Modes of Pangean lake level cyclicity driven by astronomical climate pacing modulated by continental position and pCO ₂

Author(s)

Jan Landwehrs, Georg Feulner, Matteo Willeit, Stefan Petri, Benjamin Sames, Michael Wagreich, Jessica H Whiteside, Paul E Olsen

Abstract

Orbital cyclicity is a fundamental pacemaker of Earth’s climate system. The Newark–Hartford Basin (NHB) lake sediment record of eastern North America contains compelling geologic expressions of this cyclicity, reflecting variations of climatic conditions in tropical Pangea during the Late Triassic and earliest Jurassic (∼233 to 199 Ma). Climate modeling enables a deeper mechanistic understanding of Earth system modulation during this unique greenhouse and supercontinent period. We link major features of the NHB record to the combined climatic effects of orbital forcing, paleogeographic changes, and atmospheric pCO

₂ variations. An ensemble of transient, orbitally driven climate simulations is assessed for nine time slices, three atmospheric pCO

₂ values, and two paleogeographic reconstructions. Climatic transitions from tropical humid to more seasonal and ultimately semiarid are associated with tectonic drift of the NHB from ∼5

^◦N to 20

^◦N. The modeled orbital modulation of the precipitation–evaporation balance is most pronounced during the 220 to 200 Ma interval, whereas it is limited by weak seasonality and increasing aridity before and after this interval. Lower pCO

₂ at around 205 Ma contributes to drier climates and could have led to the observed damping of sediment cyclicity. Eccentricity-modulated precession dominates the orbitally driven climate response in the NHB region. High obliquity further amplifies summer precipitation through the seasonal shifts in the tropical rainfall belt. Regions with other proxy records are also assessed, providing guidance toward an integrated picture of global astronomical climate forcing in the Late Triassic and ultimately of other periods in Earth history.

Organisation(s)

Department of Geology

External organisation(s)

University of Southampton, San Diego State University, Potsdam-Institut für Klimafolgenforschung, Lamont-Doherty Earth Observatory

Journal

Proceedings of the National Academy of Sciences of the United States of America

Volume

119

ISSN

0027-8424

DOI

https://doi.org/10.1073/pnas.2203818119

Publication date

11-2022

Peer reviewed

Yes

Austrian Fields of Science 2012

105204 Climatology, 105121 Sedimentology

Keywords

ASJC Scopus subject areas

General, Geology, Atmospheric Science

Sustainable Development Goals

SDG 13 - Climate Action

Portal url

https://ucris.univie.ac.at/portal/en/publications/modes-of-pangean-lake-level-cyclicity-driven-by-astronomical-climate-pacing-modulated-by-continental-position-and-pco-2(f74eff6a-8d2e-4721-ac27-cff1fe3dbe5b).html