Search results for "sedimentology"

The end of the Messinian salinity crisis: Evidences from the Chelif Basin (Algeria).

2007

How did the Messinian Salinity Crisis end is a matter of intense debate between two opposite concepts i.e., the generalised dilution event, the so-called Lago–Mare, followed by the sudden restoration of the marine conditions at the base of the Zanclean, or the early partial or complete marine refill that would have happened earlier during the upper Messinian. The Chelif Basin of Northwestern Algeria, one of the greatest Messinian marginal basins of the Mediterranean, provides an exceptional opportunity to study in detail how this major paleoenvironmental change occurred through continuous sedimentary records of the Miocene–Pliocene boundary. Five sections representative of both the central …

Pan African plate tectonics and its repercussions on the crust of northeast Africa

1979

Pan African belts of the African mainland and the Arabian-Nubian Shield exhibit evolutionary features which are either compatible with intracontinental ensialic development or with plate margin and Wilson cycle tectonics during the time period ∼ 1100–500 Ma ago.

STOP 13: Inland dune field near Daugavpils, East-Latvian Lowland

2014

CO2 and H2S concentrations in the atmosphere at the Solfatara of Pozzuoli

1984

The CO2 and H2S concentration in the Solfatara atmosphere has been measured. The concentrations of both gases are higher neraby the more active areas and decrease away from them. A sharp horizontal and vertical gradient of the CO2 content has been recognized.

Soil sedimentology at Gusev Crater from Columbia Memorial Station to Winter Haven

2008

[1] A total of 3140 individual particles were examined in 31 soils along Spirit's traverse. Their size, shape, and texture were quantified and classified. They represent a unique record of 3 years of sedimentologic exploration from landing to sol 1085 covering the Plains Unit to Winter Haven where Spirit spent the Martian winter of 2006. Samples in the Plains Unit and Columbia Hills appear as reflecting contrasting textural domains. One is heterogeneous, with a continuum of angular-to-round particles of fine sand to pebble sizes that are generally dust covered and locally cemented in place. The second shows the effect of a dominant and ongoing dynamic aeolian process that redistributes a un…

The Messinian stromatolites of the Sierra del Colmenar (Western Mediterranean): facies characterization and sedimentological interpretation

2018

A representative outcrop of the Messinian stromatolites belonging to the Terminal Carbonate Complex unit, from the northern sector of the Bajo Segura basin (Caja de Ahorros del Mediterraneo section, Sierra del Colmenar, SE Spain) has been studied. Here, we present a detailed analysis of the architecture, external morphology, and internal morphology in order to reconstruct the environmental and palaeoecological conditions for their growth. The stromatolites macrostructure consists of a continuously doming type morphology (build up and sheets areas).These developed close to the coast and acted as a palaeogeographic barrier, reducing physical stress, channeling the erosive effect of water and …

Mesozoic volcanics of western sicily

1984

The Mesozoic lavas and minor intrusions in the thrust sheets of western Sicily have the following characteristics: 1. The lavas in the Triassic Mufara Formation in the north were broken into fragments which rotated independently within the incompetent strata that enclose them. This behavior is characteristic of igneous rocks found within the more internal (northerly) thrust units. 2. The Jurassic lavas in the more external (southerly) units have consistent directions which agree with those of the Ammonitico Rosso limestones in the same zone and lie about 30° clockwise from those of coeval autochthonous formations in Tunisia.Schult's presumed Cretaceous directions from Custonaci on the north…

The sedimentary series of upper Bajocian-lower Bathonian age and their organization in the Burgundy threshold and its surroundings. Stratigraphy, sed…

1981

Three fundamental features concerning the organization of the bio-sedimentary series of the upper Bajocian-lower Bathonian of the Burgundy threshold environment are retained:- the formations are organized in a bio-sedimentary platform, composed of three sets: a deep SW platform with clay sedimentation, a superficial NE platform, a transition zone- the geochemical characteristics are consistent with the reconstitution of the NE-NW polarized platform- this device has changed over time: a migration and extension of the surface platform to the SW, development of the transition zone, a slight displacement of the deep platform correlated with a more and more opening towards the SW.

Sedimentology and isotope geochemistry of Carnian deep-water marl/limestone deposits from the Sicani Mountains, Sicily: Environmental implications an…

1995

Abstract The upper Triassic Halobia-bearing marl/limestone deposits from the Sicani Mountains (Sicily) record the sedimentary evolution of the Sicanian Basin through the middle and late Carnian time. Dark marls and interbedded grey calcilutites of Julian age are characterized by abundant pyrite, sparse bioturbation and negative carbonate carbon δ13C values. They accumulated in a basin with dominantly anoxic to dysaerobic bottom waters. Lower Tuvalian dark-grey pyritic marls and calcilutites, which contain carbonate minerals with relatively high Mn contents and widely fluctuating δ13C signatures, were deposited under dysaerobic conditions. Middle and upper Tuvalian cherty limestones show int…

Characterization and origin of permeability-porosity heterogeneity in shallow-marine carbonates: from core scale to 3D reservoir dimension (Middle Ju…

2014

21 pages; International audience; Nuclear magnetic resonance (NMR), stable isotope geochemistry of micro-sampled cores, NMR well-logs and 3D modeling are used to investigate the carbonate permeability-porosity heterogeneity along 230 m-thick limestones of the Paris Basin. Despite the global low porosity and permeability of the limestones, two aquifers units with porosity greater than 15% were identified. These two aquifers are very different in terms of pore through radii and NMR signal. The first one (A1: Aquifer 1) is a 7 m-thick mudstone unit, dominated by extended microporosity with pore throat radii of 0.25 μm to 0.3 μm. The second one (A2: Aquifer 2) is a 15 m-thick oolitic grainstone…