Search results for "Sedimentary"
showing 10 items of 455 documents
Palynofacies and calcareous nannofossils in the Upper Kimmeridgian, southeastern Paris basin (France)
2005
AbstractThe Upper Kimmeridgian Members “Calcaires blancs supérieurs” and the “Marnes à exogyres supérieures” of the southeastern Paris basin were investigated for their palynofacies and calcareous nannofossils. These members display alternating limestone-marl lithotypes and represent shallow marine palaeoenvironments. The lower carbonate member is interpreted as a proximal palaeoenvironment (palaeobathymetry = 5 to 10 m), where storm and swell deposits were prevalent and the salinity was occasionally weak. The relative richness of brown phytoclasts in this part is favoured by good preservation related to restricted conditions. These conditions would explain the dominance of the nannofoss…
Rereading a tree-ring database to illustrate depositional histories of subfossil trees
2017
Late Quaternary tree-ring chronologies have been constructed using data collected from subfossil trees preserved under favourable conditions in lake sediments and peat deposits. Tree-ring widths and densities are commonly used for reconstructions of past climate variability. An alternative way of using these data is to explore the replication curves of these chronologies. Here, we make use of previously collected data that is currently available from tree-ring databases to demonstrate the depositional histories of pine trees once accumulated into the sediment in lake (i.e., riparian trees) and peatland sites. Divergent courses of depositional histories were obtained for different sedimentar…
Tectonic evolution of the northern Austral-Magallanes basin in the Southern Patagonian Andes from provenance analysis
2019
We studied the northern tip of the Austral-Magallanes basin in the Southern Patagonian Andes, between the Buenos Aires Lake and the Mayer River at 46°35′ SL and 48°35′ SL, respectively. Proposed objectives were: i) to differentiate Mesozoic-Cenozoic tectonostratigraphic units and, ii) to characterize the different deformational events that took place in the area linked to a variable regional geodynamic context. Sandstones provenance analysis was performed on the Aptian - Albian compressive retroarc deposits and Cenozoic foreland deposits. Studied samples were classified using tectonic discrimination diagrams which show: i) for Cretaceous rocks a dominant sediment source from a recycled orog…
Detrital-zircon geochronology and provenance of the El Oro Metamorphic Complex, Ecuador: Geodynamic implications for the evolution of the western Gon…
2019
Abstract The El Oro Metamorphic Complex (EOMC) in SW Ecuador has been the subject of debate for several decades. While previous studies have focused on the metamorphic and deformation history of the complex to determine its geodynamic evolution, the pre-metamorphic history and its association to units in the north-central Andes remains poorly understood. Here we present a U-Pb detrital zircon provenance study to provide insights into the depositional history and the geodynamic setting of the EOMC. Our results imply that the southern portion of the EOMC (the Tahuin division) is composed of an older Palaeozoic (pre-Famatinian) sequence in the south (El Tigre unit; c. 525-510 Ma), and younger …
Depositional environments and iron ooid formation in condensed sections (Callovian Oxfordian, South-eastern part of the Paris basin, France)
2005
Carbonate platforms across Western Europe were superseded at the Middle–Upper Jurassic (Callovian–Oxfordian) boundary either by alternating marl–limestone and widespread marl deposits or by condensed sections containing iron ooids. The characteristics of marine condensed sections in the south-eastern part of the Paris Basin (France) and their distribution pattern are examined here, and a model of iron ooid formation is developed. Iron ooids are found from the shoreface to the offshore zone. They are most abundant in the median-to-distal offshore transition zone, where they originally formed. They also occur commonly, albeit often as reworked grains, in the proximal offshore zone, to which t…
Intact seismic-scale platforms and ramps in the Lower to Middle Jurassic of Morocco: implications for stratal anatomy and lithofacies partitioning.
2017
9 pages; International audience; The Jurassic carbonate platforms of the central High Atlas in Morocco are well known for several high-quality outcrops. In the central High Atlas, there are two complementary locations that offer critical lessons for our understanding of Jurassic carbonate system evolution in extensional basins: a Lower Jurassic high-relief, carbonate platform with steep slopes that developed on the footwall of a rotating fault block in an active half-graben (Djebel Bou Dahar [DBD]) and an upper Lower to Middle Jurassic low-angle prograding carbonate ramp rich in ooids (Amellago ramp [AR]). The DBD and AR outcrops provide superbly exposed, structurally intact, and fully acce…
Basin analysis in the Southern Tethyan margin: Facies sequences, stratal pattern and subsidence history highlight extension-to-inversion processes in…
2018
Abstract In the Mediterranean, the South-Tethys paleomargin experienced polyphased tectonic episodes and paleoenvironmental perturbations during Mesozoic time. The Cretaceous shallow-water carbonate successions of the Panormide platform, outcropping in the northern edge of the Palermo Mountains (NW Sicily), were studied by integrating facies and stratal pattern with backstripping analysis to recognize the tectonics vs. carbonate sedimentation interaction. The features of the Requienid limestone, including geometric configuration, facies sequence, lithological changes and significance of the top-unconformity, highlight that at the end of the Lower Cretaceous the carbonate platform was tecton…
Quaternary marine and continental unconformity-bounded stratigraphic units of the NW Sicily coastal belt
2017
In the coastal sector of NW Sicily, the regional correlation of relevant unconformities recognised within the Quaternary sedimentary successions allowed the mapping of seven unconformity-bounded stratigraphic units (UBSUs). The regional unconformities are marine or subaerial erosional surfaces, as well as non-depositional surfaces, locally marked by paleosoils. The erosional surfaces were produced from marine abrasion, surface water overland/concentrated flow, river erosion, karst solution, mass movement, or wind erosion. The main lithofacies of the Quaternary UBSUs consist of: (a) marine and coastal bioclastic calcarenites, (b) aeolian sandstones, (c) river deposits, (d) colluvial deposits…
Palaeoenvironmental interpretation of the Pliocene fan-delta system of the Vera Basin (SE Spain): Fossil assemblages, ichnology and taphonomy
2020
Abstract The marine fossil assemblages of the Pliocene of south Spain constitute the record of the marine fauna that colonised the western part of the Mediterranean after the Messinian Salinity Crisis. This work focuses on the analysis of lithofacies and fossil assemblages including trace fossils, invertebrates, and vertebrates with special attention to taphonomic features, for interpreting palaeoenvironmental conditions in the Vera Basin (SE Spain). The sedimentary sequences of the northern region of the Vera Basin display diverse stratigraphical, sedimentological, and palaeontological features that correspond to the evolution of a fan-delta in a narrow basin. The Vera Basin was characteri…
Modern sedimentary analogues and integrated monitoring to understand varve formation in the Mediterranean Lake Montcortès (Central Pyrenees, Spain)
2018
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