新疆达坂城西南一带奇尔古斯套组硅质岩地球化学特征及成因讨论

奇尔古斯套组硅质岩SiO2含量较高,Al2O3、TiO2含量变化较大,反映出较多的外来物质的加入;Si/ (Al+Fe+Mn)、Al/ (Al+ Fe+ Mn)、MnO/TiO2、Al2 O3/(Al2 O3+ Fe3 O2)值较高,反映其为生物化学成因,形成于大陆边缘环境;Fe2O3/TiO2对Al2O3/(Al2 O3+ Fe2O3)图解同样说明其形成于大陆边缘环境.REE较高,HREE富集不明显,北美页岩标准化后的稀土配分模式曲线较为平坦,向左倾斜不明显,(La/Ce)shale值较低,δCeshale值较高,无明显Ce负异常,反映奇尔古斯套组硅质岩属生物化学成因硅质岩,形成于大陆边缘环境; (La/Ce)shale对Al2 O3/(Al2 O3+Fe2 O3)图解亦说明其形成于大陆边缘环境.微量元素中Hf含量高,而Be、Li、Nb、Rb、Sr、Ta、Th、U、V、Zr含量低;Ba元素含量低;Co、Ni贫富相当,Co/Ni值较高,U/Th值低,说明奇尔古斯套组硅质岩属于正常的生物化学成因的硅质岩.     

我国首套拥有自主知识产权的航空伽马能谱勘查系统

<正>该系统为国内首套具有自主知识产权、高灵敏度的全数字化航空伽马能谱勘查系统.系统攻克了航空伽马能谱勘查系统全数字化主控系统以及航空伽马能谱弱峰信息提取等技术难点,可同时接收多达20条晶体探测     

新疆色日克牙依拉克蛇绿岩特征及成矿远景

论文讨论了色日克牙依拉克蛇绿岩的岩石类型组合及岩石地球化学特征,结合区域地质情况分析认为：该蛇绿岩形成于裂谷一小洋盆环境,代表了塔里木板块和伊犁中天山微板块的最后缝合线位置。蛇绿岩出露地带,二辉橄榄岩和纯橄榄岩内均见有铬铁矿、磁铁矿等,局部地表见有镍华。因此,该地对于寻找铬、镍等矿床,有较大的潜力。     

藏北羌塘中部存在志留纪洋盆——来自桃形湖蛇绿岩中斜长花岗岩的锆石U-Pb年龄证据

报道了羌塘西部桃形湖蛇绿岩中斜长花岗岩的锆石U-Pb定年结果和岩石地球化学资料及锆石Hf同位素成分。斜长花岗岩中的锆石具有典型的岩浆生长环带,结合其Th/U值(0.16~0.44),表明为典型的岩浆成因。锆石LA-ICP-MS和Cameca U-Pb定年结果分别为441Ma±2Ma和442Ma±3Ma,相当于早志留世,略年轻于伴生的堆晶辉长岩。锆石的εHf(t)值为+8.13~+11.23,平均值为+9.50,具有明显的幔源成因特征。全岩地球化学分析结果表明,斜长花岗岩是洋壳运移过程辉长岩部分熔融形成的。斜长花岗岩的年龄数据表明,羌塘中部地区存在志留纪洋盆。     

http://www.sciencedirect.com/science/article/pii/S1674987114000243

We combine a geological, geochemical and tectonic dataset from 118 ophiolite complexes of the major global Phanerozoic orogenic belts with similar datasets of ophiolites from 111 Precambrian greenstone belts to construct an overview of oceanic crust generation over 4 billion years. Geochemical discrimi- nation systematics built on immobile trace elements reveal that the basaltic units of the Phanerozoic ophiolites are dominantly subduction-related （75%）, linked to backarc processes and characterized by a strong MORB component, similar to ophiolites in Precambrian greenstone sequences （85%）. The remaining 25% Phanerozoic subduction-unrelated ophiolites are mainly （74%） of Mid-Ocean-Ridge type （MORB type）, in contrast to the equal proportion of RiftlContinental Margin, Plume, and MORB type ophiolites in the Precambrian greenstone belts. Throughout the Phanerozoic there are large geochemical variations in major and trace elements, but for average element values calculated in 5 bins of 100 million year intervals there are no obvious secular trends. By contrast, basaltic units in the ophiolites of the Precambrian greenstones （calculated in 12 bins of 250 million years intervals）, starting in late Paleo- to early Mesoproterozoic （ca. 2.0-1.8 Ga）, exhibit an apparent decrease in the average values of incom- patible elements such as Ti, P, Zr, Y and Nb, and an increase in the compatible elements Ni and Cr with deeper time to the end of the Archean and into the Hadean. These changes can be attributed to decreasing degrees of partial melting of the upper mantle from HadeanJArchean to Present. The onset of geochemical changes coincide with the timing of detectible changes in the structural architecture of the ophiolites such as greater volumes of gabbro and more common sheeted dyke complexes, and lesser occurrences of ocelli （varioles） in the pillow lavas in ophiolites younger than 2 Ga. The global data from the Precambrian ophiolites, representative of nearly 50% of all known worldwide greenston     

In-situ Moissanite in Dunite: Deep Mantle Origin of Mantle Peridotite in Luobusa Ophiolite, Tibet

We report the discovery of an in-situ natural moissanite as an inclusion in the Cr-spinel from the dunite envelope of a chromitite deposit in Luobusa ophiolite, Tibet. The moissanite occurs as a twin crystal interpenetrated by two quadrilateral signal crystals with sizes of 17 μm× 10 μm and 20 μm× 7 μm, respectively. The moissanite is green with parallel extinction. The absorption peaks in its Raman spectra are at 967-971 cm-1, 787-788 cm-1, and 766 cm-1. The absorption peaks in the infrared spectra are at 696 cm-1, 767 cm-1, 1450 cm-1, and 1551 cm-1, which are distinctly different from the peaks for synthetic silicon carbide. Moissanites have been documented to form in ultra-high pressure, high temperature, and extremely low fO2 environments and their 13C-depleted compositions indicate a lower mantle origin. Combined with previous studies about other ultra-high pressure and highly reduced minerals in Luobusa ophiolite, the in-situ natural moissanite we found indicates a deep mantle origin of some materials in the mantle sequence of Luobusa ophiolite. Further, we proposed a transformation model to explain the transfer process of UHP materials from the deep mantle to ophiolite sequence and then to the supra-subduction zone environment. Interactions between the crown of the mantle plume and mid-ocean ridge are suggested to be the dominant mechanism.     

高压富水破损严重水源孔封堵技术研究

正1破损钻孔概况1.1基本概况破损钻孔位于峰峰集团大社矿井下-120水平,由峰四勘探注浆有限责任公司于2008年4月14日~2008年7月1日施工,孔口坐标(X:4045831,Y:38521501,Z:-120),终孔孔深160.3m,开孔层位为山青1号小煤与2号小煤之间粉砂岩,终孔进入奥灰50.1m,终孔水量6.6m3/min,水压2.45MPa。该破损钻孔编号为小屯2#供水孔,担负着峰峰集团小屯矿工人村生活用水。1.2钻孔结构0~26m,Φ223mm开孔下Φ219*8mm(即套管外径为219mm,套管壁厚为8mm,后同),孔口管长25.2m;26~74.1m,Φ173mm孔径下Φ168*8mm,套管长72.6m;74.1~109.7m,Φ146mm孔径下Φ140*8mm,套管长109.6 m;     

西昆仑库地蛇绿岩的二辉辉石岩和玄武岩锆石LA-ICP-MSU-Pb年龄及其意义

西昆仑造山带划分为北昆仑地体和南昆仑地体,关于西昆仑造山带中库地蛇绿岩的形成时代一直存在争议。本文在库地布孜完沟超镁铁岩单元角闪石化二辉辉石岩和依歇克沟火山岩单元底部粒玄岩中获得了锆石LA-ICP-MS U-Pb年龄,分别为494.28±0.86Ma和500.30±8.0Ma,两者非常相近,说明超镁铁岩单元和火山岩单元下部的玄武岩形成时代均为晚寒武世-早奥陶世,是配套的蛇绿岩组成单元,即库地蛇绿岩为早古生代早期原特提斯洋的产物。根据前人已发表的年代学、古生物学资料和本文的资料分析对比,原划依莎克群火山岩单元可能是构造拼合叠置体,应予解体。     

河南夏馆-二郎坪一带叠加改造型金矿床地质特征及成矿模式

河南内乡夏馆-西峡二郎坪一带金矿床(点)广泛分布,成矿类型多样,产出条件复杂,岩体与围岩接触带以及中元古代和早古生代地层中都有金矿形成.根据成矿物质、成矿流体来源和成矿机制,将产于接触带和地层中的金矿体分为5种类型,它们是在火山、火山沉积和正常沉积等不同背景下,由岩浆热液、变质热液或地下水热液叠加改造(再造)形成的,每类矿床都经历了多期多阶段成矿过程,以后期热液交代、充填成矿为主.构造对金矿形成有明显控制作用,区域性深大断裂控制金成矿带,二级韧脆性剪切带控制金矿床分布,三级层间破碎带、断裂裂隙带和接触带构造控制矿体就位.构造热液的叠加改造或再造主导了成矿作用.