Control of the Shift in Subduction Direction on Upper Plate Tectonic Extension and Gold Mineralization: A Case Study From the Early Cretaceous Jiaodong Peninsula, Eastern China.

The subduction of the Paleo‐Pacific plate, and tectonic extension and mineralization in the upper plate, has been extensively studied in the last decades. How plate interactions along plate margins contributed to the upper plate processes, however, remains controversial. This study focuses on the Queshan Metamorphic Core Complex (MCC) and the Songjiagou gold deposit in the northern Jiaodong Peninsula, southeastern North China Craton, to uncover the processes of and factors on Early Cretaceous tectonic extension and gold mineralization. It is shown that the Queshan MCC experienced early nearly east‐west and late northwest‐southeast extensional stress fields, with a critical transition between 123 and 119 Ma. During 136–119 Ma, the average cooling rate of the lower plate exceeded 17.5°C/Myr, but decreased rapidly to 3.5°C/Myr after 119 Ma. Formation of the Songjiagou gold deposit is shown to occur in two distinct stages, that is, weak emplacement of gold‐bearing fluids along the northeast‐southwest fault from 122 to 118 Ma, and large‐scale fluid activities between 118 and 116 Ma. A detachment fault zone, formed during the rapid exhumation of the Queshan MCC due to near east‐west extension, and a brittle fracture system, created under northwest‐southeast extension, contributed to a fracture network that connect the middle and upper crust. This network facilitated the migration of hydrothermal fluids and precipitation of gold from the fluids. The Songjiagou deposit exemplifies the major gold mineralization event of around 120 Ma in the Jiaodong Peninsula. During this period, the Paleo‐Pacific plate shifted from westward to northwestward subduction. It is suggested that changes in subduction direction caused tectonic extension in the upper plate. The latter triggered reopening of pre‐existing fault systems, which enabled gold‐bearing fluids in the big mantle wedge to ascend rapidly from deep sources to the shallow crust, thereby driving large‐scale gold mineralization in the Jiaodong Peninsula. Plain Language Summary: The Paleo‐Pacific Plate began to subduct westward under the Eurasian continent in the Jurassic, that affected the tectonic evolution of the upper plate, that is, the Eurasian plate and formed significant metallic deposits in eastern China. Gold reserves in the Jiaodong gold mine province in China exceed 5,000 tons. The timing of gold mineralization is bracketed between 122 and 116 Ma, and most of the gold deposits are distributed around metamorphic core complexes (MCCs). A detailed study was conducted on the Queshan MCC and the adjacent Songjiagou gold deposit in the Jiaodong Peninsula, North China Craton. The cooling rates of the Queshan MCC decreased rapidly, being coeval with the formation of major deposits in the Jiaodong gold mine province. At the same time, the Paleo‐Pacific plate experienced a sudden shift in subduction direction, being consistent with the regional tectonic extension and gold mineralization. Therefore, we would argue that changes in the subduction direction of the Paleo‐Pacific plate and the retreat of the plate caused the continuous extension of the Jiaodong Peninsula, the sudden decrease in the uplift rate of the Queshan MCC, and the formation of this large‐scale gold mine province. Key Points: Structural and geochronologic analyses reveal that the Queshan Metamorphic Core Complex (MCC) experienced a transition from rapid to slow exhumation at 119 MaRapid exhumation of the MCC formed a complex fault system, enabling fluid transport and ore storage, and forming the Songjiagou gold depositThe subduction shift of Paleo‐Pacific Plate and slab rollback at ca. 120 Ma resulted in regional tectonic extension, and triggered the release of hydrothermal fluids and large‐scale mineralization [ABSTRACT FROM AUTHOR]