中文摘要:本文在介绍3701铀矿床的地质特征、矿石物质成分和稳定同位素组成等研究结果基础上，论述了该矿床的成因。3701铀矿床赋存在L花岗岩体外接触带泥盆系灰岩中。花岗岩的黑云母钾-氩法年龄为318-202 Ma，矿床的矿化年龄（沥青铀矿铀-铅法年龄）为65.0-30.7 Ma，矿岩时差超过l37 Ma。矿床的热液矿化特征明显。成矿温度约100-300℃，属中、低温热液矿化。矿床的近矿围岩蚀变较弱。矿床的稳定同位素研究结果表明，成矿物质是多源的，其中硫、碳主要来自围岩，铀、铅主要来自花岗岩。矿液水以大气降水为主。铀背景值较低(3.12ppm)的成矿围岩，汲取了从花岗岩中淋出的含铀水体中的铀。被燕山期、喜山期构造运动加热了的地下水汲取围岩中的铀等成矿物质，在角砾岩带等地段沉淀成矿，因此该矿床属多矿源热液叠加改造成因。在两次铀矿化间隔期间，早期矿体曾遭受地下水的改造。
Abstract:The ore deposit under discussion iq hosted by argillaceous limestone of the Middle Devonian Yingtang Formation (Fig. l) and is situated in an exocontact belt (0-120 m) of the L granite body in which the biotite has K-Ar age of 202 to 318 Ma (Fig.2). The orebodies, lenticular arid stratoid in form, mostly occur in schistosity zones and breccia zones of the host rocks. The L granite body with an area of 238 km2 is a single-stage intrusive batholith which consists chiefly of coarsemedium grained biotite granite。The ores possess brecciated, veinlet and micro-vein -disseminated structure. Four stages of mineralization are recognized in the deposit (Table l). Uranium mineralization is related to pitchblende (sporadically with a small amount of coffinite) formed in the second stage (65.0-59.2 Ma) and the third stage (30.7 Ma). Gangue minerals are mainly calcite, pyrite, galena, sphalerite, chalcopyrite and tennantite. The host rocks show planar and linear hydrothermal alterations, in which K-feldsparization, hydromuscovitization, pyritization and chloritization are commonly seen but weak in intensity. Pb, Cu and Ag associated with U in the ores may be utilized in industry. Hydrothermal mineralization in the deposit has the following features: (1) Mineralization temperature ranged approximately from 100 to 300℃, and deposition of the pitchblende took place between 150℃ and 200℃; (2) pitchblende, niccolite, tennantite, galena, chalcopyrite and sphaleritein the deposit are typical hydrothermal minerals; (3) mineralization was controlled by zones of hydrothermal alteration. The groundwater transforniation of the ore finds expression in the following facts: (1) Pitchblende I (65.0-59.2 Ma) and sulfide minerals prior to the formation of pitchblende 11 (30.7 Ma) were extensively corroded by coolwater solution; ( 2) pitchblende II was deposited in corroded holes of the sulfitle minerals; (3) pyrite and calcite were mail11y deposited at ordinary temperature. The data of sulfur, carbon, oxygen isotopic compositions and U-Pb isotopic systems in the ores indicate that ore-forming materials in the deposit were fo multi-sources: S, C were mainly derived from the host rocks, and U, Pb mostly from the granitic rocks. The hydrothermal system was dominated by meteoric fluids. The background value of uranium in the host rocks is 3.12 ppm or lower, and uranium in the ores come from surrounding source rocks., mainly from the L granitic rocks. Uranium was released and mobilized in Cretaceous time by weathering processes of the grainite rocks containing appreciable uranium and then was effectively absorpted from very dilute leaching solution by limestone with abundant carbonaceous and argillaceous matters. The solution was heated at great depth and then moved upwards, during which it under reputedly dissolved uranium from the host rocks to form the deposit. During two stage of uranium mineralization ( forming respectively pitchblende I and II ) the deposit was transformed by groundwater.
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闽茂中，孔令福，张祖还，江仪，张国文.1987.3701铀矿床地质特征及其热液叠加改造成矿作用[J].矿床地质,6(4):72~81.1987.Geological Features Of A Uranium Deposit And Its Hydrothermal Superimposition And Transformation Ore-forming Processes[J].Mineral Deposits6(4):72~81
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