中国矿物岩石地球化学学会第六届理事会第二次常务理事会(扩大)会议纪要

2004年5月31日,我会在北京召开了第六届常务理事会第二次(扩大)会议。欧阳自远名誉理事长、刘丛强理事长、胡瑞忠秘书长及部分常务理事与京区理事40人出席了会议,4位副秘书长列席了会议。     

昌宁-孟连缝合带南汀河早古生代埃达克岩锆石U-Pb年龄及其地质意义

前人在昌宁-孟连缝合带获得了大量的晚古生代岩浆活动与沉积地层的记录,但是早古生代的相关记录十分稀少,大大限制了对昌宁-孟连缝合带早古生代演化过程的理解.对南汀河地区早古生代英云闪长岩的锆石U-Pb年龄、全岩地球化学特征开展研究,并探讨其岩石成因,揭示早古生代(原)特提斯演化过程.通过LA-ICPMS锆石U-Pb定年,获得英云闪长岩206Pb/238U加权平均年龄为454.1±2.7 Ma、443.2±2.4 Ma,代表岩浆结晶时代.地球化学分析显示,南汀河英云闪长岩SiO₂含量为63.41%~68.57%,K₂O含量为1.31%~2.17%,同时具有富Na(Na₂O=4.11%~5.07%)贫Mg(MgO=0.98%~1.39%)的特点.REE配分曲线呈现出轻稀土富集、重稀土亏损的特征,大离子亲石元素Sr、Ba等富集,高场强元素Nb、Ta、Ti亏损,与岛弧岩浆的特征相吻合;指示岩浆来源于俯冲板片的部分熔融,在岩浆上升过程中受到了俯冲沉积物的混染,形成于与原特提斯洋俯冲有关的弧火山岩环境,进一步指示早古生代原特提斯洋在454~443 Ma就已经发生了俯冲消减作用.南汀河蛇绿岩与羌塘地区龙木错-双湖缝合带桃形湖等蛇绿岩形成时代一致、地球化学性质相似,由此认为昌宁-孟连缝合带与龙木错-双湖缝合带一起代表了一个统一的古特提斯洋壳的残余.      

川藏交通廊道沿线板块缝合带地质灾害效应

板块缝合带作为特殊类型的“断层”,其地质灾害效应是工程地质与灾害地质研究的重要内容,对工程建设具有重大现实意义.受特提斯洋复杂而漫长的构造演化制约,川藏交通廊道穿越了7条板块缝合带,但对其地质灾害效应的研究却鲜有涉及.为此,在搜集整理已有研究成果的基础上,结合野外地质调查和室内研究,简要分析了川藏交通廊道沿线板块缝合带的地质灾害效应,并探讨其内在机理.结果表明：板块缝合带地质灾害效应主要表现在塑造地貌、创造地形条件,劣化岩体、提供物质来源,控制地质灾害的分布和诱发地质灾害（链）等4方面.构造混杂岩因其复杂的地质演化过程和特殊的岩石类型与组合特征,使其天然具有易灾性,而板块缝合带就位过程中的构造运动是地质灾害效应的内生动力.板块缝合带的地质灾害效是贯穿于川藏交通廊道沿线板块缝合带构造演化过程中的内、外动力地质作用耦合的外在表现形式.板块缝合带地质灾害效应研究目前处于起步阶段,建议在加强基础地质与灾害地质精细化调查的基础上深化其认识;川藏交通建设工程应加强板块缝合带工程效应研究,加大地质灾害监测预警系统研发,以确保其安全施工与后期平稳运行.     

青藏高原羌塘中部高压变质带的研究进展及存在问题

羌塘中部高压变质带是目前青藏高原内部延伸规模最大的高压变质带,是理解特提斯演化的关键地质记录。高压变质带主要沿龙木措-双湖-澜沧江缝合带一线出露,主要由榴辉岩、蓝片岩、石榴子石多硅白云母片岩及少量高压麻粒岩组成。其中,榴辉岩主要出露于戈木、果干加年山、冈玛错、巴青及滇西的勐库地区,主要呈透镜状产于石榴子石多硅白云母片岩中。除巴青地区的榴辉岩外,其余地区榴辉岩的峰期变质温度较低且含有硬柱石及其假象,峰期变质条件位于硬柱石榴辉岩相稳定区域,是洋壳冷俯冲的产物。虽然对于戈木地区榴辉岩锆石成因仍有争议,但已有资料显示,羌塘中部高压变质带主体变质时代集中在晚三叠世,其相关高压变质岩石的折返可能与洋盆的闭合及随后的陆-陆碰撞相关。近期研究表明,羌塘中部可能存在二叠纪低温高压变质岩,折返于大洋俯冲阶段,可能与洋岛或海山的俯冲及引发的俯冲侵蚀作用相关。此外,羌塘香桃湖地区出露早古生代的基性高压麻粒岩,是冈瓦纳大陆北缘陆块拼贴的记录。因此,对羌塘中部高压变质带进行进一步系统的研究工作,对于深入理解冈瓦纳北缘构造演化及古特提斯的俯冲与闭合过程具有重要的意义。     

论藏东玉龙斑岩铜矿带岩浆活动的构造环境

玉龙斑岩铜矿带喜马拉雅期成矿花岗岩浆活动是在印支期古特提斯(金沙江)岛弧构造的背景上发育起来的,与白垩纪至早第三纪主特提斯(怒江)和新特提斯(雅鲁藏布江)洋板块大规模的俯冲作用所诱发的古特提斯俯冲带的继承性活动有关。矿化斑岩属火山弧型花岗岩类。岛弧地带由板块缝合线朝大陆方向的完整金属矿化分带模式是Fe→Cu→Mo。     

神奇美丽的横断山：地壳演化塑造的奇迹——“三江并流”世界自然遗产地形成地质背景浅析

三江并流是反映地球演化主要阶段的杰出代表,区内保存着反映特提斯演化不同阶段和喜马拉雅期陆内造山阶段留下的丰富的地质遗迹,这些地质遗迹为解读三江并流地壳演化的历史提供了重要的依据。有关资料表明,三江并流是与青藏高原和横断山脉一起发育成长起来的,它们均经历了特提斯的演化,并且都是印度板块与欧亚板块强烈碰撞造山作用的产物。本文比较详细地介绍了横断山脉的形成演化过程及其与青藏高原形成演化之间的关系。     

班公湖-怒江成矿带西段阿翁错地区早白垩世花岗闪长岩的成因及构造背景——来自斜长石和黑云母化学成分的约束

Located at the western part of the Bangong Co-Nujiang metallogenic belt, the Early Cretaceous granodiorites from the Awengcuo area are characterized by the widely developed mafic microgranular enclaves (MMEs) and obvious magma mixing. Plagioclase and biotite, as the main rock-forming minerals, record the material composition and physicochemical conditions of the magmatic system, which are ideal objects for studying the petrogenesis, magmatic evolution and tectonic setting. This paper focuses on the granodiorites (host rock) and MMEs from the aspects of geology, petrography and mineral chemistry. The MMEs are in various shapes and have sharp or transitional contact boundaries with the host rocks. The enclaves often contain back vein. The MMEs and host rocks are commonly interpenetrated with each other, and chilled borders with width of 1–2 mm on the enclaves’ side can be observed occasionally. Many phenocrysts in the enclaves are captured from the host rocks, and acicular apatite formed by quenching is found in both the MMEs and host rocks. The above characteristics suggest that the MMEs are the products of magma mixing and mingling, and material interchanges are common. The results show that the plagioclases in the host rocks have intensive oscillatory normal zoning features with narrow An value range of 48.16 to 59.05, which may represent the plagioclase crystallized before the injection of mafic magma. The An values of the plagioclase with normal zoning features vary widely, with a core An value of 29.86 and a sudden increase to 51.09 outward, showing an overall gradual increase, indicating the addition of calcium-rich magma. Plagioclases of the host rocks show normal and reverse zoning features, with relatively complex core to mantle variations of An values and wide oscillatory zonation. Formation of the wide core to mantle oscillatory zonation of the plagioclase may due to the abrupt changes triggered by magma mixing. With the continuous mixing and gradual cooling of the magma, the plagioclase continued to crystallize in the static environment, and formed a clean edge of normal zonation. Although there is a normal zoning in the inclusion matrix plagioclase, the An values vary significantly from 62.40 in the core to 28.63 in the edge. It is obviously different from the normal zoning characteristics of the host rock plagioclase, which may be the result of the mixing of mafic magma and felsic magma. The core of plagioclases in the matrix of the MMEs with the characteristics of reverse zoning and normal-reverse zoning suffered weak melting erosion, but the range of the An values is relatively small, with the characteristics of intensive oscillatory zoning. It is suggested that the core melting erosion may be caused by the rapid decrease of pressure during the ascent of the mafic magma and formed in a static magma chamber. The host rock biotite and enclave matrix biotite are primary magmatic biotite, with AlVI values of 0–0.16 apfu and 0–0.04 apfu, oxidation coefficients of 0.11–0.63 and 0.16–1.66, and magnesia contents of 0.40–0.47 and 0.42–0.46, respectively, indicating that both of the host rocks and MMEs are calc alkaline I-type granites, whose formation is related to the subduction of island arc. Combined with the regional tectonic setting, it is considered that the early Cretaceous granodiorites in the Awngcuo area were formed under the tectonic setting of the transition from northward subduction to collision of the Shiquanhe-Namucuo Tethys ocean basin. © 2023 Science Press. All rights reserved.     

《风云二号》气候卫星测距副站设备性能与维护

本介绍了两套测距副站设备性能、运行、日常检测及维护上的特点，并对双星管理扩建工程乌鲁木齐测距融站设备从安装至今所出现的故障中的两例进行了分析。     

青海省钻获干热岩再传捷报 有望建设全国第一个干热岩研究基地

正"通过进一步勘查,青海省水文地质工程地质环境地质调查院从共和盆地地下2735米处钻获干热岩温度达到了168摄氏度以上,此次突破使青海共和盆地发现的干热岩资源在全国意义重大,今后有望在这里建立全国第一个干热岩研究基地。"6月25日,中国地质调查局副局长王学龙一行来到海     

南海区捕捞渔业副渔获及其利用

南海位于４°Ｎ～２３°３５′Ｎ,１０５°４０′Ｅ～１１７°３０′Ｅ之间,是中国四大海区中最大的海区,面积为３．５×１０６ｋｍ２,其中大陆架面积约占总面积的一半以上,仅南海北部大陆架（２００ｍ等深线以内）海域面积约３．７４×１０５ｋｍ［１］。南海北部地理自然环境优越,渔业资源丰富,渔场广阔。南海渔民在长期的生产实践中,根据资源和渔场的实际情况开发了具有南海特色的各种适应性渔具渔法,大大地推动了南海渔业的发展。１　渔获概况　　南海区（包括广东、广西和海南三省）海洋捕捞业渔获量８０％来自南海北部沿岸近…