共查询到20条相似文献，搜索用时 46 毫秒
1.
The Upper Aillik Group is an Early Proterozoic supracrustal sequence of felsic volcanic and associated sedimentary rocks occurring in the Makkovik Province of Labrador. The unit extends from the coast inland for over 90 km and is host to numerous occurrences of metallic mineralization ranging from indications to deposits. Coastal exposures of the Upper Aillik Group are cut by numerous high level, post-tectonic cupolas, whereas, inland the cupolas are lacking. There are three types of mineralization in coastal portions of the Upper Aillik Group, viz.; lead-zinc, molybdenite and uranium. Pb isotope data indicate the age of the post-tectonic granites. Skarnoid and disseminated molybdenite mineralization associated with these same granites indicate the molybdenum was probably derived from the granites. Similarities in REE patterns for the U, Pb-Zn and Mo occurrences imply that all three different types of mineralization in the coastal regions were derived from the post-tectonic granites. Inland, the felsic volcanic rocks solely contain uranium occurrences, in which the uranium mineralization is associated with pyroxene and amphibole-rich layers or disseminations in the host volcanic rocks. The REE patterns of this mineralization are significantly different from those of the coastal occurrences. These occurrences appear to represent syn- to postvolcanic products of hydrothermal leaching of volcanic glasses. 相似文献
2.
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
3.
《International Geology Review》2012,54(11):1027-1047
New geological and petrological data on the range of magmatic complexes and formations of the Eastern Sayan show two primary magmas: basic and granitoid. These magmas were formed through melting hard deep-seated layers of the earth crust: basaltic and sialic. During the geosynclinal stage the development of magmas belonging to the Archean, Proterozoic, and Salair [Cambrian] volcanic cycles proceeded consecutively from ultrabasic and basic formations formed in a pre-orogenic or earlier-orogenic geosynclinal development stage to granitoids set up in a synorogenic or later-synorogenic development stage. During the platform stage middle Paleozoic (Lower Devonian) and Mesozoic-Cenozoic cycles of magmatism proceeded directly, without the geosynclinal preparatory stage. Their development, accompanied by faulting, proceeded in reverse order from acidic and alkalic intrusions to predominantly basic eruptives. A further development of deep-seated basic and granitoid magmas was determined first by magmatic differentiation and later by assimilation phenomena which took place during the magma's passage into upper structural layers. The granitoids of geosynclinal magmatic complexes correspond petrochemically to the intermediate types of calc-alkalic rocks of the Pacific Ocean belt. The granitoids and alkalic rocks of the Lower Devonian platform magmatic complex resemble those of the Cenozoic East-Asia alkalic province. The composition of the granitoid magma belonging to the volcanic cycle is conditioned initially chiefly by the sial environment and geosynclinal strata. Magmatic complexes and formations are characterized by definite endogenic mineralizations. Chromium, nickel, cobalt, platinum, diamond, asbestos and other deposits are genetically connected with Proterozoic basic and ultrabasic rocks; gold, muscovite and tin-rare metal pegmatite with upper Proterozoic granitoids. Copper, galenaite and gold-ore occurrences are related to the postmagmatic manifestations of Salair granitoids. Deposits of pyrochlore carbonatites, molybdenite, graphite and others belong to Lower Devonian acidic and alkalic granitoids. — Auth. English summ. 相似文献
4.
中国金矿床成矿时代及其特征 总被引：3，自引：0，他引：3
根据 70 4个主要金矿床的成矿时代研究 ,将中国金矿床划分为古元古代、中新元古代、早古生代、晚古生代、三叠纪、侏罗 -白垩纪、新生代 7个成矿期。统计分析了各成矿期形成的金矿床数量、储量及矿床类型 ,总结了各成矿期金矿床的分布特征。 相似文献
5.
中国北西部地区砂岩型铀矿含矿建造及找矿前景 总被引：3，自引：0，他引：3
本文在分析中国北西部地区大地构造背景的基础上,依据孕育中、新生代沉积盆地形成的基底构造性质,将其划分为板内陆台型、板缘褶皱造山带型和板缘过渡带型3种类型,板缘褶皱造山带型又进一步划分为洋侧造山带型和陆侧造山带型两个亚类。砂岩型铀矿的产出盆地与盆地所处的构造背景和构造类型有关,砂岩型铀矿产出盆地主要为板缘褶皱造山带型,其次为板内陆台型。砂岩型铀矿对盆地沉积建造类型具有明显的选择性,其原始沉积均为一套温湿气候条件下形成的灰色层,其岩石原生地球化学类型为黑色或灰色。中国北西部地区中新生代盆地形成可地浸的砂岩型铀矿的找矿层位或含矿建造主要为中、下侏罗统(J1-2)和上白垩统(K2),其次为下白垩统(K1),其他地质时期地层内铀矿床分布零星,成矿潜力很小。 相似文献
6.
《International Geology Review》2012,54(9):763-768
The present paper is a discussion of some aspects of the geology of the uranium deposits in lower Proterozoic carbonates of one district. The inference that uranium, phosphorus and organic matter in the carbonates is of primary sedimentary origin comes from the fact that the uranium minerals are concentrated in only one stratigraphic zone of the thick lower Proterozoic sequence, that the uraninite is always intimately associated with apatite and graphitic matter, and that the greatest degree of uranium enrichment is encountered in intensely faulted zones. This type of uranium mineralization, apparently, is the result of the deposition, diagenesis, and subsequent metamorphism of the uranium-bearing sediments. Subsequently, regional metamorphism and folding created beds and lenses of uranium-bearing dolomitic marbles; the metamorphic processes also involved a redistribution and partial migration of the material in the rocks. A redistribution of uranium, and its concentration in favorable structural zones, was produced by the tectonic stresses associated with folding and shearing in the lower Proterozoic rocks. -- J. K. Hartsock 相似文献
7.
J.P. Jones 《Precambrian Research》1985,28(2):111-135
The geology of the southeastern and southwestern margins of the Guaporé Shield is described. The Shield rocks comprise high-grade granulite and low-grade greenschist sequences. These rocks are poorly known. Oldest recorded ages include Transamazonian datings (± 2 Ma). The margins of the shield show the development of a mobile belt formed by rocks of Upper Proterozoic to Cambrian age. Within this mobile belt, the Cuiabá Group of uncertain (but possibly Upper Proterozoic) age outcrops to the east and shows tectonic contacts with younger rocks that span the Vendian (Upper Proterozoic) to Cambrian age. The rocks of Vendian to Cambrian age form three isolated elongated basins which show evidence of fault control. The axes of these basins are equally separated by angles of ～ 120° and meet at a triple junction near Corumbá. The stratigraphy of the Vendian to Cambrian basins is correlated from Bolivia to Brazil, based on tectonic continuity, sedimentological similarity and fossil content. The central location at Corumbá shows instability since the Middle Proterozoic when important igneous activity is recorded at Rincon del Tigre (Bolivia) and in Brazil. This igneous activity is interpreted as being related to hot-spot activity in an intercratonic setting from which the younger Upper Proterozoic basins originated. 相似文献
8.
非洲铀矿资源丰富,在全球占有重要地位,是我国利用铀矿资源的重要来源地。通过分析非洲259处已知铀矿床（点）的地质特征与勘查开发现状,揭示非洲铀矿资源具有分布集中、规模巨大、矿床类型多样等特点,砂岩型、古石英-卵石砾岩型、侵入岩型是最重要的铀矿类型,非洲铀矿主要分布于卡普瓦尔克拉通、新元古代褶皱带的达马拉褶皱带和西非活动带伊勒姆登大型盆地,成矿作用明显受地层、构造、岩浆岩等控制。不同类型矿床成矿时代具有各自特征,古石英-卵石砾岩型铀矿床全部形成于太古宙,侵入岩型铀矿床大多形成于元古宙,砂岩型铀矿床形成时代跨度大,从元古宙到新生代均有产出。近十年来非洲新增铀储量27万吨。建议国内企业抓住机遇,以侵入岩型和砂岩型铀矿为投资重点,加强在纳米比亚和尼日尔等铀矿资源国的勘查开发合作。 相似文献
9.
10.
11.
Willy Dyck 《Journal of Geochemical Exploration》1976,5(1-2)
A literature review of the source and occurrence of helium shows that it can, under favorable conditions, lead to the discovery of radioactive ore deposits, oil and gas pools, and fracture zones associated with mineral occurrences. Analytical results show that anomalous helium is present in groundwaters and near uranium occurrences and thus can aid in the identification of uranium occurrences or prospective target areas for uranium exploration. 相似文献
12.
Over 450 samples were collected around four Proterozoic porphyry-type occurrences and analyzed for 30 elements. Relatively broad primary halos are associated with all four occurrences in spite of their moderate size and grade. The halos are characteristic of each particular occurrence depending on the geological and geochemical conditions. Copper forms extensive and highly contrasted anomalies, whereas Mo anomalies are of limited size. Gold, Zn, Pb, As, and Sb seem to be useful pathfinders for slightly eroded or blind occurrences. Pyritization and wall-rock alteration are weaker than in Phanerozoic porphyry deposits, consequently, S halos are small and often erratic. K2O, Rb, and SiO2 produce weak anomalies near the core of the occurrences. A density of a few tens of samples per km2 is required for detailed follow-up exploration.The host granitoids have normal chemical compositions outside the mineralized areas with low and constant background contents of ore elements and are thus very suitable for lithogeochemical exploration. On a regional scale a density of one to five samples per km2 is sufficient to identify mineralized intrusive phases and areas, because the porphyrytype occurrences were formed by extensive hydrothermal processes, which produced scattered anomalies over large areas. 相似文献
13.
根据国内外发现的地洼区及其与铀成矿时代的关系,分为早元古代、中元古代、晚元古代、早古生代、晚古生代,中生代和新生代等7个不同时代的地洼区。铀的成矿富集,发生在地洼阶段激烈期向余动期的过渡时间内。元古代地洼区地壳固结早,铀成矿年龄值大,地洼余动期时间长。中新生代地洼区地壳固结晚,铀成矿年龄值小,地洼余动期时间较短。 相似文献
14.
松辽盆地构造演化划分为前中生代克拉通基底演化、晚侏罗世挤压火山穹窿演化、早白垩世伸展断陷、晚白垩世早期热冷却坳陷、晚白垩世晚期反转褶皱隆升萎缩剥蚀、古近纪伸展断陷隆升剥蚀及新近纪—第四纪挤压坳陷等7个演化阶段。本文系统讨论了松辽盆地北部构造演化与铀成矿作用的关系,指出晚白垩世早期冷却坳陷、晚白垩世晚期反转褶皱隆升萎缩剥蚀、古近纪伸展断陷隆升剥蚀3个阶段为区内主要铀成矿阶段。铀矿化的分布受基底断裂及反转构造带联合控制。松辽盆地北部构造演化对各构造分区铀矿床成矿类型具有明显的控制作用：西部斜坡区以寻找"古层间氧化"型、层间氧化型砂岩型铀矿床为主要类型;中央坳陷区及东北隆起区应围绕大庆长垣、绥棱背斜带等构造剥蚀天窗寻找"钱家店"式砂岩型铀矿床;北部倾没区及东北隆起区盆缘以寻找层间氧化型砂岩型铀矿床为主要类型。 相似文献
15.
S. M. Aleksandrov 《Geochemistry International》2007,45(2):152-169
The paper presents materials on the genesis of gold deposits of the magnesian-skarn association. It is demonstrated that sulfides are precipitated at these deposits late in the course of the mineral-forming process and often contain visible and fine gold. Post-sulfide mineral-forming processes resulted in the widespread development of hydroxisulfides: tochilinite and valleriite in high-Mg rocks and borate ores affected by serpentinization, brucitizatin, and szaibelyitization. The newly formed hydrosulfides inherit gold from the replaced sulfides. The endogenic or supergene decomposition of tochilinite and valleriite in endogenic and supergene environments stimulates the dissolution of the fine-grained gold and its remobilization, first, by hydrothermal solutions and, subsequently, by meteoric waters. The possibility is discussed of the later regeneration of gold as a consequence of electrochemical processes or at geochemical barriers. The deposition of “newly formed” gold in weathering crusts and placers is discussed, along with the significance of this process for assaying the potential of the weathering crusts and placers. It is emphasized that a significant role in this process is played by cryogenic processes, which can increase gold concentrations in naturally occurring solutions and facilitate its later regeneration. The data presented in this paper are compared with data on gold and PGE deposits of other genetic types, which are hosted in ultramafic rocks and carbonatites, i.e., rocks petrochemically similar to magnesian skarns. It is demonstrated that the occurrence of hydroxisulfides in the ores is a significant geochemical and technological problem during the exploration for sulfide ores and their mining and processing. The magnesian skarn ores of the deposits discussed in this publication were determined to be a significant source of both primary and placer gold and, perhaps, PGE also. The materials presented in the paper characterize the behavior of gold in the endogenic and supergene processes at magnesian skarn deposits. 相似文献
16.
本文研究了中条山地区基底涑水杂岩,含矿层中条群岩石和铀矿化岩石的稀土元素特征及其与铀元素的关系。发现稀土元素,尤其是重稀土元素对铀的区域富集及铀矿化作用有一定的指示意义。 相似文献
17.
N. V. Chalapathi Rao M. Anand A. Dongre I. Osborne 《International Journal of Earth Sciences》2010,99(8):1791-1804
A number of limestone and metasomatised carbonate xenoliths occur in the 1,090 Ma Siddanpalli kimberlite cluster, Raichur
kimberlite Field, Eastern Dharwar craton, southern India. These xenoliths are inferred to have been derived from the carbonate
horizons of the Kurnool (Palnad) and Bhima Proterozoic basins and provide evidence for a connection between these basins in
the geological past. A revised Mesoproterozoic age is proposed for the Bhima and Kurnool (Palnad) basins based on this kimberlite
association and is in agreement with similar proposals made recently for the Chattisgarh and Upper Vindhyan sediments in Central
India. The observed Bhima–Kurnool interbasinal uplift may have been caused by: (1) extension- or plume-related mafic alkaline
magmatism that included the emplacement of the southern Indian kimberlites at ~1.1 Ga, (2) mantle plume-related doming of
the peninsular India during the Cretaceous, or (3) Quaternary differential uplift in this region. It is not possible, with
the currently available geological information to constrain the exact timing of this uplift. The deep erosion of primary diamond
sources in the Raichur kimberlite Field in the upper reaches of the Krishna River caused by this uplift could be the elusive
source of the alluvial diamonds of the Krishna valley. Mesoproterozoic sedimentary basins can host world class unconformity-type
uranium deposits. In light of its inferred Mesoproterozoic age, a more detailed stratigraphic and metallogenic analysis of
the Kurnool basin is suggested for uranium exploration. 相似文献
18.
水口山-临武南北带铀成矿地质条件优越,前人经过多年的地质找矿工作,在带内先后发现了一批铀矿床(点)。笔者通过对该带铀矿床(点)的成矿地质背景、空间分布、矿化特征、成因类型等进行研究,总结了南北带内铀成矿特征及成矿规律。认为区域性隆起及边缘断陷带、深大断裂、背向斜和断层构造等是带内铀成矿的有利条件;带内成岩机制为"沉积变质-动力破碎-热液交代-再动力破碎-再热液交代";铀矿床成因类型主要有热液型、热液叠加型和淋积型3种;各类型铀矿床的成矿模式,总体分为硅质岩系列、花岗岩系列和碳酸盐岩系列。 相似文献
19.
华南地区新元古代花岗岩铀成矿机制——以摩天岭花岗岩为例 总被引：3，自引：3，他引：0
华南是我国重要的花岗岩型铀成矿区,印支期-燕山期花岗岩是最主要的产铀花岗岩。广西北部形成于新元古代的摩天岭岩体是我国目前已知的最古老的产铀花岗岩体之一。前人对华南印支-燕山期花岗岩的铀成矿作用研究较深入,但对以摩天岭岩体为代表的新元古代古老花岗岩的铀成矿作用研究程度较低。本文以摩天岭花岗岩体为对象,进行了岩石学、地球化学、年代学及其铀矿成矿特征和规律的深入研究,取得以下认识:1)摩天岭岩体规模巨大,相带分布明显,内部相带和过渡相带发育,岩性主要为黑云母花岗岩、二云母花岗岩和含电气石二云母花岗岩,花岗岩体具有富硅富碱、铝过饱和、钾大于钠的特点,属S型花岗岩; 2)摩天岭岩体形成于850～760Ma之间的新元古代; 3)摩天岭岩体铀成矿潜力巨大,铀矿化以铀-绿泥石型和铀-硅化带型为主,铀-绿泥石型的代表矿床——达亮矿床形成于360～401Ma,是加里东期区域变质及构造活动共同作用的结果;铀-硅化带型铀矿的代表——新村铀矿形成于47Ma,是喜马拉雅期伸展构造作用下构造-热液活动共同作用的结果; 4)摩天岭岩体中铀矿床的铀源来自于元古界四堡群、丹州群和摩天岭岩体本身;成矿流体主要来源于大气降水,同时有深部流体的参与;热源主要与加里东期区域变质作用和喜马拉雅期伸展背景下的构造作用关系密切; 5)摩天岭岩体铀成矿经过了新元古代铀预富集、加里东晚期到海西早期的区域变质-构造热液成矿作用、喜马拉雅期的构造热液成矿作用等几个阶段,形成了类型丰富、规模较大的铀矿床,铀找矿潜力巨大。 相似文献
20.
O. A. Doinikova 《Geology of Ore Deposits》2007,49(1):80-86
Data on ningyoite [CaU(PO4)2 · 2H2O] occurrences in uranium ores and on deposits with ores composed entirely or largely of this mineral are considered. Most of the recent findings of ningyoite mineralization are confined to infiltration deposits, and only sporadic ones, to pegmatites and hydrothermal deposits. The geological settings and mineral assemblages indicate that ningyoite ores are formed from neutral or slightly alkaline solutions at higher Eh values relative to other types of uranium blacks (uraninite, coffinite) and are localized in the reducing zone at the boundary of redox zoning. The factors that testify to the decisive role of microbiological processes in the formation of monomineral ningyoite ore are considered. All hydrogenic deposits (occurrences) of ningyoite ore known to date in Japan, Bulgaria, Canada, Kazakhstan, and Siberia belong to the same ground-infiltration genetic type. 相似文献