阿尔金断裂系特征及其找矿前景

阿尔金断裂系由多条次级断裂组合而成,其中各种构造形态发育,在平面上呈雁列、分支复合状。最主要的两条大断裂分别是北缘和南缘断裂,北缘为逆冲断裂,南缘为走滑断裂。阿尔金主断裂控制了南北两个不同构造区的石棉、金、铅锌、铜、稀土、宝石等多种矿产资源,具有良好的找矿前景。     

阿尔金清水泉斜长花岗岩及辉长岩同位素定年及其地球化学特征

<正>1地质概况阿尔金造山带位于新疆、青海、甘肃省区的交界地带,是塔里木、柴达木以及东西昆仑、天山、柴北缘、北祁连和北山构造带的衔接地带,其阿尔金南缘断裂是一条左型走滑深大断裂带,至今还在活动。斜长花岗岩及辉长岩位于阿尔金南缘断裂带中段的清水泉一带,属于前人划分的阿南茫崖构造混杂岩带单元     

阿尔金断裂带最大累积走滑位移量——900km？

通过变形构造几何学、岩石学和区域构造对比研究,认为阿尔金断裂西北侧的阿尔金山北缘、南缘近EW走向的蓝片岩-榴辉岩高压变质带、榴辉岩超高压变质带分别与阿尔金断裂东南侧的北祁连山、柴北缘NW—SE/NWW—SEE走向的蓝片岩-榴辉岩高压变质带、榴辉岩超高压变质带相对应,并且,高压变质带与超高压变质带的宽度和走向在断裂两侧存在较大的变化。这种在断裂带中宽度变窄、角度趋于与断裂带走向一致的变化是韧性或韧脆性走滑过程中产生的拖曳构造。因此,阿尔金断裂带走滑过程中存在较大的韧性变形,它的最大累积走滑位移量应由韧性和脆性走滑位移量组成,至少大于500km,小于1000km。另外,拖曳构造的几何特征,以及西昆仑库地北蛇绿岩、阿尔金南缘蛇绿岩和柴北缘蛇绿岩在年龄、岩石组合及地球化学特征方面均具有相似之处,暗示在早古生代时期西昆仑和阿尔金南缘、柴北缘很可能处于相同的构造背景之中,后被阿尔金断裂所切割。因此,综合得出了阿尔金断裂带最大累积左旋走滑位移量为900～1000km。     

阿尔金长清铁矿矿床地质

<正>1区域地质背景长清铁矿处于阿尔金构造带中部的阿南茫崖构造混杂岩带清水泉西,北部为青藏高原北缘、柴达木地块祁漫塔格构造带,南部为塔里木地块阿尔金构造带。阿尔金南缘大断裂带从区内通过,该断裂带为一具张扭性兼左行走滑的深大断裂带、其次级断裂发育。矿区及其邻区出露地层为长城系小庙岩组斜长角闪岩和黑云斜长角闪岩等区域变质岩。区内岩浆岩发育,从超基性     

北山候选区构造活动性评价初步研究

有研究表明,北山候选区新生代构造受阿尔金断裂系控制,而阿尔金断裂是闻名全球的一条新生代大型走滑断裂带.作为青藏高原的北缘边界之一,新生代阿尔金的走滑活动量在数百公里以上.但是,阿尔金断裂带的走滑活动主要被祁连山的变形吸收和转换了,越过酒西盆地后,只有几百米的走滑量,且呈树枝状分叉自然尖灭.因此阿尔金东北末端构造活动并不强烈.     

新疆阿尔金南缘断裂带铜金铂钯贵金属矿床特征及成因

阿尔金南缘断裂是一条深达上地幔的区域性大断裂,沿断裂分布着众多的基性-超基性杂岩体.岩浆结晶分异晚期,铜、金、铂、钯元素富集,在后期构造热液作用下,形成了清水泉等处的铜、金、铂、钯工业矿床.阿尔金一带找矿前景极大.     

新疆阿尔金南缘断裂带东段成矿地质条件及找矿前景浅析

阿尔金南缘断裂带是分划塔里木地台与东昆仑褶皱系的超岩石圈深断裂,自形成以来,历经多次活动,不仅控制了区内多种岩浆岩、变质岩的分布,同时其产生的次级断裂构造也给各种成矿热液提供了滞存空间.目前区内已发现多个不同成因类型,以铜为主的多金属矿点、矿化点,这些矿点的分布无不与南缘深断裂有着密切关系.因此,阿尔金南缘断裂带极有可能是一个以铜为主的多金属成矿带.所述阿尔金南缘断裂带东段是指自新疆若羌县清水泉至青海茫崖阿尔金南缘断裂带两侧的带状区域.     

塔里木盆地东南缘新生代断裂系统

结合野外地面地质调查成果,并通过对地震、大地电磁等地球物理资料的精细解释构建了塔里木盆地东南缘新生代断裂系统。塔东南新生代断裂系统可以划分为三大体系:阿尔金断裂体系、车尔臣断裂体系和西昆仑断裂体系。阿尔金北缘断层在存在走滑性质的同时,更多的表现为向北西的强烈冲断;车尔臣断裂体系由车尔臣断裂及次级断层和一系列反冲断层组成,除表现为向北西冲断外,还具有左行走滑特征;西昆仑断裂体系主要由自南向北的冲断的逆冲断层组成,在与阿尔金断裂交汇处,受阿尔金左行走滑的影响呈弧形弯曲。     

阿尔金高压变质岩带的特征及其构造意义

阿尔金构造带存在两条高压变质岩带,一条为高压变泥质岩带,出露在阿尔金中段北部红柳沟-拉配泉东西向蛇绿混杂岩带之中的贝克滩东侧,东西向展布约几公里;另一条为榴辉岩带,出露在阿尔金南缘的江格萨依南-米兰河上游一带的北东向隆起带上,断续延伸约200km.区域构造背景、高压变质岩石的变质历史及顺时针型P-T轨迹和年代学研究表明,这些高压变质岩石的形成应与板块俯冲、碰撞活动有关,它们分别代表了显生宙初塔里木板块东南缘的两次俯冲-碰撞活动.这一成果为阐明阿尔金左行走滑断裂系的早期演化及板块增生提供了重要依据.     

阿尔金断裂与周缘新生代盆地关系

通过野外填图工作，在阿尔金断裂附近填绘出一系列的新生代地层，对这些地层目前的展布与阿尔金活动断裂的关系分析认为，始新世以来阿尔金断裂对沉积盆地表现出明显的控制作用，表现为明显的左行走滑，并兼具向北西方向掀斜的逆冲活动。乌尊硝尔盆地(索尔库里盆地西部)中的主体沉积是第四系。盆地的东南边界是阿尔金南缘主断裂；盆地西南缘，第四系沉积受东西向北倾正断层控制；盆地北缘为近东西向北倾右行逆冲脆性断裂。盆地的西部边缘超覆在基岩之上，不受断裂控制。     

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.     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

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.)