Metallogeny of copper and iron deposits in the Eastern Yangtse Craton, east-central China

Abstract

The Eastern Yangtse Craton of central to eastern China is an important FeCu metallogenic province. Based on studies of the regional geology and tectonic evolution, this metallogenic belt is controlled by faults and aulacogens in the continental plate. In the Early Yanshan Epoch (Jurassic), the dominant west-northwest and east-west lithospheric faults controlled the distribution of Cu (Mo, and Au) mineralization, whereas in the Late Yanshan Epoch (Cretaceous) the north-northeast and northeast lithospheric faults controlled CuFe mineralization. In a mineral district, the distribution of ore-fields is under the dual control of basement fault(s) and near-surface fault(s). Based on the relation of ring and lineament faults to intrusions, a ‘three-level’ model of vertical zonation is proposed. Systematic petrochemical studies of Mesozoic igneous rocks and mineralization identify three subseries: (1) a calc-alkaline, intermediate to silicic subseries rich in potassium; (2) a calc-alkaline, intermediate to felsic subseries rich in sodium; and (3) a calc-alkaline, intermediate to mafic subseries rich in sodium. Genetic types of ore deposits are diverse, including Fe and Cu skarns, Cu porphyries, Fe ore magma injections, Ningwu-Luzong Fe deposits (from late orthomagmatic to pegmatitic-pneumato-hydrothermal, and to mesothermal-epithermal) associated with subvolcanic rocks, and remobilized sedimentary Fe and/or Cu deposits. The genetic types of ore deposits form two metallogenic series: (1) a sedimentary metallogenic series (active mainly in the Paleozoic), and (2) a magmatic-hydrothermal metallogenic series consisting of three subseries (active predominantly in the Jurassic and Cretaceous), with the latter being more important in this region. The superposition and compounding of these two metallogenic series contribute to many styles of mineralization in this mineral province.