盛源矿田南部坝口地区铀资源潜力分析

正研究区位于盛源矿田的南部、东西向坝口-庄家基底断裂与北东、北北东和北西向断裂的交汇地段。近年来核工业二七〇研究所在区内开展铀矿勘查工作,综合前人工作研究分析认为:研究区地区铀矿化(异常)在空间上受北东-北北东断裂与东西向断裂的复合控制,构造裂隙及破碎带是铀矿化的主要储矿场所,并且受岩性制约;该区具有断裂构造发育、赋矿岩层稳定、与铀成矿密切的热液蚀     

江西广丰县石人底地区铀成矿作用特征及找矿方向

石人底地区位于赣杭构造火山岩铀成矿带中段与武夷山成矿带北段交汇部位的广渡横溪中生代火山沉陷盆地中东部,区内出露上侏罗统、下白垩统火山岩系,岩浆―热液活动强烈,北东、北西向断裂构造发育。区内产有202矿床和501,275,I-40矿化点,铀矿化产于上侏罗统鹅湖岭组凝灰熔岩中,形成于红盆期伸展构造背景之下,主要受北西向构造、燕山晚期浅成侵入体、不整合面以及岩性等联合控制。文章阐述了区内铀成矿地质特征,分析了控矿因素,探讨了202矿点、202矿点至501矿化点区段、275矿化点至I-40矿化点区段的找矿方向。     

诸广山中段羊角脑地区成矿构造特征及找矿方向

羊角脑地区位于诸广山岩体中段鹿井铀矿田南部,也是重要的铀成矿区。通过对区内控矿构造基本特征、构造岩及蚀变分带特征、构造控矿及铀矿化特征进行研究,探讨了构造-岩浆活动与铀成矿成因关系,认为羊角脑铀矿床属于中低温热液充填交代成因矿床,提出了本区下一步找矿方向。     

新疆北金齐火山盆地铀-多金属矿化特征与控矿因素分析

北金齐火山盆地具有较好的铀矿找矿基础和成矿潜力,其铀矿化特征在新疆北部火山岩带具有普遍性。文章以北金齐火山盆地南、北缘和中部的3条典型铀-多金属矿化带为研究对象,较为全面地阐述了各带地质、矿化及蚀变组合等特征,并通过总结分析区内主要控矿因素及其控矿作用,初步建立了区域铀成矿模式。北金齐地区铀-多金属成矿具多因素联合控矿作用,铀-多金属矿化整体分布受火山盆地及北东东向区域大断裂控制,且盆地南、北缘大断裂较中部火山机构成矿地质条件优越。盆地内大断裂两侧的次级断裂带、裂隙带为主要含矿构造;酸性火山熔岩与酸性凝灰（角）砾岩为主要赋矿岩性,并为铀成矿提供一部分铀源;花岗斑岩等岩浆岩侵入活动为区内铀-多金属矿化主要成矿作用,推测火山机构塌陷后,花岗斑岩等岩浆岩侵入活动带来的含矿流体沿断裂贯入,在有利的构造和岩性中富集成矿。     

青海省枪口南银多金属矿床地质特征、控矿因素及矿床成因

枪口南银多金属矿床地处东昆仑多金属成矿带东段,枪口—哈龙休玛海西-燕山期铁、银、铅、锌、铜、金、钼成矿亚带部分,成矿地质条件优越。枪口南银多金属矿区目前已圈定9条矿化带,21个矿体,主要矿种有金、银、铜、铅、锌、钼等,矿石类型主要为构造热液(脉)型铜铅锌银矿石、构造蚀变岩型金矿石。枪口南矿区构造-岩浆活动强烈,印支期—燕山期构造岩浆活动为矿区成矿提供了热源、成矿物质,区内NE向断裂控制区内金、铜、铅锌等矿体的产出,NW向断裂组控制着区内金、银矿(化)体。NW向断裂组,是区内重要控矿构造;区内中部发现的Ⅳ号含矿斑岩体,具有斑岩型矿床蚀变特征,显示其具有斑岩成矿条件。枪口南银多金属矿床成因有构造热液(脉)型、构造蚀变岩型和斑岩型。     

浙江省衢州地区新路火山岩盆地西段铀成矿模式

文章在对研究区内白鹤岩、大桥坞和杨梅湾重点矿床成矿特征、控矿规律详细分析的基础上,指出该区铀成矿主要受构造、热液蚀变和侵入岩体的联合控制。依据主要控矿因素,建立了该区3阶段铀成矿模式:①火山喷发和岩浆侵入阶段;②大规模铀成矿阶段;③后期剥蚀矿体改造阶段。指出火山期后的岩浆侵位为铀成矿准备了含矿热液流体,NE、NNE向深大断裂为主要导矿构造,NW向次级断裂为主要的储矿构造,岩浆侵位和不同规模的断裂体系构成了含矿热液形成、运移和富集的完整过程。本区铀成矿在时间上可划分为2个阶段,早期为125～115Ma,晚期为90.9～70.2Ma,两期铀成矿与两期岩浆侵位相对应;在空间上呈三层楼式分布:即浅部为与砾岩层和隐爆有关的白鹤岩式铀矿化,中部为与赤铁矿化、萤石化、金属硫化物化有关的大桥坞式铀矿化,深部为与钠交代、硅化有关的杨梅湾式铀矿化。在此基础上,提出矿区外围找矿重点区域为:距NE、NNE向深大断裂出露线2km范围内上盘,且NWW向次级断层和水云母化蚀变强烈发育的地区;已知矿区深部找矿层位为:大桥坞矿床深部的杨梅湾式铀矿化、白鹤岩矿床深部的大桥坞式和杨梅湾式铀矿化。     

福建浦城银坑矿区铅锌矿地质特征及找矿方向

浦城银坑铅锌矿产于早元古代麻源(岩)群南山(岩)组、大金山(岩)组变质岩与花岗岩体的外接触带内,矿体明显受北东向断裂构造控制,呈脉状分布,北东向断裂为区内主要控矿构造,矿体总体沿北东向断裂两侧分布,而北东向断裂具有多期次活动特征,成矿物质来自早元古代含矿地层和燕山晚期岩浆热液,通过对矿区地质特征及成矿条件,认为矿床成因类型为硅化破碎带蚀变岩型铅锌矿床。     

云南弥渡宝兴厂金矿床成矿模式

宝兴厂矿区地质构造复杂,成矿条件有利。区内北东向响水断裂带是主要的控岩和控矿构造。三类金矿床分别在斑岩成矿期、热液成矿期和表生成矿期成生。文中建立相应的成矿模式。     

湖南宝山铜铅锌多金属矿床构造控岩控矿模式

湖南宝山铜铅锌多金属矿床位于南岭东西向构造带与耒阳—临武南北向构造带的复合部位,是该区大型—超大型矿床的典型代表之一。矿床（体）与燕山早期花岗闪长斑岩体在空间上关系密切,均明显受构造控制。在大比例尺构造剖面精细解析基础上,分析构造类型及其主要特征,总结构造控岩控矿规律。研究认为:矽卡岩型铜钼矿体主要受北东—北东东向褶皱控制;热液脉型铅锌银矿体主要受褶皱翼部层间断裂及北东向压扭性断裂控制。构造应力场最大主应力方向经历了成矿前近南北向→成矿期近东西向→成矿后北东—南西向的转变。北东—北东东向压扭性断裂为导矿构造,北西西向张扭性断裂为控岩构造。构造不仅控制了成矿岩体的展布,而且控制了成矿类型的变化。在此基础上,建立了构造控岩控矿模式,指示已知矿体北西侧深部是有利的找矿地段。该研究为深部找矿预测提供重要依据,对坪宝矿田的找矿部署和深部勘查具有参考意义。      

诸广山中部鹿井铀矿田构造解析与找矿远景探讨

诸广山中部是华南主要产铀地区之一,以鹿井矿田为研究对象,开展构造变形特征和构造控矿规律的研究,旨在揭示矿体产出规律,为找矿预测提供依据。本文基于野外详细观测和显微构造变形分析,揭示NE向断裂是鹿井地区主要控矿和含矿断裂,属浅层次构造变形,具有多期构造-热液活动特征:经历了早期(晚侏罗世—早白垩世)的压性、中期(早白垩世—古近纪)的张-张扭性和晚期(新近纪)的右行压扭性变形过程。铀矿(化)体主要发育在NE向断裂破碎带中,结合铀成矿时代,主成矿期断裂力学性质表现为张性、张扭性,后期NE向断裂右行压扭变形派生出近EW向、NW向和NS(NNE)向的剪裂隙,一方面对先成铀矿体具有改造作用,另一方面富集部分铀矿体。根据构造组合特征及其控矿规律,认为NE向断裂破碎带中,沿走向存在不连续的脉状、透镜状富铀矿体,而在其他方位的断裂带中可能存在部分铀矿体。     

Uranium abundance of the oceanic crust

Uranium contents of 67 oceanic basalts have been measured by fission track analysis. Average value for ridge and intraplate basalts is ~ 78 ppb, for the Easter Hot Line it is ~1600 ppb. Estimates of mantle concentrations derived from the ridge and intraplate samples are insufficient to account for the observed surface heat flow. The whole-Earth concentration of U is > 8 ppb. and < 33 ppb if all heat generated within the Earth reaches the surface.     

相山铀矿田矿床勘查模式探讨

相山铀矿田最后一期大规模火山熔岩喷发结束后,开始了大规模的铀成矿流体活动,在有利的构造部位形成热液活动中心.铀成矿流体在运移过程中,遇到圈闭构造发生矿质沉淀,形成铀矿石.因此,在相山铀矿田可以通过采用“热液活动中心十圈闭构造十多种物探方法”的铀矿床勘查模式,实现找矿新的突破.     

Uranium in Phosphorites

The uranium concentration in phosphorites on continents and modern seafloor varies from 0.nto n· 10²ppm (average 75 ppm). The average uranium concentration is 4–48 ppm in Precambrian and Cambrian deposits, 20–90 ppm in Paleozoic and Jurassic deposits, 40–130 ppm in Late Cretaceous–Paleogene deposits, 30–130 ppm in Neogene deposits, and 30–110 ppm in Quaternary (including Holocene) deposits. On the whole, the variation range is almost similar for phosphorites of different ages. The U/P₂O₅ratio in phosphorites ranges from less than unity to 24 · 10^–4(average 3.2 · 10^–4). Major phosphorite deposits of the world with ore reserves of approximately 250 Gt (or 58 Gt P₂O₅) contain up to 19 Mt of uranium. Uranium is present in phosphorites in the tetra- and hexavalent, i.e., U(IV) and U(VI) forms, and their ratio is highly variable. At the early diagenetic stage of the formation of marine phosphorites in a reductive environment, U(VI) diffuses from the near-bottom water into sediments. It is consequently reduced and precipitated as submicroscopic segregations of uranium minerals (mainly uraninite) that are probably absorbed by phosphatic material. During the subsequent reaction between phosphorites and aerated water and the weathering in a subaerial environment, uranium is partly oxidized and lost. The uranium depletion also occurs during catagenesis owing to a more complete crystallization of calcium phosphate and replacement of nonphosphatic components.     

中国最古老铀矿床成矿年龄及铅同位素示踪铀成矿省

中国发现的最古老铀矿床(点)集中分布在华北地台东部的鞍本地区及辽东地区其他铀矿化点、华北地台中部的中条山地区和华北地台西部的龙首山地区.通过多年来对这些地区所积累的47件晶质铀矿U-Pb同位素数据的整理处理,指出中国最古老铀矿床(矿点)尽管其成矿地域、成矿类型、成矿地质背景不同,但成矿年龄基本相同,在(1800±100)Ma左右成矿,铀成矿作用发生在早前寒武纪末吕梁造山期,而矿床可能主要在燕山运动期受到叠加改造.对华北地台东部诸省200多件方铅矿的铅同位素数据进行铅同位素数据处理:利用H-H模式分别计算了这些矿石铅源区的μ值及Th/U值,并统计了各省区μ值及Th/U值的均方差S和变异系数x;利用Pb构造模式获取不同地区铅的物质来源.文中还报道了特高放射性成因矿石铅的存在地域.矿石铅同位素示踪表明,我国辽东地区应该是很好的潜在铀成矿省.     

西秦岭铀矿床铀迁移形式的热力学研究

利用热力学方法计算了西秦岭铀矿床含矿热液中铀的迁移形式。结果表明，从含矿热液早阶段到主成矿作用发生之前，热液中的铀主要以「ＵＯ２（ＣＯ３）＾０」形式迁移；在晚阶段残余热液中，铀的迁移形式改变为「ＵＯ２（ＳＯ４）＾０」为主。铀迁移形式改变的原因与大气降水中ＳＯ＾２－４离子的大量带入有关，表明含矿热液来自深部而非大气降水。     

鄂尔多斯盆地东胜砂岩型铀矿中铀矿物的电子显微镜研究

鄂尔多斯盆地东胜铀矿是我国一个重要的大型砂岩型铀矿床。通过电子显微技术,对该铀矿床中铀矿物的种类、产出特征进行详细的研究。研究确定东胜砂岩型铀矿床中铀矿物主要为铀石和水硅铀矿,两者紧密共生,它们均为表生铀矿物。铀矿物的颗粒十分细小,一般粒度均为微米级。铀石和水硅铀矿往往呈板状、不规则微粒状产出,铀矿物的表面溶蚀现象明显,有的还具纳米级的溶蚀孔。铀矿物的产出与蚀变黑云母、蚀变黄铁矿密切相关,也见到微脉状铀矿物集合体穿切碎屑石英等现象。研究表明在表生作用下,该铀矿床中的铀元素存在溶解(迁移)-沉淀(富集)的反复过程。     

Uranium in supergene phosphorites

The distribution of uranium was studied in supergene phosphorites from the zones of the weathering of sedimentary and endogenous rocks, as well as in nonmarine coprolitic phosphorites and, to a lesser extent, phosphorites from ocean islands. These phosphorites show a diversity of the composition of their carbonate-apatite and structural characteristics. The uranium content ranges mostly from 5 to 100 ppm, with minimum and maximum values of 0.5 and 790 ppm. There is no correlation between the uranium content of a phosphorite and the type of rock with which it is connected. Lacustrine coprolitic phosphorites show elevated uranium contents (about 200 ppm). The maximum uranium content was detected in finely laminated phosphorite encrustations. The correlation analysis of the whole data set (63 samples) showed that uranium content is not correlated with any other component of phosphorites at a confidence level of 0.95. In contrast, there is a correlation between U and P₂O₅, CaO, and F for the combined set of samples from southern Siberian deposits. The significant correlation of U with Na₂O and CO₂ is variable both for southern Siberia on the whole and for particular deposits from this region.     

Uranium in the mineralized lakes of Altai Krai

Data on the physicochemical properties (pH, Eh, salinity) and content of U and other trace elements (As, Li, B, Br, I, Sr) are provided for the mineralized lakes of the Kulundinskaya steppe of Altai Krai. The sodic lakes of the region are characterized by higher U²³⁸ contents (up to 4 mg/l). The U contents in the lake waters are positively correlated with the sum of carbonate and hydrocarbonate ions and the pH of waters and are negatively correlated with salinity. These data confirm the presence of an economic U-bearing zone of the ground reservoir oxidation located along the eastern slope of the Platovskoe uplift in the northwestern direction along the boundary with Kazakhstan.     

Uranium geochemistry of Orca Basin

Orca Basin, an anoxic, brine-filled depression at a depth of 2200 m in the Northwestern Gulf of Mexico continental slope, has been studied with respect to its uranium geochemistry. Uranium concentration profiles for four cores from within the basin were determined by delayed-neutron counting. Uranium concentrations ranged from 2.1 to 4.1 ppm on a salt-free and carbonate-corrected basis. The highest uranium concentrations were associated with the lowest percentage and δ¹³C organic carbon values.For comparison, cores frm the brine-filled Suakin and Atlantis II Deeps, both in the Red Sea, were also analyzed. Uranium concentrations ranged from 1.2 to 2.6 ppm in the Suakin Deep and from 8.0 to 11.0 ppm in the Atlantis II Deep. No significant correlation was found between uranium concentrations and organic carbon concentrations and δ¹³C values for these cores.Although anoxic conditions are necessary for significant uranium uptake by non-carbonate marine sediments, other factors such as dilution by rapidly depositing materials and uranium supply via mixing and diffusion across density gradients may be as important in determining uranium concentrations in hypersaline basin sediments.     

赣南鹿井矿田铀成矿远景预测

鹿井地区铀矿勘查工作始于1958年,至20世纪90年代结束,已落实为鹿井铀矿田。2009~2012年间核工业270研究所在该区开展了铀成矿潜力评价及普查找矿工作,取得了一系列的勘查成果。介绍了鹿井铀矿田的地质概况及地球物理场和地球化学场特征。重点介绍了区域布格重力场特征;区域航磁异常特征;航空伽玛能谱场特征。根据遥感影象资料,认为丰州盆地正好处在一个大的环形构造中,而且在盆地西北部,也可清晰的见到较小的环形构造。结合环形构造的边缘分布有花岗岩杂岩体,鹿井矿田铀矿床与火山塌陷中的环状花岗岩杂岩紧密相伴,铀矿体主要分布在环状杂岩体顶部、旁侧等接触变异部位。丰州盆地具有较好的铀成矿远景。