关于火山岩型铀矿床成矿规律中一些问题的讨论

DISCUSSION ON SOME PROBLEMS OF METALLOGENESIS OF VOLCANIC URANIUM DEPOSITS

火山岩型铀矿常位于大的地质构造单元界线附近,特别是稳定区与活动区之间的过渡带上。矿区的基底不仅需有较高的成熟度而且是在火山岩形成前或长期处于隆起状态者。负向火山构造,上叠式或拗凸型上叠式火盆是铀矿田的有利构造形式。红盆对成矿的作用不是古气候方面的而是构造方面的。火山岩型铀矿成矿深度可以较大,而且在垂向上不只一个富集高峰。铀及其主要伴生组份不是来源于赋矿围岩,而是来自基底或更深处。

The deposits of volcanic type are distributed, as a rule, near the boundary between different tectonic units, in particular, along the transitional zone between stable and active blocks. The basement of uranium deposits should be of high maturity and exist in upheaval position before volcanism for a long time. The negative volcanic structures, volcanic basins of superimposition type or basins of wraping superimposition are more favorable for ore-formation. The role of red basin for mineralization lies mainly in structure aspect. The depth of uranium mineralization may be considerably great, and there can be more than one concentration peaks in vertical distribution of uranium ore. Uranium and its main accompanying constituents are mostly derived from basement and/or deeper sites, rather than from host volcanic rocks.