252 Climate Transitions in the Paleozoic

This session will examine the major climate transitions in the Paleozoic Era, the paleoclimate evidence for their identification, their causes, and their consequence to the Earth System (e.g., ocean and atmospheric chemistry, sedimentology, biodiversity).

Wednesday, 22 October 2025
8:00 AM - 12:00 PM
HBGCC, 303C

Correlation of Continental and Marine Milanković Cycles through the Permo-Triassic Boundary Interval in China: Bogda Mountains, NW China vs. Meishan, SE China

Paper number: 252-14
Program: Technical Sessions
Time: 11:30 AM – 11:45 AM

Authors

Abstract

Milanković signals in continental and marine Permo-Triassic Boundary (PTB) records from China demonstrate the geographic exportability of ancient Milanković cycles and clarify the pattern of Milanković-climate change during the end-Permian mass extinction (EPME) interval.

The South Taodonggou (STDG) section, NW China, in paleo-mid-latitude northeastern Pangea contains a PTB record of a refugium for plants and vertebrates. The section is 282-m thick with  fluvial, lakeplain-littoral and lacustrine-deltaic cycles. Seven U-Pb dates constrain the timescale (1). The cyclic facies sequence was modeled to estimate short-term sedimentation rates (2), and tuned to the 405-kyr metronome to estimate long-term sedimentation rates. The modeled time series displays orbital eccentricity, obliquity and climatic precession cycles. In the EPME interval, climate transitioned from humid to semi-arid, with survival of plants and vertebrates (3). The Meishan section, SE China, in paleo-low-latitude eastern Paleo-Tethys, is the international GSSP for the PTB with a detailed record of the EPME interval (4,5). Five U-Pb dates constrain the timescale (6), leading to recognition of orbital eccentricity cycles in gamma-ray (GR) proxy data measured along the 26-m-thick section (7).

The PTB horizons in the two sections establish a common time point, hence the continental versus marine phasing of the orbital eccentricity cycles. GR maxima (increased runoff) at Meishan correlate with lake-level maxima at STDG. At Meishan, the EPME interval starts during a ~100-kyr GR cycle maximum in Bed 24e, and continues for 40 kyr to the top of Bed 28 (an ash clay). At STDG, the EPME interval starts during a ~100 kyr prodelta/littoral cycle maximum; two lakeplain-prodelta/littoral climatic precession cycles (40 kyr) are recorded from that point to the PTB (top of Meishan Bed 27b). The two sections have sediment accumulation rates separated by three orders of magnitude (Meishan: 0.0025 m/kyr; STDG: 1.5 m/kyr). Nonetheless, high-resolution chronostratigraphy, detailed facies analysis and sampling synchronize the records at an unprecedented degree of certainty.

References: (1) Yang et al., 2021, Earth Sci. Rev. 222, 103741; (2) Kominz, Bond, 1990, EPSL, 98, 233-244; (3) Peng et al., 2025, Sci. Adv., 11, eads5614; (4) Yin et al., 2001, Episodes, 24(4), 102–114; (5) Chen et al., 2015, Earth-Sci. Rev., 149, 67-107; (6) Burgess et al., 2014, PNAS, 111 (9) 3316-3321; (7) Li et al., 2016, Earth Plant. Sci. Lett., 441, 10-25.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412207

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