A Paleoproterozoic A—type Rhyolite

The rhyolites in the upper Lueliang Group of Shanxi,China,are Paleoproterozoic weakly alkaline volcanic rocks.They are characterized by high,SiO2,NaO K2O,Zr,Nd,Ga,Y and REE contents and large FeO^*/MgO,Rb/Sr and Ga/Al ratios,and low CaO,Sr and Eu contents,and share much in common with the A-type granitic rocks.They erupted in the rift setting at the continental margin.Chemical features and isotope data,as well as high Nd and low initial Sr ratios,suggest that the original granitic magma was derived from partial melting of Late Archean metamorphic rocks in the lower crust due to the influence of basaltic magma and hot fluid in response to rifting.The A-type rhyolites were finally formed after the fractional crystallization of the dominant mineral feldspar.     

A字钻塔

钻塔高12米,重1.2吨,其最大优点是构造简单,拆卸安装快,运输方便,过去使用四脚金属钻塔,不但运输麻烦,安装费事,光立钻塔得化二天时间,常因安装速度慢影响开孔时间,而且成本也高,现在只要在地面先将各部零件连接好,通过绞车一分钟就能将     

A Chinese Construction Elite

According to the outstanding contribution of Mr. Xu Ronglie in international communication and cooperation, night of February 5, CIOB awarded the ex-general engineer of MOC, Mr. Xu Ronglie, Honorary Fellow. As the ex-general engineer of MOC, Mr. Xu played a vital roll at many key fields in the construction market of China. He is also a magnificent master in     

伴随矩阵A*与*A的性质及应用

通过研究矩阵与其伴随矩阵Ａ＾＊,＾＊Ａ之间的关系,得到了Ａ＾＊,＾＊Ａ较为完整的一系列性质,并给出了Ａ＾＊,＾＊Ａ的一些应用。     

A living Mars?

The possibility of a living Mars is deeply ingrained in popular culture. The observations of the astronomer Percival Lowell, and his interpretation that these canals were built to channel melt-water from the polar regions down to the dying cities and farms huddled around the equator, are well known. Even into the 1960s, textbooks were being published that explained the temporal variation in surface brightness as due to the seasonal spread of vegetation. Martians are the science-fiction writer's alien invader of choice, from the heat-ray-wielding tripods of H.G. Wells to the bulbous-headed aggressors of Tim Burton's 1996 film Mars Attacks. With the armada of robotic probes currently orbiting and roving across the red planet, Mars has never been so forefront in the public eye. Much of this interest is focussed on the possibility that our planetary neighbour has supported an independent genesis of life, and that in certain regions it may remain habitable even to this day. A selection of some of the most recent results and discoveries concerning the astrobiological potential of Mars are discussed.     

高效液相色谱仪LC-20A

高效液相色谱仪LC-20A是西安地质调查中心实验测试中心于2009年引进的。高效液相色谱仪主要有进样系统、输液系统、分离系统、检测系统和数据处理系统组成。流动相被高压泵打入系统,样品溶液经进样器进人流动相,被流动相载入色谱柱（固定相）内,     

Malani Rhyolites — A Review

The late Proterozoic Malani bimodal volcanics constitute the largest suite of anorogenic acid volcanics in India. The volcanism took place during 745±10 Ma ago, succeeding the granitic activity of Abu pluton and ceased before the onset of Marwar sedimentation.On the basis of field evidences, three stages of igneous activity have been recognised. Volcanics of the first stage are mostly basalt with occasional andesite or trachybasalts. These are subsequently covered by the voluminous outpouring of peralkaline and peraluminous rhyolite, basalt, dacite and trachyte flows. The third stage ceased with the outburst of ash flow deposits.The dominant felsic volcanics are rhyolites and rhyodacites spread over an area of about 31, 000 km². The other rock types associated with rhyolite are trachytes, dacites, pitchstone, welded tuff, vitric, lithic and crystal ash, ignimbrite, obsidian, pyroclastic slates, agglomerate, volcanic breccia and volcanic conglomerates. Majority of the acid volcanics are high potassic and a few are calcalkaline or low potassic in composition.Feldspar geothermometry suggests the temperature of equilibrium to be above 650°C. Similar results were obtained by magnetite-ulvospinel geothermometry. Oxygen fugacity is estimated to be about 10⁻¹⁸ under FMQ-Ni-NiO buffer conditions.Malani volcanism was essentially under terrestrial conditions, although deposition by aqueous conditions are also indicated. The volcanic eruptions have been through fissures, shield volcanoes and central cones. The volcanism was triggered in an extensional tectonic regime of continental crust, where geotherm was raised by the repeated influx of basic magma. The initial basaltic magma was possibly generated at deeper depth by ‘hot spot’ activity. This magma while migrating upwards supplied additional heat for the partial melting of lower sialic crust resulting in the generation of felsic magma. The crustal extension has helped in the upward advancement of the felsic magma.     

A构造勘探潜力分析

运用各种物探手段对渤海海域A构造所在三维区及其东南部的二维区地震资料进行连片地震资料解释、成图,并结合以往勘探成果对目的层新近系明下段及馆上段的储盖组合、油气运移等石油地质特征进行分析、研究,为该构造区实施进一步勘探提供了可靠依据。研究运用了方差、三维可视化、波阻抗反演、分频以及基于波形的地震相分析等先进的地球物理技术。     

Luobusaite： A New Mineral

A group of mantle minerals including about 70-80 subtypes of minerals are discovered from a podiform chromitite in Tibet, China. Recovered minerals include diamond, coesite, moissanite, wustite, Fe-silides and a new mineral, luobusaite. All of these minerals were hand-picked from heavymineral separates of the podiform chromitite in the mantle peridotite of an ophiolite. The grains of luobusaite are as host mineral with inclusions of native silicon or as an intergrowth with native silicon and Fe-Si phase. Luobusaite occurs as irregular grains, with 0.1-0.2 mm in size, consisting of very finegrained aggregates. The mineral is steel-grey in color, metallic luster, and opaque. The empirical formula （based on 2 for Si） is Fe0.83Si2, according to the chemical compositions of luobusaite. X-ray powder-diffraction data： orthorhombic system, space group Cmca, a = 9.874 （14） A, b = 7.784 （5） A, c= 7.829（7） A, Z=16.     

A POROSITY INVERSION METHOD AND ITSAPPLICATION

1.IntroductionItiswellknownthattheexistingoflithologicreservoirhasmuchtodowithuncompact,andlithologiccharacteristiccouldbeindicatedbythevariationofposon'sfatioandporosity.So,estimatingtheaccuratedistributionofporosityattributefromseismicdataisveryboortanttOrecognitionofuncompactandlithologicreservoir.AporosityinversionmethodwithofficialneuralnetWorkisputforwardinthispaper.ItextrapolatesporositydatafromwellstOtheiradjacelltareas,gUidedbyseismicdata.BasedonthestandardBPneuralnetS,mismethodin…     

一个古元古代A型流纹岩

山西吕梁群流纹岩是一个古元古代的弱碱性火山岩,它具有高ＳｉＯ２,Ｎａ２Ｏ＋Ｋ２Ｏ和Ｚｒ,Ｇａ等高场强元素和高ＦｅＯ＾＊／ＭｇＯ,Ｒｂ／Ｓｒ和Ｇａ／Ａｌ比值,以及低ＣａＯ,Ｓｒ和Ｅｕ／Ｅｕ＾＊的地球化学特征,相似于Ａ型花岗质岩石。它形成于大陆边缘裂谷环境,化学成分及同位素特征为高εＮｄ（ｔ）值,低（＾８７Ｓｒ／＾８６Ｓｒ）ｉ值,表明流纹岩的原始岩浆由下地壳晚太古代变质岩受裂谷岩浆和热流作用的影响部分     

Geothermal reservoirs — A brief review

A brief discussion and review of the geothermal reservoir systems, geothermal energy and modeling and simulation of the geothermal reservoirs has been presented here. Different types of geothermal reservoirs and their governing equations have been discussed first. The conceptual and numerical modeling along with the representation of flow though fractured media, some issues related to non isothermal flow through fractured media, the efficiency of the geothermal reservoir, structure of the numerical models, boundary conditions and calibration procedures have been illustrated. A brief picture of the Indian scenario and some barriers related with geothermal power are discussed and presented thereafter. Finally some gaps of the existing knowledge and recent focuses of research are discussed.     

A Study on the Kunyang Aulacogen

The Kunyang Aulacogen is a continental rift which initiated at the beginning of the Middle Proterozoic. Itwas generated on the rigid continental crust represented by the crystalline Kangding Complex, and is boundedby two N-S-trending deep faults--Anninghe-Luzhijiang Fault and Xiaojiang Fault. Its early stage of rupturewas characterized by alkalinc mafic igneous activities in the Dahongshan Group and Hekou Group. Duringthe later tensile-depression stage the aulacogen evolved into a graben where scdimentation of the KunyangGroup took place. The sedimentary sequence comprises terrestrial red beds, algal dolomite, marine black shaleand carbonate rocks which are quite typical of rift sedimentary association, and contains stratabound copperdeposits of the well-known Dongchuan type.     

安徽茅坦A型花岗岩研究

安徽茅坦花岗岩体是由４次侵入的细粒花岗岩、花岗斑岩、中粒花岗岩和粗粒花岗岩组成的复式岩体。各期次岩石具有高硅,富碱,富ＬＲＥＥ、Ｙ,Ｎｂ,Ｚｒ等大离子高电价元素及低Ａｌ、Ｍｇ,Ｃａ、Ｎｉ、Ｃｒ,Ｔｉ,Ｖ的特点,与国内外Ａ型花岗岩相似。岩石中副矿物种类聚多,以含碳硅石,磷钛矿等深源矿物为特征。锆石晶形以正锥面（１１１）和四方柱面（１１０）最为发育,与一般Ｉ型花岗岩有明显的差异。研究表明,该复式岩体为     

A型花岗岩的微量元素地球化学

本文总结和评述了A型花岗岩典型的微量元素特征,如富集Ga、稀土元素（除Eu外）和高场强元素,亏损Ba、Sr和明显的Eu负异常。分别讨论了影响微量元素特征的多种制约因素,主要包括源区性质、岩浆的物理化学条件、岩浆作用过程和络合作用。通过对比世界范围内几个地区相伴生的碱性A型花岗岩和铝质A型花岗岩的微量元素地球化学特征,发现前者Ga、F含量更高,而轻重稀土比值小,Eu、Ba、Sr等元素含量更低,显示了前者的岩浆分异作用更强,同时说明了碱性A型花岗岩可以由与之伴生的铝质A型花岗岩分异而来。