A revised terrace stratigraphy and chronology for the early Middle Pleistocene Bytham River in the Breckland of East Anglia, UK

The Bytham River was one of the major pre-Anglian (MIS 12) rivers of eastern England. Flowing from the Midlands to the East Anglian coast, it has been recognised at numerous sites by its distinctive lithological suite, containing significant quantities of quartzite, quartz and Carboniferous chert that originate from central England. In the Breckland of Suffolk and Norfolk, deposits of the Bytham River can be identified at 26 sites by this distinctive clast lithological composition. These sediments, referred to as the Ingham Formation, consist of a series of sand and gravel aggradations, which due to their differences in elevation can be interpreted as at least four early Middle Pleistocene terrace remnants of the former river, and a final phase of deposition along the river valley prior to its destruction. This paper reports on recent fieldwork at six of these sites, which through stratigraphic and lithological analyses, together with new Electron Spin Resonance age estimates, contribute to a revised geological framework for the Bytham River as represented in the Breckland. These sites can be attributed to the four lowest fluvial aggradations, with the lowest and youngest of these aggradations shown to be early Anglian in age. The river was subsequently overrun by Anglian ice during Marine Isotope Stage 12. This revised geological and chronological interpretation provides an important framework for understanding the Lower Palaeolithic artefacts that have been found within these gravel aggradations, and contributes to the understanding of the human occupation of north-west Europe during the early Middle Pleistocene

A escadaria de terraços marinhos de Peniche (Portugal centro-oeste)-estratégias para a datação

Summary:The Peniche staircase of marine terraces (central-west Portugal) dating strategies At the rocky coast of Peniche Peninsula, a staircase of six wave-cut surfaces and associated sedimentary deposits was identified. The strategies for the absolute dating of the several records of the Pliocene and Pleistocene marine incursions is here presented. The three lower marine terraces could be dated by optically stimulated luminescence, by using the proto-col pIRIR (k-feldspar as the dosimeter). The three upper terraces and the culminant marine unit could be dated by electron spin resonance. The limited thickness of the deposits does not allow the use of Cosmogenic (TNC) dating. The uppermost deposits of some of the marine terraces contain vertebrate bones and travertines, which could also be used for U-series dating (13) (PDF) A escadaria de terraços marinhos de Peniche (Portugal centro-oeste)-estratégias para a datação. Available from: https://www.researchgate.net/publication/327582780_A_escadaria_de_terracos_marinhos_de_Peniche_Portugal_centro-oeste-estrategias_para_a_datacao [accessed Feb 15 2019]

Geomorphic markers of Quaternary tectonics in Westernmost Iberia: insights from the Lower Mondego River terraces (central Portugal)

The Lower Mondego Valley (LMV), located in the Western Iberian passive margin which is under compressive tectonic reactivation since ca. 80 Ma, is used for deciphering long-term landscape evolution during the Quaternary and the control played by active tectonics, eustasy and climate. The elaboration of a detailed geomorphological map allowed the establishment of the spatial and temporal distribution of the different geomorphological units and morphogenetic systems operating in the LMV. The culminant unit of the Mondego Cenozoic Basin (allostratigraphic unit UBS13, recording an Atlantic fan-delta and adjacent shallow marine siliciclastic environments) and terrace levels (river and marine) are used as geomorphic markers to quantify fluvial development and tectonic activity. The main stages of evolution are a transition of endorheic to exorheic (Atlantic base level) drainage in the Mondego Cenozoic Basin, ca. 3.7 Ma ago, followed by onset of the fluvial incision stage (valley entrenchment) by ca. 1.8 Ma. Electron spin resonance (ESR) dating is used to improve the chronological framework for the terrace staircases of the LMV and to decipher the response of the river to the regional uplift and other longterm controls (resistance of the substratum to erosion, eustasy and climate). Six river terrace levels (T1, the older, to T6, the younger), inset in the UBS13 and previous to the modern alluvial plain, were characterized and correlated with marine terraces represented at Cape Mondego, near the river mouth. The fluctuating eustatic and climate controls are superimposed on a long-term crustal uplift. The data show marked compartmentalization of fluvial system behaviour with changes in incision rates (acting as a proxy of uplift rates) from east to west, creating distinctly different sectors. Differential uplift is inferred between the valley sides and between the four main reaches in which the LMV is subdivided by major faults. Differential uplift is mainly related to regional fault sets trending N-S to NNW-SSE, NNE-SSW, ENE-WSW, and E-W to WNW-ESE. Using as geomorphic references the topmost deposits of the UBS13 unit and river terraces located above the alluvial plain, average long term incision rates were estimated ranging from 0.03 to 0.16 m/ka, dependin

Electron spin resonance dating of the culminant allostratigraphic unit of the Mondego and Lower Tejo Cenozoic basins (W Iberia), which predates fluvial incision into the basin-fill sediments

The Cenozoic basins of western Iberia have a culminant allostratigraphic unit (designated UBS13), which records the beginning of Atlantic drainage and predates the fluvial incision that led to the development of the present drainage networks. However, the available numerical dating is quite limited and mainly restricted to the lower-level terrace deposits. Therefore, this study uses for the first time the electron spin resonance (ESR) method to date this culminant unit in the Mondego and Lower Tejo Cenozoic basins of Portugal. The depositional age of this unit is supposed to lie between ~3.7 Ma (basal deposits) and ~1.8 Ma (uppermost deposits). The Al-centre provided reliable ESR data, but the dates obtained by using the TiLi centre clearly underestimate the burial ages. With reference to the existing independent dating of the Vale Farpado site (3.7–3.6 Ma) at the lowermost basal level of the UBS13 deposits, the ESR (Al-centre) ages of 3.0 to 2.3 Ma obtained for the UBS13 basal and middle deposits give reliable estimates of the burial age. The ESR ages (Al-centre) obtained for the UBS13 uppermost deposits indicate a probable age of ~1.8 Ma. Thus, these results are of international significance, in that they constitutes the first numerical ages obtained for the uppermost levels of the Cenozoic basin-fills of western Iberia, which predate the fluvial incision that took place in response to lower Quaternary base levels

Vallée de la Dives : étude des terrasses à Morteaux-Couliboeuf (L’Herbage Vieille), Le Mesnil-Mauger (Écajeul) et Biéville-Quétiéville (Quétiéville)

Dans le cadre des projets soutenus par le PCR « les premiers Hommes en Normandie », de nouvelles recherches de terrain portant sur l’étude géomorphologique et sédimentaire de vallées fluviatiles pléistocènes de la Dives ont été engagées, afin de préciser les contextes environnementaux et de tenter de mettre en évidence d’éventuelles occupations humaines. Le fleuve Dives s’inscrit dans le contexte de bordure du système Manche-Atlantique qui a laissé des replats recouverts de nappes alluviales ..

Les nappes alluviales pléistocènes de la vallée moyenne du Cher (Région Centre, France) : contexte morphosédimentaire, chronologie ESR et Préhistoire. Premiers résultats

L’inventaire des nappes alluviales fossiles conservées dans la vallée moyenne du Cher, l’un des principaux affluents de la Loire en rive gauche, a été entrepris depuis 2003. Une fois repérées, les formations alluviales ont été sondées mécaniquement jusqu’au substratum, étudiées stratigraphiquement et échantillonnées pour analyses géochronologiques par la méthode de la résonance électronique de spin (ESR) appliquée aux quartz fluviatiles optiquement blanchis.Deux secteurs ont été définis dans la moyenne vallée du Cher, de part et d’autre de Vierzon, et appelés respectivement secteurs « Berry » et « Sologne ».Dans le secteur « Berry », la vallée a une orientation N 160o et suit de grands accidents tectoniques qui mettent au contact les formations calcaires du Jurassique et les dépôts calcaires lacustres tertiaires. Dans ce secteur, l’incision totale de la vallée est de 50 m et neuf formations alluviales étagées ont été inventoriées. Elles sont généralement conservées sur la rive gauche de la vallée actuelle, dans des systèmes karstiques et sur des blocs basculés ou abaissés. Trois de ces formations ont été particulièrement étudiées et datées.Dans le secteur « Sologne », la vallée suit un axe synclinal orienté est-ouest. Elle traverse les formations crétacées, puis les sables burdigaliens, et son incision passe d’amont en aval de 35 m à 20 m seulement. Dans ce secteur, quatre ou cinq nappes alluviales ont été individualisées selon les sous-secteurs. Pour les plus hautes d’entre elles, les différences d’altitudes relatives sont très faibles, ce qui complique l’étude. Par ailleurs, les nappes moyennes sont mal conservées.La datation des nappes de la vallée moyenne du Cher par ESR est en cours. Les premiers résultats indiquent que la mise en place de la vallée du Cher a débuté dès le Pléistocène inférieur. Les industries du Très-Ancien Paléolithique du site de Lunery (Cher), dont la situation a pu être précisée par des fouilles, sont ainsi datées de 1,1 Ma, en accord avec les données biochronologiques obtenues sur le site voisin de Rosières, et confirment la présence de l’Homme dès cette époque dans le bassin de la Loire moyenne. Par ailleurs, les âges obtenus sur les nappes moyennes, s’ils sont confirmés, indiqueraient que les industries à bifaces étaient déjà présentes dans cette zone et très développées il y a 700 ka.Since 2003, field surveys in the Middle Cher River Valley, a left tributary of the Loire River, have allowed the inventory of the Pleistocene alluvial formations. Most of them have been mechanically bored as far as the substratum, stratigraphically studied and sampled for Electronic Spin Resonance (ESR) geochronological analyses.Two different sectors, called respectively “Berry” and “Sologne”, have been defined upstream and downstream of Vierzon.In the “Berry” Sector, the river flow N. 160o along a major tectonic accident which cuts Jurassic limestones and Tertiary lacustrine calcareous deposits. The incision of the valley is about 50 m and nine Pleistocene alluvial formations have been recognized on the left side of the modern valley only. The deposits are often preserved in karstic systems or on tilted down blocks.In the “Sologne” Sector, the river flows along an east-west syncline through the Cretaceous chalky and clayeous formations and the Burdigalian sands. In this sector, the incision, about 35 m upstream, reduces to 20 m downstream and four or five alluvial formations have been studied. Differences between the relative altitudes of the highest terraces are very small. The middle sheets are rarely preserved and the lower formations spread out the two kilometres wide alluvial plain.The dating of the different sheets by the ESR method applied to optically bleached fluvial quartz is in progress. First results indicate that the present Cher Valley began its incision during the Lower Pleistocene, in spite of a low incision referred to the other main tributary valleys of the Middle Loire Basin.The Early Lower Palaeolithic artifacts founded by excavations in the alluvial deposits of the Lunery site (Cher) have been dated about 1.1Ma and confirm other evidences of such ancient human settlement of the Middle Loire Basin. The ESR ages obtained for the middle formations, if they will be confirmed, indicate that Acheulian handaxes industries were present and developed in this area since 700 ka

Plio-Quaternary coastal uplift along the western Iberian margin: insights from dated marine terraces (Peniche, central Portugal)

This study provides a detailed geomorphological study of the Peniche Peninsula, located in westernmost Iberia, a resistant rocky limestone headland subjected to high energy Atlantic Ocean coastal processes. We have used field mapping, surveying, sedimentary facies analysis, geochronology (electron spin resonance [ESR]; U-Series), but also identification of fossils and lithic artefacts, in order to: 1) reconstruct styles and timing of paleoenvironmental changes, 2) correlate to Marine Isotope Stages (MIS), and 3) quantify coastal uplift rates during the Quaternary. The marine terrace deposits, comprising calcite cemented conglomerates and siliciclastic sandstones, sometimes capped by travertines, were studied in detail along the SW sector of the peninsula, at the Furninha Cave site. The mapping (1/10,000 scale) and dating results obtained allow to identify several marine levels and to correlate them to MIS’s: 1) a culminant wave-cut platform at 29-33 m (above mean sea level) (Pm), with a probable age of 3.7 Ma; 2) a wave-cut platform at 24-28 m (Tm1), dated as 883±120 ka, probably correlated with high sea level conditions spanning ca.1000-790 ka (MIS25-19); 3) a wave-cut platform at 19-21 m (Tm2), with a beach conglomerate and sandstone, dated as 707±32 ka and correlated to 790-680 ka (MIS17); 4) a wave-cut platform at 14-16 m (Tm3), with a beach conglomerate and sandstone, and capping travertine, probably recording aggradation during 620-460 ka (MIS15-13) (ESR: 598±160, 563±63, 490±44 ka; U-series: >620 ka); 5) a wave-cut platform at 11-13 m (Tm4), with beach conglomerate and sandstone followed by travertine, dated as 315±48 ka, probably recording 430-275 ka (MIS11-9); 6) a wave-cut platform at 6-9 m (Tm5), with beach conglomerate, sandstone and travertine, dated as 288±53 ka, probably spanning 290-180 ka (MIS7); 7) a wave-cut platform at 4.0 m (Tm6), probably spanning 125-85 ka (MIS5); 8) aeolian sand units, respectively, of Late Pleistocene and Holocene age; 9) modern beach sediments, ranging from sands to boulders. A long term Plio-Quaternary corrected uplift rate of 0.004-0.006 m/ka is obtained using the Pm level as a key geomorphic marker (eustatic level = +10-20 m). In contrast, for the last ~1 Ma the inset Pleistocene marine terrace levels (Tm1-Tm6) indicate apparent short-term uplift rates between 0.02 and 0.05 m/ka (means of 0.03 to 0.04 m/ka) and corrected short-term uplift rates between -0.05 and 0.05 m/ka (means of -0.02 to 0.05 m/ka). This study demonstrates that the Quaternary compressive reactivation of the Western Iberian Margin has determined coastal low to moderate uplift rates; active tectonics play an important role in the geomorphic expression and distribution of Pleistocene marine terraces, recording vertical ground motions (uplift/subsidence) superimposed onto global sea-level oscillations

Electron Spin resonance (ESR) dating of some European Late Lower Pleistocene sites

InWestern Europe, most of the oldest prehistoric sites (ranging from 2 Ma to 500 ka) are associated with clastic or carbonated karstic environments. Here, the electron spin resonance (ESR) dating method is often the only one method permitting to place these localities in the global Quaternary framework, which is mainly based on marine isotopic data and palaeomagnetical record. ESR can be applied on different materials frequently recovered in archaeological sites such as tooth enamel, quartz grains or carbonates. In this paper, we present the results, which have been obtained for more than ten years on different archaeological sites of the late Lower Pleistocene or the early Middle Pleistocene, which are crucial for the understanding of the first human settlements of Europe: Pont-de-Lavaud and Grâce-Autoroute (France), Atapuerca Gran Dolina (Spain), Monte Poggiolo and Isernia La Pineta (Italy). Wherever possible, the ESR results were compared with those of independent dating methods, including 39Ar/40Ar, palaeomagnetism and biostratigraphy. In some cases, the ESR method applied on bleached quartz extracted from fluvial sediments and the ESR/U-series method on tooth enamel were the only available methods to provide geochronological data.En Europe occidentale, la plupart des sites préhistoriques les plus anciens (compris entre 2 millions d’années et 500 000 ans) se trouvent en contexte détritique ou carbonaté karstique. Dans de tels cas, la méthode de datation par résonance de spin électronique (ESR) est souvent la seuleméthode géochronologique permettant de replacer ces gisements dans le cadre chronologique du Quaternaire établi notamment à partir des données isotopiques marines et du paléomagnétisme. Cette méthode a également pour avantage d’être applicable sur plusieurs types de supports que l’on retrouve fréquemment sur les sites préhistoriques : émail dentaire, grains de quartz ou carbonates. Nous présentons dans ce travail les résultats obtenus depuis une dizaine d’années sur des sites préhistoriques de la fin du Pléistocène inférieur ou du début du Pléistocène moyen, sites importants pour la compréhension des premiers peuplements de l’Europe : Pont-de-Lavaud et Grâce-Autoroute (France), Atapuerca Gran Dolina (Espagne), Monte Poggiolo et Isernia La Pineta (Italie). Chaque fois que cela était possible, les résultats ESR ont été comparés avec ceux obtenus par des méthodes indépendantes, comme le paléomagnétisme, la biostratigraphie ou la méthode 39Ar/40Ar mais, dans certains cas, les méthodes ESR sur grains de quartz extraits de sédiments fluviatiles et ESR/U-Th sur émail dentaire se sont révélées comme les seules méthodes utilisables pour fournir des points de repère chronologiques

Le tuf de Caours (Somme, France) : mise en évidence d'une séquence eemienne et d'un site paléolithique associé

Les nouvelles investigations menées sur les tufs du bassin de la Somme dans le cadre du programme SITEP (CNRS) ont permis de mettre en évidence une formation tufacée reposant sur une nappe alluviale en position de très basse terrasse à Caours (Scardon). La séquence de tufs est séparée de la nappe alluviale périglaciaire sous-jacente par des limons fluviatiles calcaires se terminant par un petit sol de marais coiffé par un liseré de tourbe compactée. La formation tufacée proprement dite comporte essentiellement des faciès palustres à nombreux restes végétaux encroûtés en place et des concrétions travertineuses de type stromatolithes. En direction de la vallée actuelle l’ensemble passe rapidement à des faciès nettement fluviatiles à oncolithes structurés en grandes lentilles à stratifications obliques. La séquence de tuf ainsi que les limons fluviatiles ont livré une abondante faune malacologique qui a permis de décrire une évolution climatique contemporaine des phases initiales d’un interglaciaire, suivi d’un optimum climatique, puis d’une phase de réouverture du milieu exprimant le déclin des conditions tempérées. La base du tuf comporte plusieurs horizons organiques qui ont livré des restes de grands mammifères et de rongeurs contemporains de l’optimum interglaciaire déterminé par les assemblages malacologiques. Dans ces horizons, plusieurs niveaux du Paléolithique moyen ont été découverts en place, en association avec des restes de grande faune interglaciaire fortement fracturés par l’action de l’homme et présentant des traces de découpe. Compte tenu de sa position dans le système de la Somme, des datations par U/Th obtenues sur le tuf (moyenne : ± 120 ka BP) et des conclusions des études bioclimatiques, la séquence de Caours représente le premier témoin de l’interglaciaire Eemien en contexte fluviatile dans le bassin de la Somme. Enfin, les niveaux archéologiques découverts à Caours constituent un exemple unique d’occupation humaine contemporaine du dernier interglaciaire dans la France septentrionale.The new investigation lead on the tufa deposits of the River Somme basin, within the SITEP (CNRS) Program, have allowed the discovery of a new tufa sequence overlying an alluvial formation in low terrace position at Caours (Scardon valley). The tufa sequence is separated from the underlying periglacial alluvial gravels by fluvial calcareous silts overlain by a thin marshy soil and a thin peat layer. The tufa formation is mainly composed by paludal (marshy) soil facies showing numerous in situ incrusted vegetal remains and travertine concretions (stromatoliths). Downslope, looking to the present day valley the whole tufa formation quickly evolves toward typical fluvial facies including oncolithic sands and large scale cross beddings. The tufa sequence and the fluvial silts have provided abundant malacological faunas that have allowed describing a climatic evolution contemporaneous of the initial phases of an interglacial, followed by a climatic optimum and then a decline of temperate conditions. The lower part of the tufa includes several organic horizons that have yielded numerous large mammals and rodent remains contemporaneous of the interglacial optimum previously evidenced by malacology. Within these horizons, several Palaeolithic layers have been discovered in situ in association with interglacial large mammal remains showing evidences of human operation (systematic breaking of long bones and cut marks). Taking into account its relative position within the Somme terraces system, the U/Th ages (average ± 120 ka BP) and the results of the various bioclimatic studies, the Caours sequence represents the first record of the Eemian interglacial in the Somme basin. In addition, the archaeological levels discovered at Caours are a unique example of Human occupation during the Last Interglacial in Northern France

Datación por ESR del yacimiento arqueológico del Pleistoceno inferior de Vallparadís (Terrassa, Cataluña, España)

Excavated between 2005 and 2007, the site of Vallparadís (Terrassa, Spain) has given an abundant and diversified fauna associated with a rich Mode 1 industry. In order to complete the chronostratigraphic framework, we performed ESR and combined US-ESR dating applied to quartz grains extracted from sediments and fossil teeth, respectively. The results obtained are very significant, giving a weighted mean ESR age of 0.83 ± 0.13 Ma (2σ) for the reference archaeological level of the site (level 10) and another of 0.79 ± 0.23 Ma (2σ) for the archaeological level 12 of the Vallparadís sequence. These ESR results are in total agreement with the ones derived from biochronology and paleomagnetism. This whole dataset allows the elaboration of a reliable and consistent chronostratigraphic framework which chronologically places Vallparadís site in the late Early Pleistocene period, i.e. within a time range comprised between Jaramillo and Brunhes geomagnetic events. Consequently, as well as Gran Dolina-TD6 and Sima del Elefante- TE9 sites, in Atapuerca, Burgos, Vallparadís can be therefore considered as a key site for the study of early hominid settlements in Europe.Excavado entre 2005 y 2007, el yacimiento de Vallparadís (Terrassa, España) ha aportado una fauna rica y diversa en asociación con un importante conjunto lítico de Modo 1. Con el objetivo de completar el marco cronoestratigráfico, se hicieron dataciones por los métodos de Resonancia Paramagnética Electrónica (Electron Spin Resonance, ESR) y ESR combinada con uranio-torio sobre algunas muestras de granos de cuarzo extraídos de sedimentos y dientes fósiles, respectivamente. Los resultados obtenidos son muy significativos, ofreciendo edades ESR promedias de 0,83 ± 0,13 Ma (2σ) para el nivel arqueológico de referencia del yacimiento (nivel 10) y de 0,79 ± 0,23 Ma (2σ) para el nivel arqueológico 12 de la secuencia de Vallparadís. Dichos resultados por ESR concuerdan con los obtenidos a partir de la biocronología y del paleomagnetismo. El yacimiento de Vallparadís dispone ahora de un marco cronoestratigráfico fiable y coherente, que permite situarlo cronológicamente a finales del Pleistoceno inferior, dentro de un rango temporal comprendido entre los eventos geomagnéticos de Jaramillo y Brunhes. Dicho yacimiento junto a los de Gran Dolina TD-6 y Sima del Elefante TE-9, en Atapuerca, Burgos, se posiciona como un yacimiento clave para el estudio de los primeros poblamientos humanos de Europa