Search results for "Surface Processes"
showing 10 items of 1294 documents
Prehistoric palaeodemographics and regional land cover change in eastern Iberia
2019
Much attention has been placed on the drivers of vegetation change on the Iberian Peninsula. While climate plays a key role in determining the species pools within different regions and exerts a strong influence on broad vegetation patterning, the role of humans, particularly during prehistory, is less clear. The aim of this paper is to assess the influence of prehistoric population change on shaping vegetation patterns in eastern Iberia and the Balearic Islands between the start of the Neolithic and the late Bronze Age. In all, 3385 radiocarbon dates have been compiled across the study area to provide a palaeodemographic proxy (radiocarbon summed probability distributions (SPDs)). Modelled…
Environmental responses of past and recent agropastoral activities on south Greenlandic ecosystems through molecular biomarkers
2016
Paleoenvironmental studies previously performed on Lake Igaliku revealed two agropastoral phases in south Greenland: the Norse settlement from AD 986 to ca. AD 1450 and the recent installation of sheep farmers, since the 1920s. To improve the knowledge of the timing and magnitude of the Greenlandic agropastoral activities, a lipid inventory was realized and compared with biological and geochemical data. During the 12th century, a major increase in deoxycholic acid (DOC) and coprophilous fungal spores revealed a maximum of herbivores. Synchronously, a minimum of the n-C29/ n-C31 alkane ratio and tree and shrub pollen and a maximum of triterpenyl acetates showed a reduction in the tree and s…
Patch-based survey methods for studying prehistoric human land-use in agriculturally modified landscapes: A case study from the Canal de Navarrés, ea…
2018
Abstract In landscapes whose surface has been modified by terracing and other agricultural land-use, the spatial and temporal patterning of prehistoric settlement can be difficult to detect using traditional, site-orientated archaeological survey methods, especially for small-scale societies. In these contexts, methods that can reveal occupational patterns at landscape scales, without the need to pinpoint specific sites of human occupation, can be especially useful. We employ a stratified, randomly selected patch-based survey strategy to examine socio-ecological dynamics from the Middle Paleolithic through Bell Beaker (Chalcolithic) periods within the Canal de Navarres, eastern Spain. We di…
Astrochronology of the Valanginian Stage from reference sections (Vocontian Basin, France) and palaeoenvironmental implications for the Weissert Even…
2013
12 pages; International audience; High-resolution gamma-ray measurements performed on five biostratigraphically well-dated reference sections from the Vocontian Basin (south-eastern France) are used to develop a new astrochronology of the Valanginian Stage and its subdivisions (i.e. ammonite and calcareous nannofossil zones and subzones). Spectral analyses show a pervasive dominance of 405-kyr eccentricity cycles with the expression of 100-kyr eccentricity, obliquity and precession. Previous rough estimates of Valanginian Stage duration ranged from 3.9 to 6.5 myr but were generally based on less reliable or indirect methods. This study provides a precise duration of 5.08 myr, tuning the ser…
Record of latest Barremian-Cenomanian environmental change in tectonically controlled depressions from the Jura-Burgundy threshold (Jura Mountains, e…
2019
Abstract The area of the western Jura Mountains constitutes the former Jura-Burgundy threshold between the Tethys Ocean and the epicontinental Paris Basin Sea. During the Barremian, the area was covered by a shallow-water Urgonian carbonate platform. Tectonic processes influenced the architecture of the Urgonian platform and were notably responsible for the formation of fault-related depressions on top of the Urgonian series, which were subsequently transformed into incised valleys and then to marine depocenters. Their sedimentary infills are mostly represented by the Perte-du-Rhone Formation and record stepwise environmental change on the innermost platform, which was strongly influenced b…
Community replacement of neritic carbonate organisms during the late Valanginian platform demise: a new record from the Provence Platform.
2012
24 pages; International audience; The Valanginian is marked by amajor platform demise inducing a hiatus in the northern Tethyan neritic carbonate record from the top of the lower Valanginian to the lower Hauterivian. New biostratigraphic and chemostratigraphic data from the Ollioules section (Provence Platform, southern France) are presented here, demonstrating that a large part of the upper Valanginian is preserved in an inner platform environment. The thick, upper Valanginian, aggrading carbonate succession is observed in an aborted rift domain, implying relatively low subsidence. In this context, a relatively long-term sea-level rise was required to sustain a keep-up style of carbonate p…
Sr isotope variations in the Upper Triassic succession at Pizzo Mondello, Sicily: Constraints on the timing of the Cimmerian Orogeny
2018
Abstract The Late Triassic Cimmerian Orogeny was a result of the final closure of the Palaeotethys Ocean and the accretion of Gondwana-derived (Cimmerian) continents to southern Eurasia. Determining the timing of the Cimmerian Orogeny is crucial to our understanding of the large-scale climate changes driven by the uplift of the Cimmerian Mountains. Here we present stratigraphic variations in 87Sr/86Sr values of Upper Triassic pelagic limestone from the Pizzo Mondello section, Sicily, Italy, that constrain the timing of uplift of the Cimmerian Mountains. The 87Sr/86Sr values remain relatively constant in the lower part of the section, decreasing slightly in the Tuvalian (upper Carnian) and L…
Changes of shell microstructural characteristics of Cerastoderma edule (Bivalvia) — A novel proxy for water temperature
2017
Abstract Shells of bivalves potentially provide an excellent archive for high-resolution paleoclimate studies. However, quantification of environmental variables, specifically water temperature remains a very challenging task. Here, we explore the possibility to infer water temperature from changes of microstructural characteristics of shells of the common cockle, Cerastoderma edule . The size and elongation of individual microstructural units, i.e., prisms, in the outer shell layer of seven three to five year-old, specimens collected alive from the intertidal zone of the North Sea near Texel, The Netherlands, and Schillig, Germany, were measured by means of automatic image processing. Grow…
Detailed record of the mid-Oxfordian (Late Jurassic) positive carbon-isotope excursion in two hemipelagic sections (France and Switzerland): A plate …
2007
14 pages; International audience; The Oxfordian (Late Jurassic) was a time of widespread change in Jurassic marine (carbonate) sedimentation patterns. A marked positive excursion in δ13C is dated as Middle Oxfordian in age. In this study we investigate if changes in carbonate sedimentation coincided with altered carbon cycling and climate. We use C-isotope records as a proxy for the evolution of the carbon cycle and compare δ13C-trends with the evolution of sedimentation in a segment of the opening Tethys seaway. One of the studied sections is located in the Subalpine basin of France (Trescléoux and Oze), the other in the Swiss Jura mountains (Liesberg). Carbon-isotope stratigraphy of carbo…
A tale of two gorges: Late Quaternary site formation and surface dynamics in the Mula basin (Murcia, Spain)
2018
Abstract We present a case-study in Palaeolithic archaeology focusing on formation processes at cave- and rock-shelter-sites in a Mediterranean context and on the correlation between site deposits, Quaternary surface sediments and the morphology of the surrounding land. We study three sites located in the basin of River Mula (Murcia, Spain): the cave-site of Cueva Anton and the rock-shelters of Finca Dona Martina and Abrigo de la Boja, in the Rambla Perea valley. They are examined through an integrated geoarchaeological approach that takes into account geomorphological, stratigraphic and soil micromorphological data. The three sites are found within a short distance and cover similar time s…