Discovery of detrital high-pressure metamorphic minerals from Paleocene-Eocene strata in Jiyang basin, eastern North China, and its implication for tectonic-paleogeographic setting
济阳盆地南缘古近系碎屑高压变质矿物的发现及其构造古地理含义

Through detrital heavy mineral separation, microscopic identification and probe measure and compositional data analysis, some detrital high-pressure metamorphic minerals, including glaucophane, barroisite and phengite, were found from the Kongdian Formation and the No.4 segment of Shahejie Formation, Paleogene, in the Boxing Sag located in the south margin of Jiyang basin near the north foot of Luxi Uplift. Provenance correlation analysis, with depositional records of detrital heavy mineral assemblages and petrologic tectonic attributes of regional collisional orogenic belts, shows that the detrital high-pressure minerals sourced from the Sulu orogenic belt, in which high-pressure metamorphic rocks probably resulted from return of deep subducted oceanic crust (more research proofs needed). Further discussion on provenances of detrital high-pressure minerals in the Boxing Sag most probably directly sourced from the Sulu orogenic belt during the Early Paleogene. At the same time, exhumation materials (including recycled deposits) of the Luxi Uplift probably become partial provenances of the Boxing Sag. Therefore, evident topography in west high to east low once occurred over the Luxi Uplift-Sulu orogenic belt during Late Mesozoic-Early Paleogene, and, however, gradually reversed since 45Ma (corresponding to age of top layer of the No.4 segment of Shahejie Formation). In other words, the Luxi Uplift basically obstruct provenances directly derived from the Sulu orogenic belt since 45Ma.