甘肃小柳沟钨钼多金属矿田构造叠加晕浅析及找矿预测

Analysis of Structural Superimposed Halos and Ore Prospecting Prediction of the Xiaoliugou Wolfram-Molybdenum Polymetallic Ore Field in Gansu Province

通过对小柳沟钨钼多金属矿田地质地球化学特征及前人资料的综合研究,以小柳沟矿田中部祁青钼矿床4线构造叠加晕和深部成矿预测研究为重点,用围岩31件背景样品的几何平均值,为构造叠加晕分带提供地球化学背景依据;以小柳沟钨钼多金属矿单期次成矿原生晕轴向分带序列(自下而上)Cr、Co、Ni、V、Ti→W、Mn、Be、Sn、Bi、Mo、Cu→Pb、Zn、Ag→Au、As、Sb为基础,分析认为祁青钼矿4线构造叠加晕轴向分带序列(自下而上)Cu、Mo、Pb、Sb→As、Zn、Sn、Nb→Bi、V、Ti、Ba、Cr→Mn、W、B具"反分带"特征,且存在地球化学参数"反转"现象,指示成矿作用有叠加,预测深部存在第二成矿空间,钻探工程验证在祁青钼矿深部发现含钼隐伏花岗岩体,且岩体上部仍有石英脉型钼矿体,证实了构造叠加晕对深部找矿预测的有效性。认为小柳沟矿田深部斑岩型钼矿资源潜力较大,晚期花岗岩体凸起部位和外围分别是是寻找钼、中低温硫化物有关的铅锌矿床的有利地带。

This paper presents a comprehensive study of geological and geochemical characteristics of the Xiaoliugou wolfram- molybdenum polymetallic ore field in Gansu Province. It focuses on the structural superimposed halos of exploration line No. 4 and metallogenic prediction of the Qiqing molybdenum deposit in the deep subsurface. Using the geometric mean of 31 background samples from country rock,it provides the basis for anomaly zoning of structural superimposed halos. The analysis is based on the order of primary halo axial zoning related with mineralization of Tungsten and molybdenum polymetallic ore,i. e. Cr,Co,Ni,V and Ti → W,Mn,Be,Mo,Bi,Sn and Cu→Pb,Zn and Ag→Au,As and Sb. Analysis suggests that the vertical zoning sequence of exploration line 4 at the Qiqing molybdenum deposit is,from lower to upper,Cu,Mo,Pb and Sb→As,Zn,Sn and Nb→Bi,V,Ti,Ba and Cr→Mn,W and B,which is a ＂ anti- zoning＂ sequence,indicating mineralization stacked and multi- metallogenetic characteristics. Meanwhile,geochemical parameters have an ＂ inverting＂ phenomenon. So it predicts the existence of second metallogenesis space in the Qiqing molybdenum deposit at depth. As varified by drilling,a quartz vein molybdenum ore body and molybdenum containing concealed granite are present in the deep subsurface. It confirms the effectiveness of structural superimposed halos in prospecting prediction toward depth. It suggests that the deep porphyry type molybdenum ore resource potential is large in the Xiaoliugou ore field. The protrudent parts and periphery of later granite mass are favorable locations for looking for molybdenum and associated medium- low temperature sulphide lead- zinc deposits,respectively.