Triassic radiolarite and carbonate components from a Jurassic ophiolitic mélange (Dinaridic Ophiolite Belt)

Abstract

The late Middle to early Late Jurassic melange of the eastern Zlatibor Mountain (Gostilje–Ljubis–Visoka–Radosevo areas) in the Dinaridic Ophiolite Belt contains a mixture of (A) blocks of Triassic oceanic crust and radiolarites, and (B) open marine limestone and radiolarite blocks of the overthrusted distal Adria margin. We describe the microfacies and present biostratigraphic data from radiolarite and carbonate clasts and blocks and the radiolaritic-argillaceous matrix. The radiolarians and conodonts yield Middle to Late Triassic (Ladinian to Norian) ages for the provenance areas from which the ophiolite, radiolarite and carbonate blocks and clasts derived. The provenance areas of the components in the Gostilje–Ljubis–Visoka–Radosevo melange are determined as (1) the ocean floor of the Neo-Tethys, and (2) the continental slope/distal parts of the shelf. In the course of ophiolite obduction, the continental slope and the ocean floor components were transported by mass movements into newly-formed, trench-like basins in front of the westward propagating obduction of the Dinaridic ophiolite nappe stack. These basins were later incorporated in the nappe stack forming the typical features of a syntectonic melange. The new radiolarian biostratigraphic data confirm Middle Triassic formation of the Neo-Tethys Ocean, parts of which were closed during obduction commencing in the late Early or early Middle Jurassic. The data clearly speak in favour of one Neo-Tethys Ocean to the east, from which the ophiolites of the Dinaridic Ophiolite Belt derived as far-travelled ophiolitic sheets.