Publications by authors named "Thomas Wotte"

2 Publications

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Chemostratigraphic correlations across the first major trilobite extinction and faunal turnovers between Laurentia and South China.

Sci Rep 2019 11 22;9(1):17392. Epub 2019 Nov 22.

Institut für Geologie, Technische Universität Bergakademie Freiberg, Bernhard-von-Cotta-Straße 2, D-09599, Freiberg, Germany.

During Cambrian Stage 4 (~514 Ma) the oceans were widely populated with endemic trilobites and three major faunas can be distinguished: olenellids, redlichiids, and paradoxidids. The lower-middle Cambrian boundary in Laurentia was based on the first major trilobite extinction event that is known as the Olenellid Biomere boundary. However, international correlation across this boundary (the Cambrian Series 2-Series 3 boundary) has been a challenge since the formal proposal of a four-series subdivision of the Cambrian System in 2005. Recently, the base of the international Cambrian Series 3 and of Stage 5 has been named as the base of the Miaolingian Series and Wuliuan Stage. This study provides detailed chemostratigraphy coupled with biostratigraphy and sequence stratigraphy across this critical boundary interval based on eight sections in North America and South China. Our results show robust isotopic evidence associated with major faunal turnovers across the Cambrian Series 2-Series 3 boundary in both Laurentia and South China. While the olenellid extinction event in Laurentia and the gradual extinction of redlichiids in South China are linked by an abrupt negative carbonate carbon excursion, the first appearance datum of Oryctocephalus indicus is currently the best horizon to achieve correlation between the two regions.
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http://dx.doi.org/10.1038/s41598-019-53685-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6874646PMC
November 2019

Isotopic evidence for temperate oceans during the Cambrian Explosion.

Sci Rep 2019 04 19;9(1):6330. Epub 2019 Apr 19.

Department of Palaeobiology, Swedish Museum of Natural History, Box 50007, SE-104 05, Stockholm, Sweden.

The Cambrian Explosion was a key event in the evolution of life on Earth. This event took place at a time when sea surface temperatures have been proposed to reach about 60 °C. Such high temperatures are clearly above the upper thermal limit of 38 °C for modern marine invertebrates and preclude a major biological revolution. To address this dichotomy, we performed in situ δO analyses of Cambrian phosphatic brachiopods via secondary ion mass spectrometry (SIMS). The δO data, which are considered to represent the most primary δO signature, were identified by evaluating the diagenetic alteration of the analyzed shells. Assuming ice-free conditions for the Cambrian ocean and no change in δO (-1.4‰ to -1‰; V-SMOW) through time, our temperatures vary between 35 °C ± 12 °C and 41 °C ± 12 °C. They are thus clearly above (1) recent subequatorial sea surface temperatures of 27 °C-35 °C and (2) the upper lethal limit of 38 °C of marine organisms. Our new data can therefore be used to infer a minimal depletion in early Cambrian δO relative to today of about -3‰. With this presumption, our most pristine δO values translate into sea surface temperatures of about 30 °C indicating habitable temperatures for subequatorial oceans during the Cambrian Explosion.
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http://dx.doi.org/10.1038/s41598-019-42719-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6474879PMC
April 2019