香炉碗子金矿床稳定同位素研究及矿床成因探讨     

李长顺  于文卿 《黄金地质》1996,2(2):50-55

香炉碗子金矿床产于脆一韧性剪切带内，控矿围岩为火山隐爆角砾岩体，通过硫，铅，氢，氧，碳，锶等同位素及稀土元素的研究可以看出，该矿床是一个中，低温有大气水参与火山热液型金矿床，其火山岩岩浆属太古宙结晶基底重熔再造，壳幔混合型。  相似文献   

陆相火山岩铜矿床成矿条件研究   总被引：1，自引：1，他引：1  

胡正纲 《四川地质学报》1996,(1)

研究陆相火山岩铜矿床的成矿条件，对于多发现新的铜矿资源有着重要的意义。本文就陆相火山岩型铜矿床的实际存在，大陆玄武岩型铜矿的成矿系列，大陆裂谷的成矿环境和热液成矿作用等方面进行讨论。  相似文献   

北祁连造山带东段白银地区的构造单元划分及韧性变形   总被引：15，自引：0，他引：15  

张建新  许志琴 《高校地质学报》1996,2(2):146-154

北祁连造山带东段的白银地区可划分出四个构造单元（Ｂ１、Ｂ２、Ｂ３和Ｂ４）：Ｂ１属于中宫变质地块，Ｂ２为古祁洋在俯冲过程中形成的增生杂岩，Ｂ３属于加里东期的古火山岛弧Ｂ４为弧后残余海盆。本区存在两期韧性变形，和线期韧性变形以形成近垂直于造山带的ＮＥ－ＳＷ向拉伸线理为特征，剪切标志显示其主要为一系列从Ｎ－Ｓ的逆冲叠覆构造２，与古祁连洋向北的俯冲作用有关，第二期韧性变形形成四条韧性平移剪切带（ＳＺ１、Ｓ  相似文献   

NW断裂构造──鹅公山火山盆地铀矿成矿的关键要素     

张万良 《铀矿地质》1996,(2)

鹅公山火山盆地受郯庐断裂系影响，ＮＷ断裂构造尤为特色：张扭性，倾向ＮＥ，右行下滑，对盆地中３个铀矿床及绝大多数铀矿（化）点具明显控制作用，是铀矿成矿的关键要素。研究ＮＷ断裂对在鹅公山火山盆地及其它地区找矿都具有实际意义。  相似文献   

VAMSD矿床系列最基性端员——青德尔尼大型铜钴矿床的地质特征和成因类型   总被引：8，自引：0，他引：8  

王玉往  秦克章 《矿床地质》1997,16(1):1-10

在调查分析德尔尼Ｃｕ－Ｃｏ矿床地质特征的基础上，结合矿床剖面，针对矿区容矿蛇纹岩类进行了系统的岩矿鉴定和地球化学研究，确定矿区广泛发育的各类蛇纹岩基原岩主要为超基性角砾集块岩、凝灰岩等火山岩类。将德尔尼型Ｃｕ－Ｃｏ矿床作为火山岩块状硫化物矿床系列中的最基性端员明确划分出来具有重要意义。  相似文献   

中国火山岩地区金的成矿环境及分布规律   总被引：5，自引：1，他引：5  

王碧香  杨岳清  史仁灯  银剑钊  石森 《矿床地质》1997,16(1):11-20,40

中国是一个火山岩广泛分布的国家，火山岩区的金矿不论其数量和储量在全国均占有重要地位，根据金和火山活动的关系，可划分出６种金矿类型，它们主要分布在６个火山岩区中，不同地区金的成矿作用各有其特色，总体可概括出７条成矿特征，这对于在我国广阔的火山岩区寻找金矿具有重要的指导意义。  相似文献   

石源龙地区岩浆岩的稀土元素和同位素地球化学     

张萍  王玉生 《矿物岩石》1997,17(2):89-93

本章系统研究石源龙地区流纹质熔结凝灰岩、粒状碎斑熔岩、英安岩、星村中细粒黑云母花岗岩的铷锶同位素地质年龄，并根据锶、氧同位素和稀土元素含量讨论其地质意义  相似文献   

海南同安岭-牛腊岭火山地层划分与对比     

蔡道冠  符国祥 《地质通报》1997,(4)

将同安岭—牛腊岭火山地层划分为六罗村组、汤他大岭组、岭壳村组，总厚度达５４２９ｍ。六罗村组下部以玄武安山质火山岩为主，上部为流纹质火山碎屑岩、熔岩；汤他大岭组主要为英安岩类火山岩，岭壳村组为流纹岩类的岩石，构成２个喷发旋回。根据同位素年龄，确定火山岩的时代为早白垩世，与海南岛下白垩统鹿母湾组为同期产物，相当于我国东南沿海白垩纪火山岩。  相似文献   

A model study on the decay of volcanic aerosol layer and verification with Pinatubo and El Chichon data     

S. Ramachandran  A. Jayaraman  B. R. Sitaram 《Journal of Earth System Science》1997,106(3):157-167

The time evolution of stratospheric aerosol layer formed after a volcanic eruption is studied taking into account the aerosol microphysical processes of growth, coagulation and sedimentation. Using a simple model we could explain the observed evolution of the Pinatubo volcanic layer which decayed in about 3 years. The experimental data obtained by Nd:YAG backscatter lidar over Ahmedabad further supports this finding. The data obtained after the El Chichon volcanic eruption also showed that the El Chichon aerosol layer decayed in about 3 years time. Thus, though the amount of SO₂ injected has been higher, in the case of Pinatubo, about two to three times more than El Chichon, it has resulted in the production of larger aerosol particles due to faster growth and coagulation processes, and subsequently a faster removal rate, to give more or less a similar background aerosol amount at the stratosphere in about 3 years time.  相似文献   

The color of pumice: case study on a trachytic fall deposit, Meidob volcanic field, Sudan   总被引：1，自引：0，他引：1  

H. Paulick  G. Franz 《Bulletin of Volcanology》1997,59(3):171-185

 This paper examines the cause of color variations of trachytic pumices which are essentially uniform in chemical composition and proposes a geological model for their formation. A pyroclastic sequence of distinct subunits with brown, buff, and black pumices was deposited during the 5000-B.P. eruption of a tuff ring in the central Meidob volcanic field (Sudan). Subunits of buff pumices locally contain minor amounts of streaky pumice with pale-gray and dark-gray domains. The combined evidence of petrographic studies, chemical analyses of whole pumices and groundmass separates, electron microprobe analyses, optical spectroscopy, transmission electron microscopy, and magnetic susceptibility measurements show that color variations of the pumice clasts are related to the size and distribution of Fe³⁺-rich oxide microcrysts. Buff pumice and light-gray domains of streaky pumice have a colorless, transparent groundmass with very few microcrysts. Dark-gray domains of streaky pumice contain abundant hematite and/or magnetite microcrysts visible in thin section within a transparent, colorless glass groundmass. The groundmass of the black pumice clasts is brown in thin section which is most likely caused by submicroscopic magnetite microcrysts. Brown pumice clasts have a mixed groundmass consisting of brown domains and domains with opaque microcrysts in transparent glass. Variations in the eruption dynamics have been inferred from lithological observations. Subunits of black pumices are related to eruption pulses with low magma discharge and high water/magma mass ratio, whereas subunits of buff pumice were deposited during eruption pulses with high magma discharge and low water/magma mass ratio. Brown pumices represent the top part of the magma body, and the initial stage of the eruption probably had a low magma discharge. Streaky pumices are interpreted as the product of syn-eruptive mixing of Fe³⁺-rich oxide microcryst-bearing magma and microcryst-free magma. Received: 3 February 1997 / Accepted: 28 July 1997  相似文献