达盆地中部地区,北秦岭陆块该时期已与华北板块南缘发生碰撞是南部物源体系重要组成部分。     

澜沧江河流沉积物碎屑锆石U-Pb年龄、Hf同位素组成及其地质意义

为研究澜沧江沉积物的物质来源及相邻地块的地壳生长和演化规律,利用LA-MC-ICP-MS分析技术,对澜沧江河流沉积物碎屑锆石进行了U-Pb年龄和Hf同位素研究。结果表明：锆石U-Pb年龄主要有5个年龄段,分别是＜177 Ma、201~418 Ma、428~544 Ma、581~1189 Ma和1406~2533 Ma,主要峰值为260 Ma、788 Ma、1 827 Ma和2 474 Ma。其年龄分布特征与北羌塘地块的年龄分布非常一致,说明澜沧江沉积物主要来源于北羌塘地块;结合Hf同位素分析结果,能够反映源区北羌塘地块的形成与演化历史。新太古代-中元古代是北羌塘地块从亏损地幔物质增生的地壳持续生长阶段,它们构成现今北羌塘地块全部地壳物质的78%以上,此后直到0.64 Ga,北羌塘地块的地壳增生作用基本结束。     

唐古拉山北坡侏罗纪双壳类化石新材料

唐古拉山地区侏罗系发育良好,是国内侏罗纪双壳类最丰富的地区之一。本文描述其中的8属17种,大多数为国内首次报道的种。由于唐古拉山地区在侏罗纪时正好位于东亚分区(East Asian province)、埃塞俄比亚分区(Ethiopian province)和欧洲分区(European province)3个不同的双壳类生物地理分区接合处,因此本区双壳类显示出一定的混生色彩,具有上述各区的一些特征属或种。但是更值得注意的是自唐古拉山向东南方向,包括西藏东部、云南、缅甸及泰国的侏罗系中,双壳类动物群含有大量的共同分子,并形成特殊的地方性生物群,考虑到侏罗纪古板块的构造格局,对上述特提斯北岸东缘进行进一步研究,将有助于建立侏罗纪的一个新的双壳类生物地理分区。     

唐古拉山北坡侏罗纪双壳类化石新材料

唐古拉山地区侏罗系发育良好,是国内侏罗纪双壳类最丰富的地区之一。本文描述其中的8属17种,大多数为国内首次报道的种。由于唐古拉山地区在侏罗纪时正好位于东亚分区（East Asian province）、埃塞俄比亚分区（Ethiopian province）和欧洲分区（European province）3个不同的双壳类生物地理分区接合处,因此本区双壳类显示出一定的混生色彩,具有上述各区的一些特征属或种。但是更值得注意的是自唐古拉山向东南方向,包括西藏东部、云南、缅甸及泰国的侏罗系中,双壳类动物群含有大量的共同分子,并形成特殊的地方性生物群,考虑到侏罗纪古板块的构造格局,对上述特提斯北岸东缘进行进一步研究,将有助于建立侏罗纪的一个新的双壳类生物地理分区。     

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