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1.
新疆吐哈盆地南缘铜矿带含矿斑岩的地球化学及形成环境   总被引:13,自引:6,他引:7  
吐哈盆地南缘斑岩铜矿带位于中亚造山带东天山的中段。研究表明该铜矿带含矿斑岩的形成时代可分早石炭世和晚石炭世-早二叠世两期,前者以土屋-延东含矿斜长花岗斑岩为例,形成于与洋壳俯冲有关的岛弧环境,后者以赤湖和三岔口斜长花岗斑岩为例,形成于同碰撞造山的中-晚期。主量、微量元素和Sr—Nd同位素地球化学数据表明,吐哈盆地南缘铜矿带大多数斑岩具有钙碱性和岛弧花岗岩的特征,初始锶比值一般小于0.7046,εNd(t)值为5.3—7.6,反映成岩物质的深源性;进一步可将斑岩划分为埃达克岩和非埃达克岩,其中延东-土屋和三岔口含矿斑岩具有埃达克岩的特征,而赤湖、灵龙、卡拉塔格和垅西矿化斑岩和成矿后斑岩不具埃迭克岩特征。埃迭克岩成因有两种:土屋-延东埃迭克岩为洋壳板片熔融成因,三岔口埃达克岩为加厚下地壳的熔融成因。土屋-延东洋壳熔融埃达克岩的确定,进一步肯定了晚古生代石炭纪吐哈盆地南缘的岛弧环境。研究表明侵位于中亚造山带晚古生代岛弧环境和洋壳熔融成因的埃达克岩最有利于形成大型斑岩铜矿。  相似文献   

2.
新疆东天山地区岩浆岩的岩石成因和地球动力学背景备受关注.本文获得的东天山土屋斑岩铜矿床SIMS锆石U-Pb定年、全岩元素地球化学和Lu-Hf同位素数据,以对这一问题进行约束.土屋斑岩铜矿床位于新疆东天山造山带晚古生代大南湖-头苏泉岛弧带中,赋矿地层为下石炭统企鹅山群,赋矿围岩主要为安山岩和闪长玢岩,含矿岩石主要为英云闪长岩.本文SIMS锆石U-Pb定年结果表明,土屋地区含矿岩体大约侵位于335Ma,土屋斑岩铜矿床成矿时代与成岩时代基本一致或稍晚.地球化学数据显示安山岩和闪长玢岩具有同源性及岛弧火山岩的特点,英云闪长岩具有埃达克质岩石的特征.土屋英云闪长岩具不均一的锆石εHf(t)正值(+6.3~+16.1),表明其可能来源于俯冲板片的部分熔融.土屋斑岩铜矿床含矿岩体很可能是在早石炭世北天山洋板块北向俯冲的地球动力学背景下,大洋板片发生部分熔融形成埃达克质岩浆,在熔融过程中同时析出金属,随埃达克质岩浆一起上升,并与地幔橄榄岩发生交代作用,在岩体顶部富集成矿.  相似文献   

3.
甘肃黑石山早古生代埃达克质岩的发现及其构造动力学意义   总被引:17,自引:6,他引:11  
笔者近期在甘肃黑石山地区早古生代火成岩的研究中发现了埃达克质岩,埃达克质岩的岩石类型为奥长花岗岩、花岗闪长岩及花岗癍岩,侵入于北祁连东段的白银陆缘弧火山岩中。岩石具高Sr低Y,Sr/Y>40;富钠贫钾(Na2O/K2O>2), 富SiO,但含量变化不大;富集LREE,亏损重稀土元素,La/Yb>20,无Eu负异常或轻微正异常(δEu=1.0-1.19)。与典型的俯冲板块熔融的埃达克岩比较,黑石山埃达克质岩具有更高的SiO2含量和更低的MgO、Mg#(-46)、Cr(均11.6μg/g)、Ni(均 6.52μg/g),未显示出初始埃达克质熔体与地幔橄榄岩明显的交代过程,因而不大可能由俯冲板块直接熔融形成的;与中国东部燕山期高钾钙碱性埃达克岩相比,具有较高的Na2O(Na2O>4.0%;Na2O/K2O=1.97-2.59),但类似Cordilera Blanca岩基的(非板片熔融成因的埃达克质岩),推测形成于加厚的陆缘弧中基性下地壳的部分熔融。黑石山埃达克质岩的发现表明, 在早古生代晚期,北祁连东段经历了洋盆闭合、板块碰撞、陆缘弧地壳加厚、玄武质岩浆底侵作用及下地壳再造作用的构造演化过程。同时指出,在本区寻找与埃达克质岩有关的斑岩型铜、金矿可能是一个新的有希望的找矿方向。  相似文献   

4.
张达玉  周涛发  袁峰  范裕  刘帅  彭明兴 《岩石学报》2010,26(11):3327-3338
延西铜矿床位于新疆东天山觉罗塔格地区北部的哈尔里克-大南湖岛弧带内,是延东-土屋斑岩型成矿带的西延部分。矿床的赋矿地层主要为石炭系企鹅山群,被含矿斜长花岗斑岩侵入。矿床中的主要岩石类型为安山岩、闪长玢岩以及斜长花岗斑岩,安山岩和闪长玢岩具有同源性及岛弧火山岩的特点,是主要的赋矿围岩;斜长花岗斑岩具有埃达克质岩石的特征,与成矿作用直接相关,其形成晚于安山岩、闪长玢岩。本文测得延西铜矿床辉钼矿Re-Os年龄为326.2±4.5Ma,可以代表其成矿年龄,与土屋-延东铜矿床322.7±2.3Ma的辉钼矿Re-Os年龄基本相同;包括延西铜矿床在内的土屋-延东斑岩型铜矿带成矿时代与成岩时代基本一致或稍晚。延西铜矿床具有斑岩型铜矿床的矿化和围岩蚀变特征,与土屋-延东斑岩型铜矿带内其它矿床均为中石炭世同源岩浆演化的产物,具有相似的成矿作用过程,成矿物质均为岩浆来源,这些矿床可能为同一岩浆活动在不同部位发生矿化的产物。延西铜矿床以及土屋-延东斑岩型铜矿带形成于东天山觉罗塔格地区晚古生代的挤压岛弧背景,应与哈尔里克-大南湖晚古生代岛弧的形成相伴,可能与康古尔塔格大洋板块向北部哈尔里克-大南湖岛弧的俯冲有关。  相似文献   

5.
东天山晚古生代埃达克岩成因及铜金成矿意义   总被引:34,自引:16,他引:18  
东天山晚古生代岛弧带位于古亚洲洋成矿域的腹地,该区发育许多埃达克质的英云闪长岩、斜长花岗岩和花岗闪长岩小侵入体,本文选择尾亚北、三岔口、312国道东、312国道西、土屋-延东和巴仑台等小岩体进行了地球化学研究。这些岩石具有高Sr、Na2O和Al2O3,低Y和HREE等特征,与埃达克岩地球化学特征一致。绝大部分样品的εNd(T)为正值( 1.80 - 8.47),且(87Sr/86Sr)i很低(0.7026-0.7051),与现代MORB以及新生代俯冲洋壳熔融形成的埃达克岩的Nd和Sr同位素组成接近。东天山大部分埃达克质岩石具有高Mg#(>40)特点,且它们形成于晚古生代岛弧构造背景,暗示这些埃达克岩可能由俯冲洋壳熔融产生,并经历了与地幔楔橄榄岩的相互作用;三岔口英云闪长斑岩具有低Mg#(<40),且形成于碰撞后构造背景,可能是增厚下地壳熔融的产物。土屋-延东与埃达克岩有关的超大型斑岩铜矿的发现和突破使得东天山成为寻找斑岩铜金矿的重要靶区,本文新发现的埃达克岩无疑为在该区进一步寻找相关的矿床提供了有用的线索。特别是大部分埃达克岩由俯冲洋壳熔融产生,暗示其源区含有高丰度的Cu、Au和挥发份H2O、Cl等,且其岩浆可能在角闪岩相向榴辉岩相转变时产生,此时角闪石大规模分解有利于产生含丰富挥发份和成矿元素的埃达克质岩浆,暗示良好的成矿条件和成矿潜力。  相似文献   

6.
作者通过对 3个重要的斑岩铜矿带的综合研究和对比分析发现 ,最具成矿潜力的含矿斑岩不是典型的岛弧岩浆岩 ,而是一种高SiO2 〔w(SiO2 ) >5 6 %〕、高Al2 O3〔w(Al2 O3) >15 %〕、富Sr(多数wSr>40 0× 10 -6)、低Y(多数wY<16× 10 -6)的岩石 ,具有埃达克岩地球化学特征 ,显示埃达克岩岩浆亲合性。含矿的长英质岩浆并非来自地幔楔形区或壳幔过渡带 ,而是来自俯冲的洋壳板片的直接熔融。该俯冲板片熔融前通常变质为含水的榴辉岩。在安第斯弧造山带 ,大洋板块低缓、快速、斜向俯冲 ,诱发洋壳板片直接熔融 ,形成埃达克质熔体 ,后者通过分凝和封闭性演化 ,形成安第斯中新世_上新世巨型斑岩铜矿系统 ;在青藏高原碰撞造山带 ,俯冲并堆积于地幔岩石圈的古老洋壳物质的变质和拆沉 ,诱发榴辉岩部分熔融 ,产生埃达克质熔体 ,并与幔源熔体混合 ,形成西藏冈底斯和玉龙斑岩铜矿系统。  相似文献   

7.
西藏冈底斯中新世斑岩铜矿带:埃达克质斑岩成因与构造控制   总被引:104,自引:26,他引:78  
作为贱金属主要来源的斑岩铜矿床,大多数产出于大陆边缘和岛弧环境。普遍认为,被俯冲洋壳板片释放流体交代的地幔楔部分熔融形成的玄武质岩浆,在相对封闭系统结晶分异和/或同化混染形成含铜长英质岩浆。然而,我们的研究表明,在西藏碰撞造山带,发育一条具有巨大成矿潜力的中新世斑岩铜矿带,含铜斑岩具有埃达克岩地球化学特性,来源于被加厚的藏南镁铁质下地壳,但俯冲的新特提斯洋壳板片部分熔融也不能完全被排除。斑岩铜矿形成于陆-陆后碰撞伸展时期(13~18Ma),即青藏高原迅速抬升之后。横切碰撞造山带的南北向正断层系统,类似于岛弧环境下的横切弧的断层系统,成为埃达克质斑岩岩浆快速上升和就位的通道与场所,并使岩浆热液系统中大量的含矿流体充分地分离而成矿。  相似文献   

8.
土屋-延东铜钼矿田与成矿有关问题的讨论   总被引:55,自引:6,他引:49       下载免费PDF全文
为查明新疆土屋-延东铜矿的围岩地层时代、成矿时代和成矿环境等问题,文章通过野外调查、岩矿鉴定、古生物化石鉴定和同位素年代学等方面的研究,提出围岩地层为石炭系而不是泥盆系;锆石SHRIMP定年结果表明334.6~320Ma为围岩火山岩的形成时代,另外还有两期岩浆活动(434~426Ma和260Ma);含矿直接围岩主要是斜长花岗斑岩而不是闪长玢岩;矿田隶属觉罗塔格构造-成矿带而不是哈尔里克带;矿田内斑岩类以及矿带中的石炭纪花岗岩类具埃达克岩特征,表明区域上具良好的斑岩铜矿成矿远景。  相似文献   

9.
东天山土屋特大型斑岩铜矿成矿地质特征与矿床对比   总被引:25,自引:1,他引:24  
土屋特大型斑岩铜矿位于东天山吐鲁番-哈密陆块南部边缘岛弧环境中。多期岩浆活动和矿化是铜金属超常堆集的主要因素。海底火山活动和热泉沸腾逸散造就了铜金属的预富集(矿源层),闪长玢岩和斜长花岗斑岩的侵位和叠加矿化使铜金属进一步富化和最终成矿,以细碧角斑质为主的火山岩喷发于潮坪-滨海环境,闪长玢岩、斜长花岗斑岩形成于较强的氧化环境;强还原示踪矿物黄铁矿含量较少。矿石的低品位、矿石的结构构造、蚀变特征以及矿石建造具典型斑岩矿床特征;矿石高品位、矿床形成较低温度及大量硅化蚀变又表现为某些热液矿床特征(次火山岩热液)。典型斑岩铜矿床、次火山热液矿床、土屋铜矿床对比,土屋铜矿床矿床类型仍不失为斑岩型铜矿,并具有自身特征。  相似文献   

10.
青海省兴海县赛什塘铜矿的斑岩型矿化特征及其找矿前景   总被引:3,自引:0,他引:3  
青海省兴海县赛什塘铜矿床中局部具斑岩型矿化的特征,该矿区中酸性侵入岩发育并具明显的多期次和多类型.该类铜矿化发生于中-酸性岩浆侵入活动末期的闪长玢岩、花岗闪长斑岩、斜长花岗斑岩、石英斑岩、爆破角砾岩中,围岩蚀变强烈且具分带性.加强对蚀变闪长玢岩、花岗闪长斑岩、斜长花岗斑岩、石英斑岩、爆破角砾岩发育地段的找矿工作,有望实现本区找矿新突破.  相似文献   

11.
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.  相似文献   

12.
Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.  相似文献   

13.
Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ1 roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).  相似文献   

14.
Robert L. Linnen   《Lithos》2005,80(1-4):267-280
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H2O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H2O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.  相似文献   

15.
PALEOZOOLOGY     
正20140968Chen Xiaohong(Northeastern University,Shenyang 110819,China);Gong Enpu The Basic Characteristics of Early Carboniferous Coral Reef at Xiadong Village in Tianlin,Guangxi,and Its Sedimentary Environment(Acta Geologica Sinica,ISSN0001-5717,  相似文献   

16.
正20140985Chen Liang(Post-Doctoral Research Station of Mining Engineering,School of Nuclear Resources and Nuclear Fuel Engineering,University of South China,Heng-yang 421001,China);Huang Wei Composition of Major and Correlated Elements with Organic Matters and Paleoclimatic Implication for Lower Paleogene Sediments in Sanshui Basin  相似文献   

17.
正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-  相似文献   

18.
MINERALOGY     
正20141362 Chen Juan(Laboratory for High Temperature and High Pressure Study of the Earth’s Interior,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550002,China);Li Heping Progress in Major Element and Trace Element Analysis of Sulfide Minerals(Acta Mineralogica Sinica,ISSN1000-4734,CN52-1045/P,33(3),2013,p.351-362,5 illus.,4 tables,20 refs.)  相似文献   

19.
正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),  相似文献   

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正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)  相似文献   

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