SSP17

Paratethys - Mediterranean - Indopacific climatic, biotic and sedimentological evolution (co-sponsored by IAS)
Convener: O. Mandic  | Co-Conveners: Harzhauser , M. Wagreich 
Oral Programme
 / Wed, 22 Apr, 13:30–15:00  / Room 36
Poster Programme
 / Attendance Wed, 22 Apr, 17:30–19:00  / Hall A
The Cenozoic constitutes the final stage in the development of the Alpine Orogenic Belt, where crustal deformation induced synchronous formation and filling of enclosed sedimentary basins. Uplift and exhumation of rocks and climatic feedback influenced not only the sedimentological evolution but also the biota of the manifold foredeep basins.

The session is intended to review the state of the art in the environmental reconstruction of the Cenozoic peri-Alpine circum-Mediterranean region. The idea includes establishment of a platform in the frame of the EGU where an interdisciplinary approach in the earth sciences comes to the fore. We hope to attract geoscientists of different profiles to present their work and develop future cooperation.

Presentations on all aspects of regional Cenozoic history, including basin formation, source terrain evolution, climatic proxies, stratigraphy, sedimentology and palaeontology of basin fills, and the interplay of exhumation, uplift, erosion and deposition will be appreciated.

KEYNOTES

Environmental history

The Cenozoic history of the circum-Mediterranean area was strongly influenced by the Alpidic orogenies which caused tectonic compression and fusion of several microplates between Europe and Africa. As a consequence of this compressive tectonic regime, Eurasia moved northwards and experienced considerable uplift (e.g. Tibetan Plateau, Alpine-Carpathian Chain, Anatolian Plate). Simultaneously, the Eurasian ecosystems and landscapes were impacted by a complex pattern of changing seaways and land bridges between the Paratethys Sea, the Proto-Mediterranean Sea and the western Indo-Pacific. The marginal position of the seas covering the area and the considerable synsedimentary geodynamic control resulted in incomplete stratigraphic sequences with frequent unconformities, erosional surfaces and depositional gaps.

Climatic history

The geodynamic changes in landscapes and environments were further amplified by drastic climate changes during the Cenozoic. The warm Cretaceous climate continued into the early Paleogene with a distinct optimum during the Late Paleocene and the Early Eocene. A gradual decrease in temperature during the later Eocene culminated in the formation of the first ice-sheets in Antarctica around the Eocene/Oligocene boundary. A renewed warming trend that began during the Late Oligocene continued into the Middle Miocene with a climax at the Middle Miocene Climatic Optimum. The turning-point at around 14.2 Ma lead to the onset of the Middle Miocene Climate Transition indicated by the cooling of surface waters and the expansion of the East-Antarctic ice-sheet. A final trend reversal during the Early Pliocene is reflected by a gentle warming until 3.2 Ma when the onset of permanent Arctic glaciation heralded the Pleistocene ice-ages.

Paratethys Sea and its late Miocene to Pliocene successor Lake Pannon.

At its maximum extent, the Paratethys spread from the Rhône Basin in France towards Inner Asia. Subsequently, it was partitioned into a smaller western part consisting of the Western and the Central Paratethys and the larger Eastern Paratethys. The Western Paratethys comprises the Rhône Basin and the Alpine Foreland Basin of Switzerland, Bavaria and Austria. The Central Paratethys extends from the Vienna Basin in the West to the Carpathian Foreland in the East where it abuts the area of the Eastern Paratethys. Eurasian ecosystems and landscapes were impacted by a complex pattern of changing seaways and land bridges between the Paratethys, the North Sea and the Mediterranean as well as the western Indo-Pacific This geodynamically controlled biogeographical differentiation necessitates the establishment of different chronostratigraphic/geochronological scales.

Terminal Tethyan Event

In the Oligocene and Early Miocene, the Tethys connected the two major oceanic areas, the Atlantic and the Pacific. Hydrogeographically, this seaway existed until the geodynamically induced closure of the Tethys Gateway - the “Terminal Tethyan Event” - which resulted in the disconnection of these two oceanic realms and brought about the “birth” of the Indian Ocean and the Mediterranean Sea, changed this situation. Although the precise dating of the disconnection and when it started to affect faunal migration is still under discussion most authors agree that with the beginning of the Middle Miocene each region had developed its own distinct biota.

Palaeobiogeography

The complex regional histories are reflected in marine faunas of adjacent biogeographical areas that may develop around gradually emerging land bridges. Biogeographical divergence in marine communities may herald the final establishment of geographical barriers. In contrast, migrations of terrestrial mammal biota are straightforward proxies in such reconstructions but are usually difficult to date.