Olistostromes Research Articles

CARBONIFEROUS CORALS AND CHAETETIDS FROM EXOTIC LIMESTONE BLOCK OF THE CRIMEA

A chaetetid sponge and coral fauna from a Carboniferous exotic limestone block in the Lower Jurassic Esciorda olistostrome on the Bodrak River (Crimean Mountains) are described for the first time. The Bodrak exotic block is composed of massive limestone. It contains the chaetetid Chaetetes (Boswellia) sp., the tabulate coral Multithecopora sp., and poorly preserved rugose corals, including Dibunophyllum ? sp., Cordibia ? sp. and gen. et sp. indet. Only the fasciculate colonies of the rugose coral Lytvophyllum askynensis (Kossovaya, 2009) are confidently identified. The studied association of fossils is similar to that of the Donets Basin and the Urals and confirms the Lower Bashkirian age of the Bodrak limestone block.

THE TECTONOSTRATIGRAPHIC FEATURES OF THE BELEMEDİK TECTONIC WINDOW AND ITS SURROUNDINGS

The study area includes Belemedik and its vicinity located in the eastern part of Ecemiþ Fault Zone which constitutes the boundary between Central and Eastern Taurides.The area generally presents Belemedik sequence belonging to Aladað Unit, ophiolithic melange and ophiolithic rocks belonging to Bozkýr Unit and Tertiary sediments overlying all these units. Within Belemedik sequence, Late Devonian aged Kucukali, Carboniferous aged Belemedik, Early Permian aged Sarýoluk, Late Permian aged Kýzýlgeriþ and Yellice, Early- Middle Triassic aged Katarasý, Middle-Late Triassic aged Sarýyarma, Jurassic-Cretaceous aged Camlýk and Yavca Formations were differentiated. In the previous studies on the vicinity of Belemedik, it was suggested that an incomplete Mesozoic series overlaying the Palaeozoic core and as a result of the erosion of this cover, a tec- tonic window was exposed. However, in this study, it was demonstrated that a complete Mesozoic series of Early Triassic-Late Cretaceous age overlaying the Palaeozoic rocks in the vicinity of Belemedik are presented and hence a tectonic window does not exist in the vicinity of Belemedik. In addition, it was determined that Belemedik Sequence displayed similar features with the rock associations of Aladað Unit in terms of lithological properties and the ages of the units it comprises. In the region, at the bottom of the Bozkýr Unit, which tectonically overlies the Belemedik Sequence, Late Senonian aged Kýzýlcadað Ophiolithic Melange and olistostrome are present. And, at the top of the Bozkýr Unit, Late Cretaceous aged Pozantý-Karsantý Ophiolithic Nappe is located. While the Pozantý-Ecemiþ Corridor formed by Ecemiþ Fault Zone is represented by Oligocene-Miocene aged units, the Adana Basin is represented by Paleocene-Late Miocene units.

THE OPHIOLITE-BEARING MÉLANGE IN THE EARLY TERTIARY PINDOS FLYSCH OF ETOLIA (CENTRAL GREECE)

In Etolia (Central Greece), west of the Parnassus/Vardoussia units, the Pindos succession crops out, with its higher formation: the Pindos Flysch. In its upper portion levels of debris flow deposits and slide blocks (olistostromes and olistoliths) contain ophiolitic material with fragments derived from the Parnassus/ Vardussia formations. This ophiolitic material consists of serpentinites, basalts of WPB, E- and N-MOR affinity, and radiolarian cherts of Middle-Late Triassic and Middle-Late Jurassic age. Petrologic and biostratigraphic analyses confirm that the melange has the same features of the sub-ophiolitic melanges present at the base of the ophiolitic masses in Greece. Linked to the flysch, with contacts of unclear nature, a rhyolites body of Middle Triassic age indicates the continental nature of the Pindos Basin. In fact, here, as all over the Albanian-Greek section of the Dinarides, no record of an oceanic area in the central portion of the Dinarides exists: the Parnassus and Vardoussia units were directly thrust onto the Pindos Basin. The intercalations of ophiolitic and continent-derived material in the flysch, are interpreted as the forerunners of the Ophiolitie Nappe which, coming from the Vardar Ocean located to the east, reached during the Eocene the Pindos Basin.

FORAMINIFERA, ALGAE AND CARBONATE MICROPROBLEMATICA FROM THE LATE WUCHIAPINGIAN/DZHULFIAN (LATE PERMIAN) OF PELOPONNESUS (GREECE)

The origin of late Permian olistoliths found in the Glypia Cenozoic flysch must be seeked in regions located to the east of the Parnon Mountain and in units that were more internal to Pindos Unit, especially in the islets of Karavia in the Argolis Gulf, and the Episkopi Formation in Hydra Island, that display probably the largest outcrops of this age. The most interesting olistolith is a bioclastic grainstone. It yields about forty taxa of algae, microproblematica, smaller foraminifers and fusulinids, that are briefly described. Three markers generally not co-occurring are locally associated: Paradunbarula ( Shindella ) shindensis , Hemigordiopsis cf. luquensis and Colaniella aff. minima . The age of the Paradunbarula ( Shindella ) biozone is most probably late Wuchiapingian/Dzhulfian, although other datings have been proposed from late Capitanian to late Changhsingian. Due to this dating of the Shindella zone, the coexistence of the first Colaniella with the last Hemigordiopsis are not late Capitanian/Midian in age, but late Wuchiapingian. The similarities of the Greek microfauna with that of South China and southeastern Pamirs, are incompatible with a larger Paleotethys but support the paleogeographic reconstructions which indicate a close location of these geographic units (Pangea B).

THE EARLY DEPOSITIONAL PHASES OF THE NORTHERN APENNINE FOREDEEP-THRUST BELT SYSTEM: IMPLICATIONS FROM THE “MACIGNO COSTIERO” (LATE OLIGOCENE, ITALY)

The late Chattian “Macigno costiero” represents the innermost and the oldest portion of the well developed siliciclastic wedge of the migrating Oligo- Miocene foredeep-thrust-belt system of the Northern Apennine. Its stratigraphic features help to understand the early phases of the sin-collisional sedimentation and the evolution of such a thrust belt. In the turbiditic siliciclastic sequence, carbonates were found at different stratigraphic levels (chaotic-debris flow key-level, calcareous turbidites and Subligurian olistostromes and olistoliths). Stratigraphical studies of the sequence based on facies analysis, petrographical observations and biostratigraphical analysis of calcareous nannofossils allow to suggest some hypotheses of the palaeogeographic setting and the evolution of the foredeep-thrust belt system. The vertical distribution of the sediments and their sedimentological characters show a low efficiency sand-rich turbidite system (sensu Mutti and Normark, 1987), characterised by a prograding fan terminated by the emplacement of slices of the orogenic wedge. Olistostromes and olistoliths found in the turbidite succession were the precursor of the allochthonous nappe. The proposed hypothesis shows that turbidite sediments were probably fed transversally to the basin, from a shallow marine shelf adjacent to a crystalline basement. The “Macigno costiero” was deposited in an internal position of the foredeep system.

Origin of the Misaki Olistostrome Belt and re-examination of the Takachiho Orogeny

Origin of the Misaki Olistostrome Belt and re-examination of the Takachiho Orogeny

Pliocene-Quaternary olistostromes of Crimea and mechanism of their formation

Pliocene-Quaternary olistostromes of Crimea and mechanism of their formation

Onerahi chaos-breccia of Northland

Abstract Ferrar's Onerahi and Otamatea formations have been shown recently to be olisto stromes, composed predominantly of a near-surface incompetent sheared chaotic breccii of rocks of Upper Cretaceous - Miocene age, with the following features: 1. (1) The angular or sheared fragments, ranging from granules to 50,000 tons anc more in size, include: Upper Cretaceous - Eocene calcareous or siliceous mudstone; and siltstones, Upper Cretaceous micaceous and concretionary sandstones and blacl mudstones, Eocene-Oligocene argillaceous limestones and highly calcareous siltstonei (but excluding the Oligocene Mahurangi Limestone), and serpentinite.2. (2) The matrix is predominantly of chocolate, green, and grey sheared mudstone of Eocene-Paleocene age.3. (3) Its surface is hummocky, and typical of slump topography; and though the formation is not yet known to occur more than 500 ft above sea level, it is most commonly present at levels below 250 ft; it is over 500 ft thick locally, and may exceed 1,500 ft in some places.4. (4) The breccia overlies, with sharp unweathered contact, formations ranging in age from Permian-Jurassic to (commonly) near-basal Miocene; it is overlain by Quaternary alluvium and basalt; and was probably widespread as a surface formation in the Pliocene.5. (5) Its emplacement, perhaps from the west, was associated, at least in time, with the Miocene-Pliocene Kaikoura Orogeny.6. (6) It is closely similar in characteristics, age, and lithology of fragments and matrix to the allochthonous argille scagliose of Italy, and, by analogy, may be closely linked genetically to the Lower Miocene Waitemata Group flysch-facies sandstones which in turn resemble the Oligocene Macigno Sandstone of Italy.7. (7) Proved and probable occurrences, from Ohaeawai to Silverdale, represent 2j cubic miles in volume, and possible extensions could make the grand total many times greater. The lithologic term “chaos-breccia” is proposed for such beds, and as the type locality of the Onerahi Formation is typical the term “Onerahi” is retained. The formation is therefore renamed the “Onerahi Chaos-breccia”.