Timing, duration and role of magmatism in wide rift systems: Insights from the Jiaodong Peninsula (China, East Asia)

Abstract

In East Asia, widespread extensional sedimentary basins together with the close association of Metamorphic Core Complexes and magmatism are prominent features of the large-scale wide rift system developed during late Mesozoic times. This region thus appears as a proper place to study continental extension as well as questions about the link between continental extension and magmatism. This paper primarily provides pioneer exhumation time-constraints on the Linglong MCC (Jiaodong Peninsula) including cooling and deformation ages. MCC cooling at mid-crustal levels occurred at ca. 143 Ma. Besides, last ductile deformation occurred at ca. 134 Ma while final exhumation stages, under brittle 2 conditions, occurred as late as ca. 128 Ma. Continuous crustal stretching were then recorded by the emplacement of a synkinematic pluton in the upper crust at ca. 128 Ma that cooled fast below an intracrustal shear zone crossing the ductile-brittle transition at ca. 123 Ma. The ca. 120-118 Ma age cluster is ascribed to the fast cooling of undeformed plutons marking the end of extension that lasted, in the area, over a minimum period of ca. 30 My. Combining other MCC exhumation constraints and the onset of subsidence in the sedimentary basins, total duration of late Mesozoic extension in East Asia could be estimated at ca. 60 My, related with a rather long process for extension from 160 to at least 100 Ma. East Asian continental extension is heterogeneously distributed in space and time as revealed by fundamental differences between two end-member classes of migmatite-cored MCC already described in other wide rift systems. Extension seems to have first favoured partial melting which subsequently, in turn, maintained continental extension.

Thermochronologic constraints on evolution of the Linglong Metamorphic Core Complex and implications for gold mineralization: A case study from the Xiadian gold deposit, Jiaodong Peninsula, eastern China

“…1), which was previously regarded as a group of sheared plutons, Ore Geology Reviews 72 (2016) [165][166][167][168][169][170][171][172][173][174][175][176][177][178] is now recognized to be older at ca. 160-150 Ma (Charles et al, 2013). Most importantly, the majority of gold resources in the Jiaodong Peninsula, the largest gold producing area in China with a proven reserve of N 4000 t gold (Yang et al, 2014a,b), is hosted in the Linglong MCC (Wang et al, 2014(Wang et al, , 2015Yang et al, 2014c;Fig.…”

Emplacement Depths and Exhumation of Mesozoic Granitoids Responding to Lithospheric Destruction in the Jiaodong Peninsula, North China Craton

“…Previously, biotite from granites and mylonites of the GJL has identical cooling ages of 124 Ma (Li et al, 2003;Charles et al, 2013), which imply that the ductile shear took place before 124 Ma. Because the ductile shear generally occurred below 10 km, which imply rapid crust exhumation can be realized after 124 Ma ago.…”

Types, characteristics and metallogenesis of gold deposits in the Jiaodong Peninsula, Eastern North China Craton

“…The fluids segregated and activated by magmatic activities were the potential carriers for the migration and enrichment of gold deposits. The upwelling of magmas gave rise to extensional detachment in the overlying host rocks or processes of metamorphic core complex (Charles et al, 2013;T. Wang et al, 2011), which provided favorable locales for gold ore mineralization.…”

“…Li et al, 2005;S.Z. Li et al, 2005b;Xu et al, 2004), which has been interpreted by different models, ranging from extension (Charles et al, 2013;Li et al, 2002;T. Wang et al, 2011;Z.L.…”