50a来洮河流域降水径流变化趋势分析   总被引：7，自引：2，他引：7  

张济世  康尔泗  蓝永超  陈仁升  姚尽忠  蒲瑞丰  陈满祥 《冰川冻土》2003,25(1):77-82

洮河流域 40多年水文实测资料分析表明 ,由于受气候变化及人类活动影响 ,流域降水和径流特征发生了明显变化 ,降水与径流总体呈下降趋势 ,其下降的线性斜率分别为 - 0 .86～ - 1.34mm·a-1和 - 1.5 7～ - 3.36m3·s-1·a-1;而气温呈缓慢上升趋势 ,其上升的线性斜率为 0 0 2℃·a-1.降水的减少和温度的升高已经导致甘南草原荒漠化 ,使许多湿地和湖泊干涸 ;径流的减少和温度增加在近2 0a来有进一步加剧的趋势 .  相似文献   

~(40)Ar/~(39)Ar Dating of Deformation Events and Reconstruction of Exhumation of Ultrahigh-Pressure Metamorphic Rocks in Donghai, East China   总被引：3，自引：0，他引：3  

LI Jinyi  YANG Tiannan  CHEN Wen  ZHANG Sihong Institute of Geology  Chinese Academy of Geological Sciences  Beijing E-mail: jyli@cags.net.cn 《《地质学报》英文版》2003,77(2)

Recent investigations reveal that the ultrahigh-pressure metamorphic (UHPM) rocks in the Donghai region of East China underwent ductile and transitional ductile-brittle structural events during their exhumation. The earlier ductile deformation took place under the condition of amphibolite facies and the later transitional ductile-brittle deformation under the condition of greenschist facies. The hanging walls moved southeastward during both of these two events. The 40Ar/39Ar dating of muscovites from muscovite-plagioclase schists in the Haizhou phosphorous mine, which are structurally overlain by UHPM rocks, yields a plateau age of 218.0±2.9 Ma and isochron age of 219.8Ma, indicating that the earlier event of the ampibolite-facies deformation probably took place about 220 Ma ago. The 40Ar/39Ar dating of oriented amphiboles parallel to the movement direction of the hanging wall on a decollement plane yields a plateau age of 213.1±0.3 Ma and isochron age of 213.4±4.1 Ma, probably representing the age o  相似文献   

Isotopic Ages of the Carbonatitic Volcanic Rocks in the Kunyang Rift Zone in Central Yunnan, China     

ZHANGYongbei WANGGuilan NIEJianfeng ZHAOChongshun XUChengyan QIUJiaxiang WangHao 《《地质学报》英文版》2003,77(2):204-211

The Mesoproterozoic Kunyang rift, which is located on the western margin of the Yangtze platform and the southern section of the Kangdian axis, is a rare massive Precambrian iron-copper polymetallic mineralization zone in China. The Mesoproterozoic Wulu (Wuding-Lufeng) basin in the middle of the rift is an elliptic basin controlled by a ring fracture system. Moreover, volcanic activities in the basin display zonation of an outer ring, a middle ring and an inner ring with carbonatitic volcanic rocks and sub-volcanic dykes discovered in the outer and middle rings. The Sm-Nd isochron ages have been determined for the outer-ring carbonatitic lavas (1685 Ma) and basaltic porphyrite of the radiating dyke swarm (1645 Ma) and the Rb-Sr isochron ages for the out-ring carbonatitic lavas (893 Ma) and the middle-ring dykes (1048 Ma). In combination of the U-Pb concordant ages of zircon (1743 Ma) in trachy-andesite of the corresponding period and stratum (1569 Ma) of the Etouchang Formation, as well as the Rb-Sr iso  相似文献   

Late Caledonian Ductile Thrusting Deformation in the Central East Kunlun Belt, Qinghai, China and Its Significance: Evidence from Geochronology   总被引：5，自引：0，他引：5  

WANG Guocan  CHEN Nengsong  ZHU Yunhai  ZHANG Kexin Faculty of Earth Sciences  China University of Geosciences  Wuhan  Hubei  E-mail: wgcan@cug.edu.cn Ren Xifei  Liu Ruixun  Xie Guanglian 《《地质学报》英文版》2003,77(3)

A high-angle ductile thrusting deformation with top-to-the-north movement penetratively developed in the Proterozoic-Early Paleozoic metamorphic rocks along the Central East Kunlun belt. The deformed rocks suffered epidote-amphibolite facies metamorphism. On the basis of our previous study, we present more data in this paper to further support that the ducdle thrust deformation occurred in the later Caledonian and more detailed information about the deformation. A zircon U-Pb concordant age of 446±2.2 Ma of a deformed granodiorite in the ductile thrust zone was obtained and can be interpreted as the lower limit of the deformation. A syntectonically crystallized and also strongly deformed hornblende Ar/ Ar dating gives an Ar/Ar plateau age of 426.5±3.8 Ma, which represents the deformation age. A strongly orientated muscovite gives an Ar/Ar plateau age of 408±1.6Ma, representing the cooling age after the peak temperature, constraining the upper limit of the ductile thrust deformation. This ductile thru  相似文献   

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   

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   

甘肃北山地区成矿带划分及基本特征   总被引：7，自引：2，他引：7       下载免费PDF全文

张发荣  牛卯胜 《甘肃地质》2003,12(1):50-57

根据成矿地质背景和成矿在时空上的联系性 ,以板块构造单元为基础 ,结合地质、物探、化探、遥感等成矿信息 ,将甘肃北山成矿区带厘定为 2个Ⅱ级成矿区 ,3个Ⅲ级成矿带 ,1 0个Ⅳ级成矿带。以期为矿产勘查和地质大调查工作部署提供新的思路和依据  相似文献   

甘肃夏河—合作地区金矿特征及找矿思路   总被引：2，自引：0，他引：2       下载免费PDF全文

周会武  王伟  张发荣 《甘肃地质》2003,12(1):63-69

本文对甘肃夏河—合作地区的地层、构造、岩浆岩等与成矿有关的因素进行了综述 ,主要对已发现的金矿的类型及其特征进行了总结。该地区金矿类型主要为构造蚀变岩型、微细浸染型 ,矿床严格受构造控制。提出了今后的找矿思路和方向  相似文献   

空间分析方法、应用模型与GIS的关系   总被引：4，自引：0，他引：4  

马天智  张燕妮 《湖南地质》2003,22(1):70-72

首先阐述了空间分析和应用模型的基本概念，进而从地理信息处理系统的功能入手，分析了空间分析、应用模型和GIS的关系，最后指出加强应用模型与GIS的结合以及增强GIS的基本空间分析功能是增强GIS整体功能的二个最有效的方法．  相似文献   

地下水中铜元素的迁移富集及其控制因素     

曾昭华张志良  詹春酶 《城市地质》2003,15(4):13-17

研究了地下水中铜元素迁移富集的主要控制因素及其分布规律。结果表明，地下水铜元素的迁移富集与含水介质及其上覆土层中的铜元素含量、地下水的酸碱度、地下水的径流条件和氧化还原环境等有密切的关系。  相似文献