Genesis of the Sanbaqi deposit: a paleokarst-hosted uranium deposit in China

The Sanbaqi uranium deposit in Hunan Province, south China, is the largest of a group of paleokarst-hosted uranium deposits in Lower Carboniferous limestone. Mineralization is localized in cavities and fault-breccias formed by dissolution of carbonates. Four episodes of karst formation are recognized: late Triassic-early Jurassic, late Jurassic-early Cretaceous, Cretaceous-Tertiary and Recent. Field relations indicate that the main uranium mineralization is related to the second karst episode. This is supported by isotopic ages of two pitchblende samples at 129 Ma and 134 Ma, as indicated by their nearly concordant data points on concordia plot. These ages are in the time range of the early Yanshanian tectonic movements that affected southern China, and the faulting related to the movements likely triggered the mineralization process at the Sanbaqi deposit. Associated minerals include pyrite, millerite, ullmannite, niccolite, molybdenite, chalcopyrite, sphalerite, galena, calcite and dolomite. Fluid inclusion studies on calcite reveal that temperature of ore deposition was from 181° to 150 °C. The δ¹⁸O and δD values of the ore fluids range from 1.5 to 7.9 per mil and from −30.4 and −54.8 per mil, respectively. The mineralogical, fluid inclusion and isotopic data indicate that the minerlization took place in episodic pulses of hydrothermal fluids that were introduced along a set of ring faults. Mobilization and redeposition of earlier formed ore minerals in an open system added to the complexity of the paragenetic sequence. Younger episodes of mineralization occurred during the later karst events as suggested by the geological and additional pitchblende U-Pb isotopic data, during the Cretaceous-Tertiary late Yanshanian tectonic movements and recently. Finally, a comparison of the Sanbaqi uranium deposit with the uranium deposits hosted by solution collapse breccia pipes of the Colorado Plateau, USA, shows that they have many similarities. Received: 9 July 1996 / Accepted: 17 January 1997     

南苏鲁超高压变质带东海地区富钛榴辉岩及金红石矿的成因

苏鲁超高压变质带南部的东海地区有富Fe—Ti的钛铁矿榴辉岩和富Ti的金红石榴辉岩。富Fe—Ti榴辉岩的次要矿物主要由钛铁矿和钛磁铁矿组成,可舍少量金红石,具有很低的Si02（38．0％-42．3％）、Na20＋K20（0．48％～2．13％）和Zr、Nb、Ta、Ba、1Kb、REE含量,很高的FeO（18．24％-25．33％）、V和Co含量,并具有不同程度的LREE亏损、明显的正Eu异常;富Ti金红石榴辉岩舍有丰富的金红石和磷灰石,SiO2含量范围（38．0％-54．8％）较宽,FeO含量较低,P2O5含量较高（可达4．1％）,而X-TiO2与P205含量具正相关性。相对于原始地慢岩．富Ti金红石榴辉岩具有Rb、Th、K、Nb、Pr、Nd、Eu、Ti、Lu的负异常和Ba、Sr、Zr的正异常．并具相对较高的IKEE含量,LREE富集和HREE亏损的1KEE分配型式。岩石学和地球化学特征揭示,Fe—Ti榴辉岩的原岩是变质的Fe—Ti辉长岩,是基性岩浆强烈分离结晶作用形成的超基性-基性-中酸性层状侵入体的特征组成部分。     

赣南区域铀成矿特征

归纳总结赣南地区不同类型铀成矿特征,认为赣南铀成矿具有多期、多阶段的特点,提出区域铀成矿控制因素主要为富铀变质岩基底、富铀岩浆岩和断裂构造。     

邹家山铀矿床含矿裂隙系统研究

邹家山铀矿床位于相山铀矿田西部,是相山铀矿田最重要的矿床,该矿床属于受断裂裂隙构造控制的脉状中-低温热液矿床,以规模大、品位高而著称。对邹家山铀矿床露天采场含矿构造的详细调查显示,含矿裂隙系统由许多弧形小断层及其所夹持的透镜状岩块构成;含矿裂隙主要为北北东向和北北西向,次为其他方向;含矿裂隙是由"X"剪节理基础上发展起来的,经过持续变形而形成;矿液充填交代时NNE向断裂具有一定的左行特点,近南北向裂隙往往是矿脉膨胀部位;成矿流体压力比较大,具有明显的水压致裂作用,形成同一露头上多个方向弧形和不规则铀矿脉,并且有从高一级裂隙向低级别裂隙、微裂隙边矿化边扩展的特点。邹家山铀矿床矿带(矿体群)呈斜列状分布,平面上呈左列式,单体北东走向,轴线北东东走向;剖面上单体中-陡倾角,轴线中-低倾角倾向西。矿带(矿体群)的空间分布与邹家山-石洞断裂带明显不一致,反映出矿带可能受一组走向北东东(50°～65°)、中-缓倾角(30°～45°)倾向北西的隐性构造控制,而不是受陡倾角的北东向邹家山-石洞断裂带控制。就邹家山铀矿区而言,进一步找矿方向在现有矿带的南西西方向深部。     

云南白牛厂银多金属矿床成因

对云南白牛厂超大型银多金属矿床的地质、地球化学特征及矿床形成的长期性及多阶段性的研究认为:白牛厂银多金属矿床是热水沉积—叠生成因矿床,早期呈现寒武纪的热水同生沉积成矿作用,晚期为燕山期花岗岩浆热液成矿作用。该矿床是热水沉积成矿作用与岩浆热液成矿作用叠加成矿的产物。     

Origin of the Oligocene Tuolangla porphyry-skarn Cu-W-Mo deposit in Lhasa terrane,southern Tibet

Although some porphyry-skarn deposits occur in post-collisional extensional settings, the post-collisional deposits remain poorly understood. Here the authors describe the igneous geology, and mineralization history of Tuolangla, a newly-discovered porphyry-skarn Cu-W-Mo deposit in southern Tibet that belongs to the post-collisional class. The deposit is associated with Lower Cretaceous Bima Formation. It was intruded by granodiorite porphyry intrusions at about 23.1 Ma. Field investigation indicated that mineralization is spatially and temporally associated with granodiorite porphyry. Molybdenite yielded a Re-Os weighted mean age of 23.5 ± 0.3 Ma and is considered to represent the age of skarn mineralization at the deposit. The δ³⁴S values of sulfides, concentrated in a range between 0.6‰ to 3.4‰, show that the sulfur has a homogeneous source with characteristics of magmatic sulfur. The Pb isotopic compositions of sulfides indicate that ore-forming metal materials were derived from the mantle and ancient crust. The granodiorite porphyry displays high SiO₂ (68.78%–69.75%) and K₂O (3.40%–3.56%) contents, and relatively lower Cr (2.4×10^-6–4.09×10^-6), Ni (2.79×10^-6–3.58×10^-6) contents, and positive ε_Hf(t) values (7.7–12.9) indicating that the mineralization porphyry was derived from the partial melting of juvenile lower crust. The Tuolangla deposit is located in the central part of Zedang terrane. This terrane was once considered an ancient terrane. This terrane is in tectonic contact with Cretaceous ophiolitic rocks to its south and Mesozoic continental margin arc volcanics and intrusions of the Gangdese batholith of the Lhasa terrane to its north. Thus, the authors proposed that the Oligocene porphyry skarn Cu-W-Mo mineralization is probably associated with the Zedang terrane. This finding may clarify why the Oligocene (about 23 Ma) deposits are found only in the Zedang area and why mineralization types of the Oligocene mineralization are considerably different from those of the Miocene (17–14 Ma) mineralization.     

CSAMT法在松辽盆地南部砂岩型铀矿勘查中的应用

介绍了CSAMT法在松辽盆地南部砂岩型铀矿勘查中的应用。通过成果分析及部分钻探资料验证,认为该方法是探测深部地质构造的有效方法之一,在我国中新生代盆地的砂岩型铀矿勘查中具有较好的应用前景。     

粤北石土岭铀矿床同位素地球化学研究

石土岭铀矿床位于贵东岩体东南部与寒武纪浅变质岩接触带的内带,矿区内NWW向和NNE向基性岩脉十分发育。矿体主要赋存于帽峰岩体中,呈脉状产出,并受近EW向裂隙构造控制。沥青铀矿的U-Pb年龄(135Ma)与帽峰岩体的年龄(220Ma)相差明显,但与NWW向辉绿岩脉的年龄(143Ma)十分接近。矿石中黄铁矿的初始87Sr/86Sr值(0.71315~0.72579)介于成矿期间辉绿岩的值(0.70449~0.70632)与帽峰和下庄岩体演化至成矿时期(135Ma)的值(0.75058~0.99507)之间;黄铁矿的铅同位素组成呈线性分布,为基底变质岩铅与帽峰岩体铅及辉绿岩铅之间不同程度的混合。Sr、Pb同位素组成显示出成矿组分具多来源特征;成矿流体的δ18OH2O=2.0‰~8.1‰,δDH2O=-63‰~-51‰,反映出成矿流体主要由幔源流体组成;方解石的δ13C=-8.3‰,表明矿化剂∑CO2也来自地幔。因此,幔源流体在石土岭铀矿床的形成中具有十分重要的意义。     

Genesis of the Zhaxikang epithermal Pb-Zn-Sb deposit in southern Tibet,China: Evidence for a magmatic link

The Zhaxikang Pb-Zn-Sb deposit is one of the most important deposits in the Southern Tibet metallogenic belt. Based on field geology, petrography, melt- and fluid inclusions and C-H-O isotopes, we describe and discuss the mineralization, alteration, and their possible link with magmatic fluids. Our results show that the Zhaxikang deposit shares many geological and geochemical similarities with typical intermediate-sulfidation (IS) epithermal deposits. The Pb-Zn-Sb mineralization is closely related to Fe-Mn carbonate- and silicic alterations, which formed the outer rim around the greisen in the Cuonadong Dome. Orebodies occur mainly as structurally-controlled veins and breccia dikes, with major minerals include sphalerite, galena, pyrite, arsenopyrite, and Fe-Mn carbonates. Main stage ore-forming fluids were of medium temperature (214–292 °C), low salinity (2.6–5.3 wt.% NaCl eqv.) and CO₂-bearing.Melt/fluid inclusions in beryl and quartz from the pegmatite indicate that the primary magmatic fluids were derived from the melt-fluid immiscibility. The magmatic fluids were of low salinity (0.2–7.9 wt.% NaCl eqv.), high temperature (298–457 °C) and CO₂-rich, and contained minor CH₄, N₂, C₂H₆, C₃H₈ and C₆H₆. The presence of Mn-Fe carbonates and daughter gahnite minerals in the beryl-hosted inclusions indicates high Mn, Fe and Zn contents in the parental magma and related magmatic fluids. This implies a genetic link between magmatic fluids and the Pb-Zn-Sb mineralization, as also supported by Ar-Ar dating and H-O-C isotopic evidence. We suggest that the Zhaxikang is best classified as an IS epithermal deposit, and the ore-forming fluids are likely to be magma-derived. Boiling of the magmatic fluids led to high-salinity fluids and metal enrichment. High regional geothermal gradient caused by the thermal doming event may have facilitated long distance transportation of magmatic fluids, and led to the formation of a wide alteration zone and distal Pb-Zn-Sb mineralization. The temperature drop and meteoric water involvement may have precipitated the Pb-Zn-Sn minerals in the distal fault systems.     

鄂尔多斯盆地东北部砂岩型铀矿床成因和叠合成矿模式

从铀源、迁移和沉积方面详细论述了鄂尔多斯盆地东北部砂岩型铀矿床的成矿模式,由于成矿过程复杂而建立了油-气还原和热改造叠合的叠合成矿模式。     

Factors influencing in-situ leaching of uranium mining in a sandstone deposit in Shihongtan,Northwest China

The Shihongtan uranium deposit in northwest China is a sandstone-type deposit suitable for alkaline in-situ leaching exploitation of uranium. Alkaline leaching tends to result in CaCO3 precipitation there by affecting the porosity of the ore-bearing aquifer. CaCO3 deposits can also block pumping and injection holes if the formulation parameters of the leaching solution are not well controlled. However, controlling these parameters to operate the in-situ leaching process is challenging. Our study demonstrates that the dissolved uranium concentration in the leaching solution increases as HCO3－ concentration increases. Therefore, the most suitable HCO3－ concentration to use as leaching solution is defined by the boundary value of the HCO3－ concentration that controls CaCO3 dissolution-precipitation. That is, the dissolution and precipitation of calcite is closely related to pH, Ca2+ and HCO3－ concentration. The pH and Ca2+ concentration are the main factors limiting HCO3－ concentration in the leaching solution. The higher the pH and Ca2+ concentration, the lower the boundary value of HCO3－ concentration, and therefore the more unfavorable to in-situ leaching of uranium.     

Geochemical and mineralogical evidence for a coal-hosted uranium deposit in the Yili Basin,Xinjiang, northwestern China

The petrological, geochemical, and mineralogical compositions of the coal-hosted Jurassic uranium ore deposit in the Yili Basin of Xinjiang province, northwestern China, were investigated using optical microscopy and field emission-scanning electron microscopy in conjunction with an energy-dispersive X-ray spectrometer, as well as X-ray powder diffraction, X-ray fluorescence, and inductively coupled plasma mass spectrometry. The Yili coal is of high volatile C/B bituminous rank (0.51–0.59% vitrinite reflectance) and has a medium sulfur content (1.32% on average). Fusinite and semifusinite generally dominate the maceral assemblage, which exhibits forms suggesting fire-driven formation of those macerals together with forms suggesting degradation of wood followed by burning. The Yili coals are characterized by high concentrations of U (up to 7207 μg/g), Se (up to 253 μg/g), Mo (1248 μg/g), and Re (up to 34 μg/g), as well as As (up to 234 μg/g) and Hg (up to 3858 ng/g). Relative to the upper continental crust, the rare earth elements (REEs) in the coals are characterized by heavy or/and medium REE enrichment. The minerals in the Yili coals are mainly quartz, kaolinite, illite and illite/smectite, as well as, to a lesser extent, K-feldspar, chlorite, pyrite, and trace amounts of calcite, dolomite, amphibole, millerite, chalcopyrite, cattierite, siegenite, ferroselite, krutaite, eskebornite, pitchblende, coffinite, silicorhabdophane, and zircon. The enrichment and modes of occurrence of the trace elements, and also of the minerals in the coal, are attributed to derivation from a sediment source region of felsic and intermediate petrological composition, and to two different later-stage solutions (a U–Se–Mo–Re rich infiltrational and a Hg–As-rich exfiltrational volcanogenic solution). The main elements with high enrichment factors, U, Se, As, and Hg, overall exhibit a mixed organic–inorganic affinity. The uranium minerals, pitchblende and coffinite, occur as cavity-fillings in structured inertinite macerals. Selenium, As, and Hg in high-pyrite samples mainly show a sulfide affinity.     

浙北张家坞铀矿床矿石特征及铀的赋存状态研究

浙北湖州—安吉地区位于赣杭火山岩带北西侧,中生代火山岩分布广泛,发育有一系列的中小型火山岩型铀矿(化)点。张家坞铀矿床是浙北地区最大的火山岩型铀矿床,本文通过详实的野外观察,结合光学显微镜、扫描电镜、能谱仪和电子探针等测试技术,对张家坞铀矿的矿石特征和铀的赋存状态进行深入研究。结果表明,矿石呈现红色具流纹构造,整体表现为热液作用的特征,矿石以发育有金属矿物黄铁矿、赤铁矿、金红石和闪锌矿,非金属矿物玉髓、绿泥石、磷灰石、绢云母和方解石为特征。铀的赋存主要以独立铀矿物沥青铀矿和铀石为主,少量赋存在含铀副矿物中。铀矿物颗粒细小从核部到边部依次为沥青铀矿、"铀石化"成因硅含量偏高的铀石("高硅铀石")和正常铀石。矿石和脉石矿物特征表现出成矿时可能是张扭性的构造环境和高温迅速转变为中-低温的成矿环境。从矿体、矿石、矿物、围岩蚀变特征和成矿环境等角度,推测张家坞铀矿属于中-低温热液成因铀矿床。     

内蒙古开鲁盆地砂岩型铀矿热流体作用

开鲁盆地钱家店-白兴吐矿床的发现为中国东部晚侏罗世以来伸展裂陷型盆地中寻找可地浸砂岩型铀矿提供了典范。研究发现,钱家店-白兴吐矿床及其周围断裂构造十分发育,尤其是著名的西拉木伦河断裂在矿床中直穿而过。勘查实践表明,70%~80%的钻孔中能见到辉绿岩,矿化体多呈囊状、透镜状,空间上矿化与辉绿岩有关。通过岩心观察、镜下薄片鉴定、电子探针分析、包裹体温度与盐度的测定,发现上白垩统姚家组含矿目的层砂岩中存在大量的热流体改造证据。辉绿岩侵入过程中热作用不仅使围岩出现烘烤变色、变硬,而且辉绿岩岩浆作用带来的热流体使砂岩、泥岩产生大量的新生胶结物。与辉绿岩相关的热流体作用使姚家组含矿目的层砂岩中的碎屑颗粒被溶解和交代,无论是宏观还是微观上,均可见到碳酸盐脉体,同时碳酸盐矿物蚀变交代石英、长石。进一步研究表明,碳酸盐胶结物可分出第一期方解石、第二期铁白云石和第三期高铁白云石。碳酸盐胶结物和石英次生加大边包裹体测温显示,钱家店-白兴吐砂岩型铀矿床热流体改造有3期热流体活动,对应的温度分别为80~90℃、110~120℃和140~150℃。测定冰点获得的包裹体盐度分布也有低盐度区、中盐度区、高盐度区3个区间,它们与3期不同温度的热流体活动相对应。     

新疆伊犁盆地南缘层间氧化带砂岩型铀矿床中稀土元素地球化学特征

通过对新疆伊犁盆地南缘层间氧化带砂岩型铀矿床主要层位水西沟群中稀土元素地球化学行为特征的分析,并与蚀源区岩石对比,初步认为水西沟群的稀土元素主要来自蚀源区的安山岩和花岗岩,与玄武岩无关。伊犁盆地南缘乌库尔其地区流体和岩石的pH值分布情况表明,层间氧化岩石带和原生还原岩石带的pH值相似,而矿石带的pH值偏低,这与在偏碱性条件下,REE和U的络合物容易形成,并且REE和U的络合物随着pH值的降低而迁移和沉淀富集是相吻合的。对REE的研究表明,在层间氧化岩石带中REE有所亏损;通过对REE的分异性的研究,认为在不同的分带中REE的分异程度不同,在矿石带中分异程度最大,更加富集LREE,并且随着岩石粒径的增大,LREE和HREE的分异也有增大的趋势;根据REE和U的亲和性及活动性特征,认为U和REE在迁移沉淀规律方面具有共性,以[UO2(CO3)3]4-及[REE(CO3)3]3-形式进行迁移;即在偏碱性的条件下,容易形成碳酸盐络合物,随着pH和Eh值降低,U和REE共同沉淀、富集。     

Isotope geochemistry of ore fluids for the Dongsheng sandstone-type uranium deposit, China

The Dongsheng sandstone-type uranium deposit is one of the large-sized sandstone-type uranium deposits discovered in the northern part of the Ordos Basin of China in recent years. Geochemical characteristics of the Dongsheng uranium deposit are significantly different from those of the typical interlayered oxidized sandstone-type uranium ore deposits in the region of Middle Asia. Fluid inclusion studies of the uranium deposit showed that the uranium ore-forming temperatures are within the range of 150–160℃. Their 3He/4He ratios are within the range of 0.02–1.00 R/Ra, about 5–40 times those of the crust. Their 40Ar/36Ar ratios vary from 584 to 1243, much higher than the values of atmospheric argon. The δ18OH2O and δD values of fluid inclusions from the uranium deposit are -3.0‰– -8.75‰ and -55.8‰– -71.3‰, respectively, reflecting the characteristics of mixed fluid of meteoric water and magmatic water. The δ18OH2O and δD values of kaolinite layer at the bottom of the uranium ore deposit are 6.1‰ and -77‰, respectively, showing the characteristics of magmatic water. The δ13CV-PDB and δ18OH2O values of calcite veins in uranium ores are -8.0‰ and 5.76‰, respectively, showing the characteristics of mantle source. Geochemical characteristics of fluid inclusions indicated that the ore-formation fluid for the Dongsheng uranium deposit was a mixed fluid of meteoric water and deep-source fluid from the crust. It was proposed that the Jurassic-Cretaceous U-rich metamorphic rocks and granites widespread in the northern uplift area of the Ordos Basin had been weathered and denudated and the ore-forming elements, mainly uranium, were transported by meteoric waters to the Dongsheng region, where uranium ores were formed. Tectonothermal events and magmatic activities in the Ordos Basin during the Mesozoic made fluids in the deep interior and oil/gas at shallow levels upwarp along the fault zone and activated fractures, filling into U-bearing clastic sandstones, thus providing necessary energy for the formation of uranium ores.     

鹿井铀矿床铀矿物学特征

鹿井矿床位于南华活动带华夏褶皱带武功—诸广断隆区,闽、赣后加里东褶皱地块西缘,诸广山复式岩体中段,受遂川断裂及热水断裂组成的地堑式断陷带控制。本文主要对鹿井矿床内铀矿物的赋存状态、成分特征及组合特征进行了研究。     

The Nuheting deposit,Erlian Basin,NE China: Synsedimentary to diagenetic uranium mineralization

Sedimentary units deposited during the post-rift stage of the Erlian Basin located in northeast China present an alternation of sandstone and mudstone layers. This sedimentological architecture is at the origin of confined permeable reservoirs hosting sandstone-type uranium deposits. The study of the Nuheting deposit offered the opportunity to identify synsedimentary/early diagenetic uranium concentrations and diagenetic mineralization hosted in mudstone-dominated layers of the Erlian Formation, indicating that a stock of uranium was present in the basin prior to the genesis of sandstone-hosted uranium deposits. Therefore, this pre-existing stock may constitute a significant source of uranium for the formation of roll front deposits present in other parts of the Erlian Basin.Detailed petrographic and geochemical study of drill-core samples from the Nuheting deposit led to the characterization of different stages related to the formation of the uranium ore bodies and allowed to propose a new metallogenic model. Uranium mineralization of the Nuheting deposit is mainly hosted in dark gray silty mudstone of wetland depositional environment of the Late Cretaceous Erlian Formation. Petrographic observations and EMP analyses evidenced that a significant amount of uranium was associated with clay minerals (interstratified clays, smectite, chlorite, palygorskyte, illite and kaolinite), either adsorbed on mineral surfaces as U (VI) ions or reduced mainly as UO₂ nano to microcrystals disseminated in the clayey matrix, which corresponds to synsedimentary/early diagenetic concentrations. Trace elements on pyrite analyzed by LA-ICPMS, petrographic observations and whole-rock geochemical data led to the characterization of a diagenetic uranium mineralization. High As (1–50 ppm), Mo (10–500 ppm) and Se concentrations in the whole rock and the incorporation of these elements in pyrite highlight reducing conditions within the host-rocks during the diagenesis of the Erlian Formation. During the early diagenetic stage, uranium was either desorbed from clay minerals and organic materials to be reduced or directly reduced and precipitated as P-rich coffinite and pitchblende on pyrite crystals. During the late diagenetic stage, uranium was redistributed in situ and locally deposited mainly as coffinite on pyrites. Finally, an epigenetic stage of cementation was identified with sulfate and carbonate minerals, which may enclose some uranium minerals. This epigenetic stage of fluid circulation may be responsible for a minor uranium remobilization. Therefore, the Nuheting deposit experienced three main stages: (i) a synsedimentary/early diagenetic uranium concentration and mineralization, (ii) a late diagenetic in situ uranium remobilization and deposition on pyrite and (iii) an epigenetic cementation. Rock-Eval pyrolysis indicates that the organic matter contained in host-rocks of the Nuheting deposit is of type IV, inherited from land plant, and do not contain free hydrocarbons (very low S1). Therefore, our results do not support that migrated hydrocarbons were involved as a reducing agent for uranium mineralization.     

An excellent fossil wood cell texture with primary uranium minerals at a sandstone-hosted roll-type uranium deposit, NW China

A fossil wood cell texture with pitchblende and coffinite found at a sandstone-hosted roll-type uranium deposit, Xinjiang, NW China, is first reported here for the country. In the mineralized sandstone, detrital grains consisting of quartz, feldspar, rock fragments, carbonaceous trashes, mica and accessory minerals were deposited in early Turassic time and were cemented by clays and minor authigenic calcite and quartz. Pitchblende and minor coffinite are principal ore minerals at the deposit, and selectively replaced carbonized fossil wood remnants or filled fossil wood cells. An excellent fossil wood cell texture with primary uranium minerals formed. Replacement of organic debris by primary uranium minerals may be due to a local reducing environment resulting from the production of CH₄, H₂S or H₂SO₃ in its decomposition, and a biochemical reaction indicated by the common presence of framboidal pyrite.     

诸广岩体南部长排铀矿床勘查模式与找矿预测

长排铀矿床位于诸广岩体南部长江铀矿矿集区中部,区域上处于岩浆岩带、断陷带、深大断裂交会区和华夏古陆隆起与凹陷的交会部位,成矿地质背景有利。区内多期次岩浆活动和白云母化、绿泥石化、绢云母化等多种蚀变叠加,北北西向含矿断裂发育,成矿条件优越。通过对该矿床勘查成果的总结和成矿预测研究,认为长排铀矿床由小型到大型的突破,是在开拓找矿思路、创新找矿方法、总结前人找矿经验和棉花坑矿床成矿模式,以及建立区内地质、物探、化探"三位一体"勘查模式的基础上取得的。进一步分析区内构造、蚀变、岩性界面、成矿热液活动及铀成矿环境等控制因素,提出含矿断裂带膨胀、分支复合、多期次热液蚀变叠加等部位为成矿和赋矿的有利部位,结合物化探测量成果,预测矿床南部长坑地段60、78号带和水石地段71、73、86号带等成矿条件好,其深部有较好的找矿前景。