安徽庐枞盆地与正长岩有关的成矿作用

安徽庐枞盆地位于长江中下游成矿带内,定位于扬子板块、华北板块与大别造山带之间,为一中生代陆相火山岩断陷盆地。庐枞盆地内广泛发育中生代岩浆活动,包括龙门院、砖桥、双庙、浮山4个旋回的火山岩及同期次侵入的中酸性岩体。盆地中成矿作用类型丰富,矿种多样,与龙门院旋回有关的潜火山热液型铅锌矿床、与砖桥旋回有关的玢岩型铁矿床是盆地中重要的成矿作用系列,以往工作较为全面地对这两个成矿系列进行了研究。随着近几年找矿工作的突破,盆地中与正长岩类有关的铁氧化物-铜-铀矿床逐渐受到重视。本文以深部探测ZK01孔深部铀矿化、马口铁矿、黄梅尖岩体周边铀矿床为研究对象,初步探讨区域与正长岩类有关的铁氧化物-铜-铀矿化系列,为庐枞整装勘查区找矿工作提供新思路、新方向。

The Mineralization Related with the Syenite in Luzong Basin, Anhui Province

Luzong basin located in the Middle Lower Yangtze River metallogenic belt is a Mesozoic terrestrial volcanic basin. Tectonically, Luzong basin is located among the Yangtze Plate, North China Plate and Dabie Orogeny. The volcanic rocks and synchronous intrusions occur widely in the basin, including four groups of volcanic rocks, such as Longmengyuan Group, Zhuanqiao Group, Shuangmiao Group and Fushan Group. The mineralization in the basin is of various series, including the lead zinc deposits related with Longmengyuan Group and the porphyrite type iron deposits related with Zhuanqiao Group. Recently, the researches begin to focus on the iron oxide copper uranium mineralization with syenite. Based on the study of Makou iron deposit, the uranium mineralization in the ZK01 drilling and the uranium deposits around Huangmeijian intrusion, we systematically conclude the geological characteristics and the genesis of the iron oxide copper uranium mineralization with syenite in Luzong region. The iron dioxide copper uranium mineralization occurred in the inner syenite intrusions and the contact zone, which has genetic relationship with the Cretaceous magmatism. According to the tectonic background and geochemical characteristics, the iron dioxide copper uranium mineralization in Luzong basin can be classified into two types, including iron dioxide copper uranium mineralization related with the alkaline syenite and iron dioxide copper mineralization related with A type granite. The iron dioxide copper uranium mineralization related with the alkaline syenite locates in the inner Luzong basin, whereas iron dioxide copper mineralization related with A type granite locates at the southeast boundary of Luzong basin. The age of iron dioxide copper uranium mineralization ranges from 130Ma to 110Ma when the region is in extensional setting. The mineralization similar with the IOCG type deposits probably represents the latest stage of mineralization in Luzong region and middle lower reachers of Yangtze River metallogenic belt.