Pleistocene fauna in the Sucha Wieś (Ełk Lakeland) and Czarnucha (Augustów Plain) sections, northeastern Poland

Do badań faunistycznych wykorzystano próbki osadów pobranych z otworu wiertniczego Sucha Wieś (Pojezierze Ełckie) z głębokości 153,60-178,00 m oraz z otworu wiertniczego Czarnucha (Równina Augustowska) z głębokości 96,05-118,85 m. Z badanej serii osadów jeziorno-bagiennych opisano szczątki różnych grup zwierząt: ślimaków (Gastropoda), małży (Bivalvia), małżoraczków (Ostrazoda), ryb (Pisces), chrząszczy (Coleoptera) i innych. Do określenia wieku osadów, szczególnie przydatne okazały się mięczaki (ślimaki i małże) oraz małżoraczki. Na podstawie obecności ślimaka Lithoglyphus jahni oraz małżoraczka Scottia browniana uznano, że osady nie mogą być młodsze od interglacjału mazowieckiego.Samples collected from the Sucha Wieś borehole (Ełk Lakeland) from a depth interval of 153.60-178.00 and from the Czarnucha borehole (Augustów Plain) from a depth interval of 96.05-118.85 m were analysed for faunal content. The lacustrine-marsh deposits contain fragments of various animals including gastropods, bivalves, ostracods, fish, Coleoptera and others. Especially important for age determinations are moluscs (gastropods and bivalves) and ostracods. The presence of Lithoglyphus jahni (gastropod) and Scottia browniana (ostracod) indicates that the deposits cannot be younger than the Mazovian Interglacial

Regressive-transgressive cyclothem with facies record of the re-flooding window in the Late Silurian carbonate succession (Podolia, Ukraine)

The term “re-flooding window” was recently proposed as a time-interval connected with the transgressive stage of present day peri-reefal development. In the analysis presented here, a fossil record of a re-flooding window has been recognized. Nine Late Silurian carbonate sections exposed on the banks of the Dnister River in Podolia (Ukraine) have been correlated base on bed-by-bed microfacies analysis and spectral gamma ray (SGR) measurements. Correlated were sections representing settings ranging from the inner part of a shallow-water carbonate platform to its slope, through an organic buildup. The reconstructed depositional scenario has been divided into six development stages, with the first three representing a regressive interval and the latter three a transgressive interval of the basin’s history. The re-flooding window has been identified at the beginning of a transgressive part of the succession. Surprisingly, it is characterized by an extremely fast growth of a shallow, tide-dominated platform and by deposition of calciturbiditic layers in a more basinal area. The interpreted succession is a small-scale model illustrating the reaction of carbonate depositional sub-environments to sea level changes and determining the facies position of the stromatoporoid buildups within the facies pattern on a Silurian shelf. The use of SGR analyses in shallow water, partly high-energy, carbonate facies, both for correlation purposes and for identifying depositional systems, is a relatively new method, and thus can serve as a reference for other studies of similar facies assortment

Lacustrine sediments of Eemian Interglacial at Leszczyno (Płock Upland - Central Poland)

Eemian Interglacial lacustrine sediments at Leszczyno are situated within the area of theWarta Glaciaton and slightly to the east from the maximal extent of the Vistulian Glaciaton. These sediments are situated in a wide depresion left by dead ice; its origin was controlled by tectonic and glaciotectonic conditions. Lacustrine silts and calcareus gyttja (about 2.7 m thick overlie the Warta Glacial till, and are covered by sands, silts and of the Vistulian Glaciaton (about 7.6 m thick). Palynostratigraphically, the biogenic lake sediments include 7 local pollen assemblage zones (L PAZ).Their spectra represent succession of the plant assemblages nearly of the whole protocratic stage, mesocratic stage and older segment of the telocratic stage of the Eemian Interglacial. Pollen diagram of the sediments from Leszczyno represents the north Masovian variant of the Eemian Interglacial succession, characterized by values of Abies (3%). Those of Taxus reach 5%

Stromatoporoid beds and flat-pebble conglomerates interpreted as tsunami deposits in the Upper Silurian of Podolia, Ukraine

Tsunami deposits are currently a subject of intensive studies. Tsunamis must have occurred in the geological past in the same frequency as nowadays, yet their identified depositional record is surprisingly scarce. Here we describe a hitherto unrecognized example of probable palaeotsunamites. The Upper Silurian (Pridoli) carbonate succession of Podolia (southwestern Ukraine) contains variously developed event beds forming intercalations within peritidal deposits (shallow water limestones, nodular marls and dolomites). The event beds are represented by stromatoporoid and fine-grained bioclastic limestones, in some places accompanied by flat-pebble conglomerates. The interval with event beds can be traced along the Zbruch River in separate outcrops over a distance of more than 20 km along a transect oblique to the palaeoshoreline. The stromatoporoid beds have erosional bottom surfaces and are composed of overturned and often fragmented massive skeletons. The material has been transported landward from their offshore habitats and deposited in lagoonal settings. The flat-pebble conglomerates are composed of sub-angular micritic clasts that are lithologically identical to the sediments forming the underlying beds. Large-scale landward transport of the biogenic material has to be attributed to phenomena with very high energy levels, such as tropical hurricanes or tsunamis. This paper presents a tsunamigenic interpretation. Morphometric features of redeposited stromatoporoids point to a calm original growth environment at depths well below storm wave base. Tsunami waves are the most probable factor that could cause their redeposition from such a setting. The vastness of the area covered by parabiostromal stromatoporoid beds resembles the distribution of modern tsunami deposits in offshore settings. The stromatoporoid beds with unsorted stromatoporoids of various dimensions evenly distributed throughout the thickness of the beds and with clast-supported textures most probably represent deposition by traction. In some sections, the stromatoporoids are restricted to the lowermost parts of the beds, which pass upwards into bioclastic limestones. In this case, the finer material was deposited from suspension. The coexistence of stromatoporoid beds and flat-pebble conglomerates also allows presenting a tsunami interpretation of the latter. The propagating tsunami waves, led to erosion of partly lithified thin-layered mudstones, their fragmentation into flat clasts and redeposition as flat-pebble conglomerates

Recent studies on the Silurian of the western part of Ukraine

The paper summarises the effects of recent studies carried out by a team from the Department of Historical and Regional Geology of the Faculty of Geology, University of Warsaw on the upper Silurian of Podolia (western part of Ukraine). The sedimentary history of the Silurian succession of Podolia is characterised by its cyclic pattern, with shallowing-upward cyclothems. In the traditional interpretation, the occurrence of stromatoporoid beds within each cyclothem marks the deepest (or most open-marine) sedimentary environment within the cycle. According to the results of recent studies, their occurrence is connected rather with a relatively shallow-water environment and with high energy phenomena. A substantial reinterpretation of the main sedimentary processes governing the deposition and facies distribution on the shelf is presented. Particularly, there are recognised and described high-energy sedimentary events repeatedly punctuating the generally calm sedimentation that prevailed in the lagoonal settings, some of which are interpreted as tsunami induced. Further perspectives for studies on the Silurian successions of Podolia are also discussed. The main problem is the precise correlation of particular sections that are scattered over vast distances and developed in similar facies associations

Middle/Upper Devonian brachiopod shell concentrations from the intra-shelf basinal carbonates of the Holy Cross Mountains (central Poland)

A huge isolated accumulation, more than 3 m thick and 10 m wide, of densely packed, uncrushed brachiopods has been found in Józefka Quarry within the Middle/Upper Devonian Szydłówek Beds deposited in a relatively deep environment of an intrashelf basin (Kostomłoty facies zone, western Holy Cross Mountains, Poland). The low-diversity assemblage is strongly dominated by the atrypide Desquamatia globosa jozefkae Baliński subsp. nov. and, to a lesser degree, by the rhynchonellide Coeloterorhynchus dillanus (Schmidt, 1941), which constitute 72.8% and 22.1% of the fauna, respectively. Less frequent are specimens representing the genera Hypothyridina, Schizophoria and Phlogoiderynchus. According to the conodont fauna found within the coquina bed, the stratigraphic position of the shell accumulation is close to the Givetian/ Frasnian boundary. The brachiopods are associated with numerous crinoids and less frequent bryozoans, receptaculitids (Palaeozoic problematica), sponges and solitary corals. Although it is difficult to entirely exclude the autochthonous nature of the brachiopod coquina member, its allochthonous origin and redeposition of the brachiopod shells to the deep basin by gravity flows is much more probable. Such conclusion is supported by the following facts: (1) the position of the complex in a succession of deep-marine basinal facies impoverished in oxygen; (2) its lateral thinning-out and composite internal stratification; (3) the lensshaped geometry of the coquina bed in the section perpendicular to the bedding dip; (4) high variability of the sediments preserved within the shells; and (5) the preferred orientation of the shells. The brachiopods mixed with crinoidal debris were probably transported by low-velocity, high-density, gravity-induced debris flows. Lack of fossils typical of the Middle Devonian shallows, such as massive stromatoporoids, amphiporoids and tabulates, indicates that the source area of the bioclastic material was not located in the shallowest part of the shelf, but most probably on a submarine sea-mount to the north of present-day Józefka, as suggested by earlier investigators. The triggering mechanism of the allochthonous deposition was an earthquake rather than storm activity. The enormous thickness of the brachiopod complex is probably caused by the sinking of bioclastic material, transported in succeeding depositional multi-events, in a soft, muddy bottom, typical of the Szydłówek Beds deposition