秦岭晋宁期的两条蛇绿岩带及其对秦岭——大别构造演化的制约

本文在总结前人对秦岭造山带中蛇绿岩研究成果的基础上,结合我们的工作实践,对秦岭南北两条蛇绿岩形成时代、构造背景以及它们对秦岭－大别山构造演化的制约提出以下认识：①北秦岭构造带不存在显生宙的蛇绿岩套。分布于北秦岭商丹构造带的松树沟蛇绿岩是秦岭造山带中保存最完整的蛇绿岩,形成时代不晚于１０００Ｍａ,就位于９８０Ｍａ。分布于二郎坪群、丹凤群中的超镁铁岩及镁铁质岩可能不属于典型的蛇绿岩,形成时代不晚于８０     

青藏高原北缘首次获得格林威尔期造山事件同位素年龄值

对西昆仑北缘中元古代变质双峰式火山岩中变质矿物角闪石和黑云母进行Ar-Ar测年,获得角闪石理想的坪年龄为1050.85±0.93Ma,黑云母理想的坪年龄为1021±1.08Ma。这是在青藏高原北缘首次获得的格林威尔期造山事件同位素年代学的可靠证据,为研究该区中新元古代构造演化、塔里木板块在Rodinia超大陆中的位置提供了新的地质素材。     

可行域无界的约束优化问题

设Ω＝｛ｘ∈Ｒ￣ｍ｜ｈ＿ｉ（ｘ）＝０，ｉ＝１，…，ｌ；ｇ＿ｉ（ｘ）≤０，ｊ＝１，…，ｍ｝为一无界集合，ｆ（ｘ）在Ω下方有界但达不到下确界。对ｆ（ｘ）在Ω的某一点处取得广义极小值给出了一个必要条件，并对ｆ（ｘ）为凸函数时给出了一个充分条件。     

福建紫金山外围东留花岗斑岩体地质特征及成矿作用分析

福建紫金山及其外围地区分布的浅成-超浅成斑岩体与成矿关切密切.紫金山外围东留花岗斑岩体位于福建省武平县境内,花岗斑岩体内外接触带普遍发育强烈的矿化蚀变带.通过对东留花岗斑岩体进行野外地质调查及全岩地球化学分析,结果表明东留花岗斑岩体具有过铝质A型花岗岩的特征：富硅、钾、铁,贫钙、钠、镁,A/CNK值大于1.1,分异指数高,富集HFSE、Ga、LREE、Y（Ce）,亏损Ba、Sr、P、Ti,具有强烈的铕负异常.东留花岗斑岩体作为矿化蚀变岩石的母岩,可能为矿化作用提供热源和成矿物质,具有寻找锡多金属矿的前景.     

Chemostratigraphy and lithological characters of Neoproterozoic cap carbonates from the Kuruktag Mountain, Xinjiang, western China

The Neoproterozoic Era includes some of the most largest ice ages in the geological history. The exact number of glaciations is unknown, though there were at least two events of global glaciation. Neoproterozoic glacial deposits in the Kuruktag Mountain, Xinjiang, western China have proven that there had occurred three discrete Neoproterozoic glaciations. Diamictite units occurred in the Bayisi, Tereeken, and Hankalchough formations, carbonate units were recognized among the diamictites and immediately overlied the Bayisi, Tereeken and Hankalchough diamictites. Carbonates at the top of the Bayisi Formation are characterized by the dolo-sility stones with negative δ13C values ranging from -4.10‰ to -8.17‰ (PDB), comparable to the Sturtian cap carbonates that overlie the Sturtian glacial deposits from other Neoproterozoic sequences. Carbonates overlying the Tereeken Formation are characterized by the pinkish cap dolostones (ca. 10 m thick) with negative δ13C values ranging from -2.58‰ to -4.77‰ (PDB), comparable to the Marinoan cap carbonates. The cap is also characterized by tepee-like structures, barite precipitates and pseudomorphous aragonite crystal fan limestones. Carbonates at the top of the Hankalchough Formation are characterized by subaerial exposure crust (vadose pisolite structure, calcareous crust structure) dolostones with negative δ13C values ranging from -4.56‰ to -11.45‰ (PDB) and the calcareous crust dolostones, implying that the Hankalchough cap carbonates differ from either the Sturtian or Marinoan cap carbonates in sedimentary environment and carbon isotopic composition. In addition, it is suggested the Hankalchough glaciation belongs to a terrestrial glaciation and it is the third largest glaciation during the Neoproterozoic period on the Tarim platform.     

锶、钕同位素对德兴斑岩铜矿元素迁移的示踪

Sr同位素（而不是Sr浓度）由斑岩体内部向围岩接触带呈有规律升高（0．705→0．711），指示了德兴铜厂斑岩铜矿的成矿元素是从岩体内部随成矿流体迁移到接触带附近的，这符合斑岩铜矿的正岩浆成因模式。Nd同位素则相对稳定，可作为蚀变侵入体岩浆起源的研究手段。     

西昆仑造山带中元古代火山岩地球化学——板块构造演化的证据

西昆仑北缘出露的中元古代火山—沉积岩系可分为两大系列,一是北带的巨厚逆向演化的双峰式火山岩,其上部为复理石、磨拉石,火山岩的岩石地球化学特征表明,从早到晚岩石的碱度逐渐降低,从碱性、钙碱性向拉斑系列演化,代表了一个伸展构造背景下火山岩演化序列,火山—沉积岩系