北喜马拉雅然巴穹隆的构造、运动学特征、年代学及演化

然巴穹隆构造位于北喜马拉雅片麻岩穹隆带,由上、下两个拆离断层及3个构造层组成。低变质特提斯喜马拉雅沉积岩系形成上构造层,底部为脆性上拆离断层;糜棱状片麻岩及核部浅色花岗岩体组成下构造层,顶部是韧性下拆离断层;中级变质糜棱状石榴石、十字石、红柱石片岩构成两拆离断层间的中构造层,可能是上构造层底部经拆离作用形成。穹隆构造主要经历3期变形：第1期上盘向北北西运动,可能与藏南拆离系活动有关;第2期为主期变形,与东西向伸展相关,各单元统一地上盘向东运动,形成然巴穹隆的主要构造特征;第3期为穹隆向外的垮塌下滑。然巴穹隆构造可能是东西向伸展和岩浆底辟作用的结果,下拆离断层可能是将上盘沉积岩系与结晶基底分开的主拆离断层,为主变形期东西向伸展形成,后期岩体的底辟作用形成穹隆的形态。穹隆核部主变形晚期侵位的浅色花岗岩冷却年龄为6Ma左右,说明穹隆主期伸展与该区东西向伸展作用活动时代一致,然巴穹隆构造的形成与青藏高原南北走向裂谷系的东西向伸展相关。     

生物降解高分子--聚乳酸的合成

以天然矿石--改性片麻岩为聚合反应的催化剂,通过直接缩聚方法制备了不同分子量的聚乳酸.并应用FTIR,^1H-NMR,DSC等测试手段对两种不同催化剂制备的聚乳酸的结构进行对比研究.同时也研究了反应时间对聚合产物分子量的影响.     

云母片麻岩风化料填筑高速公路路基的应用研究

通过对云母片麻岩的性状进行分析,以外掺粘土、水泥、砂进行对比试验,确定了云母片麻岩风化料用作路基填筑的施工方案,同时提出了有关技术措施和施工工艺。     

SHRIMP U-Pb zircon age of the Jinchuan ultramafic intrusion and its geological significance

The Jinchuan ultramafic intrusion is located in the Longshoushan Uplift on the southwestern margin of the Alxa Block, to the north of the Northern Qilian Orogenic Belt (Fig.1). It is broadly dyke-like, and was intruded into a Paleoproterozoic sequence of migmatites, gneisses and marbles (Baijiazhuizi Formation). The intrusion is northwest-elongated, -6500 m long and 20-527 m wide, and     

Zircon SHRIMP geochronology of the Xinkailing-Kele complex in the northwestern Lesser Xing＇an Range, and its geological implications

Located in the eastern portion of the Xing'an-Mongolian Orogenic Belt (XMOB), the Xinkailing-Kele complex has previously been considered to be Precambrian metamorphic rocks, mainly according to its relatively high metamorphic grade. Our filed observation, however, revealed that the complex is composed mainly of metamorphic rocks (Kele complex), tectono-schists ("Xinkailing Group"), and granitoids (Xinkailing granitic complex). Dating on these rocks using advanced SHRIMP zircon U-Pb technique indicates that: (1) Biotite-plagioclase gneiss from the Kele complex has a protolith age of 337±7 Ma (2σ) and a metamorphic age of 216±3 Ma (2σ); (2) the tectono-schist of the "Xinkailing Group" gave a magmatic age of 292±6 Ma (2σ), indicative of felsic volcanic protolith of the schist formed in late Paleozoic time; and (3) the Menluhedingzi and Lengchuan granites of the Xinkailing granitic complex were emplaced at 167±4 (2σ) and 164±4 Ma (2σ), respectively. These results suggest that the Xinkailing-Kele complex is not Precambrian metamorphic rocks and the so-called Precambrian "Nenji-ang Block" does essentially not exist. In combination with regional geological data, we propose that the Kele metamorphic complex is likely related to a collisional tectonism that took place in Triassic time, as indicted by its metamorphic age of 216±3 Ma. The Xinkailing granitic complex was em-placed along the collisional zone during Mid-Jurassic time, likely in a post-orogenic or anorogenic setting.     

苏鲁超高压带的研究现状

最近几年,国内外专家对苏鲁超高压变质岩带的研究已经有了不少成果,并对存在的具体问题进行了深入的讨论.榴辉岩作为高压超高压产物,与围岩的关系一直存在着激烈的争论.新元古代和印支期是苏鲁造山带两个重要的构造时期,现在的研究已经基本否定了印支期为榴辉岩形成的年代,而是高压榴辉岩相的年代.榴辉岩的围岩大部分为花岗质片麻岩,多具A型花岗岩特征,代表着相对安静的拉张环境.本文从这三个方面进行了详细介绍,确定了榴辉岩与围岩花岗质片麻岩的关系、榴辉岩的形成年代以及花岗质片麻岩的母岩性质,对研究中国东部两大板块碰撞、折返机制具有重要的地质意义.     

泰安市北集坡曹庄玉的研究

从矿物学岩石学的角度研究了曹庄玉这一新的玉石品种。描述了玉石的赋存状态和规模,对其成因机制做了较深刻地分析。指明深入研究这一新的玉石类型,不仅从理论上,而且从利用上都有重要意义。     

SHRIMP U-Pb zircon ages for the UHP metamorphosed granitoid gneiss in Altyn Tagh and their geological significance

Different types of UHP metamorphic rocks havebeen recently discovered in the Altyn Tagh[1—4], the north-ern margin of Qadam Basin[5—7], the southwestern Tian-shan Mountains[8,9] and the northern Qinling Moun-tains[10,11] in Central and Western China. And these areashave attracted focus attention of geologists at home andabroad to the studying of UHP metamorphism and conti-nental deep subduction. However, as newly discoveredUHP metamorphic terranes, some questions have beenarisen abou…     

河北平山深熔伟晶岩锆石成因及SHRIMP U-Pb年龄

深熔伟晶岩中的锆石具有典型的岩浆锆石的形态和结构,但却具有较低的Th/U比值,是非常特殊的,研究表明其为深熔作用所形成.进而说明并不是所有的具有自形柱状和密集振荡环带/韵律的锆石都是严格意义上的岩浆锆石.两样品锆石的SHRIMP U-Pb年龄表明伟晶岩的结晶年龄在1.87～1.89 Ga之间,大致代表了母岩深熔的时间,其核部残留的锆石年龄在2.5 Ga左右.伟晶岩形成于张性环境的浅部层次,表明陆-陆碰撞的时代可能早于1.9 Ga.     

浅谈滇西及滇南地区全风化片麻岩中滑坡问题

在云南的西部及东南部广泛分布有花岗片麻岩,其表层全风化带较厚,具有特殊的工程地质特性,形成一些大规模滑坡,本文通过多个工程实践,对滑坡的成因进行分析,并提出了常用的防治措施,可作为该地区滑坡防治的参考,也可供当地管理部门在防灾减灾方面作为参考。     

陇县地区新街片麻岩套锆石年龄及其地质意义

目的寻找秦-祁结合部位早古生代岛弧型岩浆活动的证据,为秦岭和祁连造山带的对比研究提供依据。方法依据岩石主、微量地球化学特征判别新街片麻岩套的构造属性,并通过LA-ICP-MS对其中的锆石进行U-Pb测年。结果新街片麻岩套富集大离子亲石元素(LILE)和轻稀土元素(LREE),亏损高场强元素(HSFE)和重稀土元素(HREE),指示其形成与俯冲作用有关,在构造判别图解中落入岛弧火山岩范围;U-Pb锆石测年结果显示,花岗质片麻岩的形成年龄为447.7±5.4Ma。结论该年龄与北秦岭和北祁连造山带内部的岛弧火山岩活动的时限一致。     

辽宁省新宾县徐家堡子韧性变形变质带的特征及变形变质作用

徐家堡子地区以黑云英云闪长质片麻岩（２．４７Ｇａ）为围岩的上壳岩（〉２．９８Ｇａ）包体中,发育几条近东西走向的韧性变形变质带（２．７Ｇａ）。研究表明,该韧性变形变质带在平面和剖面上的均呈舒缓波状,发育糜棱叶理,矿物线理和Ｓ－Ｃ组构。带内的糜棱片麻央矿物成分复且多世代矿物共存,变形前以石榴石,黑云母,斜长石和石英矿物组合为代表,形成温度为５００～５２０℃,压力为０．４ＧＰａ;韧性变形同期以夕线石,石     

新集矿区开发片麻岩矿泉水的水文地质研究

新集矿区是从推覆体下采煤。从水文地质角度，对推覆体片麻岩的分布特征、水文地质特征、水质及储量进行分析研究，从而提出开发片麻岩矿泉水的理论可行性和有待于进一步研究的问题。     

片麻岩大断面双洞隧道施工的动态特性

以兰州市北环路大断面双洞隧道工程为研究背景,采用台阶法进行施工,以ADINA有限元软件为计算平台,建立隧道开挖数值模型,对片麻岩大断面双洞隧道模型进行分析:研究地表位移、围岩位移与内力、锚杆轴力的特点及其变化规律.结果表明对片麻岩大断面双洞隧道采用台阶法施工时,分步开挖对地表竖向位移较水平位移影响大,最大竖向位移值为10.71mm,位于双洞隧道间岩柱上方;上、下台阶土体开挖会对隧道围岩位移及等效应力产生较大影响,应及时进行拱顶初期支护;锚杆轴力集中分布于边墙部位,且沿其辐射方向呈现不断减小的趋势,应对边墙部位锚杆进行加强处理.     

伊春花岗质片麻岩锆石 U-Pb 年代学特征

通过1∶5万朱拉比拉河等图幅区域地质调查工作,在伊春地区发现了新元古代花岗质片麻岩。应用锆石 U-Pb 测龄方法对花岗质片麻岩进行了年代学研究,23个点的206 Pb／238 U表面谐和年龄均在850 Ma 左右,加权平均为850．2±2．1 Ma。该年龄代表花岗质片麻岩体的侵位时间为新元古代;而较新的499 Ma 年龄可能是后期构造事件改造的新生锆石,反映后期构造热事件的年龄;1518 Ma 的年龄应是本次岩浆作用过程中捕获的早期锆石的年龄,该锆石年龄可能代表本区花岗岩的继承性锆石年龄。伊春花岗质片麻岩所在的地区存在前寒武纪的古老微陆块。     

Multi-stage evolution of gneiss from North Dabie： evidence from zircon U-Pb chronology

TTG gneiss is a common rock to outcrop in the northern part of the Dabie orogen, a few of which are closely associated with eclogites that experienced the Triassic ultrahigh pressure metamorphism. Although they were thermally metamorphosed by a large-scale magma activity in this region at the Early Cretaceous, it is unclear whether or not they are also affected by the Triassic metamorphism during continental subduction and exhumation. In order to resolve this issue, SHRIMP zircon U-Pb dating was carried out for the host gneiss of eclogites in North Dabie. The results show that cores from the gneiss have an age of 746~.31 Ma, consistent with the protolith ages of granitic gneisses in the Dabie orogen. Zircon overgrowing with different U and Th concentrations give concordant ages of 212~21 and 120~11 Ma, respectively. Th/U ratios of overgrown zircons are both lower than 0.1, suggesting a metamorphic genesis. The present resuits suggest that the gneiss in North Dabie has the similar protolith ages of Neoproterozoic to those granitic gneisses elsewhere in the Dabie orogen, and experienced not only the Triassic metamorphism but also the thermal metamorphism due to the Early Cretaceous magmatism. This provides an important insight into the geodynamic evolution of gneissic rocks in the Dabie orogen.     

黑云二长片麻岩--榴辉岩相变的纵波速度

利用YJ-3000t压力机的弹性波速度测量装置在4.5 GPa,25～1 360℃条件下测量了黑云二长片麻岩的纵波速度,发现随温度升高,岩石的纵波速度经历了缓慢下降-逐渐升高-缓慢下降的复杂过程.详细观察相同条件下的实验产物证实黑云二长片麻岩向榴辉岩的转变是岩石纵波速度随温度升高而升高这一异常现象的主要原因,讨论了岩石中矿物相变与岩石纵波速度变化的关系.这一实验结果为初步了解陆陆俯冲过程中,俯冲陆壳的弹性波速度结构演化提供了高温高压实验资料.     

Structures, kinematics, thermochronology and tectonic evolution of the Ramba gneiss dome in the northern Himalaya

The Ramba gneiss dome, one of the north Himalayan gneiss domes, is composed of three tectono-lithologic units separated by an upper and a lower detachment fault. Low-grade metamorphic Tethyan Himalayan sedimentary sequence formed the upper unit above the brittle upper detachment fault. Mylonitic gneiss and a leucogranite pluton made up the lower unit beneath the ductile lower detachment fault. Mylonitic middle-grade garnet-, staurolite- and andalusite-schist constituted the middle unit between the two faults, which may be that the basal part of the upper unit experienced detachment shear. The Ramba dome underwent three episodes of deformation in its tectonic evolution. The first episode was a top-down-to-north-northwest sliding possibly related to the activity of the south Tibetan detachment system （STDS）. The second episode was the dominant deformation related to a east west extension, which resulted in a unique top-down-to-east kinematics and the major tectonic features of the dome. The third episode was a collapse sliding toward the outsides of the dome. The Ramba gneiss dome is possibly a result of the east-west extension and magmatic diapir. The lower detachment fault is probably the main detachment fault separating the sedimentary sequence from the crystalline basement during the eas-west extension in the dominant deformation episode. The diapir of the leucogranite pluton formed the doming shape of the Ramba gneiss dome. This pluton intruded in the core of the dome in a late stage of the dominant deformation, and its Ar-Ar cooling ages are about 6 Myr. This indicates that the dominant deformation of the dome happened at the same time of the east west extension represented by the nort-south trending rifts throughout the northern Himalaya and southern Tibet. Therefore, the formation of the Ramba gneiss dome should be related to this east west extension.