Paper No. 6
Presentation Time: 3:10 PM
STROMATACTIS LIMESTONE BELOW AND ABOVE THE PERMIAN-TRIASSIC BOUNDARY EVENT ("GREAT DYING")
BAUD, Aymon, BGC, Parc de la Rouvraie 28, Lausanne, CH-1018, Switzerland, BUCHER, Hugo, Paleontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, Zürich, 8006, Switzerland, BROSSE, Morgane, Paläontologisches Institut und Museum, Universität Zürich, Karl-Schmid-Strasse 4, Zürich, CH-8006, Switzerland, FRISK, Åsa M., Paläontologisches Institut und Museum, University of Zurich, Karl-Schmid-Strasse 4, Zürich, CH-8006, Switzerland and GUODUN, Kuang, Research Institute, Guangxi Regional Geological Survey, Nanning, 530023, China, Aymon.Baud@unil.ch
A new quarry in the upper Permian to basal Triassic carbonate succession near Shanggan (Leye County, NW Guangxi, South China) shows an upper Permian stromatactis mound above a coral reef. The top of this Late Permian stromatactis buildup is cut by an irregular surface overlain by a 1.5m thick high-energy laminated lime grainstone followed by a 5m thick basal Triassic stromatolite facies. The upper, domal part of this microbial buildup displays centimetric cavities of stromatactis type cemented by blocky calcite.
Abundant and larger stromatactis type cavities with fibro-radial calcite cement occur in the overlying upper Griesbachian coquina limestone (coquina described by Hautmann et al., 2011, and in part by Frisk et al., this session). Just above, within the lower Dienerian lime siltstone, elongated stromatactis cavities and sheet cracks type filled by gray lime mud and microlayered isopachous cements are recorded.
The Shanggan section fills a gap between previously known stromatactis occurrences and bridges Paleozoic and Mesozoic stromatactis limestone. This continuum was favored by the local persistence of open marine carbonate deposition from the Permian into the Triassic, on a tectonically uplifted submarine plateau.
Due to their partly microbial origin, the open marine stromatactis buildup seems not to be affected by the "great dying".
