Age and microfacies of oceanic Upper Triassic radiolarite components from the Middle Jurassic ophiolitic mélange in the Zlatibor Mountains (Inner Dinarides, Serbia) and their provenance

Abstract

Oceanic radiolarite components from the Middle Jurassic ophiolitic mélange between Trnava and Rožanstvo in the Zlatibor Mountains (Dinaridic Ophiolite Belt) west of the Drina-Ivanjica unit yield Late Triassic radiolarian ages. The microfacies characteristics of the radiolarites show pure ribbon radiolarites without crinoids or thin-shelled bivalves. Beside their age and the preservation of the radiolarians this points to a deposition of the radiolarites on top of the oceanic crust of the Neo-Tethys, which started to open in the Late Anisian. South of the study area the ophiolitic mélange (Gostilje-Ljubiš-Visoka-Radoševo mélange) contains a mixture of blocks of 1) oceanic crust, 2) Middle and Upper Triassic ribbon radiolarites, and 3) open marine limestones from the continental slope. On the basis of this composition we can conclude that the Upper Triassic radiolarite clasts derive either from 1) the younger parts of the sedimentary succession above the oceanic crust near the continental slope or, more convincingly 2) the sedimentary cover of ophiolites in a higher nappe position, because Upper Triassic ribbon radiolarites are only expected in more distal oceanic areas. The ophiolitic mélange in the study area overlies different carbonate blocks of an underlying carbonate-clastic mélange (Sirogojno mélange). We date and describe three localities with different Upper Triassic radiolarite clasts in a mélange, which occurs A) on top of Upper Triassic fore-reef to reefal limestones (Dachstein reef), B) between an Upper Triassic reefal limestone block and a Lower Carnian reef limestone (Wetterstein reef), and C) in fissures of an Upper Triassic lagoonal to back-reef limestone (Dachstein lagoon). The sedimentary features point to a sedimentary and not to a tectonic emplacement of the ophiolitic mélange (= sedimentary mélange) filling the rough topography of the topmost carbonate-clastic mélange below. The block spectrum of the underlying and slightly older carbonate-clastic mélange points to a deposition of the sedimentary ophiolitic mélange east of or on top of the Drina-Ivanjica unit.

Continuity and Episodicity in the Early Alpine Tectonic Evolution of the Western Carpathians: How Large‐Scale Processes Are Expressed by the Orogenic Architecture and Rock Record Data

“…Triassic events related to the Neotethyan rifting and origin of the Meliata Ocean are widely recorded in the western circum-Pannonian mountains. Namely, the short-termed Pelsonian rifting event and subsequent disintegration of the carbonate shelf areas and development of proximal passive margin carbonate platforms grading into distal pelagic facies oceanward were described by a number of researchers (e.g., Gawlick et al, 2017;Haas et al, 1995;Kovács et al, 2011, and references therein). Ma; Hettangian-Sinemurian)…”

Latest Triassic and Early Jurassic Spiriferinida (Brachiopoda) of Zealandia(New Zealand and New Caledonia)

“…Callospiriferina is known from Spain (Alméras & Fauré 2000), France (Alméras &Fauré 2000, Alméras andCougnon 2013), Portugal (Alméras et al 1996), Italy (Taddei Ruggiero & Vörös 1987), Austria (Boehm et al 1999, Siblík 1999, Hungary (Dulai 1992(Dulai , 2003, the Balkans (Radulovic 1995), Britain (Hollingworth et al 1990), Morocco (Rousselle 1977), Algeria (Alméras et al 2007), Alaska (Sandy & Blodgett 2000) and Argentina (Manceñido 1981, Damborenea & Manceñido 1992). The genus is reviewed, mainly from a western European perspective by Alméras & Cougnon (2013).…”

Mesozoic basins on the Adriatic continental margin – a cross-section through the Dinarides in Montenegro / Mezozojski bazeni na kontinentalnem robu Jadranske plošče – presek čez Dinaride v Črni gori

“…The progressive development of trench-like basins in front of the propagating nappes is best documented in the age and composition of sedimentary mélanges; towards west, mélanges become younger and contain less ophiolite-derived material but more and more blocks reworked from the continental margin. Gawlick and co-workers (Gawlick et al 2017b;Gawlick & Missoni 2019) distinguished two types of mélanges: 1) the ophiolitic mélange composed of serpentinites, basalts, cherts and in places carbonate blocks, and 2) the Hallstatt Mélange containing continental-margin limestone and chert blocks in a radiolaritic-argillaceous matrix. They further subdivided the Hallstatt Mélange according to the provenance of continental-margin blocks; mélanges with outer-shelf Hallstatt-limestone blocks were deposited during the Bathonian to Oxfordian and those containing Triassic reef blocks were formed in the Callovian to Oxfordian.…”

“…The alternative model considers the Pelagonian unit as a microcontinent between the Pindos Ocean in the west and the Vardar Ocean in the east; ophiolites from both oceans were obducted with opposite vergence onto the Pelagonian microcontinent (Robertson et al 1991;Robertson & Karamata 1994;Robertson & Shallo 2000;Dilek et al 2005). A comparison of both basic models and their modifications are discussed in detail in several papers (Saccani et al 2011;Robertson 2012;Gawlick et al, 2017bGawlick et al, , 2018. The interpretation that both ophiolite belts were derived from one oceanic basin located to the east of the Pelagonian domain has been widely accepted in recent literature and is also adopted in this paper (Figure 3).…”