康滇地轴中南段铀成矿条件及远景分析

本文对康滇地轴中南段铀矿化划分出３种类型（砂岩型、钠交代岩型和元古代浅变质岩型），并阐明其主要特征。提出了元古代地壳演化曾经历了原始古陆形成阶段、沉降活动阶段和基底再团结阶段，认为中元古界昆阳群是有别于典型的含铀碳硅泥岩沉积建造。通过对该区部分岩石原始铀含量进行研究，提出了有关岩石可作为该区铀源岩的新认识；划分出碱性和酸性两大类型的热液蚀变，指出本区以发育碱性蚀变地段的成矿前景较好。指出该区铀成矿前景：（１）该区不具备形成澳加式元古代不整合面型铀矿床的地质条件；（２）非澳加式元古代不整合面型的铀成矿前景较差；（３）本区碱（钠）交代岩型铀矿化具有一定的找矿前景。

ANALYSIS OF CRANIUM METALLOGENIC CODITIONS AND PROSPECT IN THE CENTRAL-SOUTH PART OF THE XIKANG-YUNNAN AXIS

Three types of uranium mineralizations (sandstone type, sodium metasomatite type and Pro-terozoic slightly metamophic rock type)are distinguished in the central-south-part of the XikangYunnan Axis, and their major characteristics are expounded. It is proposed that the Early Pro-terozoic crustal evolution of the region includes primitive oldland formation stage, subsidencestage and basement reconsolidation stage, and that the Middle Proterozoic Kunyang Group is different from typical uraniferous carbonate-siliceous-argillitic sed imentary formation. The primitiveuranium contents of some rocks are studied in this region, and the uranium source rocks of theregion are proposed. It is also pointed out that there were two kinds of hydrothermal alterations,namely alkaline and acidic alteration, and the areas with the development of alkaline alteration arepromising for uranium metallogenesis.As for the U-metallogenic prospect of the region, three conclusions are summarized: (1)This region does not have favourable geologic conditions for the formation of Australian-Canadiantype Proterozoic unconformity-related uranium dePOSit; (2) It does not have promising U-metallogenic potential for non-Australian-Canadian type Proterozoic unconformity-related uraninm deposits either;(3) The alkaline (sodium) metasomatite uranium mineralizations in the region havesome prospecting potential.