Pannonian ostracods from the southwestern Transylvanian basin

Erika Kovacs,Radovan Pipik,Orsolya Sztano,Imre Magyar

doi:10.4154/gc.2016.16

Abstract

Pannonian (Late Miocene) ostracods were investigated from 7 outcrops, exposing deep-water lacustrine sediments along the western margin of the Transylvanian Basin. Sedimentological patterns in the outcrops indicate deposition in sublittoral to profundal environments where fine-grained, suspension fall-out sediments are intercalated with various types of mass transport deposits, most commonly turbidites. The ostracod fauna, consisting of 30 taxa, is dominated by endemic species of the brackish Lake Pannon. The assemblages indicate a mixture of deep-water (sublittoral to profundal) species, such as Paratethyan Candoninae, and shallow-water (littoral) species, belonging to Cyprideis, Loxoconcha, Amnicythere and Hemicytheria. The mixed character of the assemblages is most probably a consequence of the reworking of littoral specimens into deeper environments, a phenomenon also observed in the molluscan fauna from some of the investigated outcrops. Alternatively, some endemic and extinct species of the littoral genera might have adapted to the deep-water environment. A significant decrease in the abundance and diversity of ostracods from west to east is interpreted reflecting increasingly distal environments. The ostracod fauna indicates the Hemicytheria hungarica (2 outcrops), Hemicytheria tenuistriata (3 outcrops), and Propontoniella candeo Zones (2 outcrops) of the lower Pannonian Slavonian Substage.

Highlights

Study of ostracods of the Neogene Paratethys has substantially contributed to the stratigraphic, environmental, and palaeogeographic understanding of this huge and complex marine to lacustrine depositional system (DANIELOPOL et al, 2008a)
Pannonian (Late Miocene) ostracods were investigated from 7 outcrops, exposing deep-water lacustrine sediments along the western margin of the Transylvanian Basin
The assemblages indicate a mixture of deepwater species, such as Paratethyan Candoninae, and shallow-water species, belonging to Cyprideis, Loxoconcha, Amnicythere and Hemicytheria

Summary

Introduction

Study of ostracods of the Neogene Paratethys has substantially contributed to the stratigraphic, environmental, and palaeogeographic understanding of this huge and complex marine to lacustrine depositional system (DANIELOPOL et al, 2008a). Of the large brackish lakes that repeatedly formed during the history of the Paratethys, the Late Miocene-Early Pliocene Lake Pannon was probably the longest-lived (MÜLLER et al, 1999; HARZ HAUSER & MANDIC, 2008). As a consequence, this lake was inhabited by an astonishingly diverse lacustrine biota (e.g. PAPP et al, 1985; STEVANOVIĆ et al, 1990). The objective of this paper is to present the Late Miocene (Pannonian) ostracod faunas from several outcrops of the southwestern TB, and to explore their palaeoecological, palaeobiogeographic and biostratigraphic context

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