M. Krobicki

Geodynamic evolution and palaeogeography of the Polish Carpathians and adjacent areas during Neo-Cimmerian and preceding events (latest Triassic-earliest cretaceous)

Abstract The aim of this paper is to place the geodynamic and palaeogeographical evolution and position of the major crustal elements of the Polish Carpathians within a global framework. Neo-Cimmerian movements and their synsedimentary consequences are the main objects of our elaboration in relation to sedimentary record. Five time-interval maps are presented, which depict the plate-tectonic configuration, palaeogeography and lithofacies for the circum-Carpathian region and adjacent areas from the Late Triassic through to the Early Cretaceous. Almost simultaneous tectonic events proceeding within different types of Carpathian sedimentary basins (Pieniny Klippen Belt and Outer Carpathian Silesian Basins) indicate the very important role of the Neo-Cimmerian movements (mainly of the Osterwald Phase) in the geodynamic history of the northernmost margin of the Tethyan Ocean. The global plate reorganization is related to this Tethyan Neo-Cimmerian tectonic activity.

The Northern Carpathians plate tectonic evolutionary stages and origin of olistoliths and olistostromes

The olistostromes formed in Northern Carpathians during the different stages of the development of flysch basins, from rift trough post-rift, orogenic to postorogenic stage. They are known from the Cretaceous, Paleocene, Eocene, Oligocene and Early Miocene flysch deposits of main tectonic units. Those units are the Skole, Subsilesian, Silesian, Dukla and Magura nappes as well as the Pieniny Klippen Belt suture zone. The oldest olistoliths in the Northern Carpathians represent the Late Jurassic-Early Cretaceous rifting and post-rifting stage of the Northern Carpathians and origin of the proto-Silesian basin. They are known from the Upper Jurassic as well as Upper Jurassic-Lower Cretaceous formations. In the southern part of the Polish Northern Carpathians as well as in the adjacent part of Slovakia, the olistoliths are known in the Cretaceous- Paleocene flysch deposits of the Pieniny Klippen Belt Zlatne Unit and in Magura Nappe marking the second stage of the plate tectonic evolution - an early stage of the development of the accretionary prism. The most spectacular olistostromes have been found in the vicinity of Haligovce village in the Pieniny Klippen Belt and in Jaworki village in the border zone between the Magura Nappe and the Pieniny Klippen Belt. Olistoliths that originated during the second stage of the plate tectonic evolution occur also in the northern part of the Polish Carpathians, in the various Upper Cretaceous-Early Miocene flysch deposits within the Magura, Fore-Magura, Dukla, Silesian and Subsilesian nappes. The Fore-Magura and Silesian ridges were destroyed totally and are only interpreted from olistoliths and exotic pebbles in the Outer Carpathian flysch. Their destruction is related to the advance of the accretionary prism. This prism has obliquely overridden the ridges leading to the origin of the Menilite-Krosno basin. In the final, postcollisional stage of the Northern Carpathian plate tectonic development, some olistoliths were deposited within the late Early Miocene molasse. These are known mainly from the subsurface sequences reached by numerous bore-holes in the western part of the Polish Carpathians as well as from outcrops in Poland and the Czech Republic. The largest olistoliths (kilometers in size bodies of shallow-water rocks of Late Jurassic-Early Cretaceous age) are known from the Moravia region. The largest olistoliths in Poland were found in the vicinity of Andrychów and are known as Andrychów Klippen. The olistostromes bear witness to the processes of the destruction of the Northern Carpathian ridges. The ridge basement rocks, their Mesozoic platform cover, Paleogene deposits of the slope as well as older Cretaceous flysch deposits partly folded and thrust within the prism slid northward toward the basin, forming the olistostromes.

JURASSIC PALEOGEOGRAPHY OF THE PIENINY AND OUTER CARPATHIAN BASINS

The Jurassic history of the Pieniny/Outer Carpathian basins reflects the evolution of the Circum-Tethyan area, especially its Alpine Tethys part. The Alpine Tethys that is Ligurian, Penninic Oceans and Pieniny/Magura Basin constitute the extension of the Central Atlantic system. The synrift stage lasted in the Pieniny/Magura Basin from late Early Jurassic to Tithonian (the Magura Unit constitutes the southernmost part of the Outer Flysch Carpathians). The Pieniny rift opened during Pliensbachian – Aalenian. The central Atlantic and Alpine Tethys went into a drifting stage during the Middle Jurassic. The Late Jurassic (Oxfordian-Kimmeridgian) history of the Pieniny/Magura Basin reflects strongest facial differentiation within sedimentary basin where mixed siliceous-carbonate sedimentation took place. Greatest deepening effect is indicated by widespread Oxfordian radiolarites, which occur in the all basinal successions, whereas the shallowest zone is completely devoid of siliceous intercalations at that time (sedimentation from Ammonitico Rosso facies up to coral reef limestone). The southern part of the North European Platform, north from the Pieniny/Magura realm, started to be rifted during Late Jurassic time and Silesian Basin in the Outer Western Carpathians and Sinaia Basin in the Eastern Carpathians, with black, mainly redeposited marls have been created. The outer sub-basins were differentiated during the latest (Hauterivian-Barremian) phase of basinal development. The connection of Silesian Basin with Sinaia and Southern Carpathian Severin areas suggests the NW-SE direction of the basinal axis while the orientation of the Pieniny Klippen Belt/Magura Basin was SW-NE so, two Outer Carpathian perpendicular directions are possible within the basins. Major reorganization happened during the Tithonian-Berriasian time. It was reflected by both paleoceanographical and paleoclimatical changes. The Neo-Cimmerian tectonic events as well as main phase of the Outer Carpathian basins opening is connected with this reorganization.

Late Triassic Global Plate Tectonics

The Late Triassic was the time of the Early Cimmerian and Indosinian orogenies that closed the Paleotethys Ocean, which occurred earlier in the Alpine-Carpathian-Mediterranean area, later in the Eastern Europe-Central Asia and latest in the South-East Asia. The Indochina Southeastern Asian and Qiangtang plates were sutured to South China. The new, large Chinese-SE Asian plate, including North and South China, Mongolia and eastern Cimmerian plates, was consolidated by the end Triassic, leaving open a large embayment of Panthalassa, known as Mongol-Okhotsk Ocean, between Mongolia and Laurasia,. The Uralian Orogeny, which sutured Siberia and Europe continued during Late Triassic times and was recorded in Novaya Zemlya. The onset of Pangaea break-up constitutes the main Late Triassic extensional event. Continental rifts originating then were filled with clastic deposits comprising mainly red beds. The pulling force of the north-dipping subduction along the northern margin of Neotethys caused drifting of a new set of plates from the passive Gondwana margin, dividing the Neotethys Ocean. Carbonate sedimentation dominated platforms on the Neotethys and Paleotethys margins as well as the Cimmerian microplates. Synorogenic turbidites and postorogenic molasses were associated with the Indosinian orogeny. The late stages of the Uralian orogeny in Timan-Pechora, Novaya Zemlya and eastern Barents regions filled the foreland basin with fine-grained, molasse sediments. Siliciclastics were common in the Siberia and Arctic regions. The widespread, large magnitude, base-level changes of the Late Triassic are interpreted as an expression of relatively rapid and substantial changes in the horizontal and vertical stress fields that affected the Pangaea supercontinent. Such stress changes may be due to abrupt changes in the speed and/or direction of plate movements, which episodically affected Pangaea.

A new homolodromioid crab (Brachyura: Dromiacea: Tanidromitidae) from the Bajocian of central Poland and a review of the stratigraphical distribution and paleoenvironments of the known Middle Jurassic homolodromioids

A new homolodromioid (Brachyura, Tanidromitidae) crab from the Middle Jurassic (uppermost Bajocian) of central Poland is described and a new species, Tanidromites muelleri , is erected. The new species is not only one of the oldest representatives of true crabs, but also the most numerous in the world in terms of collected individuals (46 carapaces, including incomplete specimens) of the Middle Jurassic homolodromioid crabs. Tanidromites muelleri sp. nov. lived in a shallow-water, soft-bottom marine environment around developing oyster patch-reefs, being similar as later during the Late Jurassic when they lived in association with extensive sponge bioherms and coral reefs. The preservation of carapaces of the new species was influenced by a quick burial and rapid mineralization of calcitic concretions in which they are embedded. The stratigraphic distribution, to ammonite subzone level, of homolodromioid Middle Jurassic crabs is reviewed. Analysis of their paleoenvironmental preferences indicated that during the first step in the origin of true crabs they were connected with shallow, marine, high-energy carbonate deposits dominated by oolitic (including ferrugineus-oolitic one) facies, coralliferous reefs, and grey/black clays with carbonate concretions which hosted these crabs.

Tanidromites insignis (von Meyer, 1857) (Crustacea: Decapoda: Brachyura) from Late Jurassic non-biohermal facies of the Western Tethys (Pieniny Klippen Belt, Western Carpathians, Slovakia)

The first decapod crustacean remains from Late Jurassic limestones of the Pieniny Klip- pen Belt (Western Carpathians, Slovakia) are recorded. The material originates from a Middle Ox- fordian ammonite shell bed and comprises a single dorsal carapace of the homolodromioid crab, Tanidromites insignis, as well as several fragments of chelipeds of unknown affinity which, however, might belong to primitive brachyurans. Although they usually are considered to be bound to reefal structures, all material studied herein is non-related to biohermal facies and, as such, does not repre- sent a typical occurrence.

Tectono-Stratigraphic Position of the Kaminnyi Potik Unit in the Ukrainian Carpathians and Volcanogenic Rocks of Mt Chyvchyn

In tectono–stratigraphic terms, the Kaminnyi Potik Unit is the most internal and structurally highest unit of the Fore–Marmarosh units and in many places is directly covered by the Marmarosh nappes of the central East Carpathians (Marmarosh Massif, Transcarpathian Ukraine). This unit consists of latest Jurassic to earliest Cretaceous formations composed mainly of thin-bedded limestones, black shales, sandstones, and conglomerates, with basic effusives (including basaltic pillow lavas) and pyroclastic turbidites. The best places for studying this unit occur in the vicinity of Rahiv city and on Mt Chyvchyn, the highest peak of the Chyvchynian Mountains. The volcanic–sedimentary complex of Mt Chyvchyn does not form a single tectonic unit (cap), but four small tectonic scales with full development of the effusive–pyroclastic debris flow/turbidite complexes.

Rare fossil polychelid lobsters in turbiditic palaeoenvironments

Polychelidan lobsters are one of the rare groups of decapod crustaceans which were first discovered as fossils long before being identified in extant deep-sea environments. As for other decapods, their fossil record is highly incomplete, which complicates the reconstruction of their evolutionary history. Another problem that hinders better knowledge of the group is familial assignments, which can be difficult in the absence of a complete revision of known fossil taxa. As a result, only three fossil Polychelidae have been identified to date, the oldest dating back to the Callovian (Middle Jurassic). In the present study, we consider two rarely studied species, Palaeopolycheles crymensis Levitski, 1974 from the Toarcian–Aalenian (Early–Middle Jurassic) of Crimea (Ukraine), and Eryon neocomiensis Woodward, 1881 from the Valanginian (Early Cretaceous) of the Outer Carpathians (Czech Republic). Our reinvestigations indicate they present several characters typical of Polychelidae, and are actually morphologically quite similar to extant species, notably in the structure of the anterior part of the carapace and the small ocular incisions. Two new genera are erected to accommodate them: Tauricheles gen. nov. (type species Palaeopolycheles crymensis) and Woodwardicheles gen. nov. (type species Eryon neocomiensis). The reinvestigations show that: (1) the evolutionary history of Polychelidae is much older than previously considered; (2) Polychelidae have inhabited deep water for a long time; (3) both species are probably autochthonous or parautochthonous to turbiditic palaeoenvironments; (4) Woodwardicheles neocomiensis comb. nov. is one of the rare benthic macrofossils of the Silesian Basin. http://zoobank.org/urn:lsid:zoobank.org:pub:CE6FEEA7-4162-4AE2-9413-11FD38FE04B9