Geochronology of source materials from high-pressure and ultraigh-pressure metamorphic rocks in Jurasic sedimentary rocks of Hefei Basin

摘要

In this report, it is proven through stable isotopic geochronological study that for the Jurassic sedimentary rocks in the Dushan area of Anhui Province, the source materials derived from high-pressure and ultrahigh-pressure metamorphic rocks are the products of subduction and exhumation of the Yangtze plate under the North China plate during the Triassic period. The cobble of high-pressure or ultrahigh-pressure metamorphic rock in the Fenghuangtai Formation of Hefei Basin has Rb-Sr isotopic isochron age of phengite, apatite and whole rock, 232.1 ± 2.1 Ma (MSWD = 0.59). Plateau ages of ~(40)Ar/~(39)Ar age spectra of detrital phengites in the Sanjianpu and Fenghuangtai formations are concordant, and they are 216.5 ± 0.6 Ma and 217.4 ± 1.3 Ma, respectively.