Stratigraphic Position Research Articles

Detrital U[sbnd]Pb zircon geochronology, zircon Lu[sbnd]Hf and Sr[sbnd]Nd isotopic signatures of the Lopingian volcanic-ash-derived Nb-Zr-REY-Ga mineralized horizons from eastern Yunnan, SW China

The Lopingian altered volcanic-ash horizons in southwest China have attracted significant attention due to highly-elevated concentrations of critical element Nb-Zr-REY-Ga. Despite extensive investigation, the provenance of these distinctive horizons remains controversial. Are they a product of air-born volcaniclastic, erosional source sedimentation, or a complex mixture of multiple sources?This investigation performs a diverse array of mineralogical and isotopic geochemical analyses to investigate the provenance of these horizons and critical-element mineralization time. The results showed that the concordant ages of detrital zircons 207Pb/206Pb-206Pb/238U from five representative mineralized samples are 253.84 ± 2.60 Ma, 252.49 ± 2.39 Ma, 253.47 ± 2.99 Ma, 257.44 ± 2.01 Ma, and 243.94 ± 2.32 Ma, respectively. Importantly, this dating does not correspond to the stratigraphic position of the studied deposits. Instead, this data set indicates that the low-temperature hydrothermal alteration of the primary Nb-Zr-REY-Ga mineralized layers occurred in Late Permian-Middle Triassic times (260–240 Ma) immediately after volcanic ash deposition at 257–260 Ma. The Sr-Nd-Lu-Hf isotopic compositions, diagrams of both the Al2O3/TiO2 vs. Eu/Eu* and Zr/TiO2 vs. Nb/Y, and the trace element patterns of the zircons (Nb/Hf vs. Th/U, Hf/Th vs. Th/Nb) indicate that the mineralized horizons were derived from both ELIP alkaline rocks and arc-related intermediate-felsic magmatic rocks from the Paleo-Tethys realm. Furthermore, varying amounts of older (∼350 Ma and older) zircon grains defined by the dominant Late Permian-Middle Triassic zircons indicate that there was also some erosional-source input from the uplands surrounding the basin at the time of deposition.

Stratigraphical Position of Piran Limestone Unit in Piran Area, Erbil Governorate, Kurdistan Region, Iraq: Insights from Occurrence of Calcareous Nannofossils

Stratigraphical Position of Piran Limestone Unit in Piran Area, Erbil Governorate, Kurdistan Region, Iraq: Insights from Occurrence of Calcareous Nannofossils

NEW DATA ON THE SYSTEMATICS OF RECENT OSTRACODA OF THE GENUS AMBOSTRACON HAZEL 1962 (HEMICYTHERIDAE, PODOCOPIDA) FROM SOUTH AFRICA

The study provides a revision of the taxonomic composition (subgenuses, species) of the genus Ambostracon Hazel 1962 and a monographic description of the fossil (Holocene) and Recent marine ostracods of the genus Ambostracon of South and South-Eastern Africa. The material examined comes from geological stations on the shelf, continental slope and deep-water depression (32–3059 m water depth) of three areas (from the southern coast Mossel Bay to the eastern coast south of Durban, the outer part of Maputo Bay and the eastern coast of South Africa) and surface sediment samples from lagoons, estuaries and coastal lakes of the eastern coast of the South East Africa (Wilderness area, 0.2–1000 m water depth) (R/V METEOR M123-2016). The validity of the selection of the subgenus Ambostracon Patagonacythere is discussed. Two species (Ambostracon keeleri, A. flabellicostata) and one new species (Ambostracon frenzeli sp. nov.) were described. The systematic section provides data about synonymy (compiled on the results of a revision of the species volume), holotype (paratypes, syntypes), material, diagnosis, description, dimensions (linear, relative), sexual dimorphism, individual and geographic variability (fixation of the manifestations and the range of the variability of the morphological elements of the shell), comparison, remarks, localities, stratigraphical position, geographical distribution, environmental conditions of the site (for recent species), palaeoecology (for fossil species), zoogeography. SEM-images of external and internal structures of the carapace (macro- and mesosculpture, central muscle scar field, hinge, normal pore canals) are provided.

Stratigraphy of Late Mid‐Pleistocene in Lithuania: the current status and issues

The principal aim of this paper is to present a critical overview of the stratigraphical subdivision and correlation of the Late Mid‐Pleistocene (LMP) sediments in Lithuania. In recent decades, a number of studies of LMP sediments have been carried out, allowing clarification of the stratigraphical position of individual sedimentary sections. Particular efforts have been made to determine the age of sediments using a variety of absolute age determination methods. However, there are still several outstanding questions. It is still unclear how many warm periods occurred during the Saalian in Lithuania and of what magnitude. The least problematic issue is identification of the Butėnai (Holsteinian) Interglacial as it correlates well biostratigraphically with the contemporaneous sections of adjacent areas. The most controversial unit is the Snaigupėlė Interglacial, the age of which continues to be a subject of debate. Recently, more evidence has emerged that the sediments considered to be of the Snaigupėlė Interglacial are contemporaneous with the Merkinė (Eemian) Interglacial. The chronological placement of these sediments closely hinges on the unresolved stratigraphical classification of the Medininkai deposits (MIS 6 or MIS 8?) and the Žemaitija tills (MIS 8 or MIS 10?). The debate is centred on whether these two tills were formed during two entirely different glaciations or represent different phases of a single major glaciation event. Traditionally, these two tills were attributed to distinct glaciation events separated by the Snaigupėlė Interglacial. However, no sedimentary sections have been discovered that contain both these tills and the interglacial sediments that separate them. Given the similar lithological, geochemical and petrographic composition of the Medininkai and Žemaitija tills some research has supported their possible stadial rank. The clarification of these stratigraphical issues in the future may be facilitated by the application of new proxies and re‐examination of the existing LMP key sections.

Lithofacies and paleoenvironmental analysis of the Upper Cretaceous successions: Yagaan Khovil fossil locality, central Gobi region, Mongolia

The Upper Cretaceous successions are exposed at the Yagaan Khovil fossil locality in the central Gobi region, Mongolia. The successions comprise fluvial deposits that are divided into two units based on the lithological characteristics of the floodplain deposits. The lower unit (Unit 1) is characterized by eolian-influenced environments, whereas the upper unit (Unit 2) is composed predominantly of meandering river systems with lateral accretionary channel fill deposits that show concretion at the top of the bed. The shift in depositional processes from the lower to the upper unit can be hypothesized as the result of the change in the proximity of the eolian-affected area to the study area. The successions preserving the similar paleoenvironmental transition are also present in the Nemegt Basin, where the successions shift from reddish mud beds affected by eolian processes to meandering fluvial successions. Additionally, to the similar sedimentological features, similarities in vertebrate fossils between Yagaan Khovil and the formations in the Nemegt Basin imply the close relationship between the two areas in terms of environmental conditions, ages, and stratigraphic positions. To enhance the stratigraphic framework of the Upper Cretaceous strata in Mongolia, future work should integrate the findings of this study with new radiometric dating techniques.

Province-Wide Tapping of a Shallow, Variably Depleted, and Metasomatized Mantle to Generate Earliest Flood Basalt Magmas of the Columbia River Basalt, Northwestern USA

The Miocene Columbia River Basalt Group (CRBG) of the Pacific Northwest of the United States is the world’s youngest and smallest large igneous province. Its earliest formations are the Imnaha, Steens, and now the Picture Gorge Basalt (PGB), and they were sourced from three different dike swarms exposed from SE Washington to Nevada to northcentral Oregon. PGB is often viewed to be distinct from the other formations, as its magmas are sourced from a shallow, relatively depleted, and later subduction-induced metasomatized mantle, along with its young stratigraphic position. It has long been known that the lowermost American Bar flows (AB1&2) of the Imnaha Basalt are chemically similar to those of the PGB, yet the Imnaha Basalt is generally thought to carry the strongest plume source component. These opposing aspects motivated us to revisit the compositional relationships between AB1&2 and PGB. Our findings suggest that tapping a shallow, variably depleted, and metasomatized mantle reservoir to produce earliest CRBG lavas occurred across the province, now pinpointed to ~17 Ma. Moreover, compositional provinciality exists indicating regional differences in degree of depletion and subduction overprint that is preserved by regionally distributed lavas, which in turn implies relatively local lava emplacement at this stage.

Jewelry and ornamental concretions with fossils of the Republic of Kabardino-Balkaria. Mineral composition, gemological characteristics

Background. Along with ammonites and septaries, concretions with fossils are increasingly being used as jewelry and ornamental materials in Russia. Such concretions are characterized by a wide range of sizes, as well as high decorative and technological properties, making them attractive materials for manufacturing diverse interior and jewelry products. The collection and processing of concretions with fossils was previously carried out in the Ulyanovsk region. In this paper, similar concretions found in the Republic of Kabardino-Balkaria are studied for the first time.Aim. Tо establish the stratigraphic position, mineral composition, and decorative and technological characteristics of concretions with fossils of jewelry and ornamental quality found in the Republic of Kabardino-Balkaria.Materials and methods. The collection sites of concretions with fossils and their stratigraphic position were studied. In total, 15 samples characterizing the main decorative and technological types were selected. Interior and jewelry items were manufactured from the concretions; typical samples were studied. A set of studies included the determination of luminescence (8 samples), microhardness (8 cycles), density (6 cycles), optical-petrographic analysis (3 sections), quantitative determination of mineral and chemical composition (2 samples), electron probe studies (2 samples).Results. Concretions with fossils of commercial quality are associated with lower Aptian deposits, representing marlstone with a large number of shells, mainly ammonites, and, to a lesser extent, bivalves. These comprise (wt %): calcite — 64.0, quartz — 18.7, microcline — 7.4, illite — 5.6, smectite — 2.7, kaolinite — 1.0, strontianite — 0.5, as well as traces of pyrite, apatite, albite, ilmenite, and goethite. Among the impurity elements, Sr in the amount of 0.0402 wt % is recorded.Conclusions. For the first time, the mineral and chemical (including micro-inclusions and impurity elements) composition of concretions with fossils of jewelry and ornamental quality are established. Factors determining their decorative and technological characteristics are identified. The possibility of using concretions with fossils for manufacturing a wide range of products, including jewelry, is shown. Concretions can be collected simultaneously with ammonites and septaries in river valleys without mining, thereby involving minimal costs and having no negative effect on the environment.

Hyperspectral Facies Analysis as a Lithological Interpretation Tool for Carbonate Rocks

In a pilot study, hyperspectral image analysis was applied to four boreholes from the North Midlands Block in Ireland. The selected holes are extremely well characterised lithologically and have a detailed micropalaeontology accurately constraining stratigraphic positions. Hyperspectral facies were defined using features extracted from the hyperspectral data and compared with existing litho- and biostratigraphic logs and samples. These were able to distinguish changes in the lithologies of the cores and were useful for defining unbiased lithological contacts and for regional correlations.

Strontium isotope compositions of Late Permian evaporites from the northernmost Thuringian Basin (Germany) indicate continental influence on the marine Zechstein Sea

In the Late Permian Zechstein Sea of Central Europe, up to 2000 m of evaporitic rocks were deposited in at least four consecutive cycles. The age of these evaporitic rocks could not yet be precisely determined, because they are virtually fossil-free and do not contain radiometrically datable volcanic layers. A chemostratigraphic age of the succession can be determined by comparing 87Sr/86Sr ratios of marine gypsum and anhydrite to the worldwide marine strontium evolution curve. Unfortunately, published 87Sr/86Sr data of the Zechstein succession are characterized by frequent outliers towards higher ratios, making an age assignment challenging. The scatter in 87Sr/86Sr ratios might be induced by different processes like the contribution of meteoric water to the brine, in-situ Rb decay, or post-depositional hydrothermal or diagenetic overprint. Here, we present a dataset of 26 new gypsum and anhydrite 87Sr/86Sr ratios from drill cores situated at “Alter Stolberg” in the northernmost Thuringian Basin. Evaporites of the Werra-, Staßfurt-, and Leine cycles were sampled. The close proximity of the drillings allows a very accurate assignment of the stratigraphic position of each sample, so that trends and outliers in 87Sr/86Sr ratios can easily be recognized. While the entire Werra Formation obviously revealed non-marine 87Sr/86Sr ratios, the lowermost 87Sr/86Sr ratios in the Staßfurt and Leine Formations can be assumed to represent marine ratios and allow estimating a chemostratigraphic age of 257‒254 Ma. The combination of the 87Sr/86Sr data with the mineral composition of the samples suggests a contribution of meteoric water, probably river water, to the Zechstein Sea as the main reason for the observed increase in 87Sr/86Sr ratios. Additional in-situ Rb decay, related to the riverine input of clay minerals, cannot be excluded. Modelling the amounts of sea water and meteoric water in the brine indicates that 83‒99% of meteoric water would be necessary to explain the highest 87Sr/86Sr ratios observed in the Werra Formation.Graphical abstract

Seismic damage in Quaternary fluvial gravels in low-seismicity thrust-and-fold-belts: Case study of the Outer Western Carpathians (Poland and Slovakia)

In this contribution, we propose a model of Quaternary seismicity in the Outer Western Carpathians. The model presents results of analysis of fractured clasts performed in 268 exposures of Quaternary fluvial gravels within the ca. 5,000 km2 large segment of the Outer Western Carpathians comprising: Outer Carpathian nappes, the innermost part of the Carpathian Foredeep, and two intramontane basins – the Orava-Nowy Targ Basin and the Nowy Sącz Basin. Moreover, to precise stratigraphic position of the host gravels we performed OSL dating in 16 exposures and 14C dating in 4 exposures. Outside the intramontane basins, seismic damage in Quaternary strata is largely focused along all major overthrusts and some of the large-scale strike-slip and normal faults, whereas, within the intramontane basins, the damage is dispersed within the whole basins. Our results show that seismic damage within Quaternary strata in the Outer Western Carpathians results both from co-seismic fault rupture and from seismic shaking. During Quaternary times, the Outer Western Carpathians have been affected by earthquakes since the Pleistocene until Present. Seismic damage in Quaternary strata results from light (Mw5-) earthquakes with the exception of hanging limbs of the normal faults bordering the Orava-Nowy Targ Intramontane Basin which have been affected also by moderate (Mw5+) earthquakes. Our model can be significant for understanding seismic hazards in low-seismicity thrust-and-fold belts. In the studied case, this is important as the densely populated intramontane basins show the largest seismic damage.

Reappraisal of stratigraphic position of a sandstone included in the Bagh Formation, exposed near Belam Bujurg, Khargone District, Madhya Pradesh, India

A sandstone included in the Bagh Formation occurs at Belam Bujurg, District Khargone, Madhya Pradesh. Its stratigraphic position is controversial. Bose considered it as Nimar Sandstone. His observation, that it is capped by a limestone containing bryozoans, implies that Sitapuri Bryozoan Limestone directly overlies Nimar Sandstone at Belam Bujurg. However, it is contradictory to Chiplonkar’s (1982) observation that Nodular limestone is invariably associated with Nimar Sandstone. According to Roy Chowdhury and Sastri (1954, 1958), this sandstone is an intercalation within the Sitapuri Bryozoan Limestone. Later, Badve (1987) correlated this sandstone with Nimar Sandstone on the basis of similar ichnofauna and believed that overlying limestone cap represented calcareous facies coming at the top of Nimar Sandstone. However, elsewhere frequency and variety of trace fossils are distinctly more in limestone layers, in comparison to sandstone layers. Moreover, the presence of similar trace fossils indicates similarity in the conditions of deposition, rather than correlation. Recent fieldwork by the present authors corroborates that this sandstone is an intercalation within Sitapuri Bryozoan Limestone. Identification of the bryozoan Limestone was confirmed by petrographic study in thin section.

Milankovitch Record From Middle Jurassic Platform Supports Moderate Coolhouse Glaciation

AbstractThere are few documentations of far‐field effects of coolhouse glaciation and its signature preserved within Middle Jurassic carbonate platforms. Through outcrop logging and time series analysis we document the cyclostratigraphy of the upper Bajocian‐Bathonian interval of the Adriatic Platform, Croatia. The 200 m thick, ∼3.3 Myr duration cyclic platform record consists of peritidal carbonate parasequences (n = 109) with high‐energy grainstone‐rudstone bases fining up into micritic carbonate caps. There is little evidence of long‐term exposure near purported sequence boundaries, indicating the succession is conformable above the parasequence scale. Time series were constructed using Dunham rank and stratigraphic position, and parasequence thickness and stratigraphic position. A statistical estimation of accumulation rates using average spectral misfit (ASM) and correlation coefficient (COCO) methods that compare spectral peaks with an astronomical model at various sedimentation rates suggests that these rates ranged from 4.5 to 6 cm/kyr, which is compatible with long‐term rates based on thickness divided by duration. The time series analysis of rank series and cycle thickness series indicates long‐term obliquity modulation (∼1 Myr), short obliquity modulation (173 kyr), strong obliquity, and weak precession. The 173 kyr cycle is particularly evident in the cycle thickness series. The similarity of the spectra to the obliquity‐dominated Cenozoic coolhouse supports moderate southern hemisphere glaciation driving glacioeustatic sea level changes during the Middle Jurassic.

Composition and physico-chemical properties of aqueous extracts of lydites of the North Onega synclinorium in Karelia

Relevance. The need to obtain reliable information on chemical composition of aqueous extracts of lydites. There is lack of such information, but it is so important both for understanding dispersion of elements and their impact on natural waters of a region. It is necessary to study the composition of aqueous extracts as a result of water–rock interaction to determine possible sources of water pollution with toxic elements. Mineral composition of lydites of the North Onega synclinorium contains organic carbon and mist pyrite, which may contain increased concentrations of trace elements "harmful" for drinking water. To determine the ability of such elements to pass into a dissolved state, it is necessary to study aqueous extracts of lydites. Aim. To determine trace element composition and physico-chemical properties of aqueous extracts of lydites selected from two districts of the North Onega synclinorium to assess their environmental hazard. Objects. Geological section of the shungite-lidite-dolomite complex of the Zaonezhskaya formation of the Paleoproterozoic age of the North Onega synclinorium. Samples of lidites were taken at the Tetyugino (LT) and Shunga (LSh) sites of the Medvezhyegorsk district of the Republic of Karelia. Methods. Field studies, including investigation of stratigraphic position of lydites in geological sections of the Tetyugino and Shunga sites and sampling, laboratory experiment, aqueous extraction, scanning electron microscopy, Raman spectroscopy, X-ray fluorescence analysis, Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Results. Mineralogical composition of the lydites of both sites is similar. Taking into account high content of SiO2 and negligible content of other petrogenic oxides in chemical composition of lydites, it is possible to consider them as a source for obtaining pure quartz raw materials. The structure of lydites is clot-cryptocrystalline and clot-globular. Lydite extracts environment acidity depends on the totality of the minerals extracted from it, either basic (dolomite) or acidic (pyrite oxidation products). This factor is decisive in formation of chemical composition of lydite extracts, regardless of the location of the samples within a given geological object. Many elements extracted by water from the lydite samples of two regions under consideration are characterized by varying degrees of their extraction from the massive and veined parts of the sample. The cure coefficients of chemical elements in the form of the ratio of element average concentrations in the extract and lydite solid phase show the predominant intake of Cd, Mn, Mo, Sr, Rb, Li, Ni, Co, Li from Tetyugino lydites into water. Mo, Sb and W are predominantly extracted into the solution from the Shunga lydites. Average concentrations of most elements of the extracts of the Shunga samples satisfy the requirements for drinking water and, unlike shungite, they are not sources of harmful components in water. Therefore, it is advisable to carry out work on the possibility of their use for water purification for drinking purposes.

Organic richness and source rock potential of the La Peña Formation in the Sabinas and Piedras Negras basins, NE of Mexico

This paper investigates the petroleum generation potential of the Lower Cretaceous organic-rich rocks of the La Peña Formation in the Sabinas and Piedras Negras Basin (SB-PNB) of northeastern Mexico. In order to provide insights into the source rock potential of this unit, a total of 25 cutting samples collected from 15 wells at different stratigraphic intervals along the study area were analysed using Rock-Eval Pyrolysis technique. The analytical results revealed that all the analysed samples can be described as hydrogen-poor organic matter with HI <200 mg HC/g TOC. The organic richness indicates a poor to excellent Total Organic Carbon content suggesting that existed different conditions during the deposition and burial of this unit, causing variable organic matter production and preservation. Also, the results revealed a variation in the kerogen types that may be attributed to the relative stratigraphic positions of the selected samples in the wells.
 With respect to the organic matter thermal maturity, given by the geographical distribution of the Tmax values, the mature and overmature zone (435–508 °C) correspond to the Sabinas basin (SB).
 Overall, these results show a variability in the organic richness, thermal maturity and petroleum potential of the La Peña Formation, differentiating the values of the TOC content, petroleum potential and HI content for the samples from the Sabinas Basin and Piedras Negras Basin, respectively.

Guinea pig remains from the XVIth century Ojców castle (southern Poland)

The mandible of a guinea pig (Cavia porcellus) was found in osteological material collected during archaeological excavations at Ojców Castle (southern Poland). The bone fragment was radiocarbon dated and subjected to ancient DNA analysis. The age of this guinea pig mandible fragment was directly dated between the late 16th and the early 17th century. The radiocarbon dating results are compatible with dating based on stratigraphic position. The ancient DNA analysis confirmed the taxonomic identification and indicated possible routes of introduction of this species into Europe. Given the high-status of the castle’s possessors in the 16–17th centuries, it can be assumed that the single guinea pig bone in Ojców belonged to a pet and was probably not acquired as a source of food, which also may have been the case in the few other European archaeological sites with guinea pig remains.

First record of trace fossils in the Ediacaran–Cambrian transition on the northern Gondwana platform (Anti-Atlas, Morocco)

The Anti-Atlas Mountains of Morocco preserve one of the most complete latest Neoproterozoic to Cambrian stratigraphic successions worldwide, with high-resolution chemostratigraphic δ13Ccarb coverage. However, the exact stratigraphic position of the Ediacaran–Cambrian boundary remains unresolved. Until now, no trace fossils or body fossils have been recorded from the terminal Ediacaran strata in the Anti-Atlas Mountains. The only exception is a discoidal body fossil-like structure from the shallow-marine sandstones of the Ediacaran Tabia Member, Adoudou Formation, in the Taroudant Group in the Igherm inlier. For the first time, we document the occurrence of abundant trace fossils from the base of the Adoudou Formation, including Treptichnids, Monomorphichnus isp., Helminthoidichnites isp., Gordia isp., Palaeophycus isp., Planolites isp., and Conichnus isp. The integration of both trace fossils and carbon isotope δ13Ccarb records suggests that the Ediacaran–Cambrian transition in the Sous Basin can be placed at the contact between the Tifnout and Tabia Members, which chemostratigraphically coincides with the large negative δ13Ccarb excursion that had been previously suggested for the Ediacaran–Cambrian boundary (BACE) in the western Anti-Atlas Mountains.

New caenagnathid (Theropoda: Oviraptorosauria) dinosaur specimens from middle and upper Campanian strata of West Texas

New caenagnathid dinosaur specimens from the upper Aguja Formation of West Texas comprise the most complete examples yet described from southern North America. Two individuals are represented. Osteohistology indicates that both were mature at their times of death. Although they share no overlapping elements, the two individuals are separated by overall body size, paleohabitat, and stratigraphic position and so they almost certainly represent different species. One individual consists of a partial hindlimb, but exhibits too few (3) characters to be phylogenetically informative and is, therefore, referred to an indeterminate caenagnathid – possibly one of two species previously recognized in coastal facies of the Aguja Formation. The second individual is more complete. It was recovered higher in section from more inland fluvial paleoenvironments and preserves fragmentary elements from throughout the postcranial skeleton. A histology-based growth model – the first for a caenagnathid – indicates that the second individual required at least five years to approach fully adult size. However, only 11 character states could be derived from its preserved remains. Phylogenetic analyses found this specimen deeply nested within Caenagnathidae, but were otherwise inconclusive and so it, too, is referred to an indeterminate caenagnathid. Nevertheless, several combined morphologies (e.g., absence of cervical epipophyses, dorsoventral depth of the hypapophysis on the second cervicodorsal vertebra, and greater trochanter of the femur only weakly separated from the femoral head) implies that the second individual represents an unknown species. One critical aspect of both specimens is that they provide significant new comparative material representing the sparse ‘southern’ caenagnathid record.

Les sites Stone Age du Parc national du Niokolo-Koba, Sénégal : synthèse des données de terrains (1982–2003)

First investigations in the Niokolo-Koba National Park were undertaken in 1969 and conducted by the IFAN Archaeology laboratory (directed by Cyr Descamps) and the Geography laboratory with Christian Barbey, after the collection of a cupule stone by the director of the Park (A. Dupuy). The amateur prehistorian Dr. Gaillard also reported the presence of flakes in the Bafoulabé alluvium. These first collections of prehistoric tools, knapped mainly on jasper and jasper facies chert, were collected in the reworked levels of gravel under the bank (last and lowest alluvial level), in the minor bed of the Gambia (Gué de Bafoulabé) and Niokolo-Koba (at Passage du Koba and in a ravine, opposite the Niokolo camp). The surveys conducted between 1983 and 1984, and the excavation between 1982 and 2003 in the Falémé valley confirmed the identity of the geomorphological and stratigraphic scheme of the lower valley of the Falémé and the Middle Gambia at the crossing of the National Park of Niokolo-Koba. This research also allowed the observation of numerous new prehistoric sites, which confirm the previous data while showing the existence of industries in stratigraphic and geomorphological positions similar to those found in the Falémé valley. A final visit inside the Park in 2003 allowed to precise the GPS coordinates of the former manual locations (between 1982 and 1986). Three Stone Age periods were identified: the Acheulean, the Middle Stone Age, formerly known as the Mousteroid, and the Later Stone Age, formerly known as the Advanced/Final Palaeolithic. The present work takes up previous data presented in mission reports or master's theses in order to place Niokolo-Koba National Park in the major issues of West African prehistoric settlements.

A natural death assemblage of fishes from an early modern archeological context in Antwerp (Belgium)

AbstractAn unusual concentration of tens of thousands small fish remains discovered during rescue excavations in the town of Antwerp, Belgium, is described. The material was found in a small depression with no associated archeological material but could be dated to the first half of the 16th century based on its stratigraphic position. About 3500 freshwater fish were found in articulating position and it is shown that they died naturally during a single depositional event after an exceptional flood. The species spectrum and the reconstructed fish lengths make it possible to document the season when the catastrophic mortality occurred. This assemblage differs from the few assemblages of natural mortality reported in the literature, which are all of the attritional type.

Non-Ceramic Site of Shamanka 8 on the Southern Coast of Baikal Lake

Purpose. The southern coast of lake Baikal is a territory known in Siberian archaeology for its Kitoi cemeteries. Besides burials of the Shaman capes there are some Neolithic and Bronze age complexes at Circum–Baikal railway. In 2012 it the first non-ceramic site was discovered in South Baikal, which was named Shamanka 8. This paper presents the assemblage of this complex and discusses its chronological and cultural features.Results. The Shamanka 8 site is located on the top of the third hill of the Shaman cape. The cultural layer lies under the Holocene Optimum sediments. The site stratigraphic structure is characterized by compression. There is no bone fragments and ceramic. For lithic knapping, mainly local raw material (quartz) were used. The quartz assemblage has such features as poor formal standardization, high degree of flake fragmentation, cores with the orientation of fracture plane relative to the longitudinal axis, bipolar reduction. All of these specifics are explained by uneven fracture characteristics and bad workability of quartz, as well as its breakage patterns. Some artifacts, including single non-quartz tool, suggest that there may be a connection between the Shamanka 8 site and the industries of the Final Paleolithic sites in the Northern Baikal region and the Irkutsk region. Quartz small knife (?), carinated end-scraper and tubular core have analogies in the 2nd cultural layer of the Kurla II site, dated by 13.5 uncal kya. Similarly dated quartz components of Nirikan I and flint tool-kit of Verkholenskaya Gora I include other cultural link types.Conclusion. The similarity in the morphology of some tools with Final Paleolithic counterparts and stratigraphic position of finds allow us to assume the Final Sartan age of the Shamanka 8 site and dates it to the Bølling – Allerød warming. However, in the absence of direct radiocarbon dating, an Early Holocene/Early Neolithic attribution of the site is also possible. Further studies may help resolve this issue.