Search results for "STRATIGRAPHY"
showing 10 items of 904 documents
Chlorinated and methylated dibenzothiophenes in sediment samples from a river contaminated by organochlorine wastes
2001
Eleven sediment samples from the lower Kymijoki River were analyzed for the occurrence of polychlorinated and polymethylated dibenzothiophenes (PCDT and PMeDTs). The area was heavily polluted by wastes from a pulp chlorobleachery and by leakage from a factory producing wood preservative chlorophenol formulation Ky-5. Levels in the sediments were from <5 to 400, 200 and 50 pg g-1 dw for tetra, penta and hexa-CDT, respectively. The concentrations of mono, di, tri and tetra-MeDTs were in the range of 1–5, 5–85, 5–500 and 15–2300 ng g-1 dw, respectively. PCDT contents in surface sediment (0–3 cm layers) decreased by distance downstream from the bleachery and Ky-5 factory similar to those of the…
Paleoenvironmental evolution of the Pliocene Villarroya Lake, northern Spain. A multidisciplinary approach
2002
The Pliocene Villarroya basin fill consists of lacustrine and alluvial deposits over 100 m thick. The lacustrine deposits, up to 30 m thick, comprise three sequences. The two lower sequences consist of profundal, laminated deposits formed by mostly terrigenous facies that are overlain by charophytic carbonates and varves. The uppermost, third sequence made up of massive bioturbated mudstones corresponds to a very shallow lacustrine-palustrine environment. Bulk mineralogy comprises carbonates, clay minerals, quartz and feldspars. The carbonates are: exogenic, biogenic calcite and biogenic aragonite. Biogenic calcite constitutes ostracod shells and charophyte stem encrustations, whereas arago…
The impact of the Little ice age on coccolithophores in the central Mediterranea Sea
2010
The Little Ice Age (LIA) is the last episode of a series of Holocene climatic anomalies. There is still little knowledge on the response of the marine environment to the pronounced cooling of the LIA and to the transition towards the 20th century global warming. Here we present decadal-scale coccolithophore data from four short cores recovered from the central Mediterranean Sea (northern Sicily Channel and Tyrrhenian Sea), which on the basis of <sup>210</sup>Pb activity span the last 200–350 years. The lowermost part of the record of one of the cores from the Sicily Channel, Station 407, which extends down to 1650 AD, is characterized by drastic changes in productivity. Specific…
Morphometric Discriminant Analysis of isolated chondrichthyan scales for palaeoecological inferences: the Middle Triassic of the Iberian Chain (Spain…
2014
[EN] Palaeontological studies on exosqueletal disarticulated remains of chondrichthyans have focused on teeth and only less interest has been paid to scales due their limited taxonomic and systematic significance. However, classical works linking the morphology and the function of the squamation in extant sharks suggest that, despite their limited taxonomic value, the study of isolated scales can be a useful tool for palaeoenvironmental and palaeoecological inferences. Following this idea, we have analyzed the fossil record of shark scales from two Middle Triassic sections of the Iberian Chain (Spain), identifying different functional types by means of a morphometric discriminant analysis. …
Notostraca trackways in Permian playa environments of the Lodève basin (France).
2008
36 pages; International audience; For nearly 20 years, Dr. Lapeyrie, surgeon at Lodève, has gathered many fossils coming from the Salagou Formation of the Lodève Permian basin. They are Insects, Notostraca, plants and ichnofossils. Among the latter, appears a multitude of Arthropoda trackways, finely preserved, which were collected in the top of sequences deposited in a playa environment. The locomotion experiments undertaken with extant animals suggested allocation of the majority of these trackways to Notostraca which are also known by several hundreds of remains (carapace, appendages, body whole). From these different parts, it was described as Triops cancriformis permiensis and Lepiduru…
Rodents and insectivores from the Lower Miocene (Agenian and Ramblian) of the Tudela Formation (Ebro Basin, Spain)
2012
The rodent and insectivore faunas of Agenian and Ramblian age from the Tudela Formation (Ebro Basin, Spain) are described. Four of the localities (CH1, CA1, CC1 and CA2) contain rodent remains of Agenian age (local zone Y), and three (CA3, CA3B and CA4) of Ramblian age (local zones Z and A). Typical Agenian taxa include Armantomys cf. bijmai (CH1), Eucricetodon cf. gerandianus (CA1), Peridyromys turbatus, Simplomys aff. aljaphi and Armantomys daamsi (CA2) and Eucricetodon aff. aquitanicus (CC1). On the other hand, some typical Ramblian taxa are Armantomys cf. parsani (CA3), Ligerimys aff. magnus and Pseudotheridomys sp. (CA4) and Prodryomys cf. brailloni (CA3B). The faunas are characterized…
Astronomical calibration of the Valanginian and the Hauterivian stages (lower cretaceous) : paleoclimatic and paleooceanographic implications
2013
Orbital floating time scales are proposed for the Valanginian Stage and part of the Hauterivian Stage (Early Cretaceous). These are based on the identification of the eccentricity cycles from spectral analyses performed on high-resolution climatic proxies measured on hemipelagic marl-limestone alternations. Five reference sections were analysed in the Vocontian Basin (SE France), spanning the entire Valanginian. A duration of 5,08 myr is proposed for the Valanginian Stage from the identification of the 405-kyr eccentricity cycle. The time frame proposed, combined with available radiometric ages, shows that the mid-Valanginian 13C positive excursion (namely the Weissert Event) occurs prior …
Short communication: Driftwood provides reliable chronological markers in Arctic coastal deposits
2021
Originating from the boreal forest and often transported over large distances, driftwood characterizes many Arctic coastlines. Here we present a combined assessment of radiocarbon (14C) and dendrochronological (ring width) age estimates of driftwood samples to constrain the progradation of two Holocene beach-ridge systems near the Lena Delta in the Siberian Arctic (Laptev Sea). Our data show that the 14C ages obtained on syndepositional driftwood from beach deposits yield surprisingly coherent chronologies for the coastal evolution of the field sites. The dendrochronological analysis of wood from modern drift lines revealed the origin and recent delivery of the wood from the Lena River catc…
Decadal time scale variability recorded in the Quelccaya summit ice core δ 18 O isotopic ratio series and its relation with the sea surface temperatu…
1998
The spectral characteristics of the delta /sup 18/O isotopic ratio time series of the Quelccaya ice cap summit core are investigated with the multi taper method (MTM), the singular spectrum analysis (SSA) and the wavelet transform (WT) techniques for the 500 y long 1485-1984 period. The most significant (at the 99.8% level) cycle according to the MTM F-test has a period centered at 14.4 y while the largest variance explaining oscillation according to the SSA technique has a period centered at 12.9 y. The stability over time of these periods is investigated by performing evolutive MTM and SSA on the 500 y long delta /sup 18/O series with a 100 y wide moving window. It is shown that the cycle…
Sedimentology and sequence stratigraphy of wedge-top clastic successions: Insights and open questions from the upper Tortonian Terravecchia Formation…
2013
Abstract An up to 1250 m-thick clastic succession, the upper Tortonian Terravecchia Formation (TRV), has been analysed in detail in the middle–late Miocene Scillato wedge-top Basin grown above an already deformed tectonic stack in the northern Sicilian fold-and-thrust belt. The study involved field-based sedimentological and stratigraphic analyses aimed to determine to what extent both the depositional and sequence stratigraphic evolution of the Scillato Basin have been ruled by syn-sedimentary compressional to transpressional tectonics. Widespread intraformational angular unconformities associated with sudden change of palaeocurrents pattern and successive source area shifting suggest that…