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EN
Early Palaeocene through early Eocene silicoflagellate assemblages were examined from five southern subtropical through subpolar deep-sea sites: DSDP Holes 208 and 524, and ODP Holes 700B, 752A, and 1121B. For each site, the taxonomic composition of the silicoflagellate assemblage is documented in detail; Pseudonaviculopsis gen. nov., Dictyocha castellum sp. nov. and Stephanocha? fulbrightii sp. nov. are proposed, along with several new combinations. More importantly, however, these observations enable a considerable refinement to the existing Palaeocene–Eocene silicoflagellate biostratigraphic zonation that for the first time uses datums calibrated to the Geomagnetic Polarity Timescale. The Corbisema aspera Interval Zone occurs immediately above the K/Pg boundary and is here described from Seymour Island. The Corbisema hastata Partial Range Zone extends from near the K/Pg boundary to late early Palaeocene and has been observed in Hole 208. The Pseudonaviculopsis disymmetrica Acme Zone occurs in Holes 208 and 700B. The Dictyocha precarentis Partial Range Zone, observed in Holes 208, 700B, 752A and 1121B, is subdivided into D. precarentis, Naviculopsis primativa, N. cruciata and Pseudonaviculopsis constricta subzones. The Naviculopsis constricta Partial Range Zone occurs in Holes 524, 700B, 752A and 1121B. This study is also the first to consider syn- and/or diachroneity in Palaeogene silicoflagellate biostratigraphy.
EN
A section over 20 m thick of the basal Middle Miocene succession exposed at Lipowiec (Roztocze, SE Poland) was studied for palynology. Thirteen samples were collected from quartz and glauconitic-quartz sands and thin clay layers. Sand samples were barren but clay samples yielded dinoflagellate cysts. Their assemblages consist of reworked Paleogene specimens dominated by the Homotryblium floripes complex (H. floripes and morphologically similar H. plectilum and H. vallum). The presence of reworked Paleogene specimens indicates intense erosion of marine Paleogene strata during initial stages of the Middle Miocene transgression at Roztocze. Analysis of stratigraphical ranges of reworked dinoflagellate cysts and comparison with their occurrences in known epicontinental Paleogene sites of SE Poland suggest an Upper Eocene age of the washed-out strata. The taxonomic composition of the assemblages described suggests that the Upper Eocene deposits accumulated in a near-shore, lagoonal embayment characterized presumably by oligotrophic waters of slightly increased salinity. A high proportion of the Homotryblium floripes complex is also characteristic of reworked assemblages found in younger Miocene strata of neighbouring exposures in Roztocze, which indicates widespread Eocene lagoonal environments in this part of Roztocze. Coeval Eocene strata from the eastern part of Roztocze and from the Carpathian Foredeep show different taxonomic compositions suggesting varied sedimentary settings during Eocene transgression in this region. These differences reflect variable amounts of freshwater influence resulting in a range of environments that ranged from oligotrophic to brackish.
EN
The sedimentation of Hieroglyphic beds of the Silesian Nappe took place between the Lower and Middle Eocene and Upper Eocene within the Carpathian Silesian Basin. These beds are represented by thin-bedded flysch containing – at various stratigraphic positions – sandstone-less complexes with variegated shales and bentonite laminae developed in conditions of calm sedimentation with a limited supply of material from the land. The profiles of Hieroglyphic beds of the Silesian Nappe are diversely developed. Their variability and borderline sequences, transitory into overlying and underlying divisions, are presented. In the Ypressian, during the sedimentation of Hieroglyphic beds, foraminiferal associations with numerous small sized Trochammina developed, which formed in the Silesian Basin after the PETM crisis. Since the Lutetian, in slightly more favourable conditions, more differentiated associations have occurred, with Reticulophragmium amplectens (Grzybowski), Ammodiscus (Dolgenia) latus (Grzybowski), and Reticulophragmium gerochi Neagu et al., which preferred cool waters, being index fossils for stratigraphy. Hieroglyphic beds developed during an interval of the gradually cooling climate. The gradual decrease in temperature stimulated the transfer of species: in the Eocene associations of Hieroglyphic beds a number of thermophilous forms, whose optimum of development came in the Upper Cretaceous-Paleocene, disappeared whereas new species appeared which prefer cold waters commonly occurring in boreal basins. The deep restructuring of foraminiferal assemblages took place in the Priabonian, when massive numbers of calcareous benthonic and planktonic forms occurred.
EN
The lithologic variation and biostratigraphy of the Hieroglyphic Beds were examined in the Szczyrzyc Depression, where four lithologic complexes were distinguished. The biostratigraphy is based on agglutinated foraminifera and supported by scarce planktonic foraminifera. The lower part of the Hieroglyphic Beds contains non-characteristic, Ypresian foraminifers, including assemblages of small-sized Trochammina and at successively higher levels representatives of the Bartonian Ammodiscus latus Zone and the Priabonian Reticulophragmium gerochi Zone. The upper part of the Hieroglyphic Beds, composed of dark shales enriched in TOC (1–2%), corresponds to the deposits of the so-called Black Eocene, known from the Fore-Magura group of nappes. Redeposited flysch rocks resulting from episodes of subaqueous mass flow occur in the lower Bartonian part of the section.
EN
Shallow-marine deposits, included in the “Basal Sands” of the Eocene Paují Formation of the Maracaibo Basin in western Venezuela, record deposition in fore shore to lower off shore settings. These deposits are stacked in coarsening-upward parasequences that reflect variable intensities and frequencies of storms. Of particular interest are sharp-based, amalgamated, hummocky cross-stratified and rippled, very fine-grained sandstone beds, observed in the core MOT-X from the Motatán Field. These beds record storm deposition, under purely oscillatory to combined flows in an offshore-transition setting. The amalgamated nature of the sand stone interval indicates repeated erosion, due to multiple storm events. The ichnofabrics in these tempestites result from a distinctive taphonomic pathway, reflecting the interplay between bioturbation events and storm erosion and deposition. The storm-related trace-fossil suite is represented by Diplocraterion parallelum and local occurrences of Palaeophycus tubularis, Bergaueria isp. and Thalassinoides isp., which is consistent with the relatively high energy of formation of these deposits. Fair-weather deposits are absent from the sand stone interval. However, high densities of Chondrites isp. are present in the infills of Diplocraterion parallelum and, more rarely, Thalassinoides isp. providing the sole evidence of the establishment of a resident fauna during inter-storm intervals. Deposits containing the fair-weather suites were erosionally removed during the subsequent storm. The deep-tier emplacement of Chondrites and the ability of its producer to rework other biogenic structures favour preservation, allowing recognition of a “hidden” bioturbation event that otherwise might have remained undetected.
EN
This paper documents the presence of Eocene marine strata in the Carpathian Foredeep area in Poland. Assemblages of marine dinoflagellate cysts have been found in sands penetrated by the Łukowa-4 borehole below the Miocene succession of the foredeep. Their age is interpreted as Late Eocene. The presence of marine strata of this age in this area sheds new light on the palaeogeography of the Carpathian foreland during the Late Eocene. The dinoflagellate cysts described are compared with coeval Carpathian and epicontinental assemblages; possible connections between these two basins are discussed. Phytogenetic deposits that occur above the marine sands of the Łukowa-4 borehole contain freshwater palynomorphs, indicating their swamp and lacustrine origins. The overlying sand contains impoverished dinoflagellate cyst assemblages; their age is discussed.
EN
In the lithostratigraphic section of a sedimentary sequence of the Silesian Nappe in the area of Rożnów Lake, the strata that occur above the Ciężkowice sandstone and below the Globigerina marls are represented by a relatively thin unit informally named the Hieroglyphic beds and a succeeding thick complex of so-called Green shales. The Hieroglyphic beds, deposited over a short time interval during the Lutetian time (Reticulophragmium amplectens zone), are followed by the Green shales that were deposited from the Lutetian to the Priabonian (Reticulophrgamium amplectens, Ammodisus latus, Reticulophragmium rotundidorstum zones). This work describes the foraminiferal assemblages, on the basis of which, the age of the Green shales was established that in the area of Rożnów Lake. Deposition of the Green shale unit started in the Lutetian, while in other regions of the Silesian Basin it is documented from the Priabonian. The upper boundary of the Green shales is isochronous and defined by the base of the calcareous horizon of a specific type of marls known as the Globigerina marls.
8
Content available remote Eocene dinoflagellate cysts from the Sołokija Graben (Roztocze, SE Poland)
EN
The Sołokija Graben is a tectonic structure in Roztocze, the south-eastern Poland, unique by its infill with the Eocene marine strata. The over 40 metres thick sandy succession is the only well-dated palaeontologically trace of Eocene marine transgression at Roztocze being virtually the only remains of the Eocene epicontinental sea in this part of Poland: the surrounding area is devoid of coeval marine strata, which were eroded. This makes the Sołokija Graben succession crucial for the palaeogeography reconstruction of the south-eastern Poland during Eocene as well as the tectonic history of this region. For its precise age determination, the over 30-m-thick succession of loamy sands that fill the Sołokija Graben in a borehole at Leliszka and a 4-m-thick one at Łaszczówka were sampled for dinoflagellate cysts. Samples from Łaszczówka are barren, whereas the ones from Leliszka contain rich and taxonomically diverse assemblages. Their biostratigraphical interpretation confirms previous results suggesting the Bartonian age of the most of the Sołokija Graben succession; the postulated Priabonian age of its non-calcareous part was documented in its uppermost part only. Palynological record allows reconstruction of sedimentary setting of the Leliszka succession. Basal part of the Bartonian was deposited in a shallow but relatively vast marine basin characterized by normal salinity and high energetic hydrodynamic conditions. Subsequently, marine basin underwent gradual shallowing and temporal cease of sedimentation. During the late Bartonian basin became brackish. A short-lasting early Priabonian marine basin was characterized by shallow marine conditions; it became brackish during its final stage. Comparison with neighbouring Eocene deposits of the epicontinental and Carpathian basins shows that the marine basin at Roztocze was presumably connected with both during Bartonian, and separated from the Carpathian one during early Priabonian. Factors controlling seaways pattern of the Roztocze basin were either eustatics and substratum tectonic movements, the former dominating during Bartonian, and interfingering with uplift of the Meta-Carpathian Swell during early Priabonian.
EN
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.
EN
A total of 152 dinoflagellate cyst taxa from the Popiele beds exposed at Koniusza (Skole Nappe, Flysch Carpathians, Poland) are systematically described. The biostratigraphical interpretation of their assemblages suggests Eocene (Bartonian and Priabonian) age. The dark-coloured fossiliferous mudstone that forms bulk volume of the olistostromic Popiele beds is dated as Priabonian; and the pale-coloured marl, mainly forming clasts, is Bartonian and Priabonian. Palaeoenvironmental analysis of palynofacies and dinoflagellate cyst assemblages suggests that the deposits studied were laid down on a shelf (subsequently redeposited into deeper parts of the flysch basin). The pale-coloured Bartonian marl settled down in an environment of relatively calm, hemipelagic deposition with limi- ted terrestrial influx, possibly in an offshore shelf under relatively oligotrophic surface water conditions; their sedimentary setting was presumably influenced by waters from lagoonal environments, manifested by a high ratio of near-shore taxa. The non-calcareous pale-coloured Priabonian mudstone was deposited in an even more offshore setting; its dinoflagellate cyst assemblage shows some similarities with the one from the offshore Hieroglyphic beds. The dark-coloured Priabonian mudstone settled down under a relatively high rate of a terrestrial material influx, presumably during period of a more intense freshwater input into the shelf basin, reflected by a high ratio of land-derived organic particles. This freshwater influx led to a minor eutrophication and a possible salinity decrease in the surface water layer. A comparison of dinoflagellate cyst assemblages from the Popiele beds with coeval ones from the neighbouring areas suggests that the Skole Basin was connected with epicontinental basin of south-eastern Poland during the Bartonian, whereas it was presumably isolated during the Priabonian.
EN
During the Cenozoic, the Arabian Plate separated from continental Africa and assumed a closer geographical relationship with Eurasia. As such, the vertebrate fossil record of the Arabian Peninsula has great potential for documenting faunal interchanges that occurred as a result of such tectonic events, with a shift from a primarily Afro-Arabian fauna in the Palaeogene to a more cosmopolitan fauna in the Neogene. Understanding of the sequence and timing of this faunal interchange has long been hampered by a lack of palaeontological data. Recently recovered fossils from the Middle Eocene Kaninah Formation of Yemen constitute the earliest Palaeogene record of continental vertebrates from the Arabian Peninsula, thereby offering a rare glimpse at the region’s post--Cretaceous fauna. Here we describe fossil materials from the Kaninah Formation, a collection of dental and postcranial elements representing a mesoeucrocodylian crocodyliform of unclear affinities. The specimen exhibits ziphodont tooth morphology along with a biserial paravertebral shield and polygonal gastral osteoderms, consistent with certain mesoeucrocodylians (e.g., ziphodontan notosuchians). Yet the associated fragmentary anterior caudal vertebra, although badly abraded, preserves morphology suggestive of procoely. This vertebral type in combination with the dental and osteoderm morphology is much more taxonomically restrictive and consistent with the suite of characters exhibited by atoposaurids, a finding that would significantly extend that clade through the Cretaceous/Palaeogene boundary. Alternatively, given the relative paucity of information from the region during the Palaeogene, the combination of characteristics of the Kaninah crocodyliform may reflect a novel or poorly known form exhibiting previously unrecognised character mosaicism. We take a conservative approach, and refer the Kaninah specimen to Mesoeucrocodylia, Atoposauridae (?) pending discovery of more complete material. New fossils recovered from the Kaninah Formation raise unanticipated questions about the longevity of Mesozoic clades, underscoring the role that the region may play in revealing novel occurrences, relictual forms, and evidence of faunal dispersals from this critical interval in vertebrate evolutionary history.
EN
About 34 Ma ago there was a radical change of climate that led to the formation of Antarctic ice sheet. King George Island, located in the South Shetland Islands volcanic arc (northern Antarctic Peninsula region), is one of a few places in West Antarctica which shows a geological record of sedimentary environments preceding development of the ice sheet. The Eocene sedimentary facies occur in the dominantly volcanogenic succession of King George Island. They have been recognized in the Arctowski Cove and Point Thomas formations (Ezcurra Inlet Group) and in the Mount Wawel Formation (Point Hennequin Group) in Admiralty Bay, and in the Mazurek Point Formation (Chopin Ridge Group) and Lions Cove Formation (Polonia Glacier group) in King George Bay. They record a cooling trend in terrestrial environments that began at termination of the Early/Middle Eocene Climatic Optimum, and was followed by a significant deterioration of climate during Late Eocene and earliest Oligocene, directly preceding glacial conditions in the northern Antarctic Peninsula region. The ongoing research confirms the existence of three preglacial climatic stages (PGS-1 – PGS-3) during Eocene – earliest Oligocene, from humid, warm to moderate climate (PGS-1), through cool and dry climate (PGS-2), up to cold and humid conditions (PGS-3). Studies were carried out on usually fine-grained volcanoclastic sediments, containing Podocarpaceae–Araucaria–Nothofagus plant fossils assembly. Beds of reworked pyroclastic material alternate with lava flows or volcanic agglomerates, as well as ex situ blocks of Eocene volcanogenic sediments on a moraine. Calculated geochemical indices of weathering (CIA, PIA and CIW) confirm moderate to high chemical weathering under warm and humid climate conditions at the beginning and deterioration of conditions in the end of Eocene.
EN
Fragmentary skull bones and vertebra from the Upper Eocene La Meseta Formation on Seymour (Marambio) Island, Antarctic Peninsula have been described as gadiform fishes, informally named “Mesetaichthys”. Here we describe jaws as Mesetaichthys jerzmanskae n. g. and n. sp., and refer this taxon to the perciform suborder Notothenioidei. This group is almost unknown as fossils. Similarities to the living, ‘primitive’ nototheniid Dissostichus eleginoides are indicated in the dentition. Gadiform evolution in the Paleocene-Eocene, and the possibility of a correlation between the origin and evolution of notothenioids in connection with the deterioration of the climate in Antarctica during the Late Eocene-Oligocene is discussed.
EN
The deposition of red and variegated mudstones and claystones characterized the ancient Tethys Ocean during Cretaceous and Palaeogene times, including in its north-western part, the Alpine–Carpathian deep-water basins. Palaeogene variegated sediments, containing red mudstone and claystone layers, crop out in the Gorce Mountains (Rosocha creek, near Lubomierz) in the Magura Nappe (Bystrica Subunit) of the Polish Outer Carpathians. These sediments occur as layers 1–10 cm thick and as packages of layers 2–3 m thick that are associated with very thin-bedded turbidites. The entire succession is tectonically disturbed and parts of it belong to the Ropianka, Łabowa Shale and Beloveža Formations. The sediments studied contain 27 genera and 59 species that belong to deep-water agglutinated foraminiferal (DWAF) assemblages. Tubular taxa, which are frequent in various Mesozoic–Cenozoic flysch sediments are relatively rare in the section studied. The assemblages are moderately diverse (3–20 taxa per sample). Excluding tubular forms, the most common taxa belong to Trochamminoides – Paratrochamminoides spp., Saccammina placenta, glomospirids, Recurvoides – Recurvoidella spp. and karrerulinids. The oldest part of the red sediments, referable to the Ropianka Formation, represents the upper part of the Rzehakina fissistomata Zone (probably the Upper Palaeocene). The youngest red sediments, forming thin intercalations in the Beloveža Formation, represent the acme of Reticulophragmium amplectens (middle Lutetian). Owing to tectonic disturbances, most of the Lower Eocene part of the variegated facies of the Łabowa Shale Formation is not preserved in the section studied. The upper part of it, a package 2 m thick, represents the lower part of the Reticulophragmium amplectens Zone. The small thickness (10–15 m) of the Łabowa Shale Formation in the section studied is similar to other sections in the southern part of the Bystrica Subunit. It is probably of a sedimentary nature, reflecting a decreasing number of mud-rich, gravitational flows in the southern part of the Magura Basin during the Early Eocene. Nevertheless, the strong tectonic disturbances that took place in this area during the Oligocene–Miocene folding and overthrusting influenced the reduction in thickness of these sediments.
EN
The Kashkan Formation (?Palaeocene to Middle Eocene) in the Zagros fold-thrust belt, SW Iran, which is intercalated between to marine limestone formations, consists of conglomerates, sandstones and siltstones. The sedimentology and the palaeogeography of the Kashkan Formation had not received any attention thus far, but have now been studied in seven sections, situated in the province of Lorestan. The sediments form twelve lithofacies, three ichnosubfacies and seven architectural elements, which are described, depicted and analysed. The analysis leads to the conclusion that most sediments accumulated in a low-sinuosity, low-gradient braided-river system (characterised by mainly unidirectional palaeocurrent directions, and by sheetfloods), that occasionally showed meandering characteristics (represented by overbank deposits and large bars). The deposits of this system closely resemble those of the South Saskatchewan River in Canada, which is considered as the classical example of a sand-bed braided river. The river flowed roughly from North to South, as deduced by palaeocurrent indicators such as imbrication and large- to medium-scale trough cross-stratification (direction measured in the trough axes). This current direction is supported by the southward to south-westward thinning of the formation and by the diminishing average grain size in the same direction. The trace fossils in the Kashban Formation fit all in the Skoyenia ichnofacies, which has here three ichnosubfacies which allow a more detailed palaeoenvironmental reconstruction, indicating that the braided stream passed into the low-energy shoreface zone of a tidally-influenced sea.
EN
Eocene thin-bedded flysch, widespread in the Alpine Tethys ocean, is present within the Magura Nappe, the largest Outer Carpathian unit in Poland and Slovakia. Thin-bedded flysch sedimentation accompanied by hemipelagic shales took place accross the entire Magura Basin during Eocene times. The lithostratigraphic position of these deposits has been a subject of considerable discussion. Different names, such as the Hieroglyphic Beds, Hieroglyphic Formation, Łabowa Shale Formation, Grzechynia Sandstones and Beloveža Beds, Beloveža Formation have been used in the Outer Carpathians literature. We show a striking resemblance of the Beloveža Beds (Formation) from its type locality to the Hieroglyphic Beds from the Beskid Wysoki area and to typical Beloveža Beds from the Hańczowa Mts. We propose to the name Beloveža Formation should be applied to thin-bedded flysch within both Bystrica and Rača units of Magura Nappe and the name Hieroglyphic Formation should be restricted to the Skole Unit. The original type locality in Beloveža near Bardejov in Slovakia is selected as type section of the Beloveža Formation
EN
Radiolarian and agglutinated foraminiferal fauna within upper deposits of the Skole Unit of the Polish Flysch Outer Carpathians occur in the Variegated Shale and Hieroglyphic formations of Paleocene and Eocene age. About 70 radiolarian and 50 foraminiferal species have been identified and their stratigraphic distribution determined using both regional and local biozonations. Five radiolarian zones: the Bekoma bidartensis Interval Zone, the Buryella clinata Interval Zone, the Phormocyrtis striata striata Interval Zone, the Theocotyle cryptocephala Interval Zone and the Dictyoprora mongolfieri Interval Zone in the lower Eocene and in the lower part of the middle Eocene have been distinguished. In the upper part of the middle Eocene and in the uper Eocene the abundance of radiolarians decreases and their age assignment has not been possible. Five foraminiferal zones have been distinguished and correlated with radiolarian zones based on co-occurrence of both Protista groups in the deposits investigated. These are: the Rzehakina fissistomata Zone, the Saccamminoides carpathicus Zone, the Reticulophragmium amplectens Zone, the Ammodiscus latus Zone and the Cyclammina rotundidorsata Zone covering the time span from upper Paleocene to upper Eocene.
EN
The Gresten Klippen Zone is an individual geological unit, mainly outcropping at the northern rim of the Northern Calcareous Alps. It is best exposed between the Enns Valley in the west and the Vienna Forest in the east. It contains a rock sequence ranging from Early Jurassic to Early Cretaceous, including sandstones, various limestones, breccias and radiolarites. The late Early Cretaceous–Paleogene is represented by the Buntmergel Formation. A sandstone block from the latter yields well-preserved planktonic foraminiferids which allow an assignment to the Early Eocene (E-7 Zone). The low density currents which deposited the parallel laminated sandstones originated in the lower shelf-middle slope.
EN
La Meseta Formation is made up of estuarine and shallow marine, fossiliferous clastic deposits 720 m thick that provides a unique record of marine and terrestrial biota of Antarctic ecosystems preceding continental glaciation in the Oligocene. The lower limit of this formation has been poorly known, and therefore it has been carefully investigated. The lowest part of the La Meseta Formation, at the southern bank of a palaeodelta, is represented by relics of a prograding sequence of sediments deposited in the wave-dominated part of a deltaic system in the offshore and lower and upper shoreface environments. The sequence is completed landwards by younger tidal plain sediments deposited at 40 m lower altitude in a relatively protected, central estuarine basin, which was dominated by tidal activity and influenced by periodic fluvial inflow. These strata were deposited during a late Paleocene or Ypresian/Lutetian lowstand of sea level, which might reflect a glaciation event or glacioisostatic rebound of land following deglaciation of hypothetic Antarctic inland glaciers. Forced regression of sea level and seaward expansion of a deltaic freshwater environment, led to local extinction of a unique assemblage of marine echinoderms, bryozoans, corals and brachiopods. These marine fossils, representing a thanatocoenosis, are perfectly preserved due to syngenetic goethite permineralisation. This process owed its origin to excess reactive iron coming from sulphide-rich bedrock through weathering processes and acid sulphate drainage of the neighbouring land area.
EN
Volcanic rocks from the Lions Rump area, which are the basement for a sequence of glaciomarine sediments of the Polonez Cove Formation, and lava flows from the Turret Point–Three Sisters Point area were sampled for thermogeochronological and palaeomagnetic investigations. Generally, andesitic lavas from King George Bay area consist mainly of clinopyroxene (Ti-augite) orthopyroxene (hyperstene) and plagioclase phenocrysts. The groundmass comprises mostly plagioclase laths, clinopyroxene, titanomagnetite and rare orthopyroxene crystals. However, the modal content, size, shape and distribution of phenocrysts are variable and specific for each sample. The Ar-Ar plateaus ages calculated for lavas from the Lions Rump area are very homogenous and point to middle Eocene age (Lutetian, ~44.5 Ma). The similar and consistent ages for volcanic basement for that area excluded the thesis about separate tectonic evolution of the Warszawa and Kraków blocks at least since the middle Eocene. The lavas from Turret Point and Three Sister Point are younger and were emplaced during the late Eocene (Bartonian/Priabonian: 37.3 š0.4 Ma and Priabonian: 35.35 š0.15 Ma, respectively). The results of isotopic investigations are consistent with magnetic polarities of the rocks indicating that the samples from the Lions Rump area are coeval with the lower part of the C20 polarity chron whereas the sample from Turret Point can be correlated with the upper part of the C17 polarity chron
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