143 / 2025-04-08 09:18:17

Regulation of the Wuchiapingian sedimentary sequence evolution in Zhen’an, Central China by the Late Paleozoic last glaciation (P4): A transition from temperature- to precipitation-controlled climatic forcing?

Late Palaeozoic Ice Age; deglaciation; Wuchiapingian; climate transition; mixed siliciclastic-carbonate sequence; marine red beds

Theme 3: Earth-Life Co-evolution Through Time > Session 3d: Biotic and Environmental Changes during the Late Palaeozoic Ice Age

The climate transition between icehouse and greenhouse states may alter dominant climatic factors (temperature and precipitation), thereby influencing sedimentary records. Under icehouse conditions, temperature fluctuations drive significant sea-level oscillations and sedimentary evolution through glacial advances and retreats, whereas in ice-free greenhouse climates, the mechanisms of sea-level change differ fundamentally, with precipitation-related hydrological cycles potentially becoming the dominant driver of Earth’s surface processes. However, due to the challenge of disentangling temperature and precipitation effects, such shifts have often been overlooked in deep-time paleoclimate studies. The Wuchiapingian Stage, spanning the early to middle phases of the Late Paleozoic last glaciation (P4), represents a critical transitional period from the Late Paleozoic icehouse to the Mesozoic greenhouse. The Zhen’an area, situated at the southern margin of the united North China-Qinling block, experienced relative tectonic stability during the Permian. Influenced by the evolution of the P4 glaciation, the Wuchiapingian Stage in this region developed a unique sedimentary succession comprising a lower mixed siliciclastic-carbonate sequence and an upper marine red bed-dominated sequence, potentially recording depositional evolution governed by distinct climatic drivers under varying climatic conditions. Building on previous studies, this research investigates the sedimentary evolution of the Wuchiapingian Stage and its linkage to the P4 glaciation. Key findings include: 1) In the mixed sedimentary sequence, cyclic variations in terrigenous clastic abundance (from abundant to sparse) correlate with cold-to-warm cycles inferred from chemical weathering indices, suggesting control by temperature fluctuations during the P4 glaciation. Temperature-driven ice-volume changes modulated sea-level oscillations and terrigenous input. 2) The emergence of marine red beds coincides with climatic warming evidenced by chemical weathering indices and brachiopod shell δ¹⁸O records. Subsequent stabilization of temperatures and sea levels implies complete deglaciation of Late Paleozoic ice sheets, rendering temperature-controlled glacio-eustasy inactive. The alternation between red beds and non-red beds appears governed by precipitation patterns. Enhanced rainfall promoted input of iron-rich terrestrial minerals conducive to red bed formation, while reduced precipitation led to non-red bed deposition. Thus, the shallow marine sedimentary succession in Zhen’an not only documents high-resolution paleoclimatic fluctuations during the P4 glaciation but also provides a representative deep-time archive of sedimentary responses to shifting climatic drivers during climate state transitions. However, the specific mechanisms underlying paleoclimatic feedbacks require further investigation.