Richard Lein

Significance of Late Permian-Triassic facies zones in terrane reconstructions in the Alpine-North Pannonian domain

Abstract The present-day setting of the tectonic units (terranes) making up the pre-Neogene basement of the Pannonian Basin and the West Carpathians is the result of large-scale displacements during the Alpine collisional phases. To explain this setting, based on various concepts, a number of models have been proposed in the last decade. Most of them agree in an eastward escape of the “North Pannonian terrane” from the Alpine domain towards the Pannonian during the Palaeogene-Early Miocene period. In the present paper a reconstruction of the pre-escape setting of the displaced terranes is presented based on facies zones in selected time-slices from the Late Permian to the Late Triassic. According to our reconstruction the Inner West Carpathian units were located east of the Austroalpine units forming the northern shelf of the “Euhallstatt”-Meliatic basin of the Vardar oceanic branch. The Drauzug should have been located in a position much more external than its present-day setting. The Transdanubian Range was situated in the northern neighbourhood of the Southern Alps, whereas the Bukk may have been located adjacent to the NW Dinarides. The Mid-Transdanubian zone is a major shear-zone containing elements of the Julian Alps and Sava folds nappe system and the Inner Dinaric ophiolitic melange. Although the nappe-tectonism may have played an important role in the structural evolution of the “North Pannonian terrane”, this mechanism alone can hardly produce hundreds of kilometres of facies offset on the opposite sides of strike-slip zones.

Triassic metasediments in the internal Dinarides (Kopaonik area, southern Serbia): stratigraphy, paleogeographic and tectonic significance

Triassic metasediments in the internal Dinarides (Kopaonik area, southern Serbia): stratigraphy, paleogeographic and tectonic significance Strongly deformed and metamorphosed sediments in the Studenica Valley and Kopaonik area in southern Serbia expose the easternmost occurrences of Triassic sediments in the Dinarides. In these areas, Upper Paleozoic terrigenous sediments are overlain by Lower Triassic siliciclastics and limestones and by Anisian shallow-water carbonates. A pronounced facies change to hemipelagic and distal turbiditic, cherty metalimestones (Kopaonik Formation) testifies a Late Anisian drowning of the former shallow-water carbonate shelf. Sedimentation of the Kopaonik Formation was contemporaneous with shallow-water carbonate production on nearby carbonate platforms that were the source areas of diluted turbidity currents reaching the depositional area of this formation. The Kopaonik Formation was dated by conodont faunas as Late Anisian to Norian and possibly extends into the Early Jurassic. It is therefore considered an equivalent of the grey Hallstatt facies of the Eastern Alps, the Western Carpathians, and the Albanides-Hellenides. The coeval carbonate platforms were generally situated in more proximal areas of the Adriatic margin, whereas the distal margin was dominated by hemipelagic/pelagic and distal turbiditic sedimentation, facing the evolving Neotethys Ocean to the east. A similar arrangement of Triassic facies belts can be recognized all along the evolving Meliata-Maliac-Vardar branch of Neotethys, which is in line with a ‘one-ocean-hypothesis’ for the Dinarides: all the ophiolites presently located southwest of the Drina-Ivanjica and Kopaonik thrust sheets are derived from an area to the east, and the Drina-Ivanjica and Kopaonik units emerge in tectonic windows from below this ophiolite nappe. On the base of the Triassic facies distribution we see neither argument for an independent Dinaridic Ocean nor evidence for isolated terranes or blocks.

Facies and environment of the Leckkogel beds (Carnian;Alps)

The Carnian Leckkogel beds represent a carbonate sequence, which was deposited in front of an actively spreading carbonate platform.The typical Leckkogel beds are characterized by highly diverse sponge buildups. Sphinctozoan sponges predominate together with rare bryozoans and hydrozoans as well as red algae and thin crusts of cyanophyceans. Foraminifera are very rare and dasycladaceans are missing altogether.Oncoidal limestones containing predominantly inozoans are coeval with the Leckkogel beds. They represent a short-lived colonization of the sea-floor within a basinal environment. In addition to this autochthonous development, allochthonous intercalations of debris-flow sediments occur. The basinal facies consists of shales and argillaceous schists.Towards the edge of the platform the Leckkogel beds interfinger laterally with the Tisovec limestone, which exhibits two main facies types, a reef facies and a lagoonal facies.ZusammenfassungDie karnischen Leckkogelschichten stellen eine Karbonatabfolge dar, die im Stirnbereich einer sich aktiv ausbreitenden Karbonatplattform abgelagert wurde. Der Rand dieser Plattform wird entweder durch Riffe oder duch Oolithbarren aufgebaut.Die typischen Leckkogelschichten sind durch Schwamm-buildups gekennzeichnet. Unter den Gerüstbildner dominieren Sphinctozoen, während Bryozoen, Hydrozoen und Rotalgen, sowie dünne Cyanophyceen-Krusten eine untergeordnete Rolle spielen. Formainiferen sind sehr selten, Dasycladaceen fehlen vollständig.Onkoidische Schwammkalke innerhalb der Beckenentwicklung stellen zeitgleiche Karbonatsedimente zu den Leckkogelschichten dar, die eine kurze Besiedlung des Beckens anzeigen. Neben dieser autochthonen Entwicklung treten innerhalb des durch Tonschiefer gekennzeichneten Beckens allochthone debris flow-Sedimente auf.Am Rand der Plattform sind die Leckkogelschichten mit Tisovec-Kalken verzahnt, die in zwei Hauptfaziestypen, einer Riff Fazies und einer lagunären Fazies, entwickelt sind.

The Economy of Dürrnberg-Bei-Hallein: An Iron Age Salt-mining Centre in the Austrian Alps

For the first time in English, we present a summary of the international programme of excavation work carried out between 1990 and 2001 in and around the Iron Age salt-mining complex of the Diirrnberg region, south of Salzburg. First we describe the results of excavation in the prehistoric adits, and of work to locate and survey associated settlements. This is followed by a series of specialist reports embracing floral and faunal remains, palaeodiet and parasitology, leather and woodworking and other crafts. The evidence suggests that a complex inter-relationship existed between the Diirrnberg and other communities in the Alpine foreland. It is assumed that the Diirrnberg was under the control of an elite – perhaps a local dynasty whose wealth is reflected in the graves.

Onset and demise of the Wetterstein Carbonate Platform in the mélange areas of the Zlatibor Mountain (Sirogojno, SW Serbia)

A kilometer-sized block in the Sirogojno carbonate-clastic mélange provides a complete succession of the Wetterstein Carbonate Platform evolution. The platform starts its progradation in Early Carnian times over hemipelagic Late Ladinian cherty limestones with fine-grained allodapic limestone intercalations. Shallow-water reef-slope, reefal to back-reef/lagoonal limestones evolved in the Early Carnian. The top of the platform is recrystallized and partly slightly dolomitized, and in parts karstification is visible. After a period of omission caused by uplift, new subsidence started in the early Late Carnian. This is documented by a flooding respectively drowning sequence of the same age, starting with reefal carbonates and rapidly followed by hemipelagic-influenced limestones. The evolution of the onset and the drowning of the Wetterstein Carbonate Platform prove a paleogeographic derivation of this block from the outer shelf-area facing the Neotethys Ocean, but still in a shallow-water carbonate platform position transitional to the Hallstatt facies zone. This paleogeographic position is especially confirmed by the new pulse of subsidence in the Late Carnian after a long lasting phase of omission. The evolution of the Wetterstein Carbonate Platform in the Inner Dinarides corresponds to successions known from the Northern Calcareous Alps or the southern Western Carpathians. In the Late Triassic both regions belong to the same northeast–southwest striking shelf area facing the Neotethys Ocean to the east and southeast, respectively.

Depositional environment, age and facies of the Middle Triassic Bulog and rid formations in the Inner Dinarides (Zlatibor Mountain, SW Serbia): Evidence for the Anisian break-up of the Neotethys Ocean

Below the Middle to lower Upper Jurassic ophiolitic melange and their overlying ophiolite nappes of the Dinaridic Ophiolite Belt in the Zlatibor Mountain area occur olistoliths and slideblocks. These consist of Triassic carbonates and radiolarites of variable age and palaeogeographic provenance. The matrixes of these blocks are late Middle Jurassic radiolarites and clays. The different carbonate rocks were commonly interpreted to derive from the near-by Drina-Ivanjica Unit. In contrast, the radiolarites should represent the original sedimentary cover of the ophiolitic rocks of the Dinaridic Ophiolite Belt, i.e. the obducted oceanic crust of the Neotethys Ocean, originally located far to the east. The carbonate blocks in the Zlatibor (Sirogojno) melange reach several tens to hundreds of metres in size, occasionally even kilometres. Several olistoliths and blocks contain well-preserved parts of the Middle Triassic sedimentary succession. Their stratigraphy and facies evolution allowed the reconstruction of a sedimentary succession originating from the same palaeogeographic provenance of a relatively proximal passive continental margin setting, located originally east of the Drina-Ivanjica Unit. Different red nodular limestones of the Bulog Formation were deposited on top of a drowned Middle Anisian (Pelsonian) shallow-water carbonate ramp; beside condensed sections of red nodular limestones equal-aged thick successions with megabreccias occur, indicating the creation of steep fault escarpments and rapid subsidence. In contrast to this continuous sedimentary succession, Triassic sections of the relatively autochthonous Drina-Ivanjica Unit indicate Late Pelsonian uplift of the Middle Anisian carbonate ramp. After a hiatus (Late Pelsonian to Early Illyrian), deposition of grey cherty limestones with shallow-water debris (newly described as Rid Formation) started in the Middle to Late Illyrian. The focus of this paper is on the age, the depositional environment and the facies characteristics of the Late Anisian hemipelagic successions. Based on this study it is concluded that in the Inner Dinarides domain the Middle Anisian Neotethyan break-up resulted in the generation of a horst-and-graben topography. Blocks were uplifted in a rift shoulder manner and asymmetric basins were formed. Mass flows and slide blocks were mobilized along normal faults of the evolving western passive continental margin of the Neotethys Ocean.

Onset of an Aptian carbonate platform overlying a Middle-Late Jurassic radiolaritic-ophiolithic mélange in the Mirdita Zone of Albania

Late Jurassic and Early Cretaceous carbonate sediments of different age and facies, form the post-emplacement settings on top of the Mirdita Ophiolite Zone in northern Albania. They seal the early Late Jurassic emplacement of the ophiolite knappes, are the only datable relics overlying the ophiolites in the Late Jurassic - Early Cretaceous, aiding the evaluation of the different tectonic movements associated with uplift and erosion as well as sea-level fluctuations during that time span. These carbonates overlie ophiolite-derived clastics very often as shallowing-upward sequences. One of the largest shallow-water platforms is the Mali I Shenjtit platform, previously assigned to the Barremian-Aptian. A well-preserved section at the base of the platform can be ascribed to the Early-Late Aptian based on orbitolinid foraminifera together with dasycladalean algae. This carbonate platform is the youngest preserved Early Cretaceous platform in Albania, but was largely eroded away. Late Cretaceous shallow-water rudist limestones are widespread and preserved in the Dinaride-Albanide-Hellenide realm directly above an eroded older basement. Therefore, this Aptian platform is very important for the reconstruction of the Early Cretaceous palaeogeography in the northwestern Neotethyan realm. In addition, the stratigraphic ranges of characteristic Aptian orbitolinid foraminifera, Rectodictyoconus giganteus SCHROEDER and Mesorbitolina texana (ROEMER), are discussed on the basis of these results.

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.

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

The late Middle to early Late Jurassic mélange of the eastern Zlatibor Mountain (Gostilje–Ljubiš–Visoka–Radoševo 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–Ljubiš–Visoka–Radoševo mélange 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 mélange. 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.

Open-marine Hallstatt Limestones reworked in the Jurassic Zlatar Mélange (SW Serbia): a contribution to understanding the orogenic evolution of the Inner Dinarides

Varied west-transported and far-traveled Jurassic mélanges in southwestern Serbia represent a key to understand the geodynamic history and to solve paleogeographic questions and reconstructions in the Triassic–Jurassic passive and active margin arrangement of the Inner Dinarides. Of special interest are the carbonate-clastic radiolaritic mélange areas in the Zlatar Mountain below the Dinaridic Ophiolite nappe. The present study reports from a Middle Jurassic sedimentary mélange in the area of Vodena Poljana. Carbonate components and blocks of the mass-flow deposits consist exclusively of a reworked Middle/Late Anisian to Early Jurassic distal shelf succession. Ophiolite components from the Dinaridic Ophiolite nappe stack are missing in the spectrum. The underlying series of the Zlatar Mélange belong to Early/Middle Anisian shallow-water carbonates and to Late Anisian to Middle Jurassic deep-water sedimentary rocks of the Hallstatt facies zone. South of Vodena Poljana in the overlying ophiolitic mélange occur Late Triassic radiolaritic components from the sedimentary cover of the Late Triassic ocean floor, beside ophiolite clasts and limestone components from the continental slope. A comparison with preserved Hallstatt Limestone successions and Jurassic mélange complexes from the Eastern Alps, Western Carpathians, and Albanides strengthen the interpretation of a provenance of the Zlatar mélange from the distal passive margin facing the Neotethys Ocean to the east. An autochthonous Dinaridic Ocean west of the Drina-Ivanjica Unit cannot be confirmed.