نبذة مختصرة : The volcanic activity of the Emeishan Large Igneous Province (LIP) is widely regarded as the main cause of environmental changes and the consequent biodiversity loss around the Guadalupian-Lopingian boundary (GLB). The limited number of high-precision numerical ages, as well as the scarcity of volcanic ash layers interbedded within sedimentary profiles with bio- and chemostratigraphic controls, has hampered the establishment of a temporal correlation between the Emeishan LIP and environmental and biotic changes. Here, we present new high-precision CA-ID-TIMS Usingle bondPb ages and Hf isotope data from ash layers of the paleontologically dated early Wuchiapingian Mapojiao section in southern Guizhou (south China). Our data indicate that the Emeishan volcanic activity continued at least until 258.279 ± 0.065 Ma in the Clarkina transcaucasica conodont zone of the Wuchiapingian Stage. Based on our high-resolution Bayesian age-depth Bchron model, the calculated duration of Wuchiapingian conodont interval zones in this section are the C. transcaucasica Zone: 740 ± 150 kyr, C. guangyuanensis Zone: 195 ± 184 kyr, C. leveni Zone: 221 ± 162 kyr, C. asymmetrica Zone: 285 ± 228 kyr. Moreover, the sedimentation rate of shallow-marine bioclastic thick-bedded limestones and deep-marine radiolarian and sponge spicule-bearing thin-bedded black limestones is estimated at 10 cm/kyr and 3.84 cm/kyr, respectively. Although the GLB is not included in the studied section, our age-depth model implies that the age of the GLB is noticeably older than any currently considered GLB age. The co-occurrence of a base-level fall and drowning event, temperature rise, mantle-sourced volcanism, negative shifts in carbon and strontium isotope records, and thermal fluid activity provide a strong base to suggest two distinct phases of Emeishan volcanic activities in the mid-Capitanian and early Wuchiapingian, respectively.
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