The Discovery of Diamond from the Zhimafang Pyrope Peridotite of the Sulu UHP Metamorphic Zone, East China, and Its Geological Implications     

PAN Mingbao  ZHANG Qinglong  LU Huafu  CHEN Huogen  CHEN Shoujuand ZHU ShipengDepartment of Earth Sciences  Nanjing University  Nanjing  Jiangsu Jiangsu Institute of Geological Survey  Zhujiang Ro  Nanjing  Jiangsu  E-mail: andypans@.com Hao Ziguo  Zhu Xiling 《《地质学报》英文版》2003,77(3):332-337

From Donghai County of Jiangsu Province to Rongcheng County of Shandong Province on the southern border of the Sulu orogen, there exposes an ultramafic belt, accompanied with an ultrahigh-pressure metamorphic zone. It can be further divided into the Xugou belt (the northern belt), and the Maobei-Gangshang belt (the southern belt). One grain of diamond has been discovered from the Zhimafang pyrope peridotite in the southern belt using the heavy mineral method. The diamond grain is 2.13 mm × 1.42 mm × 0.83 mm in size and weighs 9.4 mg. The occurrence of the diamond suggests that the Zhimafang pyrope peridotite xenolith is derived from the lithospheric upper mantle. The tectonic emplacement mechanism of the pyrope peridotite xenoliths in granite-gneisses is obviously different from those in kimberlite. The Sulu orogen was located on the active continental margin of the Sino-Korean craton in the Neoproterozoic. The relatively cold and water-bearing oceanic crustal tholeiite slab subducted beneath the lith  相似文献   

SHRIMP Age and Geochemistry of the Bikou Volcanic Terrane: Implications for Neoproterozoic Tectonics on the Northern Margin of the Yangtze Craton   总被引：3，自引：0，他引：3  

A.D.HANSON  P.A.DRUSCHKE 《《地质学报》英文版》2003,77(4):479-490

The Bikou volcanic terrane is predominated by subalkaline tholeiitic lavas. Rock samples display lower initial ratios of Sr and Nd, 0.701248-0.704413 and 0.511080-0.512341 respectively. 207Pb and 208Pb are significantly enriched in the lavas. Most samples have positive εNd, which indicates that the magma was derived from EM-type mantle source, while a few samples with negative εNd indicate that there was contamination in the magma evolution. Magma differentiation is demonstrated by variations of LREE and LILE from depletion to enrichment. Additionally, normalized REE patterns and trace elements showed that lavas from the Bikou volcanic terrane have similar characteristics to those of basalts in arc settings caused by subduction and collision. Analyses showed that the Bikou volcanic terrane is a volcanic arc. New evidence proved that the Hengdan Group, north of the Bikou arc, is a turbidite terrane filling a forearc basin. Consequently, the Bikou volcanic terrane and the Hengdan turbidite terrane const  相似文献   

An Experimental Calibration on the Sphalerite-Galena Sulfur Isotope Geothermometer     

DING Tiping  ZHANG Chengxin  WAN Defang  LIU Zhijian  ZHANG Guilan Institute of Mineral Resources  Chinese Academy of Geological Sciences  Baiwanzhuang Rd.  Beijing 《《地质学报》英文版》2003,77(4):519-521

A new experimental calibration was undertaken in this study to get a more reliable sphalerite-galena sulfur isotope geothermometer. The experimental conditions selected in study were very similar to those of natural hydrothermal solution. The high-precision SF6 method was used in sulfur isotope analyses. The obtained calibration curve for sulfur isotope fractionation between sphalerite and galena can be expressed with the equation 10001nαSp-Gn= 0.74×106T-2+0.08.  相似文献   

Cascaded Evolution of Mantle Plumes and Metallogenesis of Core- and Mantle-derived Elements   总被引：1，自引：0，他引：1  

NIU Shuyin  HOU Quanlin  HOU Zengqian  SUN Aiqun  WANG Baode  LI Hongyang  XU Chuanshi Institute of Geology  Geological Survey  Shijiazhuang College of Economics  Shijiazhuang  Hebei  Institute of Geophysics  Chinese Academy of Sciences  Beijing Institute of Mineral Resources  Chinese Academy of Geological Sciences  Beijing 《《地质学报》英文版》2003,77(4):522-536

Mineral deposits are unevenly distributed in the Earth's crust, which is closely related to the formation and evolution of the Earth. In the early history of the Earth, controlled by the gravitational contraction and thermal expansion, lighter elements, such as radioactive, halogen-family, rare and rare earth elements and alkali metals, migrated upwards; whereas heavier elements, such as iron-family and platinum-family elements, base metals and noble metals, had a tendency of sinking to the Earth's core, so that the elements iron, nickel, gold and silver are mainly concentrated in the Earth's core. However, during the formation of the stratified structure of the Earth, the existence of temperature, pressure and viscosity differences inside and outside the Earth resulted in vertical material movement manifested mainly by cascaded evolution of mantle plumes in the Earth. The stratifications and vertical movement of the Earth were interdependent and constituted the motive force of the mantle-core movement.  相似文献   

A Metallogenic Model of Gold Deposits of the Jiaodong Granite-Greenstone Belt   总被引：34，自引：0，他引：34  

DENG Jun  YANG Liqiang  SUN Zhongshi  WANG Jianping  WANG QingfeiXIN Hongbo  LI Xinjun Key Laboratory of Lithospheric Tectonics  Exploration. China University of Geosciences  Ministry of Education  Beijing  Institute of Geology  Geophysics  Chinese Academy of Sciences  Beijing Faculty of Earth Sciences  Jilin University  Changchun  Jilin 《《地质学报》英文版》2003,77(4):537-546

An analysis of trace elements and isotopic geochemistry suggest that the ore-forming materials of gold deposits in the Jiaodong granite-greenstone belt have multiple sources, especially the mantle source. Seismic wave, magnetic and gravity fields show that the crust-mantle structure and its coupling mechanism are the fundamental dynamic causes for the exchange and accumulation of materials and energy in the metallogenic system. Considering the evolution history of the structural setting, the tectono-metallogenic dynamics model of the area can be summarized as follows: (1) occurrence of the greenstone belt during the Archean-Proterozoic-the embryonic form of Au-source system; (2) stable tectonic setting in the Paleozoic-an intermittence in gold mineralization; (3) intensive activation and reformation of the greenstone belt in the Mesozoic-tectono-mineralization and tectono-diagensis; (4) posthumous structural activity in the Cenozoic-destruction of orebodies in the later stage. In the middle and late Ind  相似文献   

深厚软土中超大型“悬浮”基坑水泥土重力式挡土墙位移控制措施     

陈学文 《湖南地质》2003,22(1):51-53,57

本文就珠海某基坑水泥土重力式挡土墙的位移及其控制进行分析探讨，论述了应用轻型钢管支撑对基坑位移控制的可行性，并详细阐述了其计算方法及施工工艺。  相似文献   

论桩基施工中流砂现象处理     

陈亮晶李有文  何建军 《湖南地质》2003,22(1):54-57

地下水流动对土体产生渗透力；当渗透力大于土体的抗剪强度，土体破坏，也就是当施工造成地下水水力坡度超过砂层的临界水力坡度即产生流砂现象．运用水文地质工程地质学方面的原理其处理方法有两类：—是莫尔一库仑法：即c法和φ法；二是临界水力坡度法(Ic法)．  相似文献   

机械卡盘设计中的计算误差分析与应用          下载免费PDF全文

陈宝杰  卜长根 《探矿工程》2003,30(3):30-32,34

通过对普通机构二维力因素影响的分析，利用修正公式计算求值，以修正单因素影响最大值计算所产生的误差。利用这一计算方法，对CD—3型钻机卡盘进行了计算，得到了正确的设计结果，说明用修正公式对多因素影响采用单因素影响最大值计算进行修正是可行的。  相似文献   

闽南沿海地质灾害防治对策   总被引：3，自引：0，他引：3  

苏志辉  陈旭辉 《地质灾害与环境保护》2003,14(1):1-3

根据闽南沿海环境地质条件，提出了五条地质灾害的防治基本要点；又据要点，结合本区主要的环境地质问题的实际问题，提出五点防治对策与建议。  相似文献   

贵州峨眉山玄武岩喷发期的岩相古地理研究   总被引：7，自引：0，他引：7       下载免费PDF全文

陈文一  刘家仁  王中刚  郑启钤 《古地理学报》2003,5(1):17-28

贵州峨眉山玄武岩喷发，从动态的角度可以分为茅口期晚期和龙潭期（吴家坪期），龙潭期又可分为三个喷发旋回，对应于四个不同的岩相古地理环境，体现了东吴运动在造成贵州地区地壳抬升、下沉和接受最大海侵之后，又上升、拉张、沉陷带发生地裂（又称峨眉地裂）以及地幔物质喷溢等地质活动，具间歇性和多旋回性的特点。本文从研究海陆变迁入手，揭示峨眉山玄武岩喷发与沉积作用的内在联系，进而探讨其与金、锑等矿产的成因联系，提出该期各相区与成矿区的形成模式。通过对贵州峨眉山玄武岩不同喷发期岩相古地理的研究可以看到，茅口期晚期和龙潭期早期海域的沉积韵律和相带展布格局与玄武岩喷发的间歇性和多旋回性特征完全一致。玄武岩的喷发为成矿提供了物质基础，玄武岩喷发的间歇期又为沉积矿产的富集提供机遇。这种岩浆期后气液以富硅和二氧化碳为特征的玄武岩，本身富含铁、锰、铜、铅、锌、锑、砷、汞、金、银、氟、磷以及一些稀散和放射性元素等成矿组分。在喷发过程中，气液成分有一定变化，各阶段和离岩浆的远近距离不同以及喷发性质和环境差异，形成了火山气液矿床、火山沉积矿床和沉积矿床的不同成矿带。  相似文献