Chemical Significance and Chronology of Mesoproterozoic clastic rocks in Huainan Area

Abstract

After the 1.8Ga cracking event, the North China Craton entered the development stage of paraplatform, its southern margin, the Huainan area is in lack of accurate age data, so its stratigraphic sedimentation time limit has been controversial. Therefore, this paper conducts a zircon U-Pb geochronology study on the clastic rocks of the North China Craton in the Bagongshan Fm in Huainan area. The purpose is to determine the stratigraphic sedimentation time limit of the Huainan area by the age of the clastic zircon, so as to provide a basis for the geological events happened in the North China Craton during the Neoarcheozoic-Neoproterozoic era. The results of the dating show that the youngest clastic zircon age of the Bagongshan Fm is 1120 Ma, which might belong to the system-to-be-built of the Mesoproterozoic erathem. The age peaks of clastic zircon in the Bagongshan Fm are mainly ~2.1Ga and ~2.5Ga, which have a low structural maturity, indicating that the provenance is relatively close, and the detrital matters may be mainly derived from the inside of the craton, so the age groups of clastic zircons had recorded important geological events in the Neoarcheozoic-Neoproterozoic era in North China Craton. The age older than 3.0Ga recorded the Neoarchean geological events in the North China Craton. The age groups of 2.9~2.7Ga, ~2.5Ga, 2.3~2.0Ga, and 1.9~1.8Ga recorded important geological events such as crust growth, cratonization, rifting and orogeny happened in the early Cambrian in the North China Craton. The age groups of ~1.74Ga and ~1.6Ga recorded the multi-period rifting events happened during the Paleoproterozoic-Neoproterozoic era.