Quick description of the main features of the geological formations or sedimentary deposits examined here with the key references for further information.
Description rapide des principales caractéristiques des formations géologiques ou des dépôts sédimentaires examinés ici avec les principales références pour plus d’informations.
|The Cariaco Basin, offshore Venezuela
|This small-dimensioned basin yields several specific conditions: high, upwelling-stimulated, surface productivity, and restricted bottom waters prone to recurrent development of euxinic conditions. The organic-rich sediments of Pleistocene-Holocene age are also rich in diatoms and shows annual-type laminations.
|Bout-Roumazeilles et al., 2013; Riboulleau et al., 2014
|The Jurassic formations of the Boulonnais area (northern France)
|Proximal lateral equivalent of the Kimmeridge Clay Fm., cropping alongshore the French coast of the English Channel. These sediments accumulated on a siliciclastic ramp subject to dominantly aerobic conditions with some episodes of dissolved oxygen restriction. The Kimmeridgian/Tithonian Argiles de Châtillon Fm. is made up with dark marls, mudstones and shales with marine-origin organic-matter. The Tithonian Bancs Jumeaux Fm. consists of dark marls, mudstones and siltstones with moderate marine-organic matter content. The paleoenvironments have been determined as suboxic. The Tithonian Argiles de Wimereux Fm. consists of dark marls, mudstones and siltstones with moderate to low organic-matter content. The paleoenvironments have been determined as normally oxygenated to suboxic. Cold seepage episodes were well recorded in the Bancs Jumeaux Fm.
|Proust et al., 1995; Deconinck et al., 1996; Hatem et al., 2014, 2016; Tribovillard et al., 2015
|The Vaca Muerta Formation, one of the most prolific source-rocks of the Neuquén Basin (Argentina)
|This lithostratigraphic unit consists of dark shales, marls and limestones deposited during the Tithonian-Valanginian interval, as the result of a rapid and widespread marine transgression. In the southern part of the basin (Picún Leufú Anticline), the Vaca Muerta Fm. is interpreted as a prograding siliciclastic shelf with storm and turbidity flows, and with an episodic, moderate, limitation of marine circulation, at least during the beginning of the deposition. The Vaca Muerta Fm. did not record oxygen-limited conditions, contrary to the rest of the basin, except for the very base of the formation. In addition, the organic content of the rocks is rather poor.
|Krim et al., 2017, 2019
|The “pseudo-biohermes” of Beauvoisin (S-E France)
|The carbonate biohermes of Beauvoisin, in the Baronnies Mounts (Provence) developed at cold seep sites debouching at the basin bottom during the deposition of the Terres Noires Fm. Thick accumulation (2000 m) of monotonous, dark-colored, hemipelagic marls took place during the Bathonian to Oxfordian. The bioherms, rich in lucinids, developed on synsedimentary faults.
|Gaillard et al., 1985, 1992; Tribovillard et al., 2013; Gay et al., 2019
|The Frasnian-Famennian boundary (late Devonian)
|Formations encompassing the Frasnian–Famennian boundary (a major period of biodiversity crisis and environmental modifications). The formations were studied in France (La Serre and Coumiac sections, Montagne Noire), Morocco and Germany. The Upper Frasnian interval is commonly associated with the deposition of one or two organic-rich units, the so-called Kellwasser (KW) horizons, deposited in outer shelf and epicontinental basin settings. Several factors controlling the KW organic-rich sediment accumulation have been proposed, and among them, enhanced productivity coupled to bottom-water oxygen-depletion. These factors have been connected to different driving mechanisms acting separately or combined, such as sea-level fluctuations, climatic variations, land plants spreading, volcanism or mountain building.
|Feist, 1985; Tribovillard et al., 2004; Averbuch et al., 2005; Riquier et al., 2005, 2006, 2007, 2010
|The Gulf of Mexico
|Sediments collected in the La Salle, Orca and Pigmy sub-basinson the northern border of the Gulf of Mexico (Louisiana continental slope). These sub-basins record both the terrigenous input from the North American continent and the tropical oceanic influences via the Loop Current. The sediments are dated of the Pleistocene and Holocene. The Orca Basin is an intra-slope depression that collects sedimentary particles of terrestrial origin (clastic and organic particles mainly supplied by the Mississippi River) and of marine origin (biogenic productivity). The basin is partly filled with dense brines leached from salt diapirs cropping out on the sea floor, and is permanently stratified. A strong pycnocline induces anoxic bottom conditions. The La Salle and Pigmy basins collect the same types of sedimentary particles but they are not stratified, and are thus not exposed to anoxic bottom conditions.
|Tribovillard et al., 2008; Montero-Serrano et al., 2009, 2010, 2011
|The Weddell Sea (ODP leg 113; 70°43.432’S, 13°49.195’W)
|ODP Hole 692B was drilled in the eastern Weddell Sea on the shelf of the Dronning Maud Land. The site is located on the flank of a submarine canyon (Wegener Canyon), by 2875 m of water. Early Cretaceous black shales were cored and are described as Unit III, consisting of black to very dark grey claystone/mudstone, with varying percentages of clay, carbonate, and organic matter. Parallel lamination is the dominant sedimentary structure; bioturbation is occasionally observed. The sediments are interpreted to have accumulated in an outer shelf/upper slope environment.
|Barker et al., 1988
|Adélie Land region of East Antarctica
|Piston core MD03-2603 was recovered at 3320 m depth, on the distal part of a mound located between the Cuvier and “D” canyons (Lat. 64°17.12 S, Long. 139°22.51 E), during the CADO cruise (Coring Adélie Diatom Oozes, MD130 Images X) on board R/V Marion DuFresne II. The sediment is composed of diatom ooze alternating with structureless greenish ooze and millimeter to centimeter thick green-to-dark seasonal laminations. Sediment lithology is very fine from clay to silt fraction.
|Denis et al., 2009; Presti et al., 2011
|La Charce Section
|The La Charce Section (Vocontian Basin, SE France) shows typical pelagic alternations of burrowed, beige to light-grey limestone beds and medium-grey marls, deposited during the Hauterivian times, under the influence of Milankovitch-type climate variations. Benthic conditions were oxic to suboxic.
|Baudin et al., 1999; Van de Schootbrugge et al., 2000, 2003
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