西秦岭白龙江复背斜两端弧形构造控矿特征初探

本文提出西秦岭南亚带弧形构造控矿的新认识,初步探讨了弧形构造的形成机制及控矿机制。两组斜列的弧形构造发育于白龙江复背斜东、西两端,并分别控制了两个Ａｕ（Ｕ－Ａｓ－Ｓｂ－Ｃｕ）矿集区。弧形构造顶部及附近的多组多方向次级断裂对本区大型金矿床及与成矿有关的中生代浅成－超浅成（碱质）中酸性岩浆岩具有明显的控制作用,弧形构造翼部的成矿条件则不如其顶部。

ORE-CONTROL FEATURES OF ARC STRUCTURES AT BOTH ENDS OF THE BAILONGJIANG ANTICLINORIUM OF THE WESTERN QINLING

The hydrothermal gold,uranium,arsenic and antimony deposits in the Bailongjiang anticlinorium of the western Qinling orogen are controlled by fault structures and closely related to magmatism and sub-volcanism in the Mesozoic.Two sets of en echelon arranged arc structures occur respectively at both ends of the Bailongjiang anticlinorium,controlling two highly mineralized areas (HMA) in the south-western Qinling.The Dashui-type gold deposits with gold-bearing jasperoid ores (an oxidation type),and the Lar''erma-type Au-U-Cu deposits with gold and uranium siliceous mudstone ores enriched in organic carbon (a reduction type) in the Maqu-Ruo''ergai Au-U(Cu) HMA in the west,are controlled by the Dashui arc structure and the Langmusi arc structure respectively.The Manaoke-type As-Au deposits,Xiaojinchang-type Fe-Cu-Au deposits,and the Xinguan-type hydrothermal gold deposits in the Zhouqu-Wenxian Au(Cu) HMA in the east,are controlled by the Wudu arc stucture and Wenxian arc structure respectively.As the major ore-control structures,the subsidiary fractures at the apices of the arcs have exerted some important effect on the formation of the two huge gold deposits,the Dashui super-large gold deposit and the Xinguan Lianhecun large gold deposit,as well as on the hypabyssal alkaline intermediate-acid magmatic and continental volcanic rocks which are genetically associated with the mineralization of the gold and uranium deposits.