The Jiaodong gold district, northeastern China, in the context of the Late Paleozoic and Late Mesozoic large igneous provinces, orogeny and metallogeny in Eurasia

Abstract

The Permo-Triassic continental large igneous provinces (LIPs) of Eurasia linked in to orogenic systems in decay. Their bulk appearance varies from the massive flood-basalts and (ultra)mafic intrusives to the groups of coeval, widely spread, diverse intrusions and extrusions of the Scattered Igneous Provinces (SIPs). In the interval from the demise of the orogens to the inception of the LIPs and SIPs, diverse ore deposits were formed which, depending on the predominant expression of the hosting system, have been interpreted as orogen-related and LIP- or SIPrelated. In the case of the voluminous (ultra)mafic complexes, amantle origin is indicated. This leads to the concept of active mantle plumes issuing from the core–mantle boundary in view of the exceptional volumes and the high temperature inferred to melt the source complexes. However, the substantial volumes of fluids that entered the sub-continental mantle on prior subduction of oceanic lithosphere lowered the solidus temperature and modified the composition of the sub-continental mantle. As a consequence, the conditional high temperature is superfluous. In this context, the setting of the Jiaodong Province and the evolution of the hosting North China Craton suggest that: 1 the introduction of fluids during prolonged subduction of oceanic lithosphere can also modify the rheology of the deep lithosphere; this reinforces the role of plate tectonic processes in the generation and the in-and extrusion of voluminous, mantle-derived melts; 2 the prolific gold deposits could form because of the stalled, subducted Pacific lithosphere slab with its oxidizing potential and its position within the mantle transition zone; as elsewhere, continentscale, translithospheric strike-slip deformation played an indispensable role in decompression and in the migration of melts, fluids, volatiles and metals; 3 orogenic gold deposits can form independent of orogenesis; should, after all, a relevant orogen be delineated in the coastal belt of eastern Asia, the question arises concerning the dependence of orogenic gold deposits on the nature of an orogen.