Early Holocene environmental change, the presence and disappearance of early Mesolithic habitation near Zutphen (The Netherlands)

The Early Holocene landscape near Zutphen (The Netherlands) is reconstructed by means of microfossil, macroremain and bone analyses. In this area early Mesolithic sites were found on a river dune along a former river channel. AMS¹⁴C dating provided a detailed chronology for the sites and river channel deposits. Between ca. 9800–9600 B.P. open herbaceous vegetation was present on the river dunes. The residual channels were fringed by reed swamps and willow shrubs, with birch and poplar woodlands inland. During this period there are indications of natural or man-made burning of the reed swamp vegetation along the residual channel. Also trampling zones along the lake edge were more abundant. However, no archaeological sites were discovered in the vicinity. From ca. 9600 B.P. on, the area became more densely forested; willow, birch and poplar replaced the reed swamps along the residual channels, while pine colonised the river dunes. Archaeological finds show that early Mesolithic people inhabited the area between ca. 9400 and 9200 B.P. and between ca. 8900–8700 B.P. During the earlier period, records of Urtica, Plantago and coprophilous fungi may point to trampling and/or eutrophication as a result of the presence of large herbivores and people along the channel shores. After ca. 8700 B.P. people probably left the area when open water was no longer available in the vicinity.     

Palynostratigraphical dating of the Lower Cretaceous Peñaferruz Formation,San Pedro de Antromero Beach (Asturias Region,northwestern Iberian Peninsula)

A palynological assemblage of five Lower Cretaceous stratigraphic levels corresponding to the Peñaferruz Formation in San Pedro de Antromero Beach, has been studied to determine the exact age of this formation. An age no older than the Aptian is suggested on the basis of the palynoflora, based on the presence of Trilobosporites hannonicus, Cicatricosisporites venustus, Cicatricosisporites berouensis, Ephedripites dudarensis, and Reticulisporites semireticulatus. This age assignment implies a new relationship between the Peñaferruz and Antromero formations, the Peñaferruz Formation being younger than previously thought. This possibly makes both formations contemporaneous, at least at the San Pedro de Antromero Beach section, suggesting a lateral change of facies between these deposits.     

Evolution of vegetation landscapes during the Holocene in the central and downstream Loire basin (Western France)

Nine sites along the downstream and middle section of the Loire river at Cordemais (Loire Atlantique, France) situated in the estuary to Saint-Nicolas-de-Bourgueil (Indre et Loire, France) were investigated. Interdisciplinary studies combined palynology, geography, archaeology, sedimentology and history, thus enabling us to reconstruct the evolution and the long-term response of the Loire valley ecosystem to natural variations and anthropogenic pressure from the Preboreal to the present in an integrated manner. The Atlantic marine transgression (between 7000 and 5000 B.P.) caused the level of brackish water to increase at Oudon between 6740⁺²⁰⁵/_–200 and 5010⁺¹¹⁵/_–100 B.P. This phenomenon, which was the first of its kind to be detected near the central Loire region (approximately 80 km from the current mouth of the Loire river), was accompanied by the development of subhalophile vegetation (Chenopodiaceae) and the appearance of dinoflagellate cysts. A regressive phase occurred during the Subboreal, about 4500 B.P., and led to the erosion of most of the estuarian sediments and to the disappearance of plant species linked to salinity at Oudon: peat deposits built up at most other sites. Human activities had an early effect; moderate deforestation took place at Champtocé about 6600 B.P. as farming was already orientated towards rearing animals. However, possibly cultivated plants were present towards the middle and the end of the Neolithic period (wheat, rye, buckwheat, flax) at about 5600 B.P. and chestnut and walnut were probably exploited in the Loire valley region at about 4600 B.P. The Bronze Age seemed to mark a phase when societies settled down (planting of vineyards) and deforestation peaked from the Gallo-Roman period onwards. The textile industry (flax, hemp), in the context of crop rotation set up during the Iron Age, developed rapidly during the Middle Ages, whereas nowadays the rearing of animals is the dominant activity in the Loire Valley, following the introduction of maize into the region in 1950.     

Palynology of OGS-6a and OGS-7, two new 2.6 Ma archaeological sites from Gona, Afar, Ethiopia: Insights on aspects of Late Pliocene habitats and the beginnings of stone-tool use

Fossil pollen grains extracted from sediments sampled from OGS-6a and OGS-7, two newly excavated Late Pliocene sites of Gona, in the Afar Depression of Ethiopia, indicate a high percentage of afromontane forest and highland taxa (36.8-43.3%), among which Podocarpus cf. gracilor is dominant (19.6-24.2%). Forest taxa typical of the afromontane phytogeographic region have also been identified in the samples. The overall pollen spectrum suggests a mosaic of open and closed habitats, with a considerable wooded environment present during the time associated with the beginnings of early hominid use of flaked stones at Gona. Here we provide details of the results from the pollen analyses. The two sites lie 4-8 m directly below a volcanic tuff dated by ⁴⁰Ar/³⁹Ar to 2.53 ± 0.15 million years (Ma). The materials were recovered within fine-grained sediments located just above a geomagnetic polarity transition identified as the Gauss-Matuyama boundary dated close to 2.6 Ma, also corroborating the earlier age reported for the East Gona artifacts from EG-10 and EG-12. Thus, the stone artifacts, fossilized broken fauna and pollen grains from OGS-6a and OGS-7 represent archaeological materials from the world's oldest securely dated sites, and offer insights on aspects of the palaeoenvironments around the time of the beginnings of ancestral hominid use of flaked stones, ca. 2.6 Ma.     

Microfacies,microtaphonomic traits and foraminiferal assemblages from Upper Jurassic oolitic–coral limestones: stratigraphic fluctuations in a shallowing-upward sequence (French Jura,Middle Oxfordian)

The characterization and distribution of the microfacies and the microfossil assemblages of a Middle Oxfordian section from Jura Mountains composed by thick oolitic–coral limestones is analyzed. Six microfacies types (mainly grainstones) are differentiated mainly composed by ooids, intraclasts and bioclasts. Foraminiferal assemblages are dominated by agglutinated forms. Benthic microbial communities and sessile foraminifera are the main components of the encrustations. The whole set of microfossil assemblages is typical of shallow subtidal environments rich in “algae” (Cayeuxia, “Solenopora”, Thaumatoporella, Bacinella, Girvanella and Terquemella) and foraminifera such as Nautiloculina oolithica, Redmondoides lugeoni, Ammobaculites coprolitiformis, Troglotella incrustans and Rectocyclammina. The increasing upward record of debris of algae and Nautiloculina, and the decrease of serpulids, bryozoans, nodosariids and ophthalmidiids indicate a shallowing-upward trend. The stratigraphic distribution of microfacies and microfossil assemblages lead to differentiate two main successive phases. The first is a deeper subtidal environment in an open shelf, while the second is a shallow subtidal environment with evolution from winnowed to more restricted conditions. Microfabrics of radial to concentric ooids upwards in the section correspond to higher energy environments related to an oolitic shoal. This study shows how a very detailed analysis of microfacies, which integrates oolitic features, microfossil assemblages and microtaphonomy is potentially a useful tool for interpreting hydrodynamism and sequence evolution in marine carbonate shallow environments.     

Stable isotope records (O, C) of Jurassic aragonitic shells from England and NW Poland: palaeoecologic and environmental implications

Shells of fully marine Middle to Upper Jurassic molluscs from England and north-western Poland were analysed with respect to their stable isotope (δ¹⁸O, δ¹³C) compositions, and palaeoecological and environmental life conditions of these molluscs were inferred from them. Light microscopical and SEM inspection and an analysis of the minor element content (Fe, Mn, Mg, Sr) suggest rather unaltered isotope signals. The δ¹⁸O and δ¹³C values show a characteristic distribution among three groups of co-occurring organisms. Benthic (adult) bivalves generally preserved higher δ¹⁸O and δ¹³C values than ammonites, whereas planktic bivalve larvae tend to possess the lowest δ¹⁸O but higher δ¹³C than adult bivalves. As this distribution pattern is found in numerous horizons and sections of Bathonian to Kimmeridgian age in NW Poland and England, it is thought to reflect real palaeoenvironmental parameters. All observations can be incorporated in a single model that assumes (i) seasonally induced temperature stratification of the water column, (ii) a correlation between phytoplankton blooms and reproduction season of planktic-planktotrophic bivalves, and (iii) insignificant vital effects with respect to the δ¹³C in bivalves, but strong biological control in ammonites. In addition, the δ¹⁸O evolution suggests that the Late Bajocian to Middle/Late Bathonian and Early Oxfordian to Late Kimmeridgian were considerably warmer than the latest Bathonian to Late Callovian time interval. The oxygen isotopic records from other European regions indicate a similar pattern of long-term palaeotemperature evolution. The comparatively high water temperatures during the Callovian to Oxfordian of the Isle of Skye (NW Scotland) are enigmatic, however. In the Early Oxfordian, sea surface and bottom temperatures began to rise in continental Europe and England. These changes coincide with a south-westward drift of the West European crustal plate, but a causal relationship remains to be demonstrated.     

Coral zonation of an Oxfordian reef tract in the northern French Jura

During the Middle Oxfordian, numerous coral reefs flourished on the northern margin of the Tethys Ocean. The outcrop of Bonnevaux-le-Prieuré (northern French Jura mountains) provides a rare opportunity to observe a nearly complete section allowing the installation, evolution and demise of this global carbonate reef rich event to be studied. Quantitative data on coral assemblages together with sedimentological and palaeoecological observations lead to the reconstruction of a reef tract coral zonation. Starting from the outer slope, Dimorpharaea, Microsolena, Dendraraea, Comoseris, and Stylina ecozones are recognized. This new facies model implies a central position for an oolitic shoal in the highest energy zone, within the Comoseris ecozone. Applying this facies model to the sequence stratigraphic interpretation of the vertical succession results in recognising a third-order relative sea-level fluctuation, which can be correlated at least with Lorraine (France) and Switzerland.     

Palynological indications of environmental changes during the Late Cretaceous–Eocene on the southern continental margin of Laurasia, Xizang (Tibet)

A palynostratigraphic and palynofacies study of a geological section at Cuojiangding in Zhongba County has provided a basis for discussing the palaeoenvironmental evolution of the southern continental margin of Laurasia in Xizang (Tibet) towards the end of the Cretaceous Period and during the Paleogene. It is the only record of fossil spores and pollen grains from collision- and convergence-related sediments close to the major Yarlung Zangbo Suture. Deposits of the Padana Formation at the base of the section through the Qubeiya, Quxia, and Jialazi formations to the Rujiao Zangbo Conglomerate at the top are considered to range in age from Santonian to Eocene or possibly Oligocene. During this period the India plate collided with, and continued to push against, Laurasia plate. Two spore and pollen zones and three palynofacies types are recognized. These are correlated with two transgressive–regressive cycles associated with the collision, periods of geologically rapid uplift being reflected by the molasse-like sediments of the upper Quxia Formation and the Rujiao Zangbo Conglomerate, which accumulated during the Late Paleocene and Eocene–Oligocene respectively. The first regression led to intermittent subaerial exposure and erosion of the Cuojiangding area. The second ended the marine history of the area and led first to the development of swamps in a subtropical climate, now preserved in the coal-bearing Qiuwu Formation, and later to the development of mountainous terrain, with a cooler climate at higher elevations.     

Microhermal nodules of <Emphasis Type=Italic>Renalcis</Emphasis>-like calcimicrobes from Oxfordian limestones of the Sierra Madre Oriental (Novillo Formation,Mexico)

Microhermal nodules very similar to those from the Oxfordian Smackover Formation are volumetrically important constituents of the Novillo Formation exposed in eastern Central Mexico. The nodules occur within a micritic limestone succession (Novillo Limestone). Coalescence of adjacent nodules leads to a delicate self-supported frame. Microhermal nodules consist of both microbial carbonate and clustered digitate and branching chambered microfossils. The latter occur in the form of crust-like agglomerations or bushy growth habit in small growth-framework cavities created by accretionary microbialites. Main growth patterns are branching upward, downward facing and pendant. Like Renalcis, the microfossils apparently resulted from the activity of calcimicrobes. Terebella, encrusting foraminifers, and Tubiphytes form part of the microhermal biota and occur as subordinate faunal components. The association developed on the floor of a calm, shallow-marine lagoon with restricted water interchange and reduced oxygenation at the sediment–water interface.     

Contribution palynologique à la connaissance du Triasdu Haut-Atlas de Marrakech,Maroc

This note provides a precision on the age (Carnian) of one of the terms of the High Atlas series of Marrakech by the palynological datation and gives an account on the recent palaeontological discoveries realized in course of a sedimentological study of a so called azoic series. The deposit environment is briefly sketched.     

Jurassic biostratigraphy and paleoenvironmental evolution of the Malaguide complex from Sierra Espuña (Internal Betic Zone, SE Spain)

Jurassic studies in the Internal Zones of the Betic Cordillera are scarce since this zone is composed mainly of pre-Jurassic metamorphic rocks. Only the “Dorsal” and the Malaguide domains include fossiliferous Jurassic successions, as in Sierra Espuña (SE Spain), which is one of the bigger and well-exposed Jurassic outcrops of the Internal Zones. Collected Ammonite assemblages update and improve the precision of previous biostratigraphic data by the recognition of: the Domerian (= Upper Pliensbachian, in the Mediterranean Domain) Lavinianum (Cornacaldense Subzone), Algovianum (Ragazzoni, Bertrandi, Accuratum and Levidorsatum Subzones) and Emaciatum (Solare and Elisa Subzones) Zones; the Lower Toarcian Polymorphum and Serpentinum Zones; the Middle Toarcian, Bifrons and Gradata Zone; the Upper Toarcian Reynesi Zone; the Lower/Upper Bajocian, the Lower Callovian Bullatus and Gracilis Zones; the Middle/Upper Oxfordian Transversarium, Bifurcatus, Bimammatum and Planula Zones; and the Lower and Upper Kimmeridgian Platynota, Strombecki, Divisum and Beckeri Zones.The paleoenvironmental evolution of the Malaguide Jurassic at Sierra Espuña shows similarities with other Mediterranean Tethyan paleomargins. The biostratigraphic precision along with the litho- and biofacies analyses has enabled the interpretation that the Malaguide paleomargin evolved as a passive margin, developing shallow carbonate platforms, until the Domerian (Lavinianum Zone). Then, the platform broke up (Domerian, Lavinianum Zone-Upper Toarcian, Reynesi Zone) with the beginning of the rifting stage, beginning the development of horst-graben systems and the coeval drowning of the area. This stage ended in the upper Lower Callovian (Gracilis Zone) to the Middle Oxfordian (Transversarium Zone) interval, starting the drifting stage, which accentuated the horst-graben systems, leading to the deposition of condensed nodular limestones in the raised sea bottom.     

Pollen morphology of the tribes Eritrichieae and Cynoglosseae (Boraginaceae) in the Iberian Peninsula and its taxonomic significance

DÍEZ, M. J. & VALDÉS, B., 1991. Pollen morphology of the tribes Eritrichieae and Cynoglosseae (Boraginaceae) in the Iberian Peninsula and its taxonomic significance.
The pollen morphology of 33 species of Boraginaceae from the Iberian Peninsula belonging to the tribes Eritrichieae and Cynoglosseae has been studied by light and scanning electron microscopy. The results confirm the eurypalinous character of this family, in which a large number of species can be recognized by their pollen characters.
The pollen of these two tribes is basically heterocolpate, a type which is very uncommon in the angiosperms, with 6, 8 or 10 apertures, sometimes with ectoapertures anastomosed at the equator (ectocingulum), or diorate, minute or small in size, outline elliptic or rectangular-elliptic in equatorial view, with or without a constriction at the equator, exine 0.5-1.0 urn thick and the tectum psilate with granules around the colpi. The similarity in shape and apertural system found in several genera such as Asperugo, Gyrocarion and Omphalodes, and some species of Myosotis, does not permit the two tribes to be distinguished on pollen characters. The generic limits of Cynoglossum and the infrageneric classification of Myosotis are discussed.     

Margin feeding damage on the leaves of conifers and ginkgoales from the Mesozoic of Transbaikalia

A new approach to the formal classification of arthropod margin feeding plant damage is proposed. Several types of margin feeding traces on the leaves of Pityophyllum sp. and Ginkgoites sp. from the Upper Jurassic-Lower Cretaceous Chernovskie Kopi locality, Transbaikalia, are described as five new species in the genus Pinovulnus gen. nov.