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Benthic foraminifera from the upper Collio Formation (Lower Permian, Lombardy Southern Alps): implications for the palaeogeography of the peri‐Tethyan area
Author(s) -
Sciunnach Dario
Publication year - 2001
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1046/j.1365-3121.2001.00339.x
Subject(s) - geology , marine transgression , permian , paleontology , foraminifera , structural basin , context (archaeology) , palaeogeography , sea level , ecological succession , alluvial fan , benthic zone , tectonics , oceanography , volcanism , ecology , biology
New palaeontological evidence points to a temporary marine transgression in the Early Permian into the Collio Basin, a major palaeogeographic feature of the present‐day Southern Alps. The thick volcaniclastic succession filling the basin (Collio Formation) is widely held as deposited in alluvial to lacustrine settings. Rare calcareous foraminifers were recently found in a single sandstone interval, containing phosphate nodules, from the uppermost Collio Formation. A temporary seaway, necessary for the foraminifera to spread into a continental basin, implies that (i) the Collio Basin lake was not only an intramontane (as commonly viewed), but also a coastal lake, and (ii) its altitude did not exceed the amplitude of a first‐order sea‐level rise, that is, about 100 m. These constraints, along with striking similarities as to tectonic context, accumulation rates and geochemical signature, suggest that the Collio Basin was a California‐type basin, resembling in particular the present‐day Salton Sea (CA, USA).