北祁连红土沟——川刺沟金矿与韧性剪切带的成矿关系

通过对北祁连红土沟川刺沟金矿及韧性剪切带的基本特征和成矿关系等研究,发现该区韧性剪切带形成过程中韧性、韧脆性剪切作用形成的构造蚀变岩控制了金矿的产出.韧脆性剪切带构成了该矿床的富矿和储矿构造,为矿液的迁移、富集提供了较好的条件,也是深部流体的通道.位于中、下地壳中的超临界流体能够以硫络合物形式溶解大量金和其他成矿元素,这种含金的超临界成矿流体沿韧性剪切带向浅部迁移.流体中金的溶解度迅速降低,导致金大量沉淀而形成金矿.北祁连地区的红土沟川刺沟金矿床产于早古生代碰撞造山带中,是该造山带形成和演化的阶段性产物.红土沟川刺沟金矿是一种典型的造山带中的韧性剪切带型金矿床,其主要的矿石类型为构造破碎蚀变岩型金矿石.

Relationship between the Ductile Shear Zone and the Gold Deposit at Hongtugou-Chuancigou in Northern Qilian Area

Based on the study of the relationship between the basic characteristics and gold mineralization at Hongtugou-Chuancigou in northern Qilian area,it is found that the gold mineralization in the area is controlled by the structural-altered rocks formed under ductile-brittle shearing in the ductile shear zones.The ductile shear zone served as ore-controlling and ore-hosting structures,and also severed as a channel for deep fluid transportation,provided a better condition for the movement and enrichment of the hydrothermal liquids and resulted in the formation of bonanza in the deposit.Supercritical fluids at the middle to lower crust levels could dissolve considerable amount of gold and other ore-forming elements in the form of sulfur complexes,and migrate upwards to shallow crust levels along some ductile shear zones.The rapid decrease of gold solubility in the fluid at shallow crust level led to precipitation of gold and formation of large gold deposit.The gold deposit at Hongtugou-Chuancigou in the northern Qilian area occurs in an Early Paleozoic collision orogenic belt,is a typical ductile shear zone gold depo-sit.The gold ore types are mainly cataclastic and altered rock type.