Deciphering global climate patterns in the Middle-Late Jurassic based on fossils from western India

作者:2022/07/29 02:42

A new study published in Global and Planetary Change, which is led by Dr. Matthias Alberti from the Centre for Research and Education on Biological Evolution and Environment, Nanjing University, shows that Eastern Gondwana experienced a prominent long-term cooling of 8-9 °C during the Middle and Late Jurassic. Thereby, the study changes our perception of global Jurassic climate patterns, because earlier studies were largely based on samples from Europe and it seems more and more convincing that this material reflects a series of regional instead of global processes.

The cooling reconstructed for western India agrees with data from neighboring Madagascar and the Indian Himalayas and can be connected to a plate tectonic drift of Eastern Gondwana into higher latitudes. This palaeogeographic shift is accompanied by changes in sedimentation indicating an increasingly humid climate and in the composition of ecosystems reflecting increasingly cooler water temperatures. In contrast to the southward movement of Eastern Gondwana, the western part of the supercontinent remained in a stable position and experienced constant temperature conditions during the examined time interval.

Measured Mg/Ca ratios also support a temperature decrease, but additionally reflect species-specific factors and a lower Mg/Ca ratio of Jurassic seawater compared to today. The recorded δ13C values follow sea-level changes with a positive excursion in the Oxfordian connected to a major transgressive event. Sr/Ca ratios are observed to follow changes in global ocean chemistry.

In combination, the produced datasets can serve as a standard reference for Eastern Gondwana in the Middle and Late Jurassic.

See the article

Matthias Alberti et al. 2022. Middle to Late Jurassic stable isotopes and element ratios of fossils from western India: Developing a reference temperature curve for northeastern Gondwana. Global and Planetary Change.

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