Project Outline

 
The 4D diagenetic and PETROphysical behavior of cold-water CARbonate bodies in Deep Environments (4D-PETROCARDE)

 

Contact: Anneleen Foubert (email), University of Fribourg, Switzerland

 

Sub-recent cold-water carbonate mounds localized in deeper slope settings on the continental margins can not 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 exceeds the carbonate accumulation rates of their slope settings by a factor of 4 to 12 (Titschack et al., 2009), evidencing the importance of these carbonate factories as carbonate niches on the continental margins.PetroCARDE_Pic
Recent studies on such mound structures have been mainly focused on their occurrence, stratigraphic and (palaeo)environmental control (De Mol et al., 2002), sediment dynamics and the potential of reef-forming organisms, adapted to deep and cold-water environments (such as cold-water corals (Lophelia pertusa, Madrepora oculata), Bryozoa, sponges, etc…), to baffle and trap (in an active or passive way) sediments (Huvenne et al., 2007). So, 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, 2007), 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 and so the understanding of the transformation of a recent carbonate mound body in the fossil record.
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…). The complexity of the petrophysical nature of fossil carbonate rocks is well-known. However the importance of sub-recent diagenesis in the shaping of carbonate bodies, has until now not been fully addressed. In this way, sub-recent carbonate mound bodies form a unique laboratory to study early diagenesis actively on-site, characterizing their primary petrophysical nature. Moreover, the study of early diagenetic processes driven by biogeochemical reactions and the petrophysical characterization of a carbonate mound body will help in identifying the correct boundary conditions to model potential internal fluid migration pathways, such as the occurrence of current-driven convection cells in a certain mound setting (Depreiter, 2009).

 

Objectives and approach
In this study four main objectives will be emphasized respectively moving from an analytical approach to a modelling phase. These four objectives are linked together and will be studied in relation with each other:
(1) Understanding the early diagenetic processes driven by biogeochemical reactions acting in a carbonate body: carbonate mounds as biogeochemical reactor.
(2) Petrophysical characterization (porosity, permeability, connectivity) of a carbonate mound.
(3) Modelling potential fluid migration pathways in the mound.
(4) Predictive modelling: how late diagenetic processes (cementation, fracturing, dolomitization) and burial stresses (lithostatic stress, deviatoric stress, pressure) can transform a recent cold-water carbonate mound into a fossil carbonate body.

 

Further reading and references:
Allen, D.F., Boyd, A., Massey, J., Fordham, E.J., Amabeoku, M.O., Kenyon, W.E., Ward, W.B. (2001) The practical application of NMR logging in Carbonates: 3 Case Studies, SPWLA 42nd Annual Logging Symp., Houston, Texas, 14 pp.
 
De Mol, B., Van Rensbergen, P., Pillen, S., Van Herreweghe, K., Van Rooij, D., McDonnell, A., Huvenne, V., Ivanov, M., Swennen, R., Henriet, J.P. (2002) Large deep-water coral banks in the Porcupine Basin, southwest of Ireland. Mar. Geol., 188, 193-231.
 
Depreiter, D. (2009) Sources, modes and effects of seabed fluid flow. PhD thesis, Ghent University, 207 pp.
 
Foubert, A. (2007) Nature and Significance of the Carbonate Mound Record: The Mound Challenger Code. PhD thesis, Ghent University, 341 pp.
 
Huvenne VAI, Bailey WR, Shannon PM, Naeth J, di Primio R, Henriet J-P, Horsfield B, de Haas H, Wheeler AJ, Olu-Le Roy K (2007) The Magellan mound province in the Porcupine Basin. Int. J. Earth. Sci., 96, 85-101
 
James, N.P., Feary, D.A., Betzler, C., Bone, Y., Holbourne, A.E., Li, Q., Machiyama, H., Simo, J.A., Surlyk, F. (2004) Origin of Late Pleistocene Bryozoan reef mounds; Great Australian Bight. J. Sed. Res., 74, 20-48.
 
Remeysen, K. and Swennen, R. (2008) Application of microfocus computed tomography in carbonate reservoir characterization: possibilities and limitations. Mar. Petrol. Geol., 25, 486-499.
 
Titschack, J., Thierens, M., Dorschel, B., Schulbert, C., Freiwald, A., Kano, A., Takashima, C., Kawagoe, N., Li, X. and the IODP Expedition 307 Scientific Party (in press) Carbonate budget of a cold-water coral mound (Challenger Mound, IODP Exp. 307). Mar. Geol.