蓝色翡翠的呈色机制探讨

近期广东市场上出现了一种来自缅甸的蓝色翡翠样品,该样品目前未见相关报道。为了确定其定名,通过常规宝石学测试、红外光谱和X射线粉末衍射测试对样品进行分析,表明样品的主要矿物组成为硬玉,质量分数约97．1％,检测鉴定结论为翡翠。为了对蓝色翡翠呈色机制进行研究,通过紫外一可见吸收光谱测试,表明可见光区480nm以后逐渐增强的吸收带是其产生蓝色的原因;采用电子探针进行化学成分测试,表明蓝色的成因与钒离子有关。根据3d过渡金属离子的晶体场理论和翡翠晶体场理论的研究,可以推测：由于翡翠结构中M1位的Al3＋被过渡金属离子钒（V4＋）替代,目l起八面体结构畸变而导致蓝色的产生,因此,蓝色是过渡金属离子钒（v4＋）产生的原生色。     

Timing of Magma Mixing in the Gangdisě Magmatic Belt during the India-Asia Collision： Zircon SHRIMP U-Pb Dating

Abstract  Abundant mafic microgranular enclaves (MMEs) extensively distribute in granitoids in the Gangdisê giant magmatic belt, within which the Qüxü batholith is the most typical MME‐bearing pluton. Systematic sampling for granodioritic host rock, mafic microgranular enclaves and gabbro nearby at two locations in the Qüxü batholith, and subsequent zircon SHRIMP II U‐Pb dating have been conducted. Two sets of isotopic ages for granodioritic host rock, mafic microgranular enclaves and gabbro are 50.4±1.3 Ma, 51.2±1.1 Ma, 47.0±1 Ma and 49.3±1.7 Ma, 48.9±1.1 Ma, 49.9±1.7 Ma, respectively. It thus rules out the possibilities of mafic microgranular enclaves being refractory residues after partial melting of magma source region, or being xenoliths of country rocks or later intrusions. Therefore, it is believed that the three types of rocks mentioned above likely formed in the same magmatic event, i.e., they formed by magma mixing in the Eocene (c. 50 Ma). Compositionally, granitoid host rocks incline towards acidic end member involved in magma mixing, gabbros are akin to basic end member and mafic microgranular enclaves are the incompletely mixed basic magma clots trapped in acidic magma. The isotopic dating also suggested that huge‐scale magma mixing in the Gangdisê belt took place 15–20 million years after the initiation of the India‐Asia continental collision, genetically related to the underplating of subduction‐collision‐induced basic magma at the base of the continental crust. Underplating and magma mixing were likely the main process of mass‐energy exchange between the mantle and the crust during the continental collision, and greatly contributed to the accretion of the continental crust, the evolution of the lithosphere and related mineralization beneath the portion of the Tibetan Plateau to the north of the collision zone.     

基于UDEC的隧道掘进机滚刀破岩数值模拟研究

现今全断面隧道掘进机（TBM）施工方法在长大深埋隧道工程中已被广泛采用,对滚刀破岩关键技术的进一步认识具有重要的工程价值。为了研究滚刀破岩机制,分析刀圈断面形态、岩石强度和节理角度对其的影响,运用UDEC方法建立了滚刀贯切岩石的二维数值系列模型,对TBM滚刀破岩过程进行了仿真。分析表明：滚刀破岩是滚刀下岩石拉破坏和剪破坏的综合反映,拉破坏是裂纹萌生与扩展的主要驱动机制;刃宽较大的平刀与刃角较大的楔刀破岩效果较好;平刀与楔刀在软岩中破岩效果相近,平刀在硬岩施工中比楔刀的破岩效果好;滚刀对节理角度为30°～60°的岩石破坏效果较好,由于楔刀的“劈裂”作用,楔刀比平刀更适合用于贯切含有节理的岩石。     

云南省景谷岔河地区火山岩及其构造环境

岔河地区火山岩属三江构造带澜沧江构造岩浆带的南段.晚二叠世在岔河一带喷发了一套安山岩-流纹岩与粗面岩组合的杂色火山岩系.熔岩普遍为斑状结构,斑晶为斜长石和角闪石.以钙碱性和碱性岩为主,其次是拉斑玄武岩系.据CIPW计算,除碱性岩系外,均含标准石英分子.稀土元素分配模式为无Eu异常的富轻稀土右倾型.微量元素分配形式为亏损P、Ti元素的锯齿状.w(Zr)/w(Y)值大于3.5,w(Ti)/w(Y)值小于500,W(TiO2)平均为0.82%.岩浆来源深度为138 km.表明岔河地区火山岩属大陆边缘弧构造环境的产物.     

青藏高原碰撞造山带:Ⅰ.主碰撞造山成矿作用

大陆碰撞与成矿作用是当代成矿学研究的重要前沿。与板块构造成矿作用研究相比,大陆碰撞造山带的成矿作用研究则明显薄弱。文章以青藏高原主碰撞带为对象,研究了印度-亚洲大陆主碰撞过程与区域成矿作用的耦合关系,并初步建立了主碰撞造山成矿模型。研究表明,印度-亚洲大陆主碰撞始于65Ma,延续至41Ma,形成了以藏南前陆冲断带、冈底斯主碰撞构造-岩浆带和藏北陆内褶皱-逆冲带为特征的青藏高原碰撞造山带主体。伴随陆-陆碰撞,在冈底斯带相继发育①壳源白云母花岗岩-钾质钙碱性花岗岩组合（66-50Ma）、②＋εNd花岗岩-辉长岩组合（52-47Ma）和③幔源玄武质次火山岩-辉绿岩脉组合（42Ma）,以及大面积分布的巨厚（5000m）的林子宗火山岩系（65-43Ma）,反映深部相继发生大陆碰撞和板片陡深俯冲（65-52Ma）→板片断离（52-42Ma）→板片低角度俯冲（〈40Ma）等重要过程。在主碰撞期,初步识别出4个重要的成矿事件：①与壳源花岗岩有关的Sn、稀有金属成矿事件,在藏东滇西形成腾冲Sn、稀有金属矿集区;②与壳／幔花岗岩有关的Cu-AuMo成矿事件,在冈底斯南缘形成长达百余公里的Cu-Au矿化带;③与碰撞造山有关的剪切带型Au成矿事件,沿雅鲁藏布江缝合带分布,形成具有较大成矿潜力的A-u矿化带;④与挤压抬升有关的Cu-Au成矿事件,形成以雄村大型铜金矿为代表的斑岩型／浅成低温复合型Cu-Au矿床。在综合研究基础上,初步建立了大陆主碰撞造山区域成矿模型。     

Deformation microstructures of olivine in peridotite from Spitsbergen, Svalbard and implications for seismic anisotropy

To understand the deformation mechanism and seismic anisotropy in the uppermost mantle beneath Spitsbergen, Svalbard, in the Arctic, the deformation microstructures of olivine in the peridotite of Spitsbergen were studied. Seismic anisotropy in the upper mantle can be explained mainly by the lattice-preferred orientation (LPO) of olivine. The LPOs of the olivine in the peridotites were determined using electron backscattered diffraction patterns. Eight specimens out of 10 showed that the [100] axis of the olivine was aligned subparallel to the lineation and that the (010) plane was subparallel to the foliation, showing a type A LPO. In the other two specimens the [100] axis of olivine was aligned subparallel to the lineation and both the [010] and [001] axes were distributed in a girdle nearly perpendicular to the lineation, showing a type D LPO. The dislocation density of the olivine in the samples showing a type D LPO was higher than that in the samples showing a type A LPO. The result of an Fourier transformation infrared study showed that both the types A and D samples were dry. These observations were in good agreement with a previous experimental study ( Tectonophysics , 421 , 2006, 1 ): samples showing a type D LPO for olivine were observed at a high stress condition and samples showing both types A and D LPO were deformed under dry condition. Observations of both strong LPOs and dislocations of olivine indicate that the peridotites studied were deformed by dislocation creep. The seismic anisotropy calculated from the LPOs of the olivine could be used to explain the seismic anisotropy of P - and S -waves in the lithospheric mantle beneath Spitsbergen, Svalbard.     

湘中锡矿山锑矿床成矿物质来源的同位素示踪

本文利用放射成因同位素（Pb、Sr)和轻稳定同位素（C、O）对锡矿山超大型锑矿床的成矿物质来源进行了示踪，从物源角度揭示了其在规模成矿、元素发生超常富集的原因。研究表明，锡矿山锑矿床的成矿物质不可能是来自赋矿围岩；深部地幔和基底都卷入了该矿的成矿作用；富Sb的交代型地幔和富Sb的元古界基底为其大规模成矿提供了充足的矿源，两者是形成锡成山超大型锑矿床的前提条件。     

东昆仑野马泉地区矽卡岩矿床地球化学特征及其成因意义

东昆仑西段(祁曼塔格)的野马泉地区,是青海省内一个重要的多金属成矿区.该区以往的工作程度较低,与花岗岩有关的铁、铜、多金属矿床多是近几年地质大调查中新发现的.本文通过对野马泉地区铁、铜、多金属矿床矿石矿物组合、围岩蚀变分带、黄铁矿Co/Ni比值、矿石稀土元素特征、矿床硫、铅同位素组成特征等的研究.结果表明,野马泉地区矽卡岩型多金属矿床的形成与东昆仑晚古生代-早中生代构造岩浆旋回造山后期的伸展引张环境形成的碱性A型花岗岩有关,成矿物质主要来自岩浆,具有深部来源特征,与幔源基性岩浆底侵及其与壳源酸性岩浆的混合作用有关,属于典型的钙、镁矽卡岩型矿床.     

海南文昌地区第四系沉积物特征及其地质意义

海南省文昌市东部沿海一带是华南地区第四系发育较为典型的地区之一,其分布受新生代晚期形成的新构造格局的控制。通过对第四系沉积物特征、粒度分析、重矿物锆石采用激光剥蚀等离子体质谱(LA-ICP-MS)技术进行年龄测定,并选用206Pb/238U年龄做谐和年龄频谱图。认为该区第四系松散沉积具有不完全相同的物源。八所组与烟墩组的沉积物源区具有一定的相似性,北海组的沉积物源区明显不同于八所组和烟墩组。这种物源的差异性可能直接导致了第四系成矿作用的不同。     

金沙江-哀牢山断裂带几个富碱斑岩体的锆石U-Pb定年及地质意义

运用LA-ICP-MS锆石U-Pb同位素定年方法测定了金沙江-哀牢山断裂带内4个富碱斑岩的年龄.结果表明:剑川地区角闪正长斑岩形成时间为(37.6±2.2)Ma,姚安地区黑云母二长斑岩具有2组锆石U-Pb年龄数据,较年轻的一组为(36.86±0.63)Ma,较老的一组为(40.41±0.24)Ma,姚安黑云母角闪正长斑...