岩屑测量方法在干旱荒漠区的找矿效果——以贺兰山北段嘎拉斯台白钨矿的发现为例

贺兰山北段地区构造活运强裂,中酸性侵入岩发育,化探异常普遍存在,找矿标志信息丰富,是金、钨等矿产的富集区。该区属干旱低山丘陵荒漠地球化学景观区,前人在该区完成的1∶20万水系沉积物测量工作受采样介质、样品粒级、测试设备、分析方法等条件限制,获得的有用找矿信息不强。本次化探工作采用不规则网1∶5万岩屑测量、-4～+20目采样粒级及采样层位为C层的工作技术方法,共圈定30个综合异常,呈NE向带状分布。通过异常查证,新发现各类矿点、矿化点14处,圈定出3个找矿远景区,优选出9个找矿靶区,取得了较好的找矿成果。此外,本次工作首次在太古宇贺兰山岩群第二岩组硅化浅粒岩中发现了层控型白钨矿,其形成环境与国内已知的白钨矿矿床的形成环境完全不同,矿体产于太古宙中深变质岩系中,呈层状、似层状。此类矿床鲜有报道,因此,该钨矿的发现,对在前寒武纪中深变质岩中寻找层控型白钨矿具深远意义,也为该区在白钨矿找矿上提供了参考。

The prospecting effect of rock debris measurement method in arid desert area:Exemplified by the discovery of the Galasitai scheelite deposit in northern Helan Mountain

In the northern part of Helan Mountain, the structure is active and strong, the mid-acid intrusive rock is well developed, and the metallogenic exploration is favorable. The mineral prospecting indicators have rich information, suggesting a good gold and tungsten prospecting area. This area is characterized by arid low mountain and hilly desert geochemical landscape. The 1∶200,000 river sediment measurement work completed by the previous workers in this area is limited by unfavorable conditions such as sampling media, sample grain level, test equipment, and analysis methods, making the useful prospecting information weak. In this study, the chemical exploration work used an irregular network of 1∶50,000 rock debris measurement,-4 to +20 sampling grain meshes, and a C-layer working technical method in sampling layer, which led to the delineation of 30 comprehensive anomalies. There are 9 anomalies of Au, W, As, and Sn in the distribution area of the metamorphic rock in the second rock group in Yanqun area of Helan Mountain. Through anomaly verification, 14 new ore spots and mineralization spots were discovered, and 3 of them were identified., In addition, 9 mineral target areas were selected through optimization. Thus, good ore prospecting results were obtained. For the first time, laminated scheelite was found in the silicified shallower part of the second group of Helan Mountain Rock Group. The significance of this discovery lies not only in the discovery of ore spots in the investigation area but also in the study of formation environment of known stratabound scheelite ore deposits in China. The orebodies were produced in the meso-deep horizons of metamorphic rocks and are characterized by stratiform or stratoid forms, which is very rare in the world.