- 1Columbia University, Lamont-Doherty Earth Observatory, Palisades, New York, USA
- 2Rutgers University, Department of Earth and Planetary Sciences, Piscataway, New Jersey, USA
- 3State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China
- 4Rensselaer Polytechnic Institute, Troy, NY, USA
- 5Earth and Environmental Sciences, San Diego State University, San Diego, USA
Paleotropical lacustrine strata of eastern North America are only known place where vertebrate and floral records of the end-Triassic extinction (ETE) (1) are directly interbedded with U-Pb zircon CA-TIMS-dated lavas of the CAMP (2) and a high-resolution, orbitally paced, lacustrine cyclostratigraphy (3, 4). New, continuous XRF elemental scans of Newark and Hartford rift basin cores (5) confirm previous work in showing expected climatic-precession-dominance modulated by eccentricity for most of the section (6, 7), but an emerging major surprise is that the 500 kyr interval around the Triassic-Jurassic transition is very strongly obliquity-dominated. Tied by sub-Milankovitch magnetic polarity stratigraphy [chron E23r (3)] to rich outcrop-based biostratigraphy, this new Mn/Fe, K/Al, Zr/Rb, S and Na chemostratigraphy requires a revision of environmental interpretations of the proximal cause of the continental ETE. We argue that despite the clear record of pulsed massive pCO2 increases tied to CAMP emplacement, CAMP eruptions produced extreme, sulfur-driven, mega-volcanic winters that were proximal drivers of extinction on land (8) — not the giant hyperthermal itself. We hypothesize that these extreme cold events, superimposed on a background of polar latest Triassic-earliest Jurassic cooling (9) and wintertime freezing (10, 11), enhanced polar ice-albedo feedback and possibly glaciation (12). This amplified Earth System sensitivity to obliquity forcing, perhaps not unlike the initiation of the “40 kyr” world of the Late Neogene [e.g. (13)]. Onset of this Triassic-Jurassic obliquity pacing modality marked the continental phase of the ETE, but in light of these competing radiative balance forcings, interpretations of end-Triassic sea-level drop (12) and marine extinctions require reevaluation as well, considering factors beyond global warming alone (14).
1, Olsen+ 2002 Science 296:1305. 2, Blackburn+ 2013 Science 340:941–945. 3, Kent & Olsen 1999 JGR 104:12831-12841. 4, Olsen & Kent 1996 PPP 122:1-26. 5, Kinney+ 2002 Abstract PP25D-0899, AGU Fall Meeting. 6, Van Houten 1962 AJS 260:561. 7, Olsen 1986 Science 234:842. 8, Kent+ 2024 PNAS 121:e2415486121. 9, Judd+ 2024 Science 385:eadk3705. 10, Olsen+ 2022 Science Adv. 8:eabo6342. 11, Chang+ 2024 GSL Spec Pap. 538:114. 12, Schoene+ 2010 Geology 38:387. 13, Westerhold+ 2020 Science 369:1383-1387. 14, Funded by NSF & the Heising-Simons Foundation.
How to cite: Olsen, P., Kinney, S., Tibbits, D., Fang, Y., Chang, C., Schaller, M., Slibeck, B., Whiteside, J., and Kent, D.: Obliquity pacing of tropical lacustrine cyclostratigraphy of the great end-Triassic hyperthermal and mass extinction: competing radiative balance forcings induced by the Central Atlantic Magmatic Province (CAMP) , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10277, https://doi.org/10.5194/egusphere-egu25-10277, 2025.
