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A. Foubert D. Van Rooij D. Blamart J.-P. Henriet 《International Journal of Earth Sciences》2007,96(1):141-158
Three provinces, characterized by the presence of carbonate mounds interpreted as cold-water coral banks have been reported
in Porcupine Seabight, SW of Ireland and were recently subjected to many detailed studies. This contribution discusses the
use of X-ray imagery and physical properties in deciphering palaeoceanographic, sedimentological and biological processes.
Physical property core logging and X-ray imagery are used to identify and describe sedimentation regimes and so their respective
palaeoceanographic and palaeoclimatological settings in two mound provinces, respectively the Belgica mound province and the
Magellan mound province. Both provinces show at present time clear differences in the hydrodynamic environment. This study
confirms that also during the past the oceanographic and sedimentological environment of both provinces differ clearly. Impacts
of glacial–interglacial variations and locally derived ice rafting events (IRE), comparable with the North Atlantic Heinrich
events (HE) have been recognized in both provinces. Moreover, the combination of X-ray imagery, magnetic susceptibility, gamma
density and P-wave velocity makes it possible to estimate the coral content and coral distribution in unopened cores localized
on top of carbonate mounds. A comparison between on-mound and off-mound cores in both provinces allowed revealing some mechanisms
of mound evolution and coral growth versus time. 相似文献
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L. Maignien D. Depreiter A. Foubert J. Reveillaud L. De Mol P. Boeckx D. Blamart J.-P. Henriet N. Boon 《International Journal of Earth Sciences》2011,100(6):1413-1422
The Gulf of Cadiz is an area of mud volcanism and gas venting through the seafloor. In addition, several cold-water coral
carbonate mounds have been discovered at the Pen Duick escarpment amidst the El Arraiche mud volcano field on the Moroccan
margin. One of these mounds -named Alpha mound- has been studied to examine the impact of the presence of methane on pore-water
geochemistry, potential sulphate reduction (SR) rate and dissolved inorganic carbon (DIC) budget of the mound in comparison
with off-mound and off-escarpment locations. Pore-water profiles of sulphate, sulphide, methane, and DIC from the on-mound
location showed the presence of a sulphate to methane transition zone at 350 cm below the sea floor. This was well correlated
with an increase in SR activity. 13C-depleted DIC at the transition zone (−21.9‰ vs. Vienna Pee Dee Belemnite) indicated that microbial methane oxidation significantly
contribute to the DIC budget of the mound. The Alpha mound thus represents a new carbonate mound type where the presence and
anaerobic oxidation of methane has an important imprint on both geochemistry and DIC isotopic signature and budget of this
carbonate mound. 相似文献
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Robin Fentimen Andres Rüggeberg Aaron Lim Akram El Kateb Anneleen Foubert Andrew J. Wheeler Silvia Spezzaferri 《Swiss Journal of Geoscience》2018,111(3):561-572
Cold-water coral ecosystems represent unique and exceptionally diverse environments in the deep-sea. They are well developed along the Irish margin, varying broadly in shape and size. The Moira Mounds, numerous small-sized mounds, are nestled in the Belgica Mound Province (Porcupine Seabight, North-East Atlantic). The investigation of living (Rose Bengal stained) and dead benthic foraminiferal assemblages from these mounds allowed to describe their distribution patterns and to evaluate their response to environmental variability. Quantitative data was statistically treated to define groups of species/genera associated to specific habitats. The Moira Mounds differ from their larger neighbours by the reduced spatial variability of benthic foraminiferal assemblages, living assemblages only distinguishing coral-rich and coral-barren areas. The ecological needs of corals are highlighted by the abundance of Alabaminella weddellensis and Nonionella iridea, phytodetritus-feeding species in coral supporting sediments. Living foraminifera in sediments from the Moira Mounds concentrate in the upper first centimetre. Infaunal species may be affected by bioturbation and/or reworking by the strong currents in the area. Dead foraminiferal assemblages from the Moira Mounds resemble those described for the sandwave facies in adjacent giant mounds, suggesting similar processes in facies deposition. 相似文献
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Haili Long Rudy Swennen Anneleen Foubert Manuel Dierick Patric Jacobs 《Sedimentary Geology》2009,220(1-2):116-125
Microfocus X-ray computed tomography (µCT) measurements were performed on deltaic sandstone samples from the diagenetically altered Westphalian C strata (Campine basin, north-east Belgium) in order to collect three dimensional data on mineral (quartz, kaolinite, ankerite, etc.) and porosity distribution. The acquired µCT data were compared with point counting results of stained impregnated thin-sections to qualify the sensitivity of µCT. Comparison between techniques shows positive results with regard to the quantification of main mineral phases such as quartz and ankerite, and porosity distribution. However, major discrepancies exist when studying the clay minerals. This can be explained by the influence of microporosity associated with these clay minerals, resulting in partial volume effects. 相似文献
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Giovanni Coletti Stephanie Stainbank Alessio Fabbrini Silvia Spezzaferri Anneleen Foubert Dick Kroon Christian Betzler 《Swiss Journal of Geoscience》2018,111(3):523-536
Large benthic foraminifera are important components of tropical shallow water carbonates. Their structure, developed to host algal symbionts, can be extremely elaborate and presents stratigraphically-significant evolutionary patterns. Therefore their distribution is important in biostratigraphy, especially in the Indo-Pacific area. To provide a reliable age model for two intervals of IODP Hole U1468A from the Maldives Inner-Sea, large benthic foraminifera have been studied with computed tomography. This technique provided 3D models ideal for biometric-based identifications, allowing the upper interval to be placed in the late middle-Miocene and the lower interval in the late Oligocene. 相似文献
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David Jaramillo‐Vogel Anneleen Foubert Juan Carlos Braga Jean‐Charles Schaegis Balemwal Atnafu Bernard Grobety Tesfaye Kidane 《Sedimentology》2019,66(2):480-512
Pleistocene fibrous aragonite fabrics, including crusts and spherules, occur in the Danakil Depression (Afar, Ethiopia) following the deposition of two distinctive Middle and Late Pleistocene coralgal reef units and pre‐dating the precipitation of evaporites. Crusts on top of the oldest reef unit (Marine Isotope Stage 7) cover and fill cavities within a red algal framework. The younger aragonite crusts directly cover coralgal bioherms (Marine Isotope Stage 5) and associated deposits. Their stratigraphic position between marine and evaporitic deposits, and their association to euryhaline molluscs, suggest that the crusts and spherules formed in restricted semi‐enclosed conditions. The availability of hard substrate controls crust formation with crusts more often found on steep palaeo‐slopes, from sea level up to at least 80 m depth, while spherules mainly occur associated with mobile substrate. Crusts reach up to 30 cm in thickness and can be microdigitate, columnar (branching and non‐branching) or non‐columnar, with laminated and non‐laminated fabrics. Two different lamination types are found within the crystalline fabrics: (i) isopachous lamination; and (ii) irregular lamination. These two types of lamination can be distinguished by the organization of the aragonite fibres, as well as the lateral continuity of the laminae. Scanning electron microscopy with energy dispersive X‐ray spectroscopy analyses on well‐preserved samples revealed the presence of Mg‐silicate laminae intercalated with fibrous aragonite, as well as Mg‐silicate aggregates closely associated with the fibrous aragonite crusts and spherules. The variety of observed fabrics results from a continuum of abiotic and microbial processes and, thus, reflects the tight interaction between microbially mediated and abiotic mineralization mechanisms. These are the youngest known isopachously laminated, digitate and columnar branching fibrous crusts associated with a transition from marine to evaporitic conditions. Understanding the context of formation of these deposits in Afar can help to better interpret the depositional environment of the widespread Precambrian sea‐floor precipitates. 相似文献
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