Search results for "Quaternary"
showing 10 items of 411 documents
YTTRIUM AND REE SIGNATURE RECOGNIZED IN CENTRAL MEDITERRANEAN SEA (ODP SITE 963) DURING THE MIS 6 – MIS 5 TRANSITION
2010
The Mediterranean Sea acts as a miniature ocean with the development of its own conveyor belt. It constitutes an ideal location to study and forecast how the marine environment responds to rapid climatic change. Here we present a palaeoenvironmental study carried out on the sediments of ODP Site 963, recovered in the Sicily Channel, the sill which divides the western from the eastern Mediterranean basin. We focused on the transition between the penultimate glacial (MIS 6) and the last interglacial (MIS 5), between approximately 130 and 115 kyr BP. A novel approach is proposed, taking into account centennial-scale geochemical data on major elements, selected trace elements, and yttrium and R…
Le Quaternaire franc-comtois. Essai chronologique et paléoclimatique.
1982
Le but de ce travail est d'établir le cadre chronologique et paléoclimatique du Quaternaire en Franche-Comté à partir de l'étude des formations édifiées au cours de cette période.Deux grands types de dépôts ont été plus particulièrement étudiés: ·- Les remplissages karstiques d'avens, de porches de grottes et d'abris sous roche, donnant un éclairage intense, mais ponctuel, de l'environnement physique et biologique, grâce aux faunes abondantes et aux indices climatiques d'ordre sédimentologique.- Les dépôts glaciaires et paraglaciaires (moraines, fluvioglaciaires, glacio-lacustres) qui permettent de situer des coupures climatiques au cours du temps dans l'espace géographique étudié.L'étude d…
A complex thrust sequence in western Himalaya: the active Medlicott Wadia Thrust.
2017
15 pages; International audience; The recent activity of the Medlicott-Wadia Thrust (MWT) is investigated by geomorphic and tectonic studies in the Riasi zone, south of the Pir Panjal range (India, Jammu-Kasmir state of western Himalaya). In the Riasi area, the MWT forms a splay of five faults that dip northward. The recent activity of the splay is quantified using a set of deformed Quaternary alluvial units. The central branch of the thrust splay moved Precambrian limestones above Quaternary sediments and is sealed by 36 ± 3 ka (youngest OSL age) deposits. The other branches offset the top of a 15 ± 1 ka (youngest OSL age) alluvial fan by 180 to 120 m; the two southernmost branches form 17…
Phylogeographical footprints of the Strait of Gibraltar and Quaternary climatic fluctuations in the western Mediterranean: a case study with the grea…
2005
Correspondance: cosson@supagro.inra.fr; International audience; We used mitochondrial cyt b sequences to investigate the phylogenetic relationships of Crocidura russula (sensu lato) populations across the Strait of Gibraltar, western Europe, Maghreb, and the Mediterranean and Atlantic islands. This revealed very low genetic divergence between European and Moroccan populations. The application of a molecular clock previously calibrated for shrews suggested that the separation of European from Moroccan lineages occurred less than 60 000 bp, which is at least 5 million years (Myr) after the reopening of the Strait of Gibraltar. This means that an overwater dispersal event was responsible for t…
Transmission Electron Microscopy of GroEL, GroES, and the Symmetrical GroEL/ES Complex
1994
Two new 2-D crystal forms of the Escherichia coli chaperone GroEL (cpn60) 2 x 7-mer have been produced using the negative staining-carbon film (NS-CF) technique. These 2-D crystals, which contain the cylindrical GroEL in side-on and end-on orientations, both possess p21 symmetry, with two molecules in the respective unit cells. The crystallographically averaged images correlate well with those obtained by other authors from single particle analysis of GroEL and our own previous crystallographic analysis. 2-D crystallization of the smaller chaperone GroES (cpn10) 7-mer has also been achieved using the NS-CF technique. Crystallographically averaged images of GroES single particle images indic…
Palaeoclimatic applications of large databases: developing and testing methods of palaeotemperature reconstruction using nonmarine ostracods
2008
Non-analogue methods for Quaternary palaeoclimatic reconstruction, such as the coleopteran Mutual Climate Range method and the Mutual Ostracod Temperature Range (MOTR) method, use large geographical databases combined with modern climate datasets to establish the modern climate/temperature ranges of species, which can then be applied to the interpretation of fossil assemblages. Such approaches have been criticized for their lack of attention to variation in the distributions of species within their climate ranges. The MOTR method, for example, assumes that a species has an equal probability of occurring anywhere within its temperature range (e.g. mean July air temperature range), but tests …
Climate change at the 4.2 ka BP termination of the Indus valley civilization and Holocene south Asian monsoon variability
2003
[1] Planktonic oxygen isotope ratios off the Indus delta reveal climate changes with a multi-centennial pacing during the last 6 ka, with the most prominent change recorded at 4.2 ka BP. Opposing isotopic trends across the northern Arabian Sea surface at that time indicate a reduction in Indus river discharge and suggest that later cycles also reflect variations in total annual rainfall over south Asia. The 4.2 ka event is coherent with the termination of urban Harappan civilization in the Indus valley. Thus, drought may have initiated southeastward habitat tracking within the Harappan cultural domain. The late Holocene drought cycles following the 4.2 ka BP event vary between 200 and 800 y…
The Jaguar - Panthera onca gombaszoegensis (Kretzoi, 1938) (Carnivora: Felidae) in the late lower pleistocene of Akhalkalaki (south Georgia; Transcau…
2001
Abstract A lower hemimandibula of a pantherine cat of Akhalkalaki (south Georgia, Transcaucasia) is re-examinated. The fossil originates from lacustrine sediments of late Lower Pleistocene age (0.9 − 0.8 Ma B.P.) above the Jaramillo polarity subzone. A tooth-by-tooth analysis comparing the fossil with Lower and Middle Pleistocene lions, tigers and jaguars and Holocene southwest Asian lions assigns it to the Eurasian jaguar, Panthera onca gombaszoegensis. Palaeoenvironmental reconstruction indicates a dry, warm meadow-steppe influenced by montane condition, with permanent water bodies present. This is consistent with the strong open-water affinities of the modern jaguar. The morphological pr…
Une faune très diversifiée du Pléistocène inférieur de la Sierra de Quibas (province de Murcia, Espagne)
2001
The Quaternary karstic site of Sierra de Quibas (Abanilla, province of Murcia, Spain) has provided a wide faunal list with more than 60 species. The assemblage of the taxa Arvicola deucalion, Castillomys rivas rivas, Eliomys intermedius, Equus altidens, Capra sp. aff. C. alba and cf. Praeovibos allows the correlation with other Spanish Lower Pleistocene sites in the Betic Cordillera, as Plines 1, Orce 3 and Venta Micena. Therefore Quibas can be located between 1.3 and 1.0 Ma. The palaeoenvironmental features of the area around the karstic cavity and the palaeoclimatic regime are inferred.
Late Quaternary high uplift rates in northeastern Sicily: evidence from calcareous nannofossils and benthic and planktonic foraminifera
2011
The northeastern part of Sicily is characterized by intense seismic activity. Several systems of faults have been recognized in Pliocene and Pleistocene sediments in the area and, in fact, estimates of uplift rates are among the highest recorded in Sicily and south Italy. We examined calcareous nannofossil and benthic and planktonic foraminifera assemblages from pelitic sediments of the Contrada Zura section (Barcellona Pozzo di Gotto Basin, Furnari village, Messina). The occurrence of Emiliania huxleyi, a coccolithophore species which appeared in the oceanic record about 270,000 years ago, is witness to the uniqueness of this outcrop, while the planktonic/benthic foraminifera ratio indicat…