柴达木盆地北缘锡铁山副片麻岩所记录的多期构造热事件

在柴达木盆地北缘中段的锡铁山地区,夹有榴辉岩或退变榴辉岩透镜体的2个副片麻岩样品的锆石被用于SHRIMP U pb测定。2个片麻岩样品具有类似的特征,主要由石榴子石、夕线石、长石、黑云母和石英组成,这些矿物组合形成的变质条件, 0.6～0.9GPa和710～820℃,显示两处片麻岩经历了中压麻粒岩相条件的变质作用。锆石的SHRIMP U-Pb测定显示,2个样品获得近一致的早古生代变质年龄(分别为437Ma±6Ma和441Ma±15Ma),代表早古生代的高温变质作用时代。样品XTS-1还得890Ma±14Ma的年龄,所测定的锆石具有明显的变质作用成因特征,代表了新元古代早期的变质事件,反映了这些副片麻在早古生代造山旋回之前可能还经历了晋宁期的变质作用。     

关于东昆仑地区前寒武纪地质的几点认识

以1∶25万区域地质调查资料为基础,对东昆仑造山带前寒武纪地质演化的几个关键问题进行了探讨。东昆仑地区3206Ma±14Ma的锆石207Pb/206Pb年龄信息表明,该区存在古太古代基底。代表东昆仑地区基底的"金水口岩群"可以解体为太古宙—古元古代的白沙河岩群和中元古代的小庙岩群,两者是2个不同构造旋回的产物。东昆仑地区万宝沟群的时代应限定在中元古代,而不能延续到新元古代。东昆仑地区的年代构造格架显示,前寒武纪存在3次强烈的区域性构造热事件,分别发生在2400～2500Ma、1800～1900Ma和大约1000Ma。1000Ma左右的聚合事件导致中元古代分隔的不同小陆块的有限裂解小洋盆闭合,陆块聚合形成"西域板块",并可能是整个Rodinia超大陆的组成部分。     

Geochemistry of Apatite from the Apatite-rich Iron Deposits in the Ningwu Region, East Central China

Four types of apatite have been identified in the Ningwu region.The first type of apatite is widely distributed in the middle dark colored zones(i.e.iron ores) of individual deposits.The assemblage includes magnetite,apatite and actinolite(or diopside).The second type occurs within magnetite-apatite veins in the iron ores.The third type is seen in magnetite-apatite veins and (or) nodules in host rocks(i.e.gabbro-diorite porphyry or gabbro-diorite or pyroxene diorite).The fourth type occurs within apatite-pyrite-quartz veins filling fractures in the Xiangshan Group.Rare earth elements (REE) geochemistry of apatite of the four occurrences in porphyry iron deposits is presented.The REE distribution patterns of apatite are generally similar to those of apatites in the Kiruna-type iron ores,nelsonites.They are enriched in light REE,with pronounced negative Eu anomalies.The similarity of REE distribution patterns in apatites from various deposits in different locations in the world indicates a common process of formation for various ore types,e.g. immiscibility.Early magmatic apatites contain 3031.48-12080×10~(-6) REE.Later hydrothermal apatite contains 1958×10~(-6) REE,indicating that the later hydrothermal ore-forming solution contains lower REE.Although gabbro-diorite porphyry and apatite show similar REE patterns,gabbro-diorite porphyries have no europium anomalies or feeble positive or feeble negative europium anomalies, caused both by reduction environment of mantle source region and by fractionation and crystallization(immiscibility) under a high oxygen fugacity condition.Negative Eu anomalies of apatites were formed possibly due to acquisition of Eu~(2+) by earlier diopsite during ore magma cooling. The apatites in the Aoshan and Taishan iron deposits yield a narrow variation range of ~(87)Sr/~(86)Sr values from 0.7071 to 0.7073,similar to those of the volcanic and subvolcanic rocks,indicating that apatites were formed by liquid immiscibility and differentiation of intermediate and basic magmas.     

公路工程建设地质灾害危险性评估的方法与内容——以诸永高速公路为例

地质灾害危险性评估已依法被作为地质灾害易发区工程建设可行性研究报告的组成部分。本文以诸永高速公路为例，介绍了公路工程建设场区地质灾害危险性评估工作中工程分类、现状评估、预测评估、综合评估的内容与方法。对地质环境条件复杂、地质灾害发育、工程类型繁多的公路工程地质灾害危险性评估具有借鉴作用。     

Evolution of the Mesozoic Granites in the Xiong''''ershan-Waifangshan Region,Western Henan Province,China,and Its Tectonic Implications

Based on the new data of isotopic ages and geochemical analyses, three types of Mesozoic granites have been identified for the Xiong'ershan-Waifangshan region in western Henan Province: high-Ba-SrⅠ-type granite emplaced in the early stage (～160 Ma),Ⅰ-type granite in the middle stage (～130 Ma) and anorogenic A-type granite in the late stage (～115 Ma). Geochemical characteristics of the high-Ba-SrⅠ-type granite suggest that it may have been generated from the thickened lower crust by partial melting with primary residues of amphibole and garnet. Gradual increase of negative Eu anomaly and Sr content variations reflect progressive shallowing of the source regions of these granites from the early to late stage. New 40Ar/39Ar plateau ages of the early-stage Wuzhangshan granite (156.0±1.1 Ma, amphibole) and middle-stage Heyu granite (131.8±0.7 Ma, biotite) are indistinguishable from their SHRIMP U-Pb ages previous published, indicating a rapid uplift and erosion in this region. The representative anorogenic A-type granite, Taishanmiao pluton, was emplaced at～115 Ma. The evolution of the granites in this region reveals a tectonic regime change from post-collisional to anorogenic between～160 Ma and～115 Ma. The genesis of the early- and middle-stageⅠ-type granites could be linked to delamination of subducted lithosphere of the Qiniing orogenic belt, while the late-stage A-type granites represent the onset of extension and the end of orogenic process. In fact, along the Qiniing -Dabie-Sulu belt, the Mesozoic granitoids in western Henan, Dabieshan and Jiaodong regions are comparable on the basis of these temporal evolutionary stages and their initial 87Sr/86Sr ratios, which may suggest a similar geodynamic process related to the collision between the North China and Yangtze cratons.     

Junction and Evolution of the Qinling, Qilian and Kunlun Orogenic Belts

As the main part of the "central mountain system" in the continent of China, the Qinling, Qilian and Kunlun orogenic belts have been comprehensively and deeply studied since the 1970s and rich fruits have been reaped. However, these achievements were mostly confined to an individual orogenic belt and the study of the mutual relationship among the three orogenic belts was obliged to depend on comparative studies. Different views were produced therefrom. The material composition and structural features of the junction region show that there are several epicontinental and intracontinental transform faults developed in different periods. Restricted by these transform faults, the large-scale lateral movements and, as a consequence, complicated magrnatism and tectonic deformation took place in the orogenic belts. According to these features, the authors put forward a three-stage junction and evolution model and point out that there is not a single junction zone traversing from west to east but that the three     

Geochronology of Intermediate-Acid Intrusive Rocks from Tongling, Anhui

1. Introduction Tongling district is situated in the southern part of the middle-lower reaches of the Yangtze River, Anhui province, China (Fig.1). It is one of the most important metal base in China, being rich copper material resources, also named "ancient copper capital of China". Many geologists have been working in petrology, tectonics and ore-deposits in the area for many years. Studies show none of the ore-deposits is not bound up with the intermediate-acid intrusion in the area (Ma…     

GIS在自动绘制多色航磁剖面平面图的应用

利用GIS技术自动绘制多色航磁剖面平面图是一种基础性物探图件,在地质填图、地质找矿中是一种切实可行的技术方法。改进版的多色航磁剖面平面图具有曲线伦廓清晰、层次分明等优点,应该在今后的工作中加以推广。     

基于遥感的杭埠河流域水体的提取方法研究

通过遥感数据快速、精确的获取地物专题信息已经成为未来资源调查的发展趋势。在杭埠河流域水体变化研究中,由于杭埠河流域内地表湿润状况差异很大,以往的水体提取方法很难达到理想的效果,文章通过比较分析得出,在地表湿润状况差异较大的地区,非监督分类法,差值法、闽值法对水体的提取效果很不理想,而通过几种方法的结合并对谱间关系逐步分析来提取水体,则能够达到理想的效果。     

中国科学技术协会书记处书记束为一行莅临中国地质学会调研座谈

10月28日上午,中国科学技术协会党组成员、书记处书记束为一行莅临中国地质学会开展调研。全国政协常委、中国地质调查局副局长李朋德,中国地质调查局局长特别助理、副总工程师、科技外事部主任、中国地质学会副理事长兼常务副秘书长朱立新陪同调研座谈。李朋德主持座谈会并致辞,表示中国科协一直以来非常重视学术团体发展工作,对中国地质学会的发展给予了大力支持,期待中国地质学会能在中国科协的持续支持与指导下进一步蓬勃发展。朱立新代表学会作了中国地质学会工作专题报告,介绍了学会基本情况,汇报了学会近几年在服务国家重大需求、促进地质科技进步、支撑行业转型升级、助力经济社会发展等方面取得的一系列工作成效,以及学会发展面临的问题与困难。束为书记充分肯定了中国地质学会在地质科学领域做出的贡献,认为中国地质学会作为百年老会,在学术交流、人才培养、科学普及等方面做了许多亮点工作,在国际合作交流等方面为其他学会提供了许多可供借鉴的宝贵经验。中国科协将深入研究并协助解决学会发展中遇到的困难和问题,进一步做好中国科协与学会的沟通与服务工作,促进学会的国际化发展和交流,让学会充分发挥科技交流平台优势,在全球科技治理中发挥更加重要的作用。