Paleomagnetism and calcite U-Pb geochronology from the Penglaitan GSSP section, South China

The Guadalupian-Lopingian boundary (GLB) interval is characterized by the Pangea breakup, dramatic sea-level change, Emeishan Basalt volcanism, and biotic turnover. We conducted magnetostratigraphic, mineralogical, and calcite U-Pb geochronological studies at the Penglaitan Global Stratotype Section and Point section in South China. Rock-magnetic results indicate that magnetite and rare hematite are the dominant remanence carriers. After removing the viscous remanent magnetization, three components were isolated from the limestone at the Penglaitan section. The high-temperature remanence components were isolated from the tuffaceous limestone and yielded a mean direction of D_s/I_s = 195.3°/+5.6° (α_95s = 5.3°, k_s = 22.8, n = 34) after tilt correction. It defined a reversed magnetozone from the top of conodont Jinogondolella granti Zone to the lower part of the Clarkina. dukouensis Zone, straddling the GLB. Additionally, intermediate-temperature components represent the Jurassic and Triassic remagnetization, also supported by the in-situ calcite U-Pb dating (~133-166 Ma and ~213-224 Ma), pyrite-to-magnetite alteration, or magnetite oxidization to maghemite and hematite. The new paleomagnetic results and calcite U-Pb dating provide new insights into Mesozoic multi-remagnetization in the South China Block and refine the GLB positioned in a reversed magnetozone.