Triassic palynology of central and northwestern Europe: a review of palynofloral diversity patterns and biostratigraphic subdivisions
Published:January 01, 2010
Wolfram M. Kürschner, G. F. Waldemaar Herngreen, 2010. "Triassic palynology of central and northwestern Europe: a review of palynofloral diversity patterns and biostratigraphic subdivisions", The Triassic Timescale, Spencer G. Lucas
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We document palynofloral trends through the Triassic in the Germanic and Alpine facies with an emphasis on diversity trends and possibly related palaeoenvironmental changes. As a first order approximation of palynofloral diversity, we used the range through method of the software package PAST based on a range chart compiled from several Triassic palynological studies and reviews. Our analysis suggests that during the entire Triassic the diversity of plants producing spores was largely controlled by the availability of water, while diversity among gymnosperms was also affected by other environmental and biotic factors. In general, palynofloral diversity declines by some 50% between the early Carnian and the Norian, mainly as a result of a decrease in the number of pollen species. This is the second most severe loss in pollen species after the Permian–Triassic biotic crisis. In comparison to the marked palynofloral turnover at the Permian–Triassic transition and the end-Carnian decrease in palynofloral diversity, the end-Triassic biotic crisis appears to have little affected palynofloral species diversity in Europe. A study of the palynostratigraphy of NW Europe recognizes nine zones (and nine subzones) that encompass the Triassic, most of which have their boundaries based on the first occurrences of marker species. The palynostratigraphic zones and subzones in Europe are correlated to the marine Triassic stages based on various data, including numerous palynological records in marine Alpine Triassic strata.
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The Triassic Timescale
The Mesozoic Era begins with the approximately 50-million-year-long Triassic Period, a major juncture in Earth history when the vast Pangaean supercontinent completed its assembly and began its fragmentation, and the global biota diversified and modernized after the end-Permian mass extinction, the most extensive biotic decimation of the Phanerozoic. The temporal ordering of geological and biotic events during Triassic time thus is critical to the interpretation of some unique and pivotal events in Earth history. This temporal ordering is mostly based on the Triassic timescale, which has been developed and refined for nearly two centuries. This book reviews the state of the art of the Triassic timescale and includes comprehensive analyses of Triassic radio-isotopic ages, magnetostratigraphy, isotope-based and cyclostratigraphic correlations and timescale -relevant marine and non-marine biostratigraphy.