受应力岩石吕由物理─化学反馈引起的分异构造     

Dewers  T 胡志勇 《世界地质》1993,12(2):110-119

  相似文献   

西秦岭凤太矿集区花岗闪长斑岩脉的成因类型和年龄及其地质意义   总被引：1，自引：0，他引：1  

陈绍聪  王义天  胡乔青  张娟  王瑞廷  王长安  刘协鲁  欧阳升 《地球学报》2018,39(1):14-26

凤太矿集区是西秦岭最重要的金、铅锌、铜多金属成矿区之一。本次工作对产于矿集区中北部NWW向断裂带内的孔棺和金铜沟花岗闪长斑岩脉进行了LA-ICP-MS锆石U-Pb定年,获得(230.7±1.8)Ma和(230.4±1.8)Ma的年龄,属中三叠世。两岩脉稀土元素配分呈右倾型,轻、重稀土强烈分馏,无明显Eu异常,亏损高场强元素,Nb/Ta比值接近陆壳;87Sr/86Sr同位素比值分别为0.712 833±0.000 017和0.712 365±0.000 016。地球化学分析表明成岩物质以壳源为主,岩浆可能主要来自扬子板块北缘碧口群的部分熔融,源区存在石榴子石等矿物残留,无斜长石残留,形成于同碰撞初始阶段。结合区域构造和岩浆特征,认为凤太矿集区经历了250 Ma左右的洋壳俯冲阶段、230 Ma左右的同碰撞阶段以及220—200 Ma的后碰撞阶段。岩脉230 Ma的年龄限定了区内NWW向断裂带活动的时间上限。区内NWW向构造约形成于中三叠世,NE向构造发育于晚三叠世。区域构造、岩浆及金、铅锌多金属成矿的时空耦合,暗示了三者都是印支期秦岭造山作用过程的产物。  相似文献   

陕西凤太矿集区柴蚂金矿床脉状闪锌矿Rb-Sr同位素测年及意义     

王义天  刘协鲁  胡乔青  张娟  陈绍聪  王瑞廷  代军治  高卫宏  温深文  陈明寿  张革利 《西北地质》2018,(3)

柴蚂金矿床位于陕西省凤太矿集区西北部八卦庙超大型金矿床的西侧约0.5km处,二者在成矿地质背景和控矿条件等方面均相似。该矿床共划分出5个含矿带,其产出位置受地层和构造联合控制。本次工作对柴蚂金矿床中发育的脉状闪锌矿进行了Rb-Sr同位素测年研究,获得了等时线年龄为(210.8±2.4)Ma,即晚三叠世;闪锌矿的~(87)Sr/~(86)Sr_i值为0.710 55±0.000 11,指示铅锌矿化的成矿物质可能主要来源于大陆壳。结合前人的研究成果分析认为,凤太矿集区内的铅锌矿化和金矿化是在秦岭造山带印支期碰撞-后碰撞过程中同一时代同一成矿作用的产物。  相似文献   

陕西凤太矿集区柴蚂金矿床成矿时代的⁴⁰Ar/³⁹Ar年龄证据     

刘协鲁  王义天  胡乔青  王瑞廷  彭洛宏  张革利  刘敏  欧阳升 《矿床地质》2018,37(1):163-174

柴蚂金矿床位于陕西凤太矿集区的西北部,矿体产于长沟-八卦庙向斜和长沟-打柴沟背斜核部和两翼的NWW向脆韧性剪切构造带中,赋矿地层为上泥盆统星红铺组的斑点状铁白云质粉砂质千枚岩。金矿化类型包括石英脉型和蚀变岩型2种。成矿过程划分为早期石英-碳酸盐阶段、主成矿期石英-碳酸盐-硫化物阶段和晚期石英脉阶段。对主成矿阶段热液蚀变形成的绢云母开展40Ar/39Ar测年研究,获得坪年龄为(219.0±2.0)Ma,指示其成矿作用始于219 Ma左右,即晚三叠世。前期工作获得该阶段碳酸盐矿物的Sm-Nd同位素年龄为(203.0±1.6)Ma,2个年龄值可能限定了成矿作用的上限与下限。结合前人有关区域地质与成矿作用的研究成果分析认为,柴蚂金矿床属于造山型金矿床,其成矿作用的多阶段性与剪切带长期演化过程中的构造递进变形密不可分。  相似文献   

The Discovery of Diamonds in Chromitites of the Hegenshan Ophiolite, Inner Mongolia, China   总被引：1，自引：0，他引：1  

HUANG Zhu  YANG Jingsui  Paul T. ROBINSON  ZHU Yongwang  XIONG Fahui  LIU Zhao  ZHANG Zhongming  XU Wei 《《地质学报》英文版》2015,89(2):341-350

Diamond,moissanite and a variety of other minerals,similar to those reported from ophiolites in Tibet and northern Russia,have recently been discovered in chromitites of the Hegenshan ophiolite of the Central Asian Orogenic Belt,north China. The chromitites are small,podiform and vein-like bodies hosted in dunite,clinopyroxene-bearing peridotite,troctolite and gabbro. All of the analysed chromite grains are relatively Al-rich,with Cr# [100Cr/(Cr+Al)] of about 47–53. Preliminary studies of mainly disseminated chromitite from ore body No. 3756 have identified more than 30 mineral species in addition to diamond and moissanite. These include oxides(mostly hematite,magnetite,rutile,anatase,cassiterite,and quartz),sulfides(pyrite,marcasite and others),silicates(magnesian olivine,enstatite,augite,diopside,uvarovite,pyrope,orthoclase,zircon,sphene,vesuvianite,chlorite and serpentine) and others(e.g.,calcite,monazite,glauberite,iowaite and a range of metallic alloys). This study demonstrates that diamond,moissanite and other exotic minerals can occur in high-Al,as well as high-Cr chromites,and significantly extends the geographic and age range of known diamond-bearing ophiolites.  相似文献   

Diamond Discovered in High-Al Chromitites of the Sartohay Ophiolite, Xinjiang Province, China   总被引：1，自引：0，他引：1  

TIAN Yazhou  YANG Jingsui  Paul T. ROBINSON  XIONG Fahui  LI Yuan  ZHANG Zhongming  LIU Zhao  LIU Fei  NIU Xiaolu 《《地质学报》英文版》2015,89(2):332-340

In recent years diamonds and other exotic minerals have been recovered from mantle peridotites and high-Cr chromitites of a number of ophiolites of different age and different tectonic environments. Here we report a similar collection of minerals from the Sartohay ophiolite of Xinjiang Province,western China,which is characterized by having high-Al chromitites. Several samples of massive podiform chromitite with an aggregate weight of nearly 900 kg yielded diamonds,moissanite and other highly reduced minerals,as well as common crustal minerals. Thus far,more than 20 grains each of diamond and moissanite have been recovered from heavy mineral separates of the chromitites. The diamonds are all 100-200 μm in size and range in color from pale yellow to reddish-orange to colorless. Most of the grains are anhedral to subhedral octahedra,commonly with elongate forms exhibiting well-developed striations. They all display characteristic Raman spectra with shifts between 1325 cm-1 and 1333 cm-1,mostly 1331.51 cm-1 or 1326.96 cm-1. The moissanite grains are light blue to dark blue,broken crystals,50-150 μm across,commonly occurring as small flakes or fragments. Their typical Raman spectra have shifts at 762 cm-1,785 cm-1,and 966 cm-1. This investigation extends the occurrence of diamonds and moissanite to a Paleozoic ophiolite in the Central Asian Orogenic Belt and demonstrates that these minerals can also occur in high-Al chromitites. We conclude that diamonds and moissanite are likely to be ubiquitous in ophiolitic mantle peridotites and chromitites.  相似文献   

The Zunhua-Zanhuang Ophiolitic Mélange: Traces of an Archean Suture in the North China Craton     

KUSKY T.M.  LI J.H.  PLOAT A.  WANG Junpeng  DENG Hao  WANG Lu 《《地质学报》英文版》2015,89(Z2):37-38

<正>Sutures mark places where oceans have closed and two once widely separated terranes have collided.Sutures are defined on the basis of geological relationships,and differences in the geologic,structural,magmatic,sedimentary,and metamorphic histories of the terranes on either side of the suture.Sutures are characterized by  相似文献   

地热勘查技术进展     

迈达夫  T  良可 《国土资源信息化》1999,(4):27-29

  相似文献   

一种新型下水道扫描技术的开发     

Iseley  T 刘宝林 《岩土钻凿工程》2000,(2):151-153

  相似文献   

利用日本钻孔场地的强弱地震动反演土壤与应变有关的非线性特征     

T.Satoh  M.Fushimi  Y.Tatsumi  陈学良 《世界地震译丛》2008,(1)

在1995年兵库县南部地震期间,日本尼崎、高砂和南光3处钻孔场地的地表台站分别观测到了507cm/s2以上、187cm/s2和126cm/s2的水平峰值地面加速度(PGA)的强运动。利用对强弱地震动的互相关和频谱比的分析,我们给出了除南光之外在尼崎、高砂两处强地震动期间土壤非线性响应的定性证据。我们通过对剪切波速和与频率相关的阻尼因子的反演来评估土壤的非线性。反演得到砾石土的剪切模量比的应变依赖性比粘性土的要大,这与实验室试验结果一致。剪应变在10-4～10-3之间时,反演得到的尼崎、高砂两处砾石土和粘性土的剪切模量比的应变依赖性,分别同砾石土和粘性土实验室试验结果的经验关系相一致。这些结果支持了在砾石土和粘性土场地利用实验室试验所得剪切模量比来模拟强地震动。在尼崎,由主震反演得到的砾石土的阻尼因子在3个场地之中是最大的,但是阻尼因子的应变依赖性不如剪切模量比的应变依赖性那样显著。阻尼因子的应变依赖性不太显著的原因可能是由于散射衰减在低应变范围处于相对优势地位所致。  相似文献