Estimating the magnitude of early Permian relative sea-level changes in southern North China

During the Late Paleozoic ice age high-frequency sea level changes at low latitudes have been considered far-field responses to high-latitude Gondwana glacial-deglacial cycles. Previously estimated eustatic amplitudes from low-latitude Pangea range from >80 m to <20 m. To further constrain the amplitude of relative sea level variations, especially for the eastern Tethyan region, we studied the latest Pennsylvanian-early Permian lower Taiyuan Formation in Henan Province of southern North China. Based on detailed field and microfacies analysis of biostratigraphically well-constrained successions, we identified three facies associations including coastal plain, coastal marine, and shallow marine, and revealed four transgression-regression cycles from the lower Taiyuan Formation. Cyclic facies changes, in combination with carbon isotope variations, reflect high-frequency sea level variations in southern North China. A simple 2-dimensional marine transgression model for the studied interval is proposed based on detrital zircon provenance data and correlation to coeval successions. Using the pinning-point method and assuming reasonable depositional slopes, the magnitude of sea-level rise along the transgressive slope in southern North China likely ranged from 16 to 32 m. These estimates largely overlap with the estimates from western equatorial Pangea, and are consistent with modelled sea-level variations arising from orbital forcing. This work helps to constrain the likely astronomical controls on the Late Paleozoic icehouse climate change.