云南省昭通地区大中型铅锌矿床地质特征及成因对比分析

云南省昭通地区是滇东北铅锌银矿集区的重要组成部分.通过昭通地区茂租大型、金沙厂中型铅锌矿床铅同位素特征对比分析,进一步了解昭通地区铅锌矿床的成因,为该区找矿提供理论基础.研究表明,2个矿床既有沉积成因的特征,也有后期热液改造的特征.成矿金属主要来自上部地壳岩石,少量来自下地壳或上地幔,二者均属于沉积改造矿床铅锌矿化即受热水沉积控制,又受后期改造作用影响.该区的找矿工作既要重视寻找层状、似层状矿体,也要加强寻找大脉状矿体的力度.     

陕西白河县大葫芦沟铅锌矿控矿地质条件及成因机制探讨

陕西白河县大葫芦沟铅锌矿是与海底热水喷流密切相关的沉积-改造型铅锌矿床。矿体主要赋存于下志留统梅子垭组第二岩性段第二亚段(S1m22)地层之中,围岩主要为含石榴子石、蛭石绢云母片岩、绢云母石英片岩。2008年以来,陕西地矿局第一地质队运用现代海底热水沉积成矿理论首次在白河县大葫芦沟发现了大葫芦沟铅锌矿床,为陕南地区志留系海相盆地地质找矿厘定了全新的找矿模式。     

四川布途金子铅锌矿地质特征及找矿前景

布途金子铅锌矿位于川滇黔铅锌成矿域内,矿区地层为一套碳酸盐岩沉积建造,矿体赋存于灯影组上段地层中,受地层岩性及构造控制。Ⅰ和Ⅱ号铅锌矿体目前尚未控制最大延深,全部为氧化矿石。通过对数千米探矿坑道施工,将研究区与国内及世界典型MVT铅锌矿床对比,认为布途金子铅锌矿床属MVT铅锌矿亚类;通过与周边矿床对比,指出矿床深部极有可能存在大而富的原生硫化矿,有望成为一中型铅锌矿床。     

川滇黔接壤区石炭纪岩相古地理与铅锌矿关系分析

川滇黔接壤区铅锌矿产主要分布在石炭系地层中,其中石炭系地层中的矿床数占已发现矿床的45.77%.通过研究可知,铅锌矿的赋矿层位主要为下石炭统摆佐组和大塘组和中石炭统黄龙群中.通过对本区石炭纪岩相古地理的分析可知,石炭系仍主要为海相稳定相的沉积.在矿源层形成过程中,生长断裂(同沉积断裂)起着重要作用,造成了铅锌矿产地及成型的铅锌矿床主要局限于凹陷带内,并受其控制,因此,沉积过程中铅锌矿的富集受到了古地理环境的影响很大.     

新疆乌拉根古近纪盆地铅锌矿床特征

新疆乌拉根古近纪沉积盆地位于南天山与塔里木盆地的交汇部位,铅锌矿化主要分布在始新世沉积了乌拉根组(E2w),通过对该组地层中成矿元素特征研究,总结了乌拉根古近纪沉积盆地铅锌矿床特征及找矿标志。     

青海省玉树县多那昂铅锌矿地球化学特征

矿区位青海省于西南三江北西段成矿区的江达—贝拉印支期铜、铅、锌、银、铁成矿带西北缘,该区带处在囊谦-杂多铜铅锌成矿带上,区内主要矿产为铜铅锌矿,已发现的铜铅锌矿化点10处,分布在断裂构造带上,主要与次火山岩密切相关。新发现的多那昂铅锌矿化带就位于该带东南部同一成矿构造带上。在测区根据铜银铅锌多金属成矿带的地质特征,结合地球化学异常、地质背景,确定了找矿靶区,并通过岩石测量在测区取得了较好的找矿效果。通过对该矿点的地球化学特征叙述,对该区成矿特征进行了初步总结,为该带寻找同类型矿床提供具有参考意义的资料。     

澜沧县下湾子铅锌矿床地质特征与找矿方向

澜沧县下湾子铅锌矿属老厂铅锌矿外围,地处昌宁—澜沧银铅锌成矿带,是云南省重要的成矿带和银铅锌产地。经多年矿业开发,资源日渐短缺,对矿山外围的进行地质找矿有重要意义。本文总结了下湾子铅锌矿矿床地质特征,对控矿因素、矿床成因进行分析,指明了矿区找矿方向。     

甘肃省天水市金长沟金矿地质特征

金长沟金矿位于北秦岭成矿带柴家庄—吊坝子成矿亚带的西部,南邻西成铅锌矿田,东接太阳寺金银铅锌矿床,赋存于舒家坝组第三岩性段地层中,在此地层单元中,金含量明显高于其它地层单元,该地层单元为金的富集能提供重要物质来源。矿体严格受北东向断裂控制,矿区已发现金矿带1条,金矿体1个。矿石类型以含金石英脉为主,次为构造蚀变岩型。品位较低,平均品位达1.65×10-6。该矿床属中-低温热液蚀变型金矿床。     

西秦岭铅锌矿赋矿地层地球化学特征及其沉积环境

区域上规模铅锌矿床赋矿地层的岩性具多样性。与礁灰岩无直接关系。各个地层均存在铅锌等亲硫元素的叠加作用。差别只在于叠加元素的种类。碳酸盐岩及碎屑岩中火山物质、粘土物质及亲硫元素矿物的并存是各赋层的共同特点。区域主要赋矿地层均具有较高的沉积速率,但Eh、盐度、热水沉积强度基本均处于中等水平或临界点附近;矿区岩石的盐度等参数明显有别于赋矿地层,具事件沉积特征,还原性金属硫化物沉积作用只是在总体正常沉积环境中的局部短期还原性沉积作用事件,不一定是海湾型潮坪相等沉积环境的必然产物。     

甘肃省礼县郭家沟铅锌矿床地质特征及找矿标志

郭家沟铅锌矿床所处构造单元为西秦岭印支褶皱带,合作至崖湾成矿带东段。铅锌矿化体赋存于三叠系碳酸盐建造的北西向构造破碎带中,含矿岩性为构造角砾岩及方解石脉。矿体呈似层状、透镜状产出。笔者通过工作认为,矿床成因属岩浆—构造热液蚀变岩型。该矿床的发现对西秦岭地区多金属找矿具有十分重要的意义。     

秦岭地区两栖爬行动物区系组成特点及持续发展对策

对秦岭地区内１１个县的两栖爬行动物进行了调查研究。该区共有两栖爬行动物６０种（亚种）,占陕西省总种数的７５．０％。其中两栖动物１９种,隶２目７科１２属;爬行动物４１种,分隶２目８科２６属。该区两栖爬行动物区系组成以东洋界华中区或华中－华南区共有种类为主,也有一定数量的广布种和古北界华北区种类,还有少量东洋界西南区种类,并就秦岭地区的两栖爬行动物资源现状提出了５项可持续发展对策。     

秦岭造山带岩石圈动力学模型--来自大地电磁测深的证据

目的 建立秦岭造山带的岩石圈动力学模型是探索大陆动力学的前沿问题。方法 以地质和综合地球物理资料为约束，在对秦岭造山带东、西两段电性结构对比分析基础上建立了相应的动力学模型。结果 自中新生代以来，尤其是晚白垩世之后华北和扬子两地块向秦岭造山带持续陆内深俯冲作用，导致南秦岭岩石圈强烈向北挤入，秦岭造山带的后陆冲断褶带和北秦岭厚皮叠瓦逆冲带，现今处于以岩石圈叠置加厚的构造作用为主与拆沉作用初始发动并存状态；南秦岭正在经历拆沉-底侵的物质再循环作用，佛坪和南阳-邓县之间可能发育新的地幔柱；在造山带北、南深部边界与内部不同岩石圈块体之间还伴随不同性质的强烈走滑作用，导致物质的侧向传输。结论 秦岭造山带现今深部动力学状态直接制约着今后大地构造、气候和地表过程的动态相互作用，潜在地影响着人类社会、经济的可持续发展。     

Timing of the Wudangshan, Yaolinghe volcanic sequences and mafic sills in South Qinling: U-Pb zircon geochronology and tectonic implication

The Wudangshan, Yaolinghe volcanic-sedimentary sequences and doleritic-gabbroic sills comprise the largest exposed Precambrian basement in South Qinling. Zircons separated from 5 volcanic-pyroclastic samples of the Wudangshan Group, 2 volcanic samples of the Yaolinghe Group and one sample for the mafic sills were used for U-Pb dating by laser ablation-inductively coupled plasma mass spectrometry （LA-ICPMS）. The results reveal that the Wudangshan volcanic sequence was formed at （755±3） Ma （a weighted mean from the 5 samples, MSWD=0.47）, whereas the Yaolinghe volcanic suite and the mafic sill were crystallized at （685±5） （2 samples, MSWD=0.36） and （679±3） Ma （MSWD=1.6）, respectively, which are equal to each other within analysis errors. These ages are markedly younger than those previously documented for the rocks. The newly obtained ages for the Wudangshan and Yaolinghe Groups are Identical to those of the bottom Liantuo and slightly older than those of the Nantuo Formations, respectively, lower strata of the Nanhua （middle to late Neoproterozoic） stratotype section in eastern Three Gorges, Yangtze creton. A range of inherited magmatic zircons was recognized with ages of 830 to 780 Ma, which are typical of Neoprotzrozoic magmatisms recorded along the margins and interior of the Yangtze craton. Thus, there is Neoproterozoic basement comprising 830-780 Ma igneous suites in South Qinling; the inherited zircons were detrital sediments derived from the northern margin of the Yangtze craton. Accordingly, it is suggested that the South Qinling is a segment of the Yangtze creton before the Qinling Orogeny.     

西秦岭中生代花岗岩锆石U-Pb-Lu-Hf同位素特征及地质意义

对西秦岭地区中川岩体、柏家庄岩体和教场坝花岗岩体进行LA-ICP-MS锆石U-Pb同位素年代学分析, 获得其岩浆侵位年龄分别为220±1, 216±6和222±3 Ma, 表明3个岩体均形成于中?晚三叠世。样品的全岩地球化学分析结果表明, 3个岩体具有相似的稀土及微量元素特征, 均表现为显著亏损高场强元素Nb, Ti和P等, 具有明显的右倾式球粒陨石标准化稀土元素配分模式。锆石Lu-Hf同位素分析结果表明, 3个岩体锆石测年样品的ε_Hf(t)值介于?3.31~+1.68之间, 二阶段模式年龄介于1151~1456 Ma之间。岩石成因分析表明, 这些印支期花岗岩体的母岩浆主要来源于新元古代地壳物质的部分熔融。结合岩体形成时代、岩石成因和区域岩浆作用, 认为这些岩体形成于南秦岭与华南板块沿勉略缝合带相碰撞的造山动力学背景, 可能与华南板块的俯冲板片断离有关。     

秦岭西坝花岗岩LA-ICP-MS 锆石 U-Pb 年代学及其地质意义

西坝花岗岩位于南秦岭构造带陕西境内, 主要由花岗闪长岩、二长花岗岩和英云闪长岩组成。LA-ICP-MS 锆石U-Pb 原位同位素定年结果表明, 西坝岩体侵位于印支期, 由二长花岗岩样品(XB01-2)得到了219±1 Ma的年龄, 花岗闪长岩样品(XB06-1) 给出的年龄是218±1 Ma, 二者在误差范围内一致, 约218Ma代表了西坝花岗岩体的成岩时代。西坝岩体的年龄结合区域构造背景以及前人研究的地球化学特征, 说明它可能是秦岭主造山期岩浆活动的产物。     

秦岭柞水岩体和东江口岩体的锆石U-Pb 年代学及其意义

柞水岩体和东江口岩体位于秦岭造山带南秦岭构造域, 主要由似斑状花岗闪长岩和二长花岗岩组成。通过LA-ICP-MS 锆石U-Pb 同位素定年, 结合锆石阴极发光图像, 揭示柞水岩体的似斑状二长花岗岩(样品ZS01-01)存在两个谐和年龄, 分别为209±2和199±2Ma;东江口岩体似斑状二长花岗岩(样品ZS04-01)也存在两个谐和年龄, 分别为219±2 和209±2 Ma。结合前人的地球化学和区域构造背景研究, 判定这两个岩体属于同一岩浆事件的不同阶段侵位, 东江口岩体的似斑状二长花岗岩侵位结晶略早于柞水岩体, 柞水岩体主期岩浆侵位时, 东江口岩体也有同期岩浆侵位结晶。这两个岩体年龄的准确测定, 表明在219 ～199 Ma 期间沿商丹断裂有3个阶段的构造-岩浆活动。     

蟒西地区中酸性岩体地质特征及找矿潜力

通过对陕西蟒西地区中酸性岩体地质、地层、岩体构造等进行论述,归纳总结了区域中酸性岩体的特征,并通过矿床分析得出,陕西秦岭东部地区钼矿床地质学基本特征与中国内陆地区的大部分钼矿床的地质特征大致相同,其中Eu含量有所异常,K、Ra、Ba、Nb、Ta等元素的含量较为丰富,Ti为亏损状态;造山环境下易形成矿与岩;秦岭北部地区含矿岩浆中含有更多的壳液物质,南秦岭北部钼矿床含矿岩浆中含有较多的幔源物质。秦岭南部的大型岩体中原位Hf同位素特征值较高(-6.0～5.0,通常为负数),但是亏损地幔二阶段年龄的值较低(1.47～0.79 Ga),相关数据结果表明岩浆的来源为幔源物质与新生的加厚地壳。可见,地质和地球化学特征指示,秦岭地区有形成钼矿床的有利条件,形成小-中型铜、钼矿床的潜力大。     

Age of the Shahewan rapakivi granite in the Qinling Orogen, China, and its constraints on the end time of the main orogenic stage of this orogen

The Qinling Mountains in central China are a joint orogenic zone between the Sino-Korean (or North China) and the Yangtze (or South China) craton blocks, the two major tectonic units of eastern Asia. On the end time of the main orogenic stage in this orogenic belt there are different opinions. The⁴⁰Ar/³⁹Ar Rb-Sr and zircon U-Pb ages of a recently discovered rapakivi granite in the Qinling Orogenic Belt are reported and the end time of the main orogenic stage for subduction-collision in this belt is discussed.     

Tectonic affinity of Paleozoic stratigraphic slices along the northern margin in Dabie Orogen, central China: evidence from Pb isotope of rocks

Metavolcanic and metasedimentary rocks from the Paleozoic tectono-stratigraphic units along the northern margin in the Dabie orogen show that there are two types of Pb isotopic compositions, which have some affined regularity with tectonic subdivision. Compared with the main tectonic units of the Qinling orogen, the Dingyuan Formation should be the part of the South Qinling orogenic belt or the northern margin of the Yangtze craton, characterized by less radiogenic Pb isotopic composition, and the Guishan Formation, Nanwan Formation-Foziling Group and the Carboniferous should be the part of the North Qinling orogenic belt which is extended to the east, characterized by more radiogenic Pb isotopic composition. These facts combined with the distribution of the geological units suggest that the Paleozoic subduction zone between the Yangtze and North China cratons should be located in the north boundary of the Nanwan Formation-Foziling Group or somewhere that is covered by the Nanwan Formation-Foziling Group now. From the Pb isotopic evidence and suggestion presented here, one aspect of the constraint is provided for determining the position of the Triassic collision suture between the two cratons.     

U-Pb dating of detrital zircons from the Wudangshan Group in the South Qinling and its geological significance

U-Pb dating was made by the LA-ICP-MS method for detrital zircons from the Wudangshan volcanic-sedimentary succession in the South Qinling. Samples comprise quartz sandstones of the Wudangshan Group collected from the base of the Yangping Formation and an upper layer of the Shuangtai Formation overlain its volcanic sequence, and two river-sand collections from the drainage systems cutting across the two formations, respectively. The results show that the Yangping detrital zircons are dominated by 830–780 Ma grains with a minor population of ~1.0–0.84 Ga and sporadic grains of ~2.6, ~2.4 and 2.0 Ga, whereas the Shuangtai zircons yield an upper intercept age of 763±33 Ma, identical to the timing of the Wudangshan volcanism within error, with few concordant grains of 1.9 and 0.86 Ga. Age spectra for the two river-sand samples are similar to those of the Yangping and Shuangtai Formations, respectively. It thus suggests that the Wudangshan strata are less than 780 Ma, whereas their major detrital zircon populations of 1.0–0.85 Ga and 830–780 Ma are consistent with timing of the Hannan magmatic activities along the northwestern margin of the South China Block. This suggests a Hannan or adjacent area provenance for the Wudangshan strata. The Wudang area is characterized by rift-related igneous events at ~755 and ~680 Ma, respectively, pointing to a tectono- magmatic history different from the Hannan area. It is inferred that the ~755 Ma magmatism is likely to indicate a separation of the South China Block from the supercontinent Rodinia, while the ~680 Ma event suggests a further split between the South Qinling and some unknown continent.