鲁西隆起区晚中生代地层碎屑石榴石分析及物源区构造演化示踪

Fragment Garnet Analysis and Tectonic Evolution of Its Provenance in Late Mesozoic Strata in the Luxi Uplift

以鲁西淄博、临朐、平邑、蒙阴盆地为重点研究区,通过盆地中生界砂岩中碎屑石榴石的成分分析,探讨鲁西隆起及周边地区中生代构造演化历史。研究表明,鲁西盆地砂岩中石榴石成分在早中侏罗世和中晚侏罗世期间出现变化,暗示着物源的转变,早中侏罗世时期主要物源是鲁西隆起,中晚侏罗世时期转变为胶东地区和鲁西隆起。侏罗纪时期石榴石的物源转变显示,苏鲁苏鲁造山带可能在中晚侏罗世时期已经抬升至地表。白垩纪鲁西盆地物源主要为胶东地区,鲁西隆起的物源贡献较小,但是青山组中段和王氏组中段物源略有波动。白垩纪鲁西盆地石榴石物源显示,控制鲁西盆地沉积的主要是苏鲁造山带,古地理格架显示东高西低的特征,盆地物源的波动暗示鲁西隆起可能在早白垩世中晚期和晚白垩世中期经历过抬升。

This paper takes Zibo, Linqu, Pingyi, Mengyin basin as the key study area. of fragment garnet in Mesozoic sandstone, we try to discuss the tectonic evolution history Through composition analysis of West Shandong uplift and the surroundings in Mesozoic. Research shows that garnet composition of Luxi basin changed from Early Mesozoic Ju- rassic to Mid-late Mesozoic Jurassic implying that the provenace of Luxi basin shifting The provenance mainly corned from West Shandong uplift in Early-Mid Jurassic period. Then the provenance turn to Jiaodong region and West Shan- dong uplift in Mid-late Mesozoic Jurassic period, but the mainly provenance was Jiaodong region. The changes of provenance of garnet in Jurassic Period showed that Sulu Orogen belt was probably uplifted to the earth＇s surface in Mid-late Jurassic. In Cretaceous period the mainly provenance of Luxi basin was Jiaodong area and Luxi uplift had lit- tle contribution in provenance supply, but the provenance supply of Luxi uplift shifted in mid- Qingshan Formation and mid-Wangshi Formation . In Cretaceous , Sulu Orogen belt controlled the sediment of Luxi Basin. Paleogeogra- phy framework indicates that the terrain of Shangdong is higher in the east and lower in the west. The shifts of garnet provenance in Cretaceous showed that West Shandong uplift was probably uplifted in Mid-Late period in Early Creta- ceous and mid-late period in Late Cretaceous.