西天山布吉汗扎依劳钨铜矿地质特征及锆石U-Pb成矿时限约束

Geological characteristics and Zircon U-Pb dating constraint of metallogenic time for Bujihanzailau tungsten-copper deposit in West Tianshan

新疆布吉汗扎依劳钨铜多金属矿是西天山地区发现的为数不多的钨矿之一,为厘定其成矿地质特征,探讨成矿时限,在矿区勘查评价工作基础上,开展了同位素地质年代学研究。LA-ICP-MS锆石U-Pb定年结果显示,杏仁状安山岩、中细粒二长花岗岩和正长花岗成岩年龄分别为(427.0±2.7)Ma、(297.0±1.5)Ma和(298.7±1.4)Ma,从而推断赋矿地层巴音布鲁克组应该形成于晚志留世,大面积分布的花岗岩侵位时代可能为早二叠世。布吉汗扎依劳钨铜多金属矿就位于二叠纪花岗岩外接触带志留系巴音布鲁克组地层的石英脉型钨铜多金属矿,矿(化)体呈脉状、透镜状产出,受到NWW向断裂构造和岩浆活动的双重控制,其构造充填成矿特征明显。矿石矿物组合为白钨矿、黄铜矿、闪锌矿,具有大中型钨矿床的找矿潜力。该矿床的发现丰富了新源那拉提一带找矿矿种组合和成矿类型,为西天山地区钨矿找矿工作进一步指明了方向。

Bujihanzailau tungsten-copper polymetallic deposit is one of the few tungsten deposits found in the West Tianshan.On the basis of exploration and evaluation,in order to determine the metallogenic geological characteristics and to discuss the metallogenic time limit,the isotopic chronology research is carried out in the paper.LA-ICP-MS zircon U-Pb dating result shows that the ages of amygdaloid andesite,medium-fine grain monzonite and syenite are(427.0±2.7)Ma,(297.0±1.5)Ma and(298.7±1.4)Ma,respectively.The ore-bearing strata of Bayinbuluk formation are formed in the Late Silurian,and the granites distributed in large area are emplaced in the Early Permian.Bujihanzailau W-Cu polymetallic deposit is a quartz vein type polymetallic deposit hosted in the outer contact zone of the Silurian Bayinbuluk Formation and the Permian granite,the ore bodies are veined and lenticular,and the mineral assemblages are scheelite,chalcopyrite and sphalerite,which might have the prospecting potential for at least large-middle scale tungsten deposit.The deposit discovery has enriched the ore-prospecting assemblages and ore-forming types at the Narati area,and the direction for the prospecting of tungsten deposits is proposed in the West Tianshan area.