Description: Over a decade of research on recent cold-water coral mounds in various oceans has set the stage for comparative studies between recent and ancient carbonate mound systems, with the aim to unravel generic processes and reveal the “red thread” in a fundamental strategy of Life building Geology — a strategy nearly as ancient as Life itself. Natural laboratories have been identified in the present ocean, which provide new insights in oceanographic controls on species migration and settlement, in the interaction of currents and carbonate build-up, in the earliest diagenesis which overprints environmental signals and shapes the template of compartmentalization of carbonate build-ups, and in so many other processes and factors ultimately shaping carbonate bodies, comparable in size and properties to the large-scale carbonate hydrocarbon reservoirs in the geological record. Ocean drilling and coring is an essential component of this research. Ideally, this process is a two-way avenue between Shallow and Deep Time, where fundamental and industrial knowledge about fossil carbonate mounds can drive further investigations and even experimentation in the present seas, while the discoveries and process studies on “live” systems can yield new insights in the architecture and evolution of ancient reservoir systems. This bridging exercise is the quintessence of COCARDE (Cold-Water Carbonate Reservoir Systems in Deep Environments), an international network under the auspices of IOC-UNESCO (http://www.cocarde.eu). COCARDE has organised two workshops in 2009, with a significant support of European programmes (e.g. ESF Magellan workshop series) and partner projects (e.g. ESF EuroDIVERSITY project MiCROSYSTEMS). This special issue groups 12 papers, all addressing observations which by their nature have the potential to provide keys to generic processes, of relevance for past carbonate systems. As COCARDE proceeds, it is the objective to “reciprocate” in near future with an equivalent grouping of contributions from the study of fossil studies, to guide further research in the present ocean. It is the purpose of COCARDE to strengthen such a reflux from the studies of fossil systems by stimulating relevant continental drilling exercises, with comparable sampling protocols, resolution and analytical procedures – where relevant – to allow direct comparisons with records from ocean drilling. The papers in this special issue have been structured in four themes: (i) keys to palaeoenvironmental control, (ii) mound initiation, growth and demise, (iii) of microbes and mounds, and (iv) tracking organominerals — Recent and Ancient.

Description: The recent marine carbonate world comprises two major compartments: (1) the surface domain of the photozoan carbonates, confined in space by water depth and by the penetration of light, and (2) a deep domain, where heterozoan mound-builder guilds directly forage on fluxes of nutrients, which primarily percolate from the photic zone and/or are generated by in situ benthic processes. Locally, giant cold-water coral mounds tower up to heights of 150 to 250 m above the sea floor, in general between 500 and 1300 m water depth and within sharply delineated provinces. Some 15 years of research on these giant mound provinces conveys a picture of their distribution in space and possibly sheds light on controls, acting in concert. Globally, there is no counterpart for the prolific North Atlantic Mound Basin (NAMB). A chemical control is seen by an overlay of the mound provinces on a map of the aragonite saturation horizon (ASH). An external physical control is inferred fromthe position of themound provinces, girdling a vigorous North Atlantic subtropical gyre systemand clustering close to the roof of the intermediate to deep water masses of a dynamically stratified ocean. On the eastern boundary of the NAMB, nutrient fluxes are enhanced by mixing processes, driven either by internal waves between Galicia and the Shetlands, or by the vast and heterogeneous Eastern Boundary Upwelling System along the Iberian/African margins down to 10°N. Early diagenesis by carbonate dissolution and re-precipitation driven by convecting or advecting internal fluids can contribute to stabilize such constructions, facilitating an exuberant vertical accretion. It is speculated that in theNorth Atlantic Ocean, the deep-water carbonate factory outclasses in size the shallow water coral reefs. Giant mound formation is a recurrent play of Life since the dawn of the metazoans (Nama Group, Upper Neoproterozoic), however with actors and plots, varying from act to act. Remarkably, literature reports only three occurrences of deep-water mounds in the Phanerozoic: the modern ocean, possibly the Danian, and the Carboniferous. Some striking parallelisms in the development of the Atlantic and the Paleo-Tethys oceans, combined with the developing insights in the controls on deep-watermounds in the present ocean, invite for a comparative study. This has the potential to eventually shed light on the full circulation pattern of the Paleo-Tethys Ocean, surface and deep. Comparative studies will build upon (1) modeling of ocean circulation constrained by the record of deep-water carbonate systems and supported by advances in tracer and proxy tools, and (2) field studies on representative and accessible continental locations. The mound route that develops in Morocco under the auspices of IOC-UNESCO will provide tomulti-disciplinary teams with marine and continental experience opportunities for confronting observations from the modern ocean and on key records of past oceanic basins. It has the potential to eventually qualify for a UNESCO recognition as World Heritage.

Description: Ecological and taxonomic study of the mollusk-rich fauna of the Golfe d’Arguin, North Mauritania, investigates the various environmental influences affecting this tropical shelf. The upwelling of nutrient-rich waters leads to a highly productive environment under tropical conditions. The resulting mixed carbonate-siliciclastic sediment contains a large portion of calcareous components produced by heterotrophic organisms— e.g., mollusks, foraminifers, worms, barnacles—that are reworked on the open shelf. On the basis of mollusk assemblages, six taphocoenoses are defined, all being characterized by a mixed fauna of tropical (e.g., Tellina densestriata), subtropical (e.g., Macoma cumana) and temperate (e.g., Spisula subtruncata) species. Differences between the assemblages are related to the medium—grain size ranging from mud to gravel—that results from local hydrodynamic conditions and water depth. Among carbonate grains, Donax burnupi shells are very abundant in the swellexposed, northern part of the Golfe d’Arguin and reflect the tropical to subtropical, high-energy, and high-nutrient waters. Mollusk assemblages are demonstrated to be a sensitive tool for deciphering complex environmental conditions in sedimentary archives.

Description: EGU2012-12550 Carbonate mounds are important contributors of life in different settings, from warm-water to cold-water environments, and throughout geological history. Research on modern cold-water coral carbonate mounds over the last decades made a major contribution to our overall understanding of these particular sedimentary systems. By looking to the modern carbonate mound community with cold-water corals as main framework builders, some fundamental questions could be addressed, until now not yet explored in fossil mound settings. The international network COCARDE (http://www.cocarde.eu) is a platform for exploring new insights in carbonate mound research of recent and ancient mound systems. The aim of the COCARDE network is to bring together scientific communities, studying Recent carbonate mounds in midslope environments in the present ocean and investigating fossil mounds spanning the whole Phanerozoic time, respectively. Scientific challenges in modern and ancient carbonate mound research got well defined during the ESF Magellan Workshop COCARDE in Fribourg, Switzerland (21.–24.01.2009). The Special Volume Cold-water Carbonate Reservoir systems in Deep Environments – COCARDE (Marine Geology, Vol. 282) was the major outcome of this meeting and highlights the diversity of Recent arbonate mound studies. The following first jointWorkshop and Field Seminar held in Oviedo, Spain (16.–20.09.2009) highlighted ongoing research from both Recent and fossil academic groups integrating the message from the industry. The field seminar focused on mounds from the Carboniferous platform of Asturias and Cantabria, already intensively visited by industrial and academic researchers. However, by comparing ancient, mixed carbonate-siliciclastic mound systems of Cantabria with the Recent ones in the Porcupine Seabight, striking similarities in their genesis and processes in mound development asked for an integrated drilling campaign to understand better the 3D internal mound build-up. The Oviedo Workshop and Field Seminar led to the submission of a White Paper on Carbonate Mound Drilling and the initiation of the ESF European Research Network Programme Cold-Water Carbonate Mounds in Shallow and Deep Time – The European Research Network (COCARDE-ERN) launched in June 2011. The second COCARDE Workshop and Field Seminar was held in Rabat, Morocco (24.–30.10.2011) and thematically focussed on carbonate mounds of(f) Morocco. The compact workshop invited students from Moroccan Universities to experience ongoing carbonate mound research in Recent and Ancient environments of Morocco. Two Round Tables discussed innovative approaches in carbonate mound research in Morocco (Recent vs. Ancient - offshore vs. onshore) and reviewed together with oil industry opportunities of international collaboration. The outcome of this workshop will lead into joint research projects, drilling campaigns on- and offshore, and expansion of COCARDE onto the African continent.

Description: On Earth, burial of fine-grained sediments in offshore passive margins (e.g., underwater fans and deltas) commonly results in fluid expulsion features including large-scale polygonal fractures, mud volcanoes, and pockmarks. Comparison of resulting offshore polygons and mud volcanoes with giant polygons and high-albedo mounds in the Chryse–Acidalia region of Mars shows the terrestrial and martian features to be similar in size, morphology, geologic context, and general co-occurrence within the same basin. These similarities suggest that the process of terrestrial fluid expulsion may provide an analog that could link the giant polygons and mounds in Chryse and Acidalia to a single process. Moreover, while the terrestrial offshore polygons and mud volcanoes commonly develop in the same basins, these features do not necessarily occur in exactly the same locations within those basins, as they are independent responses to compaction and dewatering. Thus, the fluid expulsion analog does not require that the martian giant polygons and mounds have identical distributions. This is the situation in Chryse and Acidalia where the giant polygons and mounds are extensively developed and generally have overlapping distributions, but where each set of features may occur in places without the other. This fluid expulsion analog is enhanced by the fact that giant polygons and mounds in Chryse and Acidalia cooccur in a regional sense and in a geologic setting that is consistent with a fluid expulsion model of formation. Implications of this analog may impact our view of the role of water in the depositional history of the martian lowlands.

Description: Published

Description: 424-432

Description: 7A. Geofisica di esplorazione

Description: JCR Journal

Description: restricted