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锡铁山矿床是中国西部的超大型铅锌矿产地之一，产于柴北缘晚奥陶世滩间山群的大理岩和片岩之中，是与海相火山喷流-沉积有关的矿床。很多学者已经从地球化学、岩石学、同位素测年等对该矿床的成矿时代、成矿流体性质、矿床成因等开展了研究，但对于锡铁山矿区构造控矿特征一直存在争议，普遍认为褶皱构造对矿区的控矿作用明显。文章主要以详实的野外观测为基础，分析了矿区的褶皱和断裂构造特征，探讨了构造对矿(床)体的控制作用，为矿区找矿勘查工作部署提供依据。通过详实的野外实测和综合对比分析表明，锡铁山矿区总体上为单斜层，不发育大型的褶皱构造，但是层内褶皱发育，包括A型褶皱和B型褶皱。发育在滩间山群a段内的A型褶皱，其褶皱枢纽与拉伸线理倾向南东，与矿区矿体的总体倾伏方向一致；而在滩间山群d段内的A型褶皱，其枢纽倾向北西；矿区内发育了多条北西西走向的大型断裂，其编号为F1—F6；分析表明，F1断层发育在早期塑性变形基础之上，晚期叠加了叠瓦逆冲推覆作用，造成了矿体及赋矿围岩的局部倒转；F2断裂大规模的左行走滑-逆冲作用导致了矿区滩间山群不同岩性段地质体的拼合接触，造成了矿区部分含矿地质体的缺失；野外填图揭示出，左行走滑的F3断裂从北西往南东，走向从330°逐渐转变为290°方向，并在南东侧末端，发育了一系列分支的左行走滑-正断层，组成"马尾状"构造，截切了矿体与围岩，并发生了横向错移。以此构造控矿特征为基础，结合矿床成因分析，进一步分析了锡铁山矿区深部的找矿方向，认为矿区南东侧深部具有良好的找矿空间；并以07号勘探线为例，根据F3及其分支断层的错移情况，分析了矿体可能被错移的位置。 相似文献
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青海锡铁山矿区滩间山群新认识 总被引：4，自引：0，他引：4
锡铁山滩间山群是重要的含矿火山-沉积建造.基于野外地质特征、古生物组合、同位素年龄、构造-热事件和火山-沉积演化等的综合分析,文章认为滩间山群形成于早-晚奥陶世,并重新厘定了4个(构造-)岩石地层单位.新建层序反映柴北缘早古生代经历了大陆裂谷开合演化过程. 相似文献
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这里主要从成矿地质背景、控矿构造、赋矿火山岩分布、矿床特征等宏观地质现象,结合岩矿石结构的构造与成份等微观特征的深入研究,首次确定了如金沟铜矿区赋矿次火山岩的存在.初步认为其主导矿床成因类型为次火山岩型,在矿区内形成次火山岩型→火山热液型→构造热液型较完整的矿化分带系列. 相似文献
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锡铁山铅锌矿床是我国西北地区大型铅锌矿床之一，但是，有关其成矿时间问题一直缺乏较好约束。本文通过对靠近矿体底部的火山岩LA-ICPMS锆石U-Pb定年，获得了三组锆石U-Pb谐和年龄，分别变化于500～470 Ma, 465～450 Ma和440～420 Ma,形成的三个权重平均年龄分别为(479.4±5.2) Ma,(455.5±6.1) Ma和(431.8±3.7) Ma。结合区域滩间山群成岩构造环境及矿床成矿构造背景，文章认为前两组权重平均年龄代表了早古生代滩间山群两期强烈火山作用的峰期年龄，其年龄跨度(500～455 Ma)代表了滩间山群岛弧火山作用的时间跨度。第三组权重平均年龄代表了滩间山群火山岩成岩之后区域造山事件的主期变质年龄。锡铁山海底喷流沉积成矿合理时间应在455 Ma左右。 相似文献
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青海锡铁山块状硫化物矿床的类型及地质特征 总被引：14，自引：0，他引：14
锡铁山铅锌矿床是我国大型块状硫化物矿床之一。本文系统地阐述了锡铁山矿床成矿的区域地质背景、含矿绿岩系和矿床地质特征,以及矿床的成因与类型。通过对柴达木北缘绿岩系区域构造、火山岩地质及成矿活动的研究,认为该矿床形成于晚奥陶世古裂谷海槽或称裂谷型优地槽环境中。同时,通过对矿体宏观特征、矿石矿物组成和组构、矿石主元素 Zn、Pb、S的变化和伴生 Au、Ag 的赋存状况与分布、稳定同位素、围岩与其蚀变以及成矿时的物理化学条件的综合研究,确定锡铁山矿床属加里东期火山喷气沉积、热液叠加改造型块状硫化物多金属矿床。从而,初步建立了“锡铁山式”矿床的成矿模式。 相似文献
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1 矿区地质概况
锡铁山铅锌矿床位于青海省柴达木盆地北缘,矿体赋存在晚奥陶统滩间山群中,赋矿岩性主要由碎屑沉积岩、薄层-中厚层块状大理岩、含碳绿泥石英绢云片岩及少量中酸性火成岩和火山碎屑岩等组成.邓吉牛等专家研究认为,矿床为SEDEX型成因,成矿作用为双基底式,经历了强烈的变质变形运动. 相似文献
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1 质概况
1.1 区域地质
锡铁山铅锌矿床位于青海省柴达木盆地北缘(图1),我国西部地区重要的成矿区带塞什腾-绿梁山-锡铁山加里东褶皱带岩系中(邬介人等,1987).矿床成因为喷流深积型(SEDEX)(张德全等,2005).矿区构造线方向与区域构造线方向一致,呈北西-南东向展布(邓吉牛,1999;祝新友等,2007)(图2).区内褶皱基底出露在北缘,由元古代的达肯大板群(Pt1dk)的混合岩、片麻岩及片岩等变质岩系组成.矿区内主要出露上奥陶统滩间山群(O3tn)含矿岩系以及上泥盆统(D,a)和下石炭统(C1)砂砾岩系.矿区火山活动较强烈,主要火山喷发物为中基性火山岩-基性凝灰岩、玄武岩夹安山岩和中酸性火山岩一流纹岩及英安岩等. 相似文献
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新疆昆仑式火山岩型块状硫化物铜矿床及成矿地质环境 总被引：7，自引：0，他引：7
新疆西昆仑奥依塔克-恰尔隆拗陷带内阿克塔什-萨落依成矿带发现多处火山岩型块状硫化物铜矿床。这些矿床产在石炭系双峰式火山岩系之内，沿着下石炭统基性火山岩和上石炭统酸性火山岩两个层位产出，分别以玄武岩和流纹岩为容矿主岩，可以明显地分成基性火山岩型和酸性火山岩型两种类型。矿石主成矿元素均以铜为主，含少量的锌，几乎不含铅，矿床类型属于铜型。这些基性火山岩型和酸性火山岩型矿床被统称为昆仑式火山岩型块状硫化物铜矿床。根据矿床产出地质环境、双峰式火山岩系、沉积建造以及火山岩地球化学特征，推断昆仑式火山岩型块状硫化物铜矿床最可能形成于泥盆纪-石炭纪弧后拉张构造环境。 相似文献
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The Xitieshan deposit (~ 64 Mt at 4.86% Zn, 4.16% Pb, 58 g/t Ag, and 0.68 g/t Au) is hosted by the Middle to Late Ordovician Tanjianshan Group of the North Qaidam tectonic metallogenic belt, NW China. This belt is characterized by island arc volcanic, ultra-high pressure (UHP) metamorphic and ophiolitic rocks. The Tanjianshan Group constitutes a succession of metamorphosed bimodal volcanic and sedimentary rocks, which are interpreted to have formed on the margin of a back-arc ocean basin between the Qaidam block and the Qilian block.Four stratigraphic units are identified within the Ordovician Tanjianshan Group. From northeast to southwest they are: 1) unit a, or the lower volcanic-sedimentary rocks, comprising bimodal volcanic rocks (unit a-1) and sedimentary rocks (unit a-2) ranging from carbonates to black carbonaceous schist; 2) unit b, or intermediate-mafic volcaniclastic rocks, characterized by intermediate to mafic volcaniclastic rocks intercalated with lamellar carbonaceous schist and minor marble lenses; 3) unit c, a purplish red sandy conglomerate that unconformably overlies unit b, representing the product of the foreland basin sedimentation during the Early Silurian; 4) unit d, or mafic volcanic rocks, from base to up, comprising the lower mafic volcaniclastic rocks (unit d-1), middle clastic sedimentary rocks (unit d-2), upper mafic volcaniclastic rocks (unit d-3), and uppermost mafic volcanic rocks (unit d-4). Unit a-2 hosts most of the massive sulfides whereas unit b contains subordinate amounts.The massive stratiform lenses constitute most of the Xitieshan deposit with significant amount of semi-massive and irregularly-shaped sulfides and minor amounts in stringer veins. Pyrite, galena and sphalerite are the dominant sulfide minerals, with subordinate pyrrhotite and chalcopyrite. Quartz is a dominant gangue mineral. Sericite, quartz, chlorite, and carbonate alteration of host rocks accompanies the mineralization.U-Pb zircon geochronology yields three ages of 454 Ma, 452 Ma and 451 Ma for the footwall felsic volcanic rocks in unit a-1, sedimentary host rocks in unit a-2 and hanging-wall unit b, respectively. The Xitieshan deposit is considered to be coeval with the sedimentation of unit a-2 and unit b of the Tanjianshan Group. The Xitieshan deposit has been intensely deformed during two phases (main ductile shear and minor ductile-brittle deformation). The main ductile shear deformation controls the general strike of the ore zones, whereas minor deformation controls the internal geometry of the ore bodies. 40Ar-39Ar age of muscovite from mylonitized granitic gneisses in the ductile shear zone is ~ 399 Ma, which is interpreted to date the Xitieshan ductile shear zone, suggesting that Early Devonian metamorphism and deformation post-dated the Tanjianshan Group.The Xitieshan deposit has many features similar to that of the Bathurst district of Canada, the Iberian Pyrite Belt of Spain, the Wolverine volcanogenic massive sulfide deposit in Canada. Based on its tectonic setting, host-rock types, local geologic setting, metal grades, geochronology, temperatures and salinities of mineralizing fluid and source of sulfur, the Xitieshan deposit has features similar to sedimentary exhalative (SEDEX) and VMS deposits and is similar to volcanic and sediment-hosted massive sulfide (VSHMS) deposits. 相似文献
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内蒙朝克山蛇绿岩地球化学: 洋内弧后盆地的产物？ 总被引：8，自引：6，他引：2
朝克山蛇绿岩是内蒙贺根山地区出露最好的蛇绿岩之一,可能形成于中晚石炭世。朝克山蛇绿岩中的基性岩具有LREE亏损、类似N-MORB的稀土配分模式,而相对N-MORB富集大离子亲石元素,亏损Nb、Ta等高场强元素又类似岛弧火山岩的成分特征,因此,我们认为朝克山蛇绿岩应形成于弧后盆地。将朝克山蛇绿岩的基性岩与现代Mariana洋内弧后盆地和Okinawa陆缘弧后盆地的玄武岩及同属中亚造山带的、形成于洋内弧后盆地的新疆库尔提蛇绿岩对比,朝克山蛇绿岩更类似于Mariana玄武岩和库尔提蛇绿岩,因此其很可能形成于洋内弧后盆地而不是大陆边缘弧后盆地环境。 相似文献
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东天山大南湖岛弧带石炭纪岩石地层与构造演化 总被引：5，自引：0，他引：5
详细的地质解剖工作表明,东天山地区大南湖岛弧带石炭纪出露4套岩石地层组合,即早石炭世小热泉子组火山岩、晚石炭世底坎儿组碎屑岩和碳酸盐岩、晚石炭世企鹅山组火山岩、晚石炭世脐山组碎屑岩夹碳酸盐岩。根据其岩石组合、岩石地球化学、生物化石、同位素资料以及彼此的产出关系,认为这4套岩石地层组合的沉积环境分别为岛弧、残余海盆、岛弧和弧后盆地。结合区域资料重塑了大南湖岛弧带晚古生代的构造格架及演化模式。早、晚石炭世的4套岩石地层组合并置体现了东天山的复杂增生过程。 相似文献
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西昆仑造山带中带上石炭统提热艾力组为一套浅变质碎屑岩沉积,四周被三叠纪岩浆岩所包围,研究其沉积环境及物源特征对揭示该区构造背景具有重要的意义。通过野外详细的剖面测制、沉积相标志的观察,结合室内岩矿鉴定和地球化学等综合分析,揭示该套碎屑岩具典型的鲍马序列结构特征,岩性成分成熟度低,主要为一套近物源的斜坡重力流沉积,其物源区较为复杂,主要为切割岩浆弧、过渡岩浆弧和再旋回造山带,源区构造环境为大陆岛弧及活动大陆边缘,表现出活动大陆边缘弧后盆地的沉积特点。 相似文献
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V. M. Grannik 《Doklady Earth Sciences》2012,445(2):934-938
It has been established that volcanic rocks of the Schmidt, Rymnik, and Terpeniya terranes are fragments of the compound Early to Late Cretaceous-Paleogene East Sakhalin island arc system of the Sea of Okhotsk region. This island arc paleosystem was composed of back-arc volcano-plutonic belt, frontal volcanic island arc, fore-arc, inter-arc, and back-arc basins, and the Sakhalin marginal paleobasin. The continental volcanic rocks dominate in the back-arc volcano-plutonic belt and frontal volcanic island arc. The petrochemical composition of basalts, basaltic andesites, andesites, and trachytes from the frontal island arc formed in submarine conditions are typical of oceanic island arc or marginal sea rocks (IAB). The petrochemical composition of volcanic rocks from the island arc structures indicates its formation on the heterogeneous basement including the continental and oceanic blocks. 相似文献
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冲绳海槽是一个处于弧后扩张作用早期的年轻的弧后盆地,是研究弧后扩张作用早期盆地演化和壳幔过程的天然实验室.随着调查研究工作的逐步展开和深入,也发现了一些新的、重要的、亟待解决的科学问题,而火山岩岩石系列归属的厘定又是其他研究工作的基础.在系统收集和整理迄今已有冲绳海槽火山岩资料的基础上,结合近期分析测试数据, 对冲绳海槽火山岩的岩石系列归属进行了重新厘定,探讨了火山岩的构造环境指示意义和浮岩与玄武岩之间的成因联系.研究结果表明:冲绳海槽火山岩分布具有以基性玄武岩和酸性(流纹)英安岩为主的双峰式特征,中性火山岩稀少,基性的玄武岩属于亚碱性系列的橄榄拉斑玄武岩,酸性浮岩可归属为亚碱性岩系的流纹英安岩或流纹岩;在构造环境判别上,冲绳海槽玄武岩表现出大洋中脊和岛弧构造环境的特点,既有别于大洋中脊扩张中心,也有别于成熟型弧后盆地,呈现出弧后早期扩张阶段盆地独特的构造环境特征;广泛分布于冲绳海槽的酸性浮岩表现出一定的岛弧环境的特点;酸性浮岩与玄武岩具有同源性,酸性岩是基性的玄武质岩浆经不同程度结晶分异和同化混染作用的产物. 相似文献
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Xu Deru Gu Xuexiang Li Pengchun Chen Guanghao Xia Bin Robert Bachlinski He Zhuanli Fu Gonggu 《Journal of Asian Earth Sciences》2007,29(5-6):637-650
The SE margin of the Yangtze Block, South China is composed of the Mesoproterozoic Lengjiaxi Group and the Neoproterozoic Banxi Group, with Sinian- and post-Sinian-cover. A geochemical study was undertaken on the Mesoproterozoic–Neoproterozoic clastic sediments in order to delineate the characteristics of the sediment source and to constrain the tectonic development and crustal evolution of South China.Our results show that the Mesoproterozoic clastic sediments have a dominant component derived from a metavolcanic-plutonic terrane, with a large of mafic component. There is a minor contribution of mafic rocks and older upper crustal rocks to the provenance. Strong chemical weathering in the source area occurred before transport and deposition. The provenance for the Neoproterozoic clastic sediments was most likely old upper continental crust composed of tonalite–granodiorite-dominated, tonalite–granodiorite–granite source rocks, which had undergone strong weathering and/or recycling. A minor component of older K-rich granitic plutonic rocks and younger volcanogenic bimodal rocks is also indicated.Based on the regional geology, the geochemical data and the inferred provenance, the Mesoproterozoic Group is interpreted as a successive sedimentary sequence, deposited in an extensional/rifting back-arc basin, adjacent to a >1.80 Ga continental margin arc-terrane. The progressive extension/rifting of the back-arc basin was followed by increasing subsidence and regional uplift during continental marginal arc-continent (the Cathaysian Block) collision at 1.0 Ga caused the deposition of the Neoproterozoic Group into back-arc to retro-arc foreland basin. Therefore, the depositional setting of the Proterozoic clastic sediments and associated volcanic rocks within the back-arc basin reflected basin development from an active continental margin (back-arc basin), with extension or rifting of the back-arc basin, to a passive continental margin. 相似文献