Subdivision of the Triassic according to the ICS, as of 2023.[5] Vertical axis scale: millions of years ago.
The Carnian pluvial episode (CPE), often called the Carnian pluvial event, was a period of major change in global climate that coincided with significant changes in Earth's biota both in the sea and on land. It occurred during the latter part of the Carnian Stage, a subdivision of the late Triassic period, and lasted for perhaps 1–2 million years (around 234–232 million years ago).[6][7]
The CPE corresponds to a significant episode in the evolution and diversification of many taxa that are important today, among them some of the earliest dinosaurs (which include the ancestors of birds), lepidosaurs (the ancestors of modern-day snakes and lizards) and mammaliaforms (ancestors of mammals). In the marine realm it saw the first appearance among the microplankton of coccoliths and dinoflagellates,[8][7][9] with the latter linked to the rapid diversification of scleractinian corals through the establishment of symbiotic zooxanthellae within them. The CPE also saw the extinction of many aquatic invertebrate species, especially among the ammonoids, bryozoa, and crinoids.[6]
Evidence for the CPE is observed in Carnian strata worldwide and in sediments of both terrestrial and marine environments. On land, the prevailing arid climate across much of the supercontinentPangea shifted briefly to a hotter and more humid climate, with a significant increase in rainfall and runoff.[6][10][8][11][12] In the oceans there was reduced deposition of carbonate minerals. This may reflect the extinction of many carbonate-forming organisms, but may also be due to a rise in the carbonate compensation depth, below which most carbonate shells dissolve and leave few carbonate particles on the ocean floor to form sediments.[13][14][15][16]
Climate change during the Carnian pluvial event is reflected in chemical changes in Carnian strata across the CPE which suggest that global warming was prevalent at the time. This climate change was probably linked to the eruption of extensive flood basalts as the Wrangellia Terrane was accreted onto the northwestern end of the North American Plate.[10]
^McElwain, J. C.; Punyasena, S. W. (2007). "Mass extinction events and the plant fossil record". Trends in Ecology & Evolution. 22 (10): 548–557. doi:10.1016/j.tree.2007.09.003. PMID17919771.
^Ogg, James G.; Ogg, Gabi M.; Gradstein, Felix M. (2016). "Triassic". A Concise Geologic Time Scale: 2016. Elsevier. pp. 133–149. ISBN978-0-444-63771-0.
^ abFurin, S.; Preto, N.; Rigo, M.; Roghi, G.; Gianolla, P.; Crowley, J.L.; Bowring, S.A. (2006). "High-precision U-Pb zircon age from the Triassic of Italy: Implications for the Triassic time scale and the Carnian origin of calcareous nanoplankton, lepidosaurs, and dinosaurs". Geology. 34 (12): 1009–1012. doi:10.1130/g22967a.1.
^ abCite error: The named reference dawn was invoked but never defined (see the help page).
^Hornung, T.; Krystin, L.; Brandner, R. (2007). "A Tethys-wide mid-Carnian (Upper Triassic) carbonate productivity crisis: Evidence for the Alpine Reingraben Event from Spiti (Indian Himalaya)?". Journal of Asian Earth Sciences. 30 (2): 285–302. Bibcode:2007JAESc..30..285H. doi:10.1016/j.jseaes.2006.10.001.
^Stefani, M.; Furin, S.; Gianolla, P. (2010). "The changing climate framework and depositional dynamics of Triassic carbonate platforms from the Dolomites". Palaeogeography, Palaeoclimatology, Palaeoecology. 290 (1–4): 43–57. Bibcode:2010PPP...290...43S. doi:10.1016/j.palaeo.2010.02.018.
^Rigo, M.; Preto, N.; Roghi, G.; Tateo, F.; Mietto, P. (2007). "A rise in the Carbonate Compensation Depth of western Tethys in the Carnian: deep-water evidence for the Carnian Pluvial Event". Palaeogeography, Palaeoclimatology, Palaeoecology. 246: 188–205. doi:10.1016/j.palaeo.2006.09.013.