西藏冈底斯带侏罗纪岩浆作用的时空分布 及构造环境   总被引：40，自引：6，他引：34  

朱弟成  潘桂棠  王立全  莫宣学  赵志丹  周长勇  廖忠礼  董国臣  袁四化 《地质通报》2008,27(4):458-468

在新近完成的1：25万区域地质调查资料和相关研究成果的基础上,初步研究了西藏冈底斯带侏罗纪岩浆作用的分布特点及其年代学,并利用已有的地球化学数据重点分析了早期关注程度较低的侏罗纪花岗岩类岩浆作用的性质。目前在冈底斯弧背断隆带未发现侏罗纪火山岩;在冈底斯东部地区,早侏罗世岩浆活动几乎同时发生于南冈底斯（叶巴组火山岩和鸟郁、尼木花岗岩类）、冈底斯弧背断隆带（宁中、金达、布久花岗岩类）和北冈底斯（聂荣花岗岩类）,中晚侏罗世接奴群和拉贡塘组火山岩断续分布于北冈底斯,晚侏罗世岩浆活动零星分布于沙莫勒一麦拉一洛巴堆～米拉山断裂以北。将冈底斯侏罗纪岩浆活动置于时空框架内分析发现,南冈底斯和北冈底斯在侏罗纪时主要受俯冲作用的影响．而冈底斯弧背断隆带和中冈底斯自早侏罗世以来除了受到俯冲作用的影响外,还受到自东向西逐步扩展的碰撞作用的影响。结合古地磁重建资料和其他新发现．认为冈底斯带侏罗纪这种岩浆活动的特点可用班公湖一怒江洋壳向南、新特提斯洋壳向北的双向剪刀式（剪刀口向西张开）俯冲模式来解释。  相似文献   

Geochemistry and Origin of Ananai Stratiform Manganese Deposit in the Northern Chichibu Belt, Central Shikoku, Japan     

Koichiro Fujinaga    Tatsuo Nozaki  Takazumi Nishiuchi  Kiyoko Kuwahara  Asuhiro Kato 《Resource Geology》2006,56(4):399-414

Abstract. Major and trace element contents are reported for Permian manganese ore and associated greenstone from the Ananai manganese deposit in the Northern Chichibu Belt, central Shikoku, Japan. The manganese deposit occurs between greenstone and red chert, or among red chert beds. Chemical compositions of manganese ore are characterized by enrichments in Mn, Ca, P, Co, Ni, Zn, Sr and Ba, and negative Ce and positive Eu anomalies relative to post-Archean average Australian Shale (PAAS). Geochemical features of the manganese ore are similar to those of modern submarine hydrother-mal manganese deposits from volcanic arc or hotspot setting. In addition, geochemical characteristics of the greenstone closely associated with the Ananai manganese deposit are analogous to those of with-in plate alkaline basalt (WPA). Consequently, the Ananai manganese deposit was most likely formed by hydrothermal activity related to hotspot volcanism in the Panthalassa Ocean during the Middle Permian. This is the first report documenting the terrestrially-exposed manganese deposit that was a submarine precipitate at hotspot.  相似文献   

Lermontovskoe Tungsten Skarn Deposit: the Oldest Mineralization in the Sikhote-Alin Orogen, Far East Russia     

Kohei Sato    Sergei M. Rodionov  Anatoly A. Brublevsky 《Resource Geology》2006,56(3):257-266

Abstract. Lermontovskoe tungsten skarn deposit in central Sikhote-Alin is concluded to have formed at 132 Ma in the Early Cretaceous, based on K-Ar age data for muscovite concentrates from high-grade scheelite ore and greisenized granite. Late Paleozoic limestone in Jurassic - early Early Cretaceous accretionary complexes was replaced during hydrothermal activity related to the Lermontovskoe granodiorite stock of reduced type. The ores, characterized by Mo-poor scheelite and Fe^3+- poor mineral assemblages, indicate that this deposit is a reduced-type tungsten skarn (Sato, 1980, 1982), in accordance with the reduced nature of the granodiorite stock.
The Lermontovskoe deposit, the oldest mineralization so far known in the Sikhote-Alin orogen, formed in the initial stage of Early Cretaceous felsic magmatism. The magmatism began shortly after the accretionary tectonics ceased, suggesting an abrupt change of subduction system. Style of the Early Cretaceous magmatism and mineralization is significantly different between central Sikhote-Alin and Northeast Japan; reduced-type and oxidized-type, respectively. The different styles may reflect different tectonic environments; compressional and extensional, respectively. These two areas, which were closer together before the opening of the Japan Sea in the Miocene, may have been juxtaposed under a transpressional tectonic regime after the magmatism.  相似文献   

Comment on 'Chemical remagnetization of the Upper Carboniferous–Lower Triassic Pyeongan Supergroup in the Jeongseon area, Korea: fluid migration through the Ogcheon Fold Belt' by Y.H. Park, S.-J. Doh and D. Suk     

Youngdo Park  Jin-Han Ree 《Geophysical Journal International》2006,164(3):481-483

  相似文献   

藏南地区金和锑矿床(点)类型及其时空分布特征   总被引：37，自引：5，他引：37       下载免费PDF全文

聂凤军  胡朋  江思宏  李振清  刘妍  周永章 《地质学报》2005,79(3):373-385

本文首次对藏南地区金和锑矿床(点)地质特征、成因类型和空间分布特点进行了总结，对金和锑成矿作用与中新生代构造一岩浆活动的关系进行了论证，对区域地壳演化过程中金和锑成矿动力学机制进行了讨论。该区的金和锑矿床(点)可按容矿围岩划分为：①变质岩为主要容矿围岩矿床(点)，包括金和金一锑矿床(点)；②沉积岩为主要容矿围岩矿床(点)，包括金、锑、金一锑和锑多金属矿床(点)；③火山岩为主要容矿围岩矿床(点)，以金一银矿床为代表。根据金和锑矿床(点)空间分布特点和地质特点，将本区划分为4个矿化集中区：拉昂错一马攸木一帕羊金矿化集中区(A)，然勒金和锑矿化集中区(B)，洛扎一措美锑矿化集中区(C)和邛多江金一锑矿化集中区(D)。各矿化集中区内大多数金和锑矿床(点)与燕山晚期～喜马拉雅早期富碱火成岩具密切时空分布关系，它们是古板块对接碰撞期和碰撞期后大规模构造一岩浆活动的产物。近东西向挤压性和南北向张性断裂交汇部位以及富碱火成岩发育区是寻找金和锑矿床(点)的有利场所。  相似文献   

攀枝花地区基性-碱性岩系Th、Ta、Hf地球化学特征     

刘峰  张成江  汪云亮  施泽明 《物探化探计算技术》2005,27(1):43-47

攀枝花地区的基性—碱性岩系,是一套与钒钛磁铁矿、稀土矿、铍、钪、镓等多种矿产有关的含矿岩浆岩系。该岩系的Th、Ta、Hf地球化学特征极为相似,其Th/Hf比值在0.3～1.0之间,Ta/Hf比值更为接近,在0.2～0.5之间。在Th/Hf-Ta/Hf双对数图上,该岩系的源区特征和演化特征非常明显。此结果与峨嵋山地区的玄武岩和会东地区的基性岩系对比,Th、Ta、Hf特征都十分相近,因此该区原来被认为是两个地质时期(华力西期与印支期)的岩系,实际上是同一地质时期(华力西晚期)同源但不同阶段的产物,均是与峨嵋地幔柱关系密切的峨嵋玄武岩浆演化的结果。  相似文献   

中国大陆科学钻探工程主孔（734～933m）榴辉岩和片麻岩元素及Sr-Nd同位素地球化学研究   总被引：15，自引：6，他引：15  

赵子福  郑永飞陈斌 吴元保 《岩石学报》2005,21(2):325-338

对中国大陆科学钻探工程主孔两段榴辉岩与片麻岩互层的岩芯样品(Ⅰ:734.21-737.16m和Ⅱ:929.67-932.86m)分别进行了主要元素和微量元素以及Sr-Nd同位素分析。结果表明:(1)榴辉岩具有较大的成分变化范围(SiO2含量为46.8%-59.8%),表现出平坦或轻稀土(LREE)富集的分布模式和大离子亲石元素(LILE)富集或亏损以及Nb、Ta负异常特征。部分榴辉岩样品具有明显低的活动性元素(Rb、Ba和K)含量,指示了板块俯冲过程中的脱水变质效应;(2)两段岩芯中的片麻岩具有明显不同的主量和微量元素组成,其中第Ⅰ段具有相对较低的SiO2含量(61.3%～66.2%)和高的重稀土(HREE)含量,而第Ⅱ段具有明显偏高的SiO2含量(73.8%～74.1%)和低的HREE含量。但两段均表现出LREE富集和Eu负异常以及LILE富集和高场强元素(Nb、Ta、Ti)负异常特征;(3)榴辉岩和第Ⅰ段岩芯中的片麻岩具有相近的且偏高的εNd(750Ma)值(-3.6- 0.5),而第Ⅱ段岩芯中的片麻岩具有明显偏低的εNd(750Ma)值(-8.7)。部分片麻岩样品表现出较高的87Sr/86Sr比值(0.7070)和非常低的Rb/Sr比值(0.008),指示岩石Rb-Sr同位素体系受到了变质扰动。非活动性元素如Zr、Hf、Nb、Ta、Ti、Y、REE和Ti在脱水变质过程中没有受到明显扰动,因此可用于恢复榴辉岩和片麻岩的原岩性质及其形成的大地构造背景。根据分析样品的元素和Nd同位素特点,推测榴辉岩原岩具有板内玄武岩性质,第Ⅰ段岩芯中的片麻岩原岩为玄武质岩浆上升过程中同化地壳物质形成的中性岩,而第Ⅱ段岩芯中的片麻岩原岩为地壳物质重熔形成的酸性岩。因此,深钻榴辉岩和片麻岩原岩为新元古代华南陆块北缘裂谷构造带双峰式岩浆活动的产物,在岩浆侵位过程中经历了高温大气降水热液蚀变。  相似文献   

河北矾山燕山期侵入岩地球化学特征及成因   总被引：8，自引：0，他引：8  

王强  许继锋  赵振华  王人镜  熊小林 《矿物学报》2002,22(2):160-168

河北矾山地区燕山期侵入岩可分为早、晚两期。早期（中侏罗世-晚侏罗世）侵入岩主要由二长闪长岩、石英二长闪长岩、石英二长岩、正长岩构成，以高钾钙碱性岩系列岩石为主；SiO2=53.58%-60.57%,Al2O3=16.16%-17.23%,Na2O K2O=5.76%-8.96%,K2O=2.25%-4.55%,Na2O/K2O=1.14-1.56;ACNK=0.72-0.86,NKA=0.47-0.77;Eu^*/Eu=0.80-0.95,轻稀土富集，重稀土和Nb、Ta、Hf、Ti亏损，相对低Zr、Rb和Rb/Sr，但高Sr和Sr/Y，具有埃达史质岩石质岩石的部分特征。晚期（白垩纪）侵入岩由碱长石英正长岩、石英正长岩、石英二长岩、碱工花岗岩、钾长花岗岩构成，以钾玄岩系列岩石为主；比早期岩石富SiO2，低Al2O3、富Na2O K2O和K2O，但低Na2O/K2O;ACNK=0.82-1.07,NKA=0.77-0.92;Eu^*/Eu=0.65-1.00，轻稀土富集，重稀土和Nb、Ta、Hf、Ti亏损，相对高Zr、Rb和Rb/Sr，但低Sr和Sr/Y。矾山地区早期侵入岩的形成可能与伊泽奈崎（Izanaqi)板块向欧亚大陆板块的俯冲所导致的挤压增厚有关；晚期侵入岩可能形成于拉张环境中。  相似文献   

Slab breakoff: a model for Caledonian, Late Granite syn-collisional magmatism in the orthotectonic (metamorphic) zone of Scotland and Donegal, Ireland   总被引：12，自引：0，他引：12  

M. P. Atherton  A. A. Ghani 《Lithos》2002,62(3-4):65-85

None of the existing models for calc-alkaline “Late Granite” (Siluro–Devonian) genesis in the metamorphic Caledonian orogenic belt of Ireland and Scotland fully explains their spatial, age or chemical character. A consistent model must involve the closure of Iapetus Ocean, where slab breakoff is a natural consequence of attempted subduction of continental crust. Expected outcome is a long linear belt of high-K, calc-alkaline magmas, some with characteristic trace element signatures, specifically high Ba, Sr and Zr. Other features include the critical magmatic association of coeval appinite and granite, rapid uplift, erosion and the low-grade regional metamorphism in the Southern Uplands. The linear heat pulse on breakoff is spatially, intensity and time limited producing small volume melts emplaced as separated plutons, over a short time span. Magmatism in the Caledonian metamorphic belt is accurately accounted for by slab breakoff on collision of Baltica with the Scoto–Greenland margin during the Scandian orogeny, following Iapetus Ocean closure. The two chemically, isotopically and areally distinctive suites in the metamorphic belt in Scotland, viz. the Argyll and Cairngorm Suites, can be modelled by reference to the Donegal granites where sequential partial melting of new, lamprophyric underplated crust, then shallower old crust, as heat conduction moved up through the crust on slab breakoff, produced magmas characteristic of the two suites.  相似文献   

Three Alkali-Rich Intrusive Rock Belts Newly Discovered in the Mt. Kunlun-Mt. Altun Region, Xinjiang, China   总被引：1，自引：0，他引：1  

朱笑青  王元龙  毕华  王中刚 《中国地球化学学报》2002,21(3)

The newly discovered three alkali-rich intrusive rock belts in the Mt. Kunlun Mt.Altun region of southern Xinjiang are the Lapeiquan-Yitunbulak alkali-rich intrusive rock belt,the Gez-Taxkorgan alkali-rich intrusive rock belt and the Beilisai-Abulash alkali-rich intrusive rock belt. The former two belts were formed during the Yanshanian period, and the third one was formed during the Himalayan period, which is the youngest alkali-rich intrusive rock belt in China. The discovery of the alkali-rich intrusive rock belts is of great significance in shedding light on the history of tectono-magmatic activities in this region.  相似文献