COCARDE: new view on old mounds – an international network of carbonate mound research

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

Central Afar: An analogue for oceanic plateau development

The structure, composition, and evolution of oceanic plateaus are poorly understood and strongly debated. Here, we compared the magmatic history and crustal structure of Afar with the Greenland−Iceland−Faroe Ridge and other oceanic plateaus. Key similarities indicate that Central Afar represents the early stage of development of a specific type of oceanic plateau: a rifted oceanic magmatic plateau (ROMP). These features begin their formation before continental rifting and develop into wide magmatic rift systems capable of isolating slivers of continental crust within the new igneous crust. Importantly, the anomalous magmatism continues through breakup and for several tens of millions of years afterward. The recognition of Central Afar as a precursor of this type of oceanic plateau allows us to better understand their formation. Increased melt production causes early and voluminous magmatism, ultrathick igneous crust, and repeated reorganization of the extension locus during rift/ridge jumps, which delay the onset of oceanization and Penrose-style crustal production. These factors differentiate ROMPs from many magma-rich rifted continental margins and from other types of oceanic plateaus, highlighting that Central Afar and other ROMPs should neither be considered as conventional magma-rich margins nor be considered as normal oceanic crust

Studying the impact of a medication use evaluation for polymedicated older patients by the community pharmacist (SIMENON) : study protocol

Background: Aged polymedicated patients are particularly vulnerable for drug-related problems. A medication review aims to optimize the medication use of patients and improve health outcomes. In this study, the effect of a pharmacist-led medication use review is investigated for polymedicated ambulatory older patients with the aim of implementing this pharmaceutical care intervention across Belgium. Methods: This article describes the study protocol of the SIMENON study and reports the results of the feasibility study, which aimed to test and optimize this study protocol. In the SIMENON intervention study, 75 Belgian community pharmacies each recruit 12 patients for a medication use review. For each patient, the identified drug-related problems and subsequent interventions are registered using the PharmDISC classification. In a subset of Dutch speaking patients, a pretest-posttest single group design is used to measure the impact of this review on patient related outcomes using questionnaires. The main outcome of the study is the type and number of drug-related problems and related interventions. A second outcome is the impact of the medication use review on adherence, objectively measured with dispensing data. Evolution in medication related quality of life is another outcome, measured with the Living with Medicines Questionnaire version 3. Other patient reported outcomes include adherence, self-management, patient satisfaction, fall incidents and use of emergency healthcare services. Discussion: The findings of this study can provide data on the effectiveness of a medication use review in the Belgian primary care setting. Furthermore, it will provide insights in which patients benefit most of this intervention and therefore facilitate the implementation of medication review in Belgium

Biogeochemistry of carbonate mounds from the Pen Duick escarpment in the Gulf of Cadiz

In the Gulf of Cadiz, carbonate mounds build by cold-water corals were recently discovered on the Renard Ridge, a zone of active fluid flow and mud volcanism. Their sizes vary from 25 to more than 60 m high, at a depth of 520 m and they are aligned along the ridge axis. These mounds, located in the close vicinity of fluid flow markers such as carbonate crusts and mud volcanoes, provided a novel opportunity to study a possible fluid flow control on the mound processes and distribution. Previous geochemical studies on the southernmost mound of the ridge indeed showed that this mound was located on focused fluid flow compared to surrounding sediments, and we observed typical profiles of methane migration and anoxic oxidation (AOM) at 3,8 m below the sea floor within the mound. Such AOM occurrence imprinted a characteristic d13C signature (down to –21,9 %¸ Vs. PDB) and significantly contributes to the overall carbonate budget of the mound.During the recent R/V Maria S. Merian cruise (April-June 2006), we sampled by mean of a gravity corer six new structures likely to be cold-water carbonate mounds, along the Pen Duick escarpment and the Renard Ridge. Our aim was to determine if the geochemical profiles observed in the first mound could be generalized to all the mounds in this area.Each core yielded a full sequence of cold-water corals down to about 5 meters below the sea floor. Hence, the numerous knoll-like structures revealed by high-resolution bathymetry along the ridge are indeed carbonate mounds build by cold-water corals and the entire Ridge has been massively colonized by corals. No live reef-forming coral could be recovered from the cores, nor observed by towed video instruments. Then, fluid migration seems to be a common feature all along the ridge. However, important discrepancies were observed: methane concentrations are higher and sulfate gradients steeper on both side of the ridge, whereas the central part of the ridge seems less active in term of fluid migration. In this case, the sulfate to methane transition zone could not be reached using conventional gravity corer. In order to obtain the full biogeochemical picture of these mounds, the use of a long piston corer, or drilling devices, will be required.The reasons of the formation of massive reefs in this area are still unknown and are probably linked to locally enhanced hydrologic conditions. However, it is possible that cold-water coral could have benefited from the hard substrate and the topographic elevations provided by fluid related structures such as carbonate crusts, chimneys and clasts, as observed in several other locations in the Gulf of Cadiz

The early diagenetic and PETROphysical behaviour of recent cold-water CARbonate mounds in Deep Environments (PETROCARDE)

Sub-recent cold-water carbonate mounds localized in deeper slope settings on the Atlantic continental margins cannot be any longer neglected in the study of carbonate systems. They clearly play a major role in the dynamics of mixed siliciclastic-carbonate and/or carbonate-dominated continental slopes. Carbonate accumulation rates of cold-water carbonate mounds are about 4 to 12 % of the carbonate accumulation rates of tropical shallow-water reefs but exceed the carbonate accumulation rates of their slope settings by a factor of 4 to 12 (Titschack et al.,2009). These findings emphasize the importance of these carbonate factories as carbonate niches on the continental margins. The primary environmental architecture of such carbonate bodies is well-characterized. However, despite proven evidences of early diagenesis overprinting the primary environmental record (e.g. aragonite dissolution) (Foubert & Henriet, 2009), the extent of early diagenetic and biogeochemical processes shaping the petrophysical nature of mounds is until now not yet fully understood.Understanding (1) the functioning of a carbonate mound as biogeochemical reactor triggering early diagenetic processes and (2) the impact of early diagenesis on the petrophysical behaviour of a carbonate mound in space and through time are necessary (vital) for the reliable prediction of potential late diagenetic processes. Approaching the fossil carbonate mound record, through a profound study of recent carbonate bodies is innovative and will help to better understand processes observed in the fossil mound world (such as cementation, brecciation, fracturing, etc. . . ).In this study, the 155-m high Challenger mound (Porcupine Seabight, SW of Ireland), drilled during IODP Expedition 307 aboard the R/V Joides Resolution (Foubert & Henriet, 2009), and mounds from the Gulf of Cadiz (Moroccan margin) will be discussed in terms of early diagenetic processes and petrophysical behaviour. Early differential diagenesis overprints the primary environmental signals in Challenger mound, with extensive coral dissolution and the genesis of small-scaled semi-lithified layers in the Ca-rich intervals. The low cementation rates compared to the extensive dissolution patterns can be explained by an open-system diagenetic model. Moreover, Pirlet et al. (2009) emphasizes the occurrence of gypsum and dolomite in another mound system (Mound Perseverance) in Porcupine Seabight, which might be also related with fluid oxidation events in a semi-open diagenetic system. Along the Moroccan margins, fluid seepage and fluxes in pore water transport affect the development of mound structures, enhancing extensive cold-water coral dissolution and precipitation of diagenetic minerals such as dolomite, calcite, pyrite, etc. (Foubert et al., 2008). Recent carbonate mounds provide indeed an excellent opportunity to study early diagenetic processes in carbonate systems without the complications of burial and/or later meteoric diagenesis

COCARDE: A research platform for a new look to ancient mounds

Carbonate mounds are important contributors of life in different settings, from warm-water to cold-water environments, and throughout geological history. Research on modern carbonate mounds over the last years made a major contribution to our overall understanding of these particular sedimentary systems. By looking to the modern carbonate mound community, some fundamental questions could be addressed, until now not yet explored in fossil mound settings.The international network COCARDE (Cold-Water Carbonate Reservoir Systems in Deep Environment) is a platform for exploring new insights in cold- and warm-water carbonate mound research of recent and ancient mound systems (http://www.cocarde.eu). One aim of the COCARDE network is to bring scientific communities together, to study recent carbonate mounds in midslope environments in the present ocean, and to investigate fossil mounds spanning the whole Phanerozoic time.Scientific challenges on modern and ancient carbonate mound systems got already well defined during two dedicated workshops of the COCARDE network: 1) the ESF Magellan COCARDEWorkshop in Fribourg, Switzerland, January 21-24, 2009, and 2) the ESF MiCROSYSTEMS – FWO COCARDE Flanders – ESF CHECREEF Workshop and Field Seminar, Oviedo, Spain, September 16–20, 2009.The wide spectrum of disciplines in geosciences and biology are summarized in the following five topics for the carbonate mound research: i) Palaeoenvironment; ii) The Microbial Filter; iii) Petrophysical Characterization; iv) Connectivity and Compartmentalization – the Fluid System; v) Advancing our Insight in Phanerozoic Reef Systems– the Slope Niche. One of the most important outcomes of these meetings was the identification of the need for combined research efforts on fossil and modern carbonate settings to provide the baseline reference standard for a better understanding of these exceptional systems and their potential as hydrocarbon reservoirs

Acoustic properties in travertines and their relation to porosity and pore types

Sonic velocities of Pleistocene travertines were measured under variable confining pressures. Combined with petrographical characteristics and petrophysical data, i.e. porosity, permeability and density, it was determined that travertine porosity, pore types and cementation control compressional-wave (Vp) and shear-wave velocity (Vs). At 40 MPa confining pressures, Vp ranges between 3695 and 6097 m/s and Vs between 2037 and 3140 m/s. Velocity variations in travertines are, as with all carbonates, primarily linked to sample heterogeneity, i.e. differences in fabric, texture and porosity. They thus not necessarily emanate from changes in mineralogy or composition. Body wave velocities have a positive correlation with sample density and an inverse correlation with porosity. The travertines, sampled in extensional settings with normal faulting activity, define a specific compressional-wave velocity (y-axis) versus porosity (x-axis) equation, i.e. (log(y) = −0.0048x + 3.7844) that differs from the Vp-porosity paths defined by marine carbonates. Acoustic wave velocities are higher for travertines than for marine carbonates. Travertine precipitates form rigid rock frames, often called framestone, with large primary pores. Marine carbonates on the other hand often consist of (cemented) transported sediments, resulting in a rock frame that permits slower wave propagation when compared to the continental limestones.Acoustic velocity variations are linked to variations in pore types. Mouldic pores (macropores) show faster wave propagation than expected from their total porosities. Microporosity, interlaminar and interpeloidal porosity result in slower acoustic velocities. Framework pores and micro-moulds are associated with lowered acoustic velocities, while vug porosity is found above, on and below the general velocity-porosity trend. Not only the pore type, but also pore shapes exert control on body wave velocities. Cuboid-and rod-like pore shapes increase the velocity, while plate-and blade-like pore shapes have a negative effect on the velocity. The study demonstrates how seismic sections in travertine systems can contain seismic reflections that are not caused by non-carbonate intercalations, but relate to geobody boundaries, in which the seismic expression is function of porosity, pore types and shapes. This study provides and relates petrophysical data, i.e. porosity, permeability and acoustic velocities of travertines and is of importance for the interpretation of seismic reflection data in subsurface continental carbonate reservoirs

A comparative study of the recent history of Thérèse and Challenger mound, two cold-water coral carbonate mounds in the Belgica Mound province, Porcupine Seabight, SW of Ireland

During the Geomound-cruise with the R/V Marion Dufresne in 2001 gravity cores were recovered on the top of Thérèse mound (MD01-2463G) and Challenger mound (MD01-2451G). Both mounds are built up by cold-water corals (Lophelia pertusa sp. and Madrepora oculata sp.). This was confirmed by the IODP drilling (expedition 307) where Challenger mound was drilled to its base and cold-water corals were observed over the entire length of the mound.The gravity core (MD01-2463G), taken on top of Thérèse mound, was described and analyzed for its foraminiferal content and grainsize. A combination of these data with the results from previous studies (P-wave velocity, gamma density, magnetic susceptibility, X-ray imagery, U/Th-dating of corals and foraminifera (Frank et al., 2005, Foubert et al., 2006)), made it possible to distinguish different units, enabling a reconstruction of the evolution of the top of Thérèse mound.In a next step, the different zones in the core on top of Thérèse mound could be correlated with the sections identified in the gravity core recovered on top of Challenger mound (MD01-2451G) (Foubert et al., 2006). The mounds unveiled a comparable recent history, implying that their growth was controlled by the same parameters. Both cores revealed at least one discontinuity in the record, corresponding with a time hiatus of more than 200 ka. This discontinuity corresponds most likely to a change in hydrodynamic environment which prohibited further coral growth but erosional processes cannot be ruled out. The hiatus is in both cases covered with a layer of fine laminated sediments and dropstones. The origin of this detritic material is still unclear and will be further investigated using the Nd isotopic signature of the sediment as a tracer

Deep-water oyster cliffs at La Chapelle Bank (Celtic Margin)

The maiden voyage of Ghent University’s ROV GENESIS on-board R/V Belgica (13-20 June 2006) has succeeded in contributing to several objectives of the EU-projects HERMES and EURODOM, as well as of the ESF Euromargins project MoundForce. After several trials in the Bay of Douarnenez, GENESIS made its first deep-water survey dives off the Banc de la Chapelle, on the Celtic margin, down to 700 m. The French canyon system near the Banc de la Chapelle offered a perfect location for rigorous trials of GENESIS: reported cold-water coral finds, rugged topography and hydrodynamics in a setting linking the shelf seas to the deep marine realm. The area was first surveyed using R/V Belgica’s multibeam echosounder, imaging deep canyons and thalweg channels between prominent spurs where corals had been reported. High resolution seismic sparker lines provided a geological context and linked in to the existing seismostratigraphy.Two successful dives revealed a sandy-muddy seabed with curious bedforms and erosion exposing consolidated sedimentary sequences, often cut by vertical cliffs up to 10m high. At the base of the cliffs, fallen blocks provided settlement sites for sessile organisms whilst the cliffs and protruding banks revealed dense communities of unidentified giant ostreidae (probably Neopycnodonte sp) forming 3D assemblage with occasional cold-water coral colonies (Lophelia pertusa). Though deep-water ‘oyster banks’ of Neopyncodonte cochlear had already been reported in the Bay of Biscay by ..Le Danois (1948) based on dredges, these dramatic seascapes had remained largely hidden to the human eye up to now