摘要
毛洋头铀（银、钼）矿床，是产于早白垩世晚期（１２６．９×１０６ａ）火山口中的火山岩型矿床。基底构造和岩浆活化对矿床的形成起明显的控制作用，研究认为，该矿床成矿热液早期为岩浆水，晚期为大气降水；成矿元素Ｕ、Ａｇ、Ｍｏ有不同来源：其中早期矿化热液中的铀主要来自次火山热液或次火山岩，而晚期成矿热液的铀主要来自基底岩石（特别是黑云母花岗岩）；Ａｇ来自于基底变质混合岩；
The Maoyangtou deposit, a large size volcano hydrothermal uranium deposit associated with silver and molybdenum mineralization, is located in the Early Cretaceous crater controlled by the arcuate faulted zone on the northwestern margin of Fuluoshan volcanic basin at the northern end of the Wuyishan uranium metallogenic belt. The ore deposit occurs where the basement rock and the upper mantle are uplifted, with the regional NE and NEE trending faults controlling the distribution of the ore bearing volcanic basin whereas the intersections of NE trending faults with NW trending faults conditioning the development of orebodies . The basement Gaoxi granite of the basin does not contain much uranium, but the proportion of active uranium in it is quite high. Especially during the alteration, the proportion of active uranium increased, and large quantities of uranium were lost. Through migmatization, uranium content of basement metamorphic rocks in this area was raised, accompanied by the formation of lots of uranium occurrences as well as mineralized spots. Volcanic rocks in the ore bearing volcanic basin are divided into Changlin Formation and Nanyuan Formation. After the principal volcanic cycle, the crater was choked up due to the collapse of the volcano, and the ascending fluids characterized by high temperature, high pressure and rich volatiles would cause crypoexplosion in a low pressure environment. In this process, rhyolite was shattered, forming host space and a pathway for hydrothermal ore forming solutions. According to geological characteristics and isotope geochemistry of the ore deposit, it is thought that the hydrothermal ore forming solutions were mainly subvolcanic hydrothermal fluids at the early stage and meteoric water at the late stage. Uranium was mainly derived from subvolcanic rocks or subvolcanic hydrothermal solution at the early stage mineralization , and from basement rocks, especially from Gaoxi biotite granite, at the late stage mineralization. Silver came chiefly from metamorphic migmatite, whereas molybdenum from subvolcanic rocks or subvolcanic hydrothermal solution.
出处
《矿床地质》
CAS
CSCD
北大核心
1997年第2期139-150,共12页
Mineral Deposits
关键词
火山岩
铀矿床
控矿因素
成因
银
钼
ore control factor, genetic model, Maoyangtou volcanic rock
