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The Olistostrome member of the Sana-Una Paleozoic complex of the Ljubija ore mine in Bosnia and Herzegovina contains limestone fragments of pebble to block size that have been examined paleontologically. The recovered conodont fauna of the first sample is characterized by the species Declinognathodus lateralis, Idiognathoides sulcatus sulcatus and Idiognathodus sp. confirming its mid-Bashkirian age. This report is the first on the occurrence of these taxa in the area. The second sample with chaetetid demosponges yields an abundant diversified microbiota consisting of cyanobacteria, algae and foraminifera. Chlorophyts are marked by the common siphonoclad occurrence of Donezella lutugini and D. lunaensis, whereas rhodophyts include rare representatives of Stacheia, Stacheoides, Pseudoungdarella and Masloviporidium. The presence of Asphaltinella horowitzi and Aphralysia carbonaria of unclear taxonomic position is also documented. Pseudostaffellids, eostaffellids and other foraminifera, mostly endothyrids are present. The examined associations of fossils point to the Bashkirian age of the primary rock that originated in a very shallow habitat most probably linked to a high-energy reef environment.

"In this paper we describe four new fossil associations of "reef and "reef'-like environments of the St. Cassian Formation (Ladinian-Carnian, Dolomites, NE Italy), based on thirty thin sections from 10 "Cipit boulders" olistoliths, which slided from the Cassian platform into coeval basin sediments. The fossil associations were determined by means of microfacies analysis using point-counting and visual estimation, as well as with aid of statistical methods, based on all fractions with a biotic significance (biomorpha and microbialites). Cluster Analyses in Q-Mode were performed, coupling three algorithms and two indices. In all samples, the main components of the framework are microbialite (average of 75%), and macrofossils (average of 20%), whereas cements and allochtonous components, such as allomicrite, do not represent a significant fraction. Based on both microbialite and fossil content, Chaetetid-microencruster Association, Microbialite-microencruster Association, Dual-type Microbialite Association and Microbialite-7ereèella Association, were differentiated. The palaeoenvironmental settings where the associations come from are separately discussed. Microencrusters helped determine energy and luminosity settings. Microencruster abundance and diversity, in addition to the conspicuousness of microbialite, indicate that all associations come either from a deep, or from a cryptic setting."

Olistostromes with calcareous olistoliths are rare components in the Ordovician successions in NW Europe and North America, having been described from only a small number of localities. One of the best exposed, but least known, is in the Garn Formation in coastal outcrops in Anglesey in northwestern Wales. Here, in the graptolite-bearing shales of the Garn Formation, there are numerous limestone olistoliths that are derived from an otherwise unknown ‘ghost’ formation whose original depositional site remains an enigma. These olistoliths contain a Baltoscandian type of conodont fauna that is otherwise unknown in Wales and England. It represents the Baltoniodus variabilis Subzone of the Amorphognathus tvaerensis Zone. Similar, but slightly older, conodont faunas are recorded from olistoliths in the Tweeddale Member of the Shinnel Formation in southern Scotland and in probable olistoliths of the Cobbs Arm Limestone in northeasternmost Newfoundland. Approximately coeval conodont faunas are present in calcareous olistoliths in the Woods Hollow Shale of West Texas and the Womble Shale in the Ouachita Mountains of Arkansas, USA. Lithological and conodont evidence indicates that the calcareous olistoliths were derived from carbonate sediments deposited in relatively shallow water. It is concluded that the study of ‘ghost’ formation olistoliths may provide otherwise unavailable but important data bearing on the marine depositional history of a particular region.

Srednje do gornjoecenska formacija Korlat koja se pruža se duž jugozapadnog ruba Prominskog bazena predstavlja najstariji dio Prominskih naslaga. Najveći dio od oko 600 m debele formacije su heterolitski slojevi izgrađeni od vrlo dobro uslojenih kalkarenita (3-40 cm debljine) i 5-300 cm debelih kalklutita i kalksiltita. Osobita značajka kroz cijelu formaciju su pojave velikih vapnenačkih olistolita i debelih slojeva izgrađenih vapnenačkih breča i/ili debelih graduiranih kalkarenita unutar heterolitskih slojeva koji su isključivo izgrađeni od različitih donjo do srednjoeocenskih foraminiferskih vapnenaca The late Middle to Upper Eocene Korlat Formation cropping out along the SW margin of the Promina basin represents the oldest part of the Promina Beds succession. Most of approximately 600 m thick Korlat Unit consists heterolithic beds composed of very well-bedded (3–40 cm thick beds) carbonate sandstones interbedded with 5–300 cm thick beds of fine-grained calcareous deposits. Outstanding characteristic throughout Korlat unit are huge carbonate olistoliths and thick beds composed of carbonate breccias and/or thick graded carbonate sandstones completely encased in the host deposits. Olistoliths and breccias are composed exclusively of various Lower–Middle Eocene foraminiferal limestones.

The Magura Nappe in the Polish sector of the Outer Carpathians consists of four tectonic subunits characterized by differing development of facies. From the south to the north, they include the Siary, Rača, Bystrica and Krynica subunits. The sedimentary succession in the Rača Subunit in the vicinity of the village of Osielec is composed of Campanian Palaeogene flysch deposited in the Magura Basin. In this succession, the Middle Eocene Pasierbiec Sandstone Fm consists of thick-bedded sandstones and conglomerates with occasional intercalations of thin-bedded shale-sandstone flysch. Within the Pasierbiec Sandstone Fm at Osielec there is an olistostrome, rich in pebbles and cobbles of exotic rocks. In addition, large blocks of Neoproterozoic metabasites and boulders of Palaeogene organogenic limestones were found. The discovery of metabasites raised the possibility that the rocks in question could be evidence of supposed oceanic crust in the basement of the Magura sedimentary basin, because of the suggestion that they represent the Alpine orogenic cycle. This concept was abandoned when investigations of the absolute age of the metabasites gave a date of ca. 600 Ma. In the Osielec area, there are two tectonic thrust sheets in the Rača Subunit, namely the Osielczyk Thrust Sheet in the north and the Bystra Thrust Sheet in the south; they are folded and cut by a transverse system of strike-slip and oblique faults. The Osielczyk Thrust Sheet was overthrust northwards on to the Siary Subunit.

Comparative research carried out within two different basins, one in the Carpathians of Poland (Late Jurassic to Early Miocene) and another in the Apenninic-Maghrebian mountain chain of Sicily (Triassic-Miocene), indicate significant similarity not only in their evolution but also in the sedimentary features of horizons with olistoliths. The olistolith-bearing units are genetically related to stages of tectonic evolution and are independent of the size of the basins and of duration of these stages. However, the observed differences in composition and size of olistoliths suggested, among the others relationship with the size of source areas and thickness of their sedimentary cover.

The terms olistostrome and olistolith have been introduced by G. Flores (4th World Petroleum Congress, Rome, 1955) to indicate either mass-transported bodies with a chaotic block-in-matrix fabric, or single slide blocks, intercalated between layered sequences in the Tertiary succession of Sicily. Both terms soon became extensively used by the international geological community world-wide. With the extended usage, they evolved to generally indicate stratally disrupted to chaotic complexes and “exotic” bed packages, which originated by mass-transport events, mainly recycling extrabasinal rocks. In this extended meaning, the concept of olistostrome played a significant role in other, important scientific debates, such as the origin of mélanges, being paradigmatically assumed as indicative of sedimentary processes (olistostromal mélanges). We will briefly discuss what happened to the terms during the 50 years of their history and how this lead to the following points: 1) Are the terms olistostrome and olistolith still to be used, and, if yes, with what meaning. 2) Olistostromes have been considered markers of either phases of basin instability and regional-scale tectonic events, or of peculiar geodynamical or tectonic stages. Are these assumptions true, or are olistostromes merely related to a specific condition of slope instability. 3) Olistostromes have been only seldom studied from sedimentological point of view. Therefore, their translational and depositional mechanics, as well as the internal processes of stratal disruption and dispersion leading to their classic, breccia-like, block-in-matrix fabric, are still poorly known. 4) The two previous points concern the genetically and regional relationships between the bodies defined to as olistostromes and the more general category of mass-transport complexes (MTC), with a particular emphasis on the basin-wide ones. In the sedimentary record of collisional chains, the majority of fossil MTC, including olistostromes, originated during the stages of intracontinental deformation, having been deposited in foreland and wedge-top basins. In some cases, collisional orogeny has allowed MTC related to extensional tectonics and passive margin to become exposed. This contrasts with the observed abundance of present-day MTC, which prevail in passive and divergent margins and along the flanks of volcanic islands atop the oceanic crust. The present-day submerged contractional margins, however, do not show a significantly high concentration of MTC, apart from the erosional margins off the coasts of Peru. Moreover, basin-wide MTC are only present when catastrophic events occur, as in the case of the subduction of seamounts and volcanoes. Some, possibly concomitant, solutions to these discrepancies will be discussed in this communication, with a special emphasis on the origin of mélanges in the accretionary wedges and relations between mass-transport processes, slope tectonics, contractional tectonics and mud diapirism.

The terms olistostrome and olistolith have been introduced by G. Flores (4th World Petroleum Congress, 1955, Rome) to indicate either sedimentary bodies with a chaotic block-in-Matrix fabric or single slide blocks, intercalated between layered sequences in the Tertiary succession of Sicily. Both terms soon became extensively used by the international geological community worldwide. With the extended usage, they evolved to generally indicate stratally disrupted to chaotic complexes and “exotic” bed packages, which originated by mass-transport events. In this extended meaning, the concept of olistostrome played a significant role in other, important scientific debates, such as the origin of mélanges. Mélanges are considered the products of either tangential tectonics, sedimentary processes, mud diapirism, or the interplay of these processes (FESTA et alii, 2010 and references therein). Among the sedimentary processes, mass gravitational transport is appointed to create chaotic, blocks-in-matrix rocks (olistostromes) that is a possible sedimentary end-member for mélanges. Most studies in literature have been aimed at distinguishing olistostromes from chaotic bodies deriving from other processes (broken formation, tectonic mélange, mud diapirs), to outline their paleogeographic distribution according to certain geodynamic and structural conditions (i.e., subduction vs.obduction, accretion vs. erosion, subduction of sea mounts), or to define more or less cyclic tectonic-stratigraphic events. As a result, olistostromes have been poorly studied from a sedimentological point of view, with some notably exceptions (see, e.g., ABBATE et alii, 1981).

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Olistoliths of various ages, provenance and dimensions are known in all of the higher-rank tectonic units of the Outer Carpathians. Their occurrences at various stratigraphic levels (Late Jurassic - Early Miocene) are related to different stages of development of the flysch basins, from the stage of rifting to post-rifting, through the orogenic phases, and further to the post-orogenic period.

The study focuses on a large olistostrome unit (~200 m thick and 4 km in strike-parallel extent) embedded in the Mid-Eocene shaly Hieroglyphic Formation of the Silesian Nappe, exposed in the Rożnów Lake area. Foraminifer biostratigraphy and petrographic comparisons are used to identify the provenance of olistoliths. The olistostrome is tripartite with respect of its olistolith composition. The lower part of the olistostrome abounds in olistoliths of sandstones derived from the Early Eocene turbiditic Ciężkowice Formation, whereas the middle part is dominated by olistoliths of Early Eocene bathyal mudshales. The upper part contains olistoliths of Middle Eocene turbiditic “banded sandstones”, known from the Hieroglyphic Formation and deposited in the bathyal zone above the CCD. The bathyal provenance of the olistostrome contrasts with the abyssal origin of the hosting green shales. The olistostrome unit is inferred to be composite, emplaced in the earliest Bartonian or at the Lutetian/ Bartonian transition by a series of at least three large debris flows that closely followed one another. Biostratigra- phical data and slump-fold vergence suggest resedimentation from the bathyal northern slope of the Silesian Cordillera that bounded the abyssal Silesian Basin to the south. Northward movement of the thrust-formed cordillera must have warped up the base-of-slope deposits of the Ciężkowice Formation, causing their gravita- tional collapse. This event destabilized the former lower-slope muddy deposits, resulting in a second phase of resedimentation by retrogressive slumping, which led to the collapse of mid-slope sandy turbidites. The slope failures involved contemporaneous Mid-Eocene sediment with an admixture of foraminifers derived from the upper slope or shelf margin and with exotic bedrock debris shed from the eroded cordillera crest. The catastrophic multi-phase emplacement of the olistostrome marked the last major thrusting pulse of the second (Late Cretaceous–Late Eocene) stage of tectonic evolution of the Outer Carpathian accretionary prism.