Detrital zircon provenance of the Wangshi and Laiyang groups of the Jiaolai basin: evidence for Early Cretaceous uplift of the Sulu orogen, Eastern China

摘要

The Late Mesozoic Jiaolai basin preserves sediment source information that can help elucidate the tectonic history of East Shandong, China. The terrestrial Wangshi and Laiyang Groups are major components of the basin succession, but are not well studied in terms of their provenance and role in basin evolution. The Early Cretaceous Laiyang Group consists primarily of fluvial and lacustrine facies siltstones and sandstones, whereas the Late Cretaceous Wangshi Group consists of reddish fluvial siltstones and sandstones with interbedded conglomerates. This study reports detrital zircon age distributions from eight sandstones collected from the two groups. Age distributions exhibited four major populations of Palaeoproterozoic (2.5-2.4Ga), Palaeoproterozoic (1.9-1.8Ga), Neoproterozoic (850-700Ma), and Jurassic to Early Cretaceous (171-107Ma) ages. We interpret a maximum depositional age of 107Ma for the Wangshi Group and a depositional age of 121-120Ma for the upper Laiyang Group. Age distributions indicate that the Sulu orogenic belt of the East Shandong complex served as the primary source area. Detrital zircon age data also indicate major changes in the types of source material contributed to the Laiyang and Wangshi groups. Based on these shifts, we propose a four-stage model for Early Cretaceous evolution of the Jiaolai basin. In this model, subduction of the Pacific plate and associated transform motion on the Tan-Lu fault influenced the transition from a transpressional to an extensional tectonic setting.