Significance of crustal extension and magmatism to gold deposits beneath Jiaodong Peninsula, eastern North China Craton: Seismic evidence from receiver function imaging with a dense array

摘要

The Jiaodong Peninsula, located in the eastern North China Craton (NCC), is a key region to study the genetic linkage between large-scale gold mineralization and craton destruction. We construct a fine crustal structural image across the Jiaodong Peninsula, using teleseismic P-wave receiver function data recorded by a dense linear array of 340 short-period seismic stations. The results reveal significant similarities and differences between the eastern and the western Jiaodong Peninsula. The presence of an intracrustal low-velocity zone, and the north-dipping interfaces beneath the Jiaolai Basin imply widespread crustal extension in the whole region. In the northwest Jiaodong metallogenic belt, the identified detachment faults, small vertical velocity gradients in the upper part of the lower crust and the thick crust-mantle transition zone provide evidences for intense crustal extension in this area, probably coeval with the peak of lithospheric thinning and destruction of the eastern NCC in the Late Mesozoic. In the Muru metallogenic belt, distinct differences are found on the opposite sides of the Wulian-Yantai Fault Zone (WYFZ), in the depth and structure of the Moho, intracrustal low-velocity zone, upper crustal Vp/Vs ratios, and Bouguer gravity anomalies, indicating that the WYFZ may be a steep transcrustal fault. We propose that the coupled effects of intense crustal extension, voluminous magmatism and water released from the subducting Paleo-Pacific slab may have been responsible for the concentrated gold deposits in the northwest Jiaodong during the peak of the NCC destruction, while limited gold deposits in the Muru metallogenic belt may have been attributed to relatively weak crustal extension and steep faults.