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- Sha, Jingeng, et al.
(author)
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Triassic-Jurassic climate in continental high-latitude Asia was dominated by obliquity-paced variations (Junggar Basin, Urumqi, China)
- 2015
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In: Proceedings of the National Academy of Sciences. - National Academy of Sciences of the United States of America : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 112:12, s. 3624-3629
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Journal article (peer-reviewed)abstract
- Empirical constraints on orbital gravitational solutions for the Solar System can be derived from the Earth's geological record of past climates. Lithologically based paleoclimate data from the thick, coal-bearing, fluvial-lacustrine sequences of the Junggar Basin of Northwestern China (paleolatitude similar to 60 degrees) show that climate variability of the warm and glacier-free high latitudes of the latest Triassic-Early Jurassic (similar to 198-202 Ma) Pangea was strongly paced by obliquity-dominated (similar to 40 ky) orbital cyclicity, based on an age model using the 405-ky cycle of eccentricity. In contrast, coeval low-latitude continental climate was much more strongly paced by climatic precession, with virtually no hint of obliquity. Although this previously unknown obliquity dominance at high latitude is not necessarily unexpected in a high CO2 world, these data deviate substantially from published orbital solutions in period and amplitude for eccentricity cycles greater than 405 ky, consistent with chaotic diffusion of the Solar System. In contrast, there are indications that the Earth-Mars orbital resonance was in today's 2-to-1 ratio of eccentricity to inclination. These empirical data underscore the need for temporally comprehensive, highly reliable data, as well as new gravitational solutions fitting those data.
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