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关于河南境内信阳群及陕西商南地区牛耳川组的时代归属问题,历来分歧较大,多数人认为属于前寒武纪,有的文献还将其定为中元古代。1992年,曾见河南西峡地区信阳群发现化石碎屑的报道;笔者近年在河南西峡八庙一陕西商南青山一带研究金红石矿床时,在陕西商南地区牛耳川组不同层位中首次发现了门类更丰富的化石,经过鉴定.并结合河南、陕西两省交界处的八庙、青山金红石矿床的对比及矿层的绝对年龄资料,认为牛耳川组与龟山组为同一套地层,均属中泥盆世。这一结论不仅对确定信阳群时代,而且对河南境内找矿方向的确定均具重要意义。 相似文献
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八庙-青山金红石矿床位于豫、陕两省交界处的西峡县与商南县之间,大地构造位置处于南秦岭地块的北缘。矿体呈层状、透镜状赋存于一套低角闪岩相变质的基性火山岩内,矿化层与大理岩互层产出。目前对于其含矿岩系的时代归属问题尚有中新元古代与中晚古生代之争。锆石年代学分析结果显示八庙矿区含矿岩系的底板围岩含石榴子石二云石英片岩主要包含3个阶段的年龄,即2664~1373 Ma、1003~874 Ma和468~411 Ma,青山矿区的含金红石斜长角闪片岩主要包含4个阶段的年龄,即1860~1441 Ma、1103~969 Ma、832~780 Ma和433~418 Ma。2个样品的最小锆石年龄数据一致,且与前人在含矿岩系大理岩中发现的古生物化石指示的时代相近。因此,八庙-青山金红石矿床的赋矿地层时代应归属于早泥盆世。全岩地球化学分析结果表明含矿岩石具洋岛玄武岩特征,源区可能为石榴橄榄岩,指示高钛的岩浆物质来自深部地幔。 相似文献
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西大明山银铅锌金钨铋矿地质特征、成矿规律及成矿模式 总被引:1,自引:0,他引:1
《矿产与地质》2015,(5)
文章简要介绍了广西西大明山地区的地质背景及银矿床、铅锌矿床、钨铋矿床、银铅锌金矿床地质特征,初步分析、总结和探讨了该区银铅锌金钨铋矿床的成矿规律,认为该区赋矿层位主要为寒武系,次为下泥盆统莲花山组,成矿物质来源于寒武系、下泥盆统岩层及深部岩浆岩,银铅锌等矿床导矿控矿主要为EW向、NE向断裂,EW向、NE向及其次级断裂为主要控矿容矿断裂,层控蚀变岩型钨铋矿受层位、岩性及褶皱构造控制明显,成矿与含钙层位关系密切,具多期成矿作用,成矿时代主要为燕山期,并提出该区银铅锌金钨铋矿成矿模式,指出银铅锌金钨铋矿的找矿方向,对该区今后的地质找矿工作具有一定的指导意义。 相似文献
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九寨沟葫芦沟金矿是川陕甘金成矿三角区典型的微细浸染型金矿床之一,矿体主要受断裂控制,赋存于中泥盆统三河口组三段上亚段灰岩(D_2s~(3-2))和下亚段板岩(D_2s~(3-1))中,容矿岩石以花岗斑岩为主,板岩次之,两者混合岩类少见。葫芦沟金矿床相关地球化学特征显示,构造-岩浆活动对成矿起了重要的控制作用,有深部流体参与成矿的迹象。富矿岩石板岩与花岗斑岩的主量、微量元素地球化学研究表明,矿石中Au、As、Ag、Hg、Cu、Fe、Zn、S、Sb等成矿元素极为富集,其形成的Au-(Fe+S)-Ag-Sb和As-Hg 2种元素组合,与矿床内黄铁矿、辉锑矿、毒砂等矿化特征极为吻合,反映它们与金成矿具紧密联系。研究表明:区内岩浆活动时代与金矿成矿时代相当,岩浆活动不仅为区内成矿提供热源动力,而且还提供了一部分颇为主要的成矿物质(岩浆水源和矿源);之后,浅成—超浅成花岗质酸性岩浆活化并萃取了矿源层中泥盆统三河口组(D_2s)中的Au,形成了含Au较高的成矿热液,在构造改造和多元含矿地热流体作用下,又以其能干性和化学活泼性等特点,为金矿的形成提供了良好的赋矿空间,直至演变形成葫芦沟金矿床。 相似文献
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八卦庙金矿成矿的某些地球化学制约因素 总被引:4,自引:1,他引:4
八卦庙金矿床是南秦岭印支褶皱造山带中新发现的超大型金矿床,其赋矿层位是中泥盆统星红铺组下岩段的一套碎屑岩沉积建造。通过对其容矿岩石的矿物组成、形成的构造环境、化学成分、微量元素、稀土元素等及金主成矿期脉石矿物铁白云石和石英的稳定同位素、矿物包裹体的系统研究后认为,容矿岩石、NWW向的断裂构造、深部岩体的热动力作用是控矿的主要因素,金的物源是深部的富金层,围岩也带入了部分成矿物质,成矿流体具有深源特 相似文献
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川西磷酸岩的特征,对阐明磷的沉积作用和磷块岩的成因,有一定的重要性。多年来,四川省地质局在该区作了大量的详细的勘查和研究。这里仅就我们的工作所及,讨论磷酸岩的一些沉积学问题。一、含磷岩系的岩性序列与岩相系列掌握含矿岩系本身在纵横两个方向上变化更替的规律,对沉积矿床的勘查是很重要的。这种变化规律,可以用岩性序列与岩相系列表示之。岩性序列是含矿岩系的各个岩类在纵剖面上转换的次序,反映它成生时期沉积盆地的地质、自然地理、物理、化学和生物等诸方面的状况及其在时间上的演化;而岩相系列则是含矿岩系的各个岩类及其组合在横向上的转换次序,反映上述诸方面状况在空间上的演变。 相似文献
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Karl Hans Wedepohl Maryse H. Delevaux Bruce R. Doe 《Contributions to Mineralogy and Petrology》1978,65(3):273-281
New lead isotopic compositions have been measured for Paleozoic bedded and vein ore deposits of Europe by the high precision thermal emission (triple filament) technique. Eleven samples have been analyzed from the Upper Permian Kupferschiefer bed with representatives from Poland to England, three samples from the Middle Devonian Rammelsberg deposit and one from the Middle Devonian Meggen deposit, both of which are conformable ore lenses and are in the Federal Republic of Germany (FRG); and also two vein deposits from the FRG were analyzed, from Ramsbeck in Devonian host rocks and from Grund in Carboniferous host rocks. For Kupferschiefer bed samples from Germany, the mineralization is of variable lead isotopic composition and appears to have been derived about 250 m.y. ago from 1700 m.y. old sources, or detritus of this age, in Paleozoic sedimentary rocks. Samples from England, Holland, and Poland have different isotopic characteristics from the German samples, indicative of significantly different source material (perhaps older). The isotopic variability of the samples from the Kupferschiefer bed in Germany probably favors the lead containing waters coming from shoreward (where poor mixing is to be expected) rather than basinward (where better mixing is likely) directions. The data thus support the interpretation of the metal source already given by Wedepohl in 1964. Data on samples from Rammelsberg and Meggen tend to be slightly less radiogenic than for the Kupferschiefer, about the amount expected if the leads were all derived from the same source material but 100 to 150 m.y. apart in time. The vein galena from Ramsbeck is similar to that from Rammelsberg conformable ore lenses, both in rocks of Devonian age; vein galena from Grund in Upper Carboniferous country rocks is similar to some bedded Kupferschiefer mineralization in Permian rocks, as if the lead composition was formed at about the same time and from similar source material as the bedded deposits. Although heat has played a more significant role in the formation of some of these deposits (veins and Rammelsberg-Meggen) than in others (Kupferschiefer), there is no indication of radically different sources for the lead, all apparently coming from sedimentary source material containing Precambrian detritus. One feldspar lead sample from the Brocken-Oker Granite is not the same in isotopic composition as any of the ores analyzed.Publication authorized by the Director, U.S. Geological Survey 相似文献
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广西大厂矿田拉么-羊角尖一带含矿地层元素地球化学特征及其指示意义 总被引:1,自引:0,他引:1
广西大厂矿田锡矿体主要赋存于上泥盆统,锌铜矿体主要赋存在锡矿体的下部,以中泥盆统为主。通过对拉么-羊角尖一带四个钻孔中不同深度、不同岩石类型样品成矿元素含量的系统分析,探讨了成矿元素在空间上的变化规律。结果显示,绝大多数成矿元素在岩体中含量最低,向上至各个地层中呈锯齿状变化,而且多数成矿元素的高值点并没有在岩体的内部或边缘,而是远离一段距离,Zn、Cu集中在罗富组灰岩蚀变后的透辉石绿帘石化矽卡岩中。这种元素含量的变化一方面反映了成矿元素运移的方向是由下而上,另一方面也反映了成矿元素的富集与岩石类型密切相关,说明矿床为岩浆热液成因。 相似文献
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凯勒克赛依铁矿床是新疆阿尔泰唯一的小型镜铁矿床,赋存于一套变质火山-沉积岩系中,近矿围岩为白云母石英片岩,矿体呈层状,与地层产状一致,矿石具有块状、条带状、条纹状构造,矿石中金属矿物主要为镜铁矿(TFeO=87349%~88988%,TiO2=0~1042%,Al2O3=0036%~0256%),矿化具有沉积特征。近矿围岩镜铁矿白云母石英片岩锆石LA MC ICP MS U Pb谐和年龄为(3756 ± 06)Ma,限定成矿时代在376 Ma左右,即中泥盆世成矿,是阿尔泰为数不多的中泥盆世成矿作用的产物。同时也厘定含矿的变质火山-沉积岩系属中—晚泥盆世阿勒泰镇组,不是前人认为的早泥盆世康布铁堡组。 相似文献
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New paleomagnetic data are obtained for Middle Devonian rocks of Central Tuva. The rocks contain one-, two-, or three-component magnetization. The low-temperature (LT) components of magnetization are close to the directions of the present-day or Cenozoic magnetic field in Tuva. Based on the directions of the high-temperature (HT) components of magnetization, which were distinguished in the magnetite spectrum of blocking temperatures of up to 580оС, we revealed a prefolding magnetization of different polarity. The time when Middle Devonian rocks acquired the prefolding HT component of magnetization almost does not differ from the time of rock formation. Middle Devonian sequences were formed at low latitudes (19°–25° N). We calculated the Middle Devonian paleomagnetic pole (Φ =–13°, Λ = 106°, A95 = 7), which can be used to describe the movement of the Caledonian block in Central Asia, and probably Siberia, if these blocks had been tectonically coupled by the Devonian. 相似文献
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新疆卡拉麦里蛇绿岩带中硅质岩的放射虫化石 总被引:41,自引:0,他引:41
新疆卡拉麦里构造带在奇台县南明水地区可划分为三个岩石一构造单元:①北带,由中泥盆世复理石组成;②南带,由中泥盆世—早石炭世沉积岩—火山质碎屑岩组成;③蛇绿岩带。三者之间均为断裂接触。蛇绿岩套上部单元的红色硅质岩中发现丰富的放射虫化石,经鉴定,其时代确定为晚泥盆世法门期一早石炭世杜内期,代表卡拉麦里蛇绿岩形成的晚期年龄。 相似文献