Chemical weathering indices on marine detrital sediments from a low-latitude Capitanian to Wuchiapingian carbonate-dominated succession and their paleoclimate significance

Abstract

The Late Paleozoic Ice Age (LPIA) represents the most recent ice-house state on Earth, attracting significant interest from those studying recent climate change and contemporary global warming. But the duration and evolutionary pattern of LPIA are still controversial, especially when it comes to the Middle-Late Permian. A series of weathering indices on detrital sediment built from a carbonate-dominated succession in central China provides an opportunity to reveal the Capitanian to Wuchiapingian climatic fluctuations in the low latitudes and their far-field responses to the Permian glacial evolution. The weathering indices exhibit consistent trends and divide the Capitanian to Wuchiapingian interval into four phases. The first and third phases are characterized by relatively lower values in weathering indices of logarithmic parameters, CIAcor, CIXcor, CIW, αAlNa, and relatively higher values of τNa and WIPcor, which suggest a relatively cold climate occurring in the early Capitanian and late Capitanian to early Wuchiapingian. These two cold phases were relevant to the Permian glacial epochs of P3 and P4. While the second and fourth phases show opposite features in those weathering indices, which indicate the middle Capitanian and late Wuchiapingian were under a relatively warm climate. The third phase was superimposed by several cooling-warming cycles, which keep consistent in tune with sea-level fluctuations. Both of them have an average duration of about 1.0 Ma, possibly suggesting an astronomical (obliquity)-forced glacioeustatic controlling mechanism for the unstable P4 epoch. The end of co-variation of climate and sea-level fluctuation and the increase of weathering indices happened in the middle Wuchiapingian, which suggests the demise of Permian glaciation. Additionally, the latest Capitanian warming period that happened during the P4 glaciation interval corresponds to the increasing strength of the eruption of the Emeishan Large Igneous Province (ELIP), which possibly indicates the interruption of P4 was mainly controlled by the active ELIP. The limited diversity loss at the end-Guadalupian was suggested as a result of climate warming to a restricted degree, due to a limited rate and magnitude of ELIP volcanism that happened in a cold period.