江西大湖塘北区石门寺矿段钨矿成矿条件与找矿预测

Metallogenic Conditions and Ore-Prospecting of Shimensi Tungsten Ore Section in the North of Dahutang Area in Jiangxi Province

在大湖塘北区钨矿找矿勘查过程中,在总结分析20世纪80年代初针对石英大脉型黑钨矿的普查资料基础上,通过地表填图和老窿编录,发现前人认为的混合黑云母花岗岩与混合白云母花岗岩之间为截然清楚的侵入接触关系,二者之间稳定地分布着一层似伟晶岩壳;由空间关系和区域成矿规律推断似斑状黑云母花岗岩为燕山期侵入于晋宁期黑云母花岗闪长岩之中的成矿母岩。晋宁期黑云母花岗闪长岩为成矿有利围岩,在云英岩化等蚀变过程中释放出形成白钨矿的钙离子。燕山期似斑状黑云母花岗岩岩株与晋宁期黑云母花岗闪长岩岩基之间的侵入接触界面是最主要的成矿构造与成矿结构面,控制了主矿体的位置、形态与产状。在研究区内首次于新元古代花岗闪长岩中发现厚大的白钨矿工业矿体,并根据不同岩块混杂、被长英质充填物胶结等特征识别出热液隐爆角砾岩型矿体。基于对矿区成矿地质条件和矿床地质特征的新认识,修改了针对石英大脉型黑钨矿所做的详查设计,抓住细脉浸染型白钨矿这一主要矿床类型,及时调整了找矿目标和勘查手段,在短时间内实现了赣北地区钨多金属找矿的重大突破。通过与石门寺矿段成矿地质条件类比,预测毗邻的苗尾矿段与太平洞矿区找矿潜力大。

By analyzing previous mineral exploration, geological mapping and old-workings of Shimensi ore section in the north of Dahutang area, it has been proven that there occurs intruding boundary and stratiform pegmatite-like crust between the mixed biotite granite and muscovite granite. According to the spatial relationship between the two intrusions and recording the clear he mixed regional metallogenic regularities, it can be concluded that the Yanshanian porphyritic-like biotite granite which played as the ore-source rock intruded into the Jinningian biotitic granodiorite. Due to the greisenization, the biotite granodiorite, the favorable ore-forming wall rock, released necessary calcium ions for the formation of scheelite. The contact interface between the Yanshanian porphyritic-like biotite granite stock and the Jinningian biotite granodiorite batholith was the major ore-forming structure or metallogenic interface, and controlled the location, shape and occurrence of main ore bodies. The thick scheelite ore body is firstly discovered within the Neoproterozoic granodiorite, which is determined as the hydrothermal cryptoexplosion breccia type, from distinct mixed rocks filled by felsic rock. The new- discovered veinlet-disseminated type scheelite ore resource is calculated, and the WO3 content is up to the industrial grade. New knowledge of the ore-forming condition and geological characteristics of the deposit lead to correcting design of the detailed survey aimed at the large quartz-wolframite vein, and important ore-prospecting breakthroughs of tungsten polymetallic deposit in the northern Jiangxi Province. Thanks to the ore-forming geological condition comparison, it can be deduced that the Miaowei ore section and Taipingdong orefield have the great ore-prospecting potential.