Naslov
Stable isotope composition (δ13C, δ18O) of Lake Slavonia mollusks from the Pliocene Viviparus beds in the region of Kravarsko (Cernikian, Central Croatia)

Autori
Kurečić, T. ; Mandic, O. ; Grunert, P.

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Program & Abstracts. Lake - Basin - Evolution, RCMNS Interim Colloquium 2016 & Croatian Geological Society Limnogeology Workshop, 19-24 May 2016, Zagreb, Croatia / Mandic, Oleg ; Pavelić, Davor ; Kovačić, Marijan ; Sant, Karin ; Andrić, Nevena ; Hrvatović, Hazim - Zagreb : Hrvatsko geološko društvo, 2016, 36-37

ISBN
978-953-95130-9-0

Skup
Lake - Basin - Evolution, RCMNS Interium Colloquium 2016, Croatian Geological Society Limnogeology Workshop

Mjesto i datum
Zagreb, Hrvatska, 20.05.2016. - 24.05.2016

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
Pliocene; Lake Slavonia; Viviparus beds; lacustrine mollusks; stable isotopes

Sažetak
Long-lived Lake Slavonia existed during the Pliocene in the southern part of Pannonian Basin System (PBS). It was characterized by the explosive adaptive radiation of viviparid snails, which enabled establishment of regional biostratigraphy and excellent stratigraphic control of lake deposits along the southern margin of PBS. The present investigation deals with samples from the region of Kravarsko, located in central Croatia, approximately 30 km south from Zagreb. Situated on the southern margin of the Sava depression, this area represents the western-most extent of Lake Slavonia. The study region is composed of Pliocene sediments deposited in predominantly lacustrine and some alluvial freshwater environments. Mandic et al. (2015) in their recent study recognized the history of Lake Slavonia as an independent phase in the geodynamic evolution of PBS. They introduced consequently a new regional stage Cernikian, defined by the complete depositional sequence of Lake Slavonia, and the Viviparus beds, respectively. In the area of Kravarsko two stratigraphic horizons are detected, Lower Cernikian Viviparus kochanskyae and Upper Cernikian Viviparus hoernesi zone. The aim of the present study is a detailed paleoenvironmental reconstruction of Cernikian at Kravarsko based on stable isotope (δ13C, δ18O) composition of mollusk shells. A total of 52 specimens was chosen belonging to seven mollusk genera. Based on the position within the new regional stratigraphic scheme of the Lake Slavonia their ages are determined from c. 4.5 Ma to c. 2.0 Ma. The samples of Viviparus kochanskyae Zone (upper part of Lower Cernikian) were collected from outcrops which are mostly clayey to silty in composition. They mark the Early Cernikian transgression in this area. Samples from upper Cernikian Viviparus hoernesi Zone (strongly sculptured viviparid shells) were collected from outcrop with predominantly silty to sandy sediments. They mark the second lacustrine transgression of Lake Slavonia, which coincides with the Pliocene Climate Optimum (PCO). In the Lower Cernikian, δ18O values range from -11.2‰ to -1.9‰ (VPDB), whereas δ13C values range from -11.8‰ to -5.4‰ (VPDB). In the Upper Cernikian δ18O values range from -11.3‰ to -10.1‰, and δ13C values from -11.7‰ to -7.4‰. Therefore, total ranges of the δ13C record are fairly similar in both horizons. In contrast, δ18O values show a wider range in Lower Cernikian than in the Upper Cernikian. This variability is probably related to different habitat preferences and life- strategies of evaluated gastropod taxa. It might also result from a larger number of species measured from the Viviparus kockanskyae Zone. In the future, our stable isotope data will serve as the basis for paleoenvironmental and paleotemperature reconstructions of Lake Slavonia in correlation with known temperature data for period of warm Pliocene Climate and also for PCO. Also it will serve for an evaluation of the impact of mollusk life- strategies and habitat preferences on expected isotope signatures (e.g., Harzhauser et al., 2007 ; 2012).

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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