Calcite U-Pb Geochronology Revealing Late Ediacaran–Early Paleozoic Hydrothermal Alteration in the Stenian-Tonian Carbonate of Northeastern North China Craton

Two calcite LA-ICP-MS U-Pb ages of 534 ± 26 Ma(MSWD = 5.9) and 456 ± 43 Ma(MSWD = 3.8) were obtained from the Nanfen Formation, Xihe Group in the southern Liaoning Province, northeastern China, which significantly postdate the theoretical depositional age of sampling horizon. This means they represent timing of post-depositional hydrothermal event possibly induced by synchronous far-field magmatism in the South Qinling. Occurrence of common Pb enriched muddy components coupled with input of “mantle”-like common Pb could account for the relatively low U contents and high common Pb contents in the dated muddy carbonates. We recommend that micro-domains of carbonates are prescreened by rapid in situ carbonate U-Pb geochronology to demonstrate whether they are of primary or secondary origin before utilizing them for chemostratigraphic study.