长英质岩浆中不混溶流体的运移机理——兼论成矿作用发生的条件

与岩浆作用有关的热液矿床的形成,在一定程度上是岩浆体系内富含挥发分流体的组成、压力及性质演变的结果。长英质岩浆中无水硅酸盐矿物的结晶导致挥发性组分以气泡形式存在。气泡的体积随岩浆演化程度增强而不断增大,由于两不混溶流体之密度差而产生的力的作用使气泡相对硅酸盐熔体（＋晶体）超前向上迁移,最终到达岩浆房顶部。长英质岩浆中富含挥发分流体的迁移运动是通过气泡的上浮实现的。气泡能否上浮主要取决于气泡的体积大小和受力的强度。只有体积较大的气泡才可能迅速迁移并到达岩浆房顶部。修正后的Ｄａｒｃｙ定律对气泡（岩浆体系中的流体）的上述运动特征给予了物理学方法的描述。     

浙江泰顺洋滨含锡黄英斑岩中的流体包裹体研究

洋滨含锡黄英斑岩是火山作用晚期形成的次火山岩。岩石地球化学特征表明，它由高度分异演化的花岗质残余岩浆形成．岩石中包裹体十分丰富，存在羟基化熔体包裹体，富气相包裹体、含NaCl子晶多相包裹体和富液相包裹体系列，表明成岩过程中，岩浆熔体与流体脉动式不混溶，以及流体经过了多阶段演化。包裹体温度和盐度显示．流体衍生和演化过程中，温度呈叠瓦式降低（变化范围580～180C），盐度（wt％NaCl）则由低到高再到低（依次为：5.1～10．5→6.9→21.4→30～48→16～22→2～10）。羟基化馆体包裹体是岩浆向热液转化的桥梁和证据。     

煌斑岩—硫化物熔体液态不混溶作用的高温高压实验研究

本文以云南老王寨金矿区煌斑岩和黄铁矿为初始物,在1.5～3.0GPa、1162～1560℃条件下进行了煌斑岩—硫化物熔体液态不混溶作用实验。结果表明,煌斑岩硫化物熔体的液态不混溶作用可能发生于岩浆演化的早期（高压条件）,但如有硫存在,在岩浆演化的各个阶段（高压条件→低压条件）均可能出现煌斑岩硫化物熔体的液态不混溶作用;与煌斑岩熔体分离的硫化物熔体在温度场、压力场中作定向运移,逐渐聚集于相对低温、低压区;由于硫化物熔体的密度相对较大,因而与煌斑岩熔体之间出现明显的分层现象。     

藏东玉龙斑岩铜矿带岩浆作用的物理化学条件

本文在对玉龙矿带花岗斑岩类矿物学、岩类学研究的基础上,应用多种地质温压计方法,计算了该区岩浆作用的物理化学条件,讨论了其岩石和矿床成因意义.岩浆结晶的P—T途径为P:（?）5kbar→0.15～0.4kbar;T:990～950℃→650～620℃;logfo2:-11.0→-15.0.岩浆源深度（?）32.3～38.5km,初始岩浆温度1050～1200℃.斑晶矿物稳定的P1120=1.4～3.6kb,熔体相水的溶解度XH20=0.083～0.325（2.4～11.7wt%）.XOH=0.114～0.156.含矿岩浆logfs2=1.33～1.59士0.54.熔体相硫的溶解度Xs=0.014～0.033（mol.%）（67～158ppm）;无矿岩浆logfs?-0.6±0.6（?）,硫的溶解度Xs=0.002～0.008（mol%）（12～40ppm）.文中提出早期岩浆阶段熔体相硫的溶解度和岩浆系统硫逸度差异是控制斑岩铜矿化的重要因素,晚期岩浆阶段岩浆结晶作用发生在强烈的水过饱和(PH20>P总)条件下是导致成矿热液活动的基本驱动力.并归纳了斑岩含矿性的物理化学条件标志.     

岩浆岩中的熔体包裹体

熔体包裹体是岩浆岩矿物生长过程中捕获的天然岩浆珠滴 ,它们有效地保存了大量有关其主矿物形成时周围岩浆介质的物理化学信息 ,所以它们是其主矿物结晶演化史的忠实记录员 ,它们能够提供岩浆系统成分和演化的重要信息。文中对熔体包裹体研究的若干基本原理进行了讨论 ,它们涉及 :(1)熔体包裹体的一般特征 ;(2 )熔体包裹体封闭过程中和封闭后的演化 ;(3)熔体包裹体的均一化研究 ;(4 )熔体包裹体化学成分和挥发组分研究。熔体包裹体研究可以对岩浆岩石学中的一些重要问题进行更为深入的探索 :(1)重建天然岩浆结晶演化的热历史 ;(2 )提供有关岩浆沿下降液相线的成分数据 ;(3)查明天然岩浆结晶演化过程中化学成分的变迁规律 ;(4 )解决岩浆岩石学中的一些疑难问题 ,如岩浆不混溶作用、岩浆混合作用、岩浆混染作用、岩浆中硫的性状、地幔部分熔融和地幔交代作用等方面的问题。将熔体包裹体数据和常规的岩石学、地球化学和实验岩石学信息综合一体 ,可以提高我们模拟岩浆作用过程的能力。熔体包裹体研究已经成为现代岩浆岩石学的一个独立的分支 ,其前景十分广阔。     

赣南西华山花岗岩的云母成分特征及其对岩浆演化与成矿过程的指示

西华山钨矿为华南地区最重要的钨矿产区之一,其形成与西华山复式岩体的岩浆演化过程密切相关。随着岩浆演化,西华山钨矿区花岗岩的云母成分发生变化,三八面体云母和二八面体云母分别按"富铁黑云母→铁叶云母→黑鳞云母"和"白云母/多硅白云母→富锂多硅白云母"的方向演化。Li主要通过"Fe2++Mg→AlⅥ+Li"置换方式进入云母晶格,在岩浆演化过程中云母的Li含量逐渐升高。F在云母-熔体间的分配系数随着云母的Mg#(Mg#=100Mg/(Mg+Mn+Fe))降低而减小,因此岩浆演化过程中云母的F含量未明显升高,有利于熔体富集F并演化至更高程度。另外,西华山成矿花岗岩的云母因受到流体交代作用而普遍发育环带结构。环带结构云母的边部与核部相比具有明显较低的Li、F,属于多硅白云母,而出现与多硅白云母共存的方解石表明交代作用流体富含CO2。因此,西华山含矿花岗岩在岩浆演化过程中存在含CO2、相对贫Li和F流体的加入。西华山花岗岩中云母成分的变化还指示体系的氧逸度曾发生变化,即从高氧逸度环境转变为氧逸度相对较低的环境,有利于钨矿的形成。     

岩浆熔体中的挥发性组分及其岩石学意义

文章论述了挥发性组分在岩浆熔体中的溶解行为及其在岩浆熔体中溶解的限制条件，在此基础上讨论了挥发性组分对岩浆演化及岩石学成因方面的意义：溶解在岩浆中的水可明显地改变矿物从岩浆中结晶出的顺序，改变岩浆熔体的演化轨迹。含水玄武岩浆在其早期结晶出铁的氧化物并与Ｓｉ和富碱质组分分异从而使其成为Ｆｅ亏损的钙－碱性系列的岩浆，而无水玄武岩浆演化的早期不能结晶出磁铁矿，因而演化成富Ｆｅ且具中等Ｓｉ含量的拉斑玄武岩系列。溶解于岩浆中Ｈ２Ｏ的离解将产生高ｆＯ２环境，从而导致Ｆｅ的氧化物在岩浆演化早期沉淀。     

浙江仕阳-百丈地区侵入岩岩浆演化特征

仕阳—百丈地区侵入岩岩浆演化岩石类型趋势一般由二长花岗岩→钾长花岗岩→碱长花岗岩方向演化。岩浆分异程度从二长花岗岩→钾长花岗岩→碱长花岗岩基本呈现递增规律,呈现铁、镁降低,而钾钠增加的趋势。稀土总量(∑REE)在演化趋势方向上呈增加趋势。随着岩浆演化分异程度的增高(分异指数DI值的增大),δEu值变化呈减小趋势。     

甘肃干沙鄂博稀土矿床熔体和流体包裹体对成矿的制约

甘肃天祝干沙鄂博稀土矿床产于霓辉正长岩和霓辉正长斑岩中,矿体形态呈不规则脉状、透镜状和板状。成矿过程可分为岩浆期、岩浆-热液期、热液期和表生期,其中岩浆-热液期为主要成矿期。本矿床中的包裹体有熔体包裹体、流体-熔体包裹体、H_2O包裹体、CO_2包裹体、CO_2-H_2O包裹体、含子矿物H_2O包裹体和含子矿物CO_2-H_2O包裹体7类,并以富含流体-熔体包裹体、CO_2-H_2O包裹体为显著特征。包裹体组合从熔体包裹体→流体-熔体包裹体、H_2O包裹体、CO_2包裹体和CO_2-H_2O包裹体→H_2O包裹体的变化,反映本矿床的形成经历了从岩浆→岩浆+热液→热液的演化过程。岩浆期熔体包裹体均一温度为780℃;岩浆-热液期均一温度为191~700℃,盐度为5.26%~22.24%,属中低盐度,成矿压力为68~95 MPa,相应的成矿深度为2.6~3.6 km;热液期均一温度为129~225℃,盐度为0.35%~7.73%,为低盐度。从岩浆期到岩浆-热液期再到热液期,温度逐渐降低,矿化作用主要发生在岩浆-热液期,属中高温、中深成岩浆-热液过渡型矿床。     

南海新生代玄武岩中单斜辉石矿物化学及成因意义

从南海南大陆坡底至北大陆坡底采集的玄武岩样品,基本可以代表南海新生代岩浆活动的代表性样品.本文中对这些玄武岩中单斜辉石的矿物化学成分进行了研究,研究的单斜辉石以顽透辉石为主(占3/4),还有少量普通辉石及次透辉石等,也出现少量较为罕见的富钙辉石,位于深绿辉石区域内.基质微晶辉石比辉石斑晶更富钙、钛、铁,可能反映了岩浆演化向着富钙、钛、铁方向发展,且碱度逐渐降低.与碱性系列的演化趋势基本一致.由单斜辉石-熔体平衡温压计计算的岩浆房深度分别为:碱玄岩岩浆房约49km左右,粗面玄武岩岩浆房约25km;玄武岩岩浆房约15km.由碱玄岩→粗面玄武岩→玄武岩,平衡温度(K)依次降低:从1535～1498→1429→1369.南海新生代玄武岩为板内碱性玄武岩.碱性玄武岩系列可能是地幔柱在上升过程中在不同深度处发生部分熔融并伴随有分离结晶作用等物理化学过程的连续演变的产物.     

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