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2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM

Paper No. 1
Presentation Time: 1:30 PM

Major Climatic Change at the Smithian/Spathian Boundary – Evidence from Low Palaeolatitudinal Records


HERMANN, Elke1, HOCHULI, Peter A.2, BUCHER, Hugo2, BRÜHWILER, Thomas1, GOUDEMAND, Nicolas1 and ROOHI, Ghazala3, (1)Paleontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, Zurich, 8006, Switzerland, (2)Paleontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, Department of Earth Sciences, ETH Zürich, Zurich, 8006, Switzerland, (3)Pakistan Museum of Natural History, Garden Avenue, Islamabad, 44000, Pakistan, ehermann@pim.uzh.ch

The delayed recovery of marine and terrestrial ecosystems after the end-Permian extinction event is still up for debate. Focusing on the Smithian/Spathian boundary, palaeoecological changes are reflected by a significant global faunal turnover as indicated by ammonoids (Brayard et al. 2006) and conodonts (Orchard 2007) as well as a change in the palynological associations of the Boreal realm. There, the Smithian/Spathian transition is marked by a conspicuous change from spore dominated assemblages in the Smithian to gymnosperm dominated assemblages in the Spathian (Galfetti et al. 2007a).

Here, we present the composition of the Early Triassic microfloras of Nammal, Salt Range, Pakistan. Ammonoids and conodonts provide the high resolution age control of the studied section (Brühwiler et al. 2007).

The late Smithian palynological assemblages are characterized by a general dominance of hygrophytic elements. Slightly below the Smithian/Spathian boundary, between the Anasibirites beds and the Glyptophiceras beds, the composition changes dramatically with a drastically increasing proportion of xerophytic elements. This event coincides with the onset of a positive shift in the δ13C record marking the Smithian/Spathian boundary (Galfetti et al. 2007b). Preliminary results from southern Tibet also indicate a similar trend from hygrophyte-dominated to xerophyte-dominated assemblages across the boundary.

Thus the Smithian/Spathian boundary climatic event can be traced from high to low latitudes, demonstrating its global significance.

Brayard, A. et al. 2006: PPP 239:374-395.

Brühwiler, T. et al. 2007: New Mexico Mus. Nat.Hist.& Sci. Bull. 41: 25-26.

Galfetti, T. et al. 2007a: Geology 35: 291-294.

Galfetti, T. et al. 2007b: EPSL 258: 593-604.

Orchard, M.J. 2007: PPP 252: 93-117

Session No. 318

T41. Recoveries from Mass Extinction: Patterns, Processes, and Comparisons II
Wednesday, 8 October 2008: 1:30 PM-5:30 PM
Geological Society of America Abstracts with Programs. Vol. 40, No. 6, p.505
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