Skarn Mineral and Stable Isotopic Characteristics of Tonglushan Cu-Fe Deposit in Hubei Province     

ZHAO Haijie  XIE Guiqing  WEI Ketao  KE Yufu 《地质论评》2012,58(2)

湖北大冶铜绿山铜铁矿床是长江中下游西段鄂东南矿集区一个大型夕卡岩矿床.围岩为三叠系大理岩及白云质大理岩,决定了其发育丰富的钙镁质复合夕卡岩矿物组合,包括石榴子石、辉石、角闪石、绿帘石、金云母、绿泥石等.本文详细描述了夕卡岩不同阶段矿物的特征,并对矿物进行了电子探针分析(EPMA)及碳、氧、硫稳定同位素研究.结果表明石榴子石形成于三期,成分上属于钙铝—钙铁系列,且从早到晚具有从钙铝向钙铁榴石演化趋势,反映出成矿溶液由酸性向碱性演化.环带结构的石榴子石和绿帘石从核部到边部Fe含量增高,说明磁铁矿是在Fe浓度升高的碱性溶液中沉淀.辉石为透辉石.角闪石属于单斜角闪石中的钙质角闪石,包括透闪石,韭闪石和少量阳起石.矿物成分分析表明辉石和石榴子石的Mn/Fe值与矿化金属元素存在一定的联系.相对于钙质夕卡岩,镁质或含镁质夕卡岩是铜铁矿体交代的更有利岩石.矿床硫化物的δ34 SV-CDT均为正值且变化范围较窄,介于0.6‰～3.8‰.成矿阶段方解石δ13CV-PDB变化于-2.9‰～6.3‰,δ18OV-SMOW变化于9.6‰ ～ 12.6‰,成矿后方解石的同位素值明显增大,δ13CV-PDB为-0.9‰ ～ 1.3‰,δ18OV-SMOW为15.2‰ ～ 17.3‰,趋向于围岩的同位素值.研究结果说明成矿阶段的硫和碳来自于深源或地幔,而成矿后期碳与地层发生明显的同位素交换反应.  相似文献   

辽西河坎子碱性侵入杂岩体及钼多金属矿床同位素年代学研究   总被引：2，自引：1，他引：1  

刘勇  聂凤军  方俊钦 《矿床地质》2012,31(6):1326-1336

对辽西河坎子地区与碱性杂岩体相关的钼多金属矿床进行了同位素年代学研究。所获黑云母正长花岗岩锆石LA-ICP-MS U-Pb同位素加权平均年龄为(235.3±1.0) Ma,MSWD值为0.68;河坎子钼多金属矿床内辉钼矿的Re-Os同位素等时线年龄为(224.0±1.3) Ma,MSWD值为0.72。碱性杂岩体与相关的钼多金属矿床具有密切的空间关系,两者的形成时间亦比较接近,据此可推测,河坎子碱性杂岩体与相关的钼多金属矿床均为印支期构造-岩浆作用及流体活动的产物。印支期内频繁的岩浆-热液活动为该地区内钼、铜、金多金属元素的活化、迁移、富集提供了充足的热源条件。古大陆内部伸展构造环境中的碱性岩浆作用及流体活动为钼多金属矿床的形成提供了动力、物质和流体来源。  相似文献   

黑龙江省东宁县金厂金矿石英和闪锌矿激光⁴⁰Ar-³⁹Ar法年龄及其找矿意义     

卿敏  唐明国  肖力  赵玉锁  韩先菊 《地质与勘探》2012,48(5):991-999

黑龙江省东宁县金厂金矿是滨太平洋成矿域浅成低温-斑岩成矿系统中极具代表性的特大型金矿床。矿区已发现爆破角砾岩筒型、环状一放射状裂隙充填型、似层状微细脉浸染型和断控构造破碎带蚀变岩型等矿化类型。为确定成矿时间,作者应用高精度单颗粒激光熔蚀氩氩法,选择Ⅻ号破碎带蚀变岩型矿体中多金属硫化物一石英脉中石英和J-9号爆破角砾岩筒型矿体中闪锌矿进行年龄测定。获得Ⅻ号矿体石英40Ar/39Ar等时线年龄为119±5Ma（MSWD：6．3）,J-9号矿体闪锌矿40Ar/39Ar等时线年龄为129±0．8Ma（MSWD=3．7）,限定了成矿作用的上限。结合最新获得的相关成矿地质体精细年代学成果,进一步认定金厂金矿成矿时代为燕山晚期,成矿与同时代闪长玢岩一花岗闪长斑岩关系密切。金厂金矿成岩、成矿环境具备寻找富金斑岩型铜矿的有利条件,与成矿关系密切侵入岩呈岩脉、岩枝状,指示矿区剥蚀程度浅,深部还有发现斑岩型Au（cu）矿化的可能。  相似文献   

东准噶尔西缘晚古生代火山岩的锆石U-Pb年龄和Hf同位素特征及构造意义          下载免费PDF全文

史基安  唐相路  张顺存  张宏福  肖燕 《地质科学》2012,(4):955-979

白碱沟和帐篷沟剖面位于东准噶尔西缘,出露有大量古生代火山岩,是研究东准噶尔古生代火山岩及构造演化的有利区域.本文利用LA-MC-ICP-MS锆石U-Pb定年法和Hf同位素系统对该区中的玄武岩、玄武质安山岩、流纹岩、角斑岩以及少量的凝灰岩和正长斑岩进行了地质年代学研究,认为它们形成于早泥盆世至晚石炭世之间(400～307...  相似文献   

Zircon ages and Hf isotopic compositions of Permian and Triassic A-type granites from central Inner Mongolia and their significance for late Palaeozoic and early Mesozoic evolution of the Central Asian Orogenic Belt     

《International Geology Review》2012,54(8):967-982

ABSTRACT

This work presents zircon ages and Hf-in-zircon isotopic data for Permian and Triassic A-type granitoids and reviews the evolution of central Inner Mongolia, China, during the early Permian and Late Triassic. SHRIMP U–Pb dating of zircons of peralkaline granites yielded ²⁰⁶Pb/²³⁸U ages of 294 ± 4 Ma and 293 ± 9 Ma that reflect the time of Permian magmatism. Zircon ages were also obtained for Late Triassic granites (226 ± 4 Ma, 224 ± 4 Ma). Our results, in combination with published zircon ages and geochemical data, document distinct magmatic episodes in central Inner Mongolia.

The Permian peralkaline granites show typical geochemical features of A-type granites, which also have highly positive zircon ε_Hf(t) values (+4.9 – +17.1), indicating a significant contribution of an isotopically depleted source, likely formed from mantle-derived magmas. Late Triassic A-type granitoids, however, in central Inner Mongolia show large variations and mostly positive in zircon ε_Hf(t) values (?1.3 – +13.5), suggesting derivation from a mixture of crust and mantle or metasomatized lithospheric mantle with crustal contamination. The geochemical characteristics of the Permian peralkaline granites and Late Triassic A-type granitoids are consistent with a post-collisional setting and were likely related to asthenosphere upwelling during the evolution of the Northern Block and Central Asian Orogenic Belt (CAOB).  相似文献   

Detrital zircon ages and Hf isotopic compositions of metasedimentary rocks in the Wuqia area of Southwest Tianshan,NW China: implications for the early Paleozoic tectonic evolution of the Tianshan orogenic belt     

《International Geology Review》2012,54(16):2036-2056

ABSTRACT

The Chinese Southwest Tianshan Orogenic Belt is located along the boundary between the Central Asian Orogenic Belt (CAOB) and the Tarim Block (TB), NW China. It records the convergence of the Tarim Block and the Middle Tianshan, and is, therefore, a crucial region for understanding the Eurasia continental growth and evolution. The Wulagen (geographical name) metasedimentary rocks of the Wuqia area (mainly metamorphic sandstones and mica schists) form one of the metamorphic terranes in the Southwestern Tianshan Orogenic Belt. The geochronology of these rocks is poorly known, which hampers our understanding of the tectonic evolution of the belt. We analyzed 517 zircon grains for detrital zircon U–Pb dating and 93 zircon grains for in situ Lu–Hf isotopic compositions from the Wulagen metasedimentary rocks. The analyzed zircon grains yield Neoarchean to late Paleozoic U–Pb ages with major age peaks at ~2543 Ma, 1814 Ma, 830 Ma, 460 Ma, and the youngest cluster of zircon (magmatogene) ages is 395 Ma. The zircon U–Pb data show that the late Paleozoic (Early Devonian) is the maximum depositional age of the Wulagen metasedimentary rocks, rather than the previously considered Precambrian period. The zircons with Paleozoic ages yield εHf(t) values of ?22.0 to +11.3 and two-stage model ages (TDM₂) of 3.95 to 1.30 Ga, suggesting that the parental magmas were formed from partial melting of pre-existing crustal rocks. Our zircon U–Pb geochronology and Hf isotopic data indicate the major source regions for the Wulagen metasedimentary rocks was the Kyrgyzstan North Tianshan. The zircon age population of 600–400 Ma (peak at ~460 Ma) has negative εHf(t) values (?15.0 to ?0.6) and Mesoproterozoic two-stage model ages, suggesting that the early Paleozoic magmatism resulted mainly from the melting of ancient crust, which played an important role in crustal evolution in the southern CAOB.  相似文献   

澜沧江南带三叠纪火山岩岩石学、地球化学特征、Ar-Ar年代学研究及其构造意义   总被引：5，自引：3，他引：2  

王硕  董国臣  莫宣学  赵志丹  朱弟成  孔会磊  王霞  聂飞 《岩石学报》2012,28(4):1148-1162

滇西三江地区澜沧江南带广泛发育三叠纪火山岩。在北部云县一带,中晚三叠世火山岩出露齐全,自下而上可划分为中三叠统忙怀组(T₂m),上三叠统小定西组(T₃x)和上三叠统芒汇河组(T₃mh)。忙怀组以酸性火山岩为主,为一套流纹岩夹火山碎屑岩组合;小定西组发育为中基性火山熔岩夹火山碎屑岩;芒汇河组具有流纹质火山碎屑岩与玄武岩共存的"双峰式"火山岩特征。地球化学特征表明,南澜沧江带三叠纪火山岩具有弧火山岩与大陆板内火山岩的双重属性,推测其形成环境为过渡型的大陆边缘造山带环境。对南澜沧江带南部景洪附近采集到的石英安山岩样品进行Ar-Ar年龄测试,得到的坪年龄为236.7±2.2Ma,为中三叠世。结合火山岩年代学结果,推测澜沧江洋主碰撞期为早三叠世,中三叠世与晚三叠世早期分别为碰撞后的应力松弛阶段与洋盆继续俯冲期,到晚三叠世末期,俯冲作用结束,澜沧江洋关闭。  相似文献   

西天山CuNi-VTiFe复合型矿化镁铁-超镁铁杂岩 ——哈拉达拉岩体成岩成矿背景特殊性讨论   总被引：6，自引：4，他引：2  

龙灵利  王玉往  唐萍芝  王莉娟  王京彬  廖震 《岩石学报》2012,28(7):2015-2028

西天山哈拉达拉镁铁-超镁铁杂岩为一CuNi-VTiFe复合型矿化岩体,主要由橄长岩、橄榄辉长岩、角闪辉长岩、辉长岩和辉绿岩组成。获得岩体中橄榄辉长岩SHRIMP锆石U-Pb年龄为308.8±1.9Ma,辉长岩SHRIMP锆石U-Pb年龄307.3±8.2Ma。岩石具堆晶结构、辉长-辉绿结构,岩体韵律层发育;各类岩石稀土和微量元素配分曲线模式相似,多具Eu,Sr正异常,它们可能为同一岩浆结晶分异演化的产物;Sr-Nd同位素特征(87Sr/86Sr初始比值=0.703913～0.705259,εNd(t)=4.00～8.42)表明原始岩浆来自于亏损地幔源区。推测哈拉达拉岩体形成于后碰撞造山早期伸展环境、叠加近同期地幔柱活动的特殊地质背景中。  相似文献   

新疆准噶尔北缘玉勒肯哈腊苏斑岩铜矿床年代学研究   总被引：7，自引：3，他引：4  

杨富全  张志欣  刘国仁  屈文俊  张立武  魏广智  刘锋  柴凤梅 《岩石学报》2012,28(7):2029-2042

玉勒肯哈腊苏铜矿是近几年准噶尔北缘卡拉先格尔斑岩铜矿带发现的又一个中型斑岩铜矿,其成岩成矿年代学的研究可以对矿床模型构建、区域成矿规律的总结提供制约。矿区侵入岩发育,矿化主要受闪长玢岩控制,少部分赋存在似斑状黑云母石英二长岩和北塔山组火山岩、火山碎屑岩中。本文利用锆石LA-ICP-MSU-Pb法和辉钼矿Re-Os法对矿区岩体和矿化进行了成岩成矿年代学研究。结合前人的研究,认为矿区存在5次主要岩浆侵入事件:382Ma石英闪长岩侵入,379Ma形成含矿闪长玢岩,375～374Ma形成似斑状黑云石英二长岩,348Ma形成黑云母石英斑岩脉,266Ma形成二长斑岩,前三次岩浆侵入活动对应构造环境为板块俯冲阶段,后二次岩浆侵入活动为后碰撞阶段。9件辉钼矿样品Re-Os同位素等时线年龄为373.9±2.2Ma,表明铜钼成矿时代为中泥盆世晚期,与闪长玢岩侵入有关。  相似文献   

阿尔金山喀腊大湾地区中酸性侵入岩SHRIMP年龄及其意义   总被引：11，自引：5，他引：6  

韩凤彬  陈柏林  崔玲玲  王世新  陈正乐  蒋荣宝  李丽  祁万修 《岩石学报》2012,28(7):2277-2291

阿尔金山东段喀腊大湾地区位于北东向阿尔金走滑断裂北侧与东西向阿尔金北缘断裂所夹持的区域,该区广泛发育中酸性侵入岩,前人将其确定为晚古生代。本文运用锆石SHRIMPU-Pb方法对该区的中酸性侵入岩进行测年,获得413～514Ma的年龄,确认喀腊大湾地区早古生代岩浆活动的存在。结合前人其他方法测年数据和红柳沟一带(喀腊大湾以西180km)中酸性侵入岩的SHRIMP测年资料和蛇绿岩的时代,将阿尔金山东段喀腊大湾地区中酸性岩浆活动划分为碰撞前岩浆活动(520～500Ma)、碰撞期岩浆活动(490～470Ma)和碰撞后岩浆活动(440～410Ma)三个阶段。  相似文献