Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Acta Geologica Polonica

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Echinoids and pectinid bivalves from the Early Miocene Mishan Formation of Iran

Kroh A., Gholamalian H., Mandic O., Ćorić S., Harzhauser M., Reuter M., Piller W.

Acta Geologica Polonica

2011

Vol. 61, no. 4

419-439

Shallow marine echinoids and pectinid bivalves from the Early Miocene Guri Member of the Mishan Formation cropping out at the Gery Sheikh section north of Bandar Pohl in the area of the Hormuz Strait, Iran, are reported. The echinoid fauna indicates a Burdigalian age for the Guri Member. This is supported by new calcareous nannoplankton data from this unit, which suggest an age from Aquitanian to middle Burdigalian (NN1-NN3). From a palaeobiogeographic point of view the fauna of the Guri Member is related to the faunas from central Saudi Arabia, southeast Pakistan and northwest India. The absence of Western Tethyan elements supports earlier data suggesting that a faunal separation between Proto-Mediterranean and Proto-Indian Ocean faunas was well developed before the terminal Tethyan Event. The echinoids Fibularia damensis Kier, 1972 and Anisaster arabica Kier, 1972 are new records for Iran, having been known before solely from Saudi Arabia. Brissus daviesi Jain, 2002 is transferred to Rhynobrissus based on the characters of its fascioles, petalodium and plas tron; this constituting the first fossil record of the genus.

Changes in Paratethyan marine molluscs at the Early/Middle Miocene transition : diversity, palaeogeography and palaeoclimate

Harzhauser M., Mandic O., Zuschin M.

Acta Geologica Polonica

2003

Vol. 53, nr 4

323-339

The transition from the Early Miocene to the Middle Miocene is a crucial point for the development of mollusc faunas (gastropods and bivalves) in the Central Paratethys. Here, we first discuss the confusing and partly contradictory stratigraphic concepts and correlations of Paratethyan and Mediterranean reference faunas. Then we show that the interplay of sea level fluctuations, climatic amelioration, immigrations, and blooms in autochthonous elements causes a complex pattern of faunal development. We focus on the so-called "Ground Fauna", which flourised during the Early Badenian and is here treated as transitional between typical late Early Miocene and typical Middle Miocene faunas. This faunal type, originally defined in Austria, is represented within the entire Central Paratethys and is strictly stratigraphically determined. It developed during the early Middle Miocene and is interpreted by us to mirror a phase of optimal climatic conditions. This is most plausible in respect to the marginal position of the Central Paratethys. As a northern appendix of the early Mediterraneas Sea, it spans a north-south gradient of about 4 stopnie latitude and is suggested to represent a type of "palaeo-thermometer" which reflects slight expansions or restrictions of climatic belts. The Langhian climatic optimum, for example, seems to be reflected within Paratethyan mollusc faunas by the northward migration of Mediterranean thermophilic species during the Early Badenian.