安微向心铁硫矿区硅夺特征及成因意义

宇芜向山－皇姑山地区铁硫矿床中及附近存在大片硅质岩,属热泵沉积的硅华。其微量元素Ａｌ、Ｍｎ、Ｃｕ、Ｐｂ、Ｚｎ含量较高,且具有稀土元素总量较低,Ｃｅ明显亏损,Ｅｕ明显富集等特征。据这,岩石化学特征,结合微量元素、稀土元素同位素等研究表明,矿床附近硅质岩为热水成因,硅质可能来自下伏及深部地层。     

论石门雄黄矿床硅质岩的热水成因

湖南石门雄黄矿床附近存在大片硅质岩。硅质岩是热泉沉积的硅华，其微量元素组成与矿石中以及该区现代热泉体系沉积物类似，成矿溶液富Ｎａ＋、Ｃａ２＋、Ｃｌ－、ＨＣＯ３－、ＳＯ２－４，与该区现代热泉类似。根据岩石学、岩石化学特征，结合微量元素、稀土元素与同位素等综合研究表明：矿床附近硅质岩为热水沉积成因，硅质可能来自下伏及深部地层。     

青城子地区辽河群地层中硅质岩及其与金银矿的关系

以显微镜下观察到的微观现象论述辽河群地层中硅质岩的特征，阐述硅质岩与成矿的关系。通过镜下发现的特征矿物，结构，构造，标型矿物特征并结合岩石化学特点、稀土元素分析规律以及微量元素分布特征等，认为可群地层中硅质岩属海火山喷气成因。空间上与金，银等金属元素有关密切，硅质岩本身或附近就是金，银矿体。     

辽东中朝裂谷硅质岩的特征及成因①

文章对中朝裂谷硅质岩的产出、组构、岩石化学成分、微量元素、稀土元素特征、稳定同位素及包裹体等特征进行了研究,阐述了硅质岩为海底火山喷流—热水沉积环境的存在。     

甘肃大桥金矿硅质岩地球化学特征及其地质意义探讨

通过对甘肃大桥金矿硅质岩野外及岩石学特征、主元素、微量元素及稀土元素等地球化学分析,研究了该矿区硅质岩的成因特征,并探讨了其地质意义。结果表明,硅质岩化学成分中SiO_2含量为75.59%~93.00%,Al/(Al+Fe+Mn)平均值为0.82;大部分微量元素与克拉克值相比处于亏损状态,而Au、Ag、As、Sb、Hg等微量元素富集;稀土元素SREE平均值为88.68μg/g,经北美页岩标准化后其δCe值为0.68~1.21,δEu值为0.77~1.32,LREE/HREE值为2.76~23.32,平均值为14.54,轻稀土元素富集明显,(La/Ce)N平均值为1.22,(La/Yb)N平均值为2.33。地球化学数据在反映大桥金矿硅质岩成因上具有不一致性,但是通过与国内金矿床硅质岩的稀土元素地球化学特征对比,并结合区域地层对比,可以初步判定大桥金矿硅质岩沉积环境靠近大陆边缘,使得该套硅质岩既受到了海底热液作用,同时又受到了陆源沉积作用的影响,属于热水沉积与正常沉积的过渡类型。然而硅质岩对于该矿床中金在矿源层形成阶段的初步富集所起的作用还需进一步研究。     

江西永平地区石炭纪硅质岩成因地球化学特征及沉积环境

对永平地区石炭纪硅质岩的常量元素、微量元素、稀土元素、硅和氧同位素地球化学特征研究证明其为热水沉积硅质岩。硅质岩沉积大地构造地球化学表明硅质岩的沉积环境是大陆边缘的浅海。     

甘肃大桥金矿硅质岩地球化学特征及其地质意义探讨北大核心CSCD

通过对甘肃大桥金矿硅质岩野外及岩石学特征、主元素、微量元素及稀土元素等地球化学分析,研究了该矿区硅质岩的成因特征,并探讨了其地质意义。结果表明,硅质岩化学成分中SiO2含量为75．59％～93．00％,Al／（Al＋Fe＋Mn）平均值为0．82;大部分微量元素与克拉克值相比处于亏损状态,而Au、Ag、As、Sb、Hg等微量元素富集;稀土元素EREE平均值为88．68μg／g,经北美页岩标准化后其占ce值为0．68～1．21,JEu值为0．77-1．32,LREE／HREE值为2．76～23．32,平均值为14．54,轻稀土元素富集明显,（La／Ce）N平均值为1．22,（La／Yb）。平均值为2．33。地球化学数据在反映大桥金矿硅质岩成因上具有不一致性,但是通过与国内金矿床硅质岩的稀土元素地球化学特征对比,并结合区域地层对比,可以初步判定大桥金矿硅质岩沉积环境靠近大陆边缘,使得该套硅质岩既受到了海底热液作用,同时又受到了陆源沉积作用的影响,属于热水沉积与正常沉积的过渡类型。然而硅质岩对于该矿床中金在矿源层形成阶段的初步富集所起的作用还需进一步研究。     

秦岭深盆系热水沉积硅质岩的地球化学特征

秦岭泥盆系中广泛发育一套与Ｐｂ、Ｚｎ、Ａｇ矿化有关的热水沉积硅质岩，主要为铁白云石硅质岩和似碧玉岩两类，前者代表海底热水喷水口附近的产物，后者代表距喷水口较远的沉积产物。由于二者沉积环境的差异，造成了二者化学成分、矿物成分、微量元素、稀土元素及氧同位素等方面的不同。因而，可以根据这些特征来判断热水沉积硅质岩的沉积环境，这对阐明该类矿床的成因有重要的意义。     

桂西北高龙金矿床含矿硅质岩成因及沉积环境分析

高龙金矿床含矿硅质岩的野外宏观特征、镜下组构特征和稀土元素地球化学特征一致表明硅质岩的形成主要与热水沉积作用有关,而非前人认为的断裂破碎 -热液硅化交代岩。岩石化学、稀土元素和微量元素地球化学特征表明,硅质岩可能形成于大陆边缘 -远洋盆地过渡位置,但更靠近大陆边缘的半深海 -深海环境。     

粤西长坑金银矿区硅质岩的地质地球化学特征及成因探讨

下石碳统梓门桥组硅质岩是粤西长坑金银矿床的直接容矿岩石。本区硅质岩内层纹状、多孔状、同生角砾状等沉积组构发育，岩石化学成分，微量元素及稀土元素等地球化学特征与加拿大沙利文热液沉积岩等世界著名的热水沉积硅质岩相似，属于热水沉积成因。     

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