陕西北秦岭地区构造作用与成矿初探     

戴文晗 《铀矿地质》1985,(4)

陕西北秦岭地区具有多旋回构造发展史及多旋四成矿作用。主要表现:断裂构造作用的多期性,板块多次俯冲碰撞,构造带多次由北向南迁移以及多期次岩浆活动和变质作用等方面。其结果使得该区显示出由北向南的构造发展规律,并形成了最终的构造格局。根据该区多旋回的构造发展历史,可将该区铀及其有关矿产分为五个矿化旋回期:太古代,元古代、早古生代、晚古-中生代和新生代。其中早古生代、晚古-中生代和新生代,是区内三个主要矿化旋回期。深大断裂带系统在成岩成矿中占有相当重要的地位,它们不但控制了区内内生矿化的形成,而且是控制变质怍用与矿化的重要因素。断裂作用破坏了地壳岩石的完整性,使处于封闭状态的铀及其它成矿元素得以活化转移,从而形成了矿化作用的有利条件。燕山-喜山期构造和岩浆活化作用,对原有地质构造和矿化进行了强烈的改造。形成了新的矿化排列组合及新类型矿化。铀矿化则以淋积型为主。该区有利的找矿方向是:地台边缘冒地槽区,深大断裂带通过富铀建造的地区,北东向隆起一沉降过渡区。  相似文献   

长江中下游地区早白垩世埃达克质岩的大地构造背景及其成矿意义   总被引：28，自引：22，他引：28  

汪洋邓晋福  姬广义 《岩石学报》2004,20(2):297-314

长江中下游地区是中国重要的铜资源基地之一。该成矿带广泛发育与Cu-Au成矿作用密切相关的早白垩世火成岩。大多数与成矿有关的中酸性侵入岩具有类似埃达克岩的地球化学特征,即富集Sr而贫HREE(如:Y和Yb);但它们具有负的εNd(t)值和相对富集的Sr同位素初始比值(>0.704.),因此,被称为埃达克质岩。根据岩石化学数据,研究区埃达克质侵入岩多数属于高钾钙碱性系列,部分属于钙碱性系列;而火山岩和A型花岗岩类由于其高钾和富铁特征而属于钾质碱性系列。岩石地球化学资料显示,与成矿作用有关的中酸性埃达克质侵入岩经历了复杂的成岩过程,至少包括在深位岩浆房(>35～40 km深度)的分离结晶和在高位岩浆房内的分离结晶或AFC过程两个阶段。同时不排除有下地壳直接熔融形成的埃达克质熔体参与的可能性。富钾的火山岩则是原生岩浆在深位岩浆房(>40-50 km深度)经镁铁矿物的分离结晶过程演化而来。基于长江中下游地区及其邻区的区域地质构造、早白垩世岩浆岩的岩石化学和地球化学特征和岩浆活动的时空演变特征的综合分析,推测该成矿带在早白垩世早期处于大陆边缘岩浆弧内陆一侧,岩浆活动与古太平洋板块的斜向俯冲作用有关;晚期由于俯冲板片迁移(变陡),岩浆岩具有弧后环境特征。俯冲板片上部所释放的超临界流体提高了地幔  相似文献   

Mineralization Controls in Island Arc Settings: Insights from Philippine Metallic Deposits   总被引：1，自引：0，他引：1  

G.P. Yumul  Jr.  C.B. Dimalanta  V.B. Maglambayan  R.A. Tamayo  Jr. 《Gondwana Research》2003,6(4):767-776

A review of the gold-copper, volcanogenic massive sulfide and ultramafic-hosted (i.e., chromitite, nickel sulfide, platinum-group minerals) deposits in the Philippines is presented. It is critical that a thorough understanding of the spatial and temporal relationship among magmatism, structures and mineralization must be gained if the correct evaluation of the economic potential of a particular deposit is to be done. Structural features conducive to precious and base metal mineralizations are associated with shear zones, extensional jogs and collision zones. In Northern Luzon, alkali and adakitic magmatism are considered good markers for gold-copper mineralization. Volcanogenic massive sulfide deposits are hosted by either ophiolites of marginal basin origin or metamorphic terranes. Exploration works on these deposits have been geared in determining the gold content of the massive sulfides. Chromitite deposits are related with ultramafic rock-hosted deposits. Their occurrence is attributed to crystallization, magma mixing and mantle-melt interaction processes in subduction-related settings. The multiple stages of partial melting responsible for the formation of supra-subduction zone ophiolites result in the generation of second to third stage melts that are enriched in nickel sulfides and platinum group minerals. On the basis of structural, geochemical and tectonic controls, Panay, Mindoro and Central Mindanao and the Sierra Madre, Leyte, and Samar are good exploration targets for precious and base metal deposition in the western and eastern sides of the Philippines, respectively.  相似文献   

地层水矿化度检测的地球物理测井方法   总被引：1，自引：1，他引：1  

赵发展  戚洪彬  王赟 《地球物理学进展》2002,17(3):551-558

传统的水文地质研究方法在进行地下水的矿化度评价时，是通过地层水的取样进行室内分析化验，确定含水岩组中地层水的矿化度，目前，在利用已有的地质、地球物理资料进行西部地下水资源评价的研究中，鉴于大多数石油井不含有浅层地层水的水样化验资料，因而本文介绍一种利用石油测井数据（主要为自然电位曲线）计算地层水矿化度的方法，并将之应用于鄂尔多斯白垩系自流水盆地地层水的矿化度估算，方法研究和应用实例证明这种方法是较为可靠的，虽然求取的地层水的矿化度的数值存在一定的误差，但完全可以满足地层水矿化度分级评价的需求，从而开发了石油测井数据在水文地质中的应用，也降低了单纯利用水文取样，由于样点少，矿化度预测精度低的缺点。  相似文献   

新疆蒙库铁矿床稀土元素地球化学及对铁成矿作用的指示   总被引：16，自引：4，他引：16  

杨富全毛景文  徐林刚张岩刘锋  黄成林周刚刘国仁  代军治 《岩石学报》2007,23(10):2443-2456

新疆富蕴县蒙库大型铁矿呈层状、似层状、透镜状赋存于下泥盆统康布铁堡组变质火山-沉积岩系中.矿体中发育矽卡岩,但矽卡岩并不产在侵入岩接触带上.绿帘石、石榴石和矿石的稀土配分模式具有相似性,均为轻稀土富集,正铕异常,基本上无铈异常,暗示它们之间存在成因联系.石榴石稀土配分模式呈折线型,具有明显的正铕异常,石榴石流体包裹体中熔融包裹体、熔流包裹体和气液包裹体共存,表明石榴石矽卡岩具有岩浆成因和热液成因的特征,形成于晶体 熔体 流体三相共存的岩浆-热液过渡阶段.矿床地质特征、矽卡岩矿物和矿石稀土特征表明蒙库铁矿为矽卡岩型矿床.  相似文献   

The Merensky Cyclic Unit and its impact on footwall cumulates below Normal and Regional Pothole reef types in the Western Bushveld Complex     

M. D. Roberts  D. L. Reid  J. A. Miller  I. J. Basson  M. Roberts  D. Smith 《Mineralium Deposita》2007,42(3):271-292

The Merensky Reef of the Bushveld Complex occurs in its highest stratigraphic position as a heterogeneous, pegmatitic, feldspathic melanorite bounded by two narrow chromitite stringers at the base of the Merensky Cyclic Unit (MCU). In the Swartklip Facies of the Rustenburg Layered Suite, the occurrence of widespread thermal and mechanical erosion termed “potholing” has led to the subdivision of the Merensky Reef into Normal Reef and Regional Pothole Reef sub-facies. The transition between the two sub-facies occurs where the MCU transgresses the lower chromitite stringer of the Normal Merensky Reef and cuts down into the underlying cumulate lithologies. In the Regional Pothole Reef at the Northam Platinum Mine, several economic reef types are identified, where the Merensky Reef becomes conformable to cumulate layering, in particular, to the footwall marker (NP2 reef type) and the upper pseudoReef (P2 reef type). The Normal Merensky Reef, as well as the P2 and NP2 Reefs, contains economic platinum group element (PGE) grades and includes the lower portion of the MCU melanorite and the Merensky Chromitite. Whole rock geochemistry indicates that this package is compositionally identical in Normal, P2, and NP2 Reefs, suggesting that the base of the MCU is a relatively homogeneous drape over both Normal and Regional Pothole Reef regions. However, the lower sections of the three Reefs are variables depending on the depth of transgression of the MCU. In the Normal and P2 reef types, transgression by the MCU was arrested within harzburgites, melanorites, and norites, resulting in coarse, pegmatitic textures in the immediate footwall units. For the NP2 Reef, transgression by the MCU was arrested within leucocratic rocks and resulted in the formation of troctolites below the Merensky Chromitite. These troctolites are characterised by a coupled relationship between olivine and sulphides and by changes in major element chemistry and PGE contents relative to equivalent units in the footwall of the Normal Reef. Along with micro-textural relationships, these features suggest that troctolization of leucocratic cumulates in the NP2 Reef beneath the Merensky chromitite was a result of a reactive infiltration of a chromite-saturated melt and an immiscible sulphide liquid from the overlying MCU, rather than a significant fluid flux from below. In all reef types, the concentration of S defines symmetrical peaks centred on the Merensky Chromitite (and chromitites from pre-existing cyclic units in Normal and P2 Reefs), whereas PGE concentrations define asymmetrical peaks with higher PGE contents in reconstituted footwall rocks relative to the MCU melanorite. This signature is attributable to a magmatic model of PGE collection followed by deposition towards the base of the MCU and within reconstituted footwall rocks. The continuity of the asymmetrical magmatic PGE signature between the Normal Reef and Regional Pothole Reef sub-facies indicates that PGE mineralization inherent to the Merensky magma occurred as a drape over a variably eroded and subsequent texturally and geochemically reworked or reconstituted footwall.  相似文献   

兰坪盆地水泄铜(钴)矿床石英的⁴⁰Ar-³⁹Ar快中子活化年龄   总被引：2，自引：2，他引：0  

黄震  徐晓春  谢巧勤  陈天虎  岳书仓 《地质科学》2005,40(1):125-128

选取水泄铜(钴)矿床主成矿阶段的石英样品进行⁴⁰Ar-³⁹快中子活化法同位素地质年龄测定,获得坪年龄59.2±0.8Ma,对应的等时年龄为59.8±0.5Ma,反等时线年龄为59.9±0.1Ma,三者在误差范围内完全一致,都可代表矿石的形成年龄。该年龄与兰坪盆地铜多金属矿集区的矿床形成时代一致,反映包括水泄铜(钴)矿床在内的区域矿床形成于喜马拉雅造山运动早期统一的构造地质背景之下,受同一期构造—热演化事件的制约。  相似文献   

The origin and evolution of mineralizing fluids in the Cretaceous Gyeongsang Basin, Southeastern Korea   总被引：1，自引：0，他引：1  

S.-G. Choi  S.J. Pak  C.S. Kim  I.-C. Ryu  S.-M. Wee 《Journal of Geochemical Exploration》2006,89(1-3):61

Ferroalloy, base-metal and precious-metal deposits in or around the Gyeongsang Basin, which is located in the Cretaceous volcano-sedimentary terrain at the southeastern Korea, displays a genetic relationship with subvolcanic activities of Late Cretaceous to Tertiary age. Diverse mineralization, which occurs as vein, breccia-pipe, porphyry-style and skarn deposits, took place from 108 to 45 Ma that overlapped with polyphase episodes of igneous activity. Based on the mineralogy, host rock, fluid inclusion and stable isotope data of the deposits, the systematic variation of physicochemical conditions is thought to be due to their relative positions with respect to a magma source that is genetically related to a low to intermediate-sulfidation porphyry system. There appears to be a systematic decrease towards δ¹⁸O_H2O values from copper (-gold) and ferroalloy deposits through polymetallic to precious-metal ones. However, Cu (-Au) or Fe–Mo–W deposits are proximal to a magmatic source, whereas polymetallic or precious-metal deposits are more distal to transitional.  相似文献   

阔尔真阔腊浅成低温热液金矿床成矿作用与成矿模式初探   总被引：4，自引：0，他引：4  

廖启林  戴塔根  刘悟辉 《大地构造与成矿学》2000,24(1):57-64

对阔尔真阔腊金矿床的成矿温度、微量元素与稀土元素含量、流体包裹体成份、硫、氢、氧、铷、锶等同位素资料的分析对比 ,探讨了该金矿床的成矿作用及其主要过程。认为该金矿床是一产于地洼区的浅成低温热液矿床 ,具有一系列多因复成矿床的基本成矿特征 ,其成矿至少经历了海西期地槽阶段的低温热液富集及中亚期地洼阶段的活化改造这两个重要阶段 ,并建立了其新的成矿模式。  相似文献   

辽宁白云金矿床成矿时代探讨   总被引：17，自引：3，他引：14  

刘国平  艾永富 《岩石学报》2000,16(4):627-632

白云金矿和上于辽宁东部古元代变质岩系分布区,辽东地区已发现多个大型金矿床,为中国东部重要金矿集中区之一,对于包括白放在内的该区金矿的成因和成矿时代有多种观点。西方关Ｋ－Ａｒ法测年的基础上,采用了石英＾４０Ａｒ／＾３９Ａｒ法研究白放床的成矿时代,样品从４６０℃到１６００℃进行了九个阶段的加热分析,从白云金矿床含金铁硅钾蚀变岩中分离的两个石英单矿物样品通过＾４０Ａｒ／Ａｒ快中子活化、阶段加热法获得的坪  相似文献