Late Carboniferous Levipustula fauna in the Leoncito Formation, San Juan province, Argentine Precordillera: biostratigraphical and palaeoclimatological implications

CISTERNA, G.A. & STERREN, A.F.

Proceedings of the Royal Society of Victoria

Royal Society of Victoria

Lugar: Melbourne; Año: 2008 vol. 120 p. 137 - 147

0035-9211

The Carboniferous Levipustula Fauna from the glacial marine sequence of the Leoncito Formation (Calingasta-Uspallata Basin, San Juan Province, Argentina) is reviewed. In the middle part of the section, associated with sandstone and mudstone horizons located below the glacial diamictitic beds, two different fossil assemblages are recognised. One is associated with sandstone beds, composed of brachiopods (Septosyringothyris keideli (Harrington), Costuloplica leoncitensis (Harrington), ?Spiriferellina? octoplicata Sowerby, Beecheria sp. and Levipustula levis Maxwell), bivalves (Phestia sp., Schizodus sp. and Pleurophorella? sp.), bryozoans (Fenestella? sp.) and gastropods (Barrealispira? sp.). The other, in a mudstone interval, is composed of brachiopods (Levipustula levis? and Beecheria sp.), bivalves (Nuculopsis?), ostracods (probably some Aurykirkbya), gastropods, crinoids and bryozoans. Because of its stratigraphical position in relation to the diamictitic horizons, as well as its compositional and taphonomical features, the fossil assemblage associated with the mudstone interval can be compared with the ?Intra-glacial Levipustula Fauna? recently identified in the Hoyada Verde Formation (Calingasta-Uspallata Basin, San Juan Province). Proximity to a glacier would have placed the fauna under stressed environmental conditions. The occurrence of common fauna in the Hoyada Verde and Leoncito formations links the two stratigraphic sections affected by glaciation within the Calingasta-Uspallata Basin.