Three-order ore-controlling structural system of orogenic gold deposits in the northern Qaidam margin-East Kunlun region

Abstract：The regional distribution and occurrence and distribution of mineralization concentration areas, ore deposits and orebodies of orogenic gold deposits in the northern Qaidam margin-East Kunlun region were controlled by structures of different orders. In a second-order tectonic unit and/or metallogenic zone, orogenic deposits mostly occur near the tectonic boundary and/or a deep fault, i.e. the tectonic boundary of an orogen and/or a deep fault is the first-order ore-controlling structure of orogenic gold deposits in the northern Qaidam margin-East Kunlun region. Gold geochemical anomalies and orogenic gold deposits in a mineralization concentration area or an ore field are controlled by a large-scale shear zone developed at the side of a deep fault mentioned above, which is the second-order ore-controlling structure of orogenic gold deposits in the northern Qaidam margin-East Kunlun region. Folds and fault systems derived from the above-mentioned large-scale shear zone are the third-order ore-controlling structure of orogenic gold deposits in the region, which control the occurrence and distribution of orebodies in ore deposits. The Tanjianshan gold deposit and Dachang gold deposit are typical examples for fold controls on mineralization, while the Wulonggou gold deposit is a typical example of controls of mineralization by the fault-fissure system association with the shear zone. In contrast with those gold deposits under control of the fault system, the orebodies in gold deposits controlled by folds are larger in size and less variable in space. The tectonic boundaries of orogens and/or deep faults, large-scale shear zones and folds and fault systems derived from the above-mentioned large-scale shear zones mainly resulted form the regional Caledonian and late Variscan-Indosinian collisional orogeny, and they have about the same or interrelated geometry, kinematics and geochronology, of which the latter are commonly structures of lower order derived from the former. Therefore, the three structures of different orders form an ore-controlling structural system of orogenic gold deposits in the northern Qaidam margin-East Kunlun region.