新疆阿尔金地区卡尔恰尔超大型萤石矿床地质特征及成因

近期在新疆阿尔金地区发现的卡尔恰尔超大型萤石矿床位于阿尔金造山带中部地块变质杂岩带。该矿床主要沿中奥陶世二长花岗岩及变质杂岩的接触带分布,并受韧性剪切断裂及裂隙构造控制。矿石主要类型为萤石方解石脉型,矿物成分以方解石和萤石为主,含少量石英和钾长石。该矿床研究程度低,成矿物质来源及矿床成因不清。在系统总结萤石矿床地质特征基础上,重点开展了萤石矿床垂向分带、矿石结构与构造、矿石与围岩的稀土元素地球化学特征等方面的研究。结果表明:萤石方解石脉的球粒陨石标准化稀土元素配分模式呈明显的右倾“海鸥式”模型,Eu具明显的负异常(0.33～0.44),Ce异常不明显(1.02～1.07); 萤石方解石脉与古元古代变质杂岩、中奥陶世二长花岗岩的球粒陨石标准化稀土元素配分模式基本一致,反映了萤石方解石脉的成矿物质来源与古元古代变质杂岩和中奥陶世二长花岗岩有关。最后,在上述基础上提出了该萤石矿床的成矿模型。

Geological Characteristics and Genesis of the Super-large Kalqiar Fluorite Deposit in Altyn Tagh Area of Xinjiang,China

The super-large Kalqiar fluorite deposit was discovered recently in Altyn Tagh area of Xinjiang. The deposit is located at Azhong micro-massif in central Altyn Tagh orogeny. The ore bodies are distributed along the contact zone of Middle Ordovician monzogranite and metamorphic complexes, and controlled by ductile shear zone and fracture structure. The main ore type is fluorite calcite veins. The mineral composition is mainly calcite and fluorite with a small amount of quartz and K-feldspar. The source of ore-forming materials and genesis of the deposit are unclear. The geological characteristics of fluorite deposit were systemly summarized, and the vertical zoning of ore vein, ore fabric, and REE compositions of ores and surrounding rocks were detailed studied. The results show that the chondrite-normalized REE patterns of fluorite calcite veins display right-dipping, the Eu has obvious negative anomaly(0.33-0.44), and Ce abnormality is not obvious(1.02-1.07); the chondrite-normalized REE patterns of fluorite calcite veins are basically consistent with those of metamorphic complexes and monzogranites. It is suggested that the ore-forming materials are derived from Palaeoproterozoic metamorphic complexes and Middle Ordovician monzogranites. Finally, the ore-forming model of the super-large Kalqiar fluorite deposit is established.