Detailed clay mineralogy of the TriassicJurassic boundary section at Kendlbachgraben (Northern Calcareous Alps, Austria)

Zajzon, N. and Kristály, F. and Pálfy, J. and Németh, T. (2012) Detailed clay mineralogy of the TriassicJurassic boundary section at Kendlbachgraben (Northern Calcareous Alps, Austria). Clay Minerals, 47 (2). pp. 177-189. ISSN 00098558

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The Triassic-Jurassic boundary (TJB) is marked by one of the five largest Phanerozoic mass extinctions. To constrain existing models for TJB events, we obtained a stratigraphically highly resolved dataset from a marine section at Kendlbachgraben, Austria. The topmost Triassic Ko¨ssen Formation contains low to medium-charged smectite and vermiculite as alteration products of mafic-ultramafic minerals. The clay minerals in the boundary mudstone are kaolinite 5 illite + muscovite >> smectite > chlorite. Predominant kaolinite suggests humid climate and abundant terrigenous input. In the lowermost Jurassic, the clay mineral pattern changes to illite + muscovite >> kaolinite >> smectite, which reflects change to less humid and more moderate climate. The topmost Ko¨ssen Formation also contains clay spherules. Their composition, shape and size indicate that they are alteration products of airborne volcanic glass droplets solidified in the air, settled in the sea and altered rapidly with negligible transport in terrestrial or marine environments. Our data are consistent with sudden climatic change at the TJB, as a result of large-scale volcanic activity of the Central Atlantic Magmatic Province which produced distal airfall volcanic ash.

Item Type: Article
Uncontrolled Keywords: Triassic-Jurassic boundary Kendlbachgraben clay mineralogy volcanic spherules climate change Austria
Subjects: Q Science / természettudomány > QD Chemistry / kémia > QD06 Mineralogy / ásványtan
Q Science / természettudomány > QE Geology / földtudományok > QE05 Historical geology. Stratigraphy / Földtörténet, rétegtan
Depositing User: Mariann Bosnakoff
Date Deposited: 10 Dec 2013 15:11
Last Modified: 30 Jun 2014 23:15

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