北秦岭丹凤地区伟晶岩型铀矿控矿因素分析及找矿方向

Ore-controlling Factor and Exploration Direction of Granite Pegmatite Uranium Deposit in North Qinling Region

丹凤地区位于北秦岭造山带陕、豫交界处,夹持于商丹构造带与朱夏构造带之间,是我国伟晶岩型铀矿的重要产地。根据该地区的基础地质和近年铀矿科研成果,文章对晚加里东-早海西期北秦岭造山带东段伸展作用与铀成矿的关系进行了讨论,分析了伟晶岩型铀矿的控制因素,提出了找矿方向。研究认为,北秦岭造山带晚古生代的拉伸作用在丹凤地区表现明显,同期产生的富钾花岗岩-伟晶岩是铀的主要来源;历经多次区域热流变质、韧性流变变形并叠加热接触变质作用,对主要变质体中铀的活化、迁移起到了累积作用;同期产生的区域A型褶皱为有利的成矿空间。区内早泥盆世富钾花岗岩小岩体外接触带伟晶岩密集区或小岩体内部粗-伟晶状正长花岗岩分布区,是今后找矿的有利地段。明确指出,区内主要铀矿床深部仍有较好的找矿前景。

Danfeng area is an important producing base of pegmatite type uranium deposit in China, which is clamped by Shangdan and Zhuxia structural zone in the northern Qinling orogenic belt along the border of Shaanxi and Henan. Based on the geological and recent uranium research results, the relationship between the extension of the eastern section of the northern Qinling orogenic belt and the uranium mineralization in the Late Caledonian to Early Hercynian was studied and the control thctors were analyzed so as to find the direction of uranium exploration. The results showed that there were obvious tectonic extension in the Late Paleozoic in the north Qinling orogenic belt, and the K-enriched granite-pegmatite series tormed during the stretching are the main uranium source. The regional heat metamorphic and ductile rheological deiormation superimposed by thermal contact metamorphism played a cumulative role in the activation and migration of uranium in the main metamorphic rocks. The regional A-type tolds produced in the same period are the thvorable metallogenic spaces. The contact zone of Early Devonian K-enriched small granite intrusions to Qinling group or the distribution area of pegmatite-anhydrite granosyenite within the small intrusions are the thvorable prospect tor tuture prospecting. It was explicitly pointed out that there are good prospects in the depth of the main deposits.