Nature and significance of the recent carbonate mound record: The Mound Challenger code
Foubert, A.; Henriet, J.-P. (2009). Nature and significance of the recent carbonate mound record: The Mound Challenger code. Lecture Notes in Earth Sciences, 126. Springer: Dordrecht. ISBN 978-3-642-00289-2; e-ISBN 978-3-642-00290-8. XX, 298 pp. https://dx.doi.org/10.1007/978-3-642-00290-8
Deel van: Lecture Notes in Earth Sciences. Springer: Heidelberg; Berlin. ISSN 0930-0317; e-ISSN 1613-2580, meer
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VLIZ: Geology and geophysics GEO.62 [103347]
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| Abstract |
Carbonate mounds appear to be an important feature along the northeastern Atlantic margins. The presence of giant carbonate mounds in Porcupine Seabight, on Porcupine Bank, in Rockall Trough and on Rockall Bank,Wof Ireland is already known since the nineties (Hovland et al. 1994; Henriet et al. 1998; De Mol et al. 2002; Huvenne et al. 2002, 2003; van Weering et al. 2003). These mounds have been the target of several cruises during the last decade. An exploratory cruise of R/V Belgica in 2002 off Larache (Morocco, Gulf of Cadiz) has led to the discovery of similar mound structures topping ridges and structural heights (Foubert et al. 2008). Because of their unique setting (focused fluid seepage, mud volcanoes), also the carbonate mound sites on the Moroccan margin become rapidly involved in a developing stage of focused multidisciplinary research. Scientific campaigns, industrial surveys and extensive mapping studies reveal each year new mound structures. However, the processes of mound build-up and mound nucleation are not yet completely understood.What keeps a mound growing over extended time periods? How does the biosphere interact with sedimentary fluxes to make a mound grow? On which level do palaeoclimatological and palaeoceanographic changes control mound growth? Which diagenetic processes play an important role in carbonate mound generation and how do they affect the mound?The principal aim of the present study is twofold, focusing in a first phase on the nature of the carbonate mound record, and discussing in a second phase its significance. The nature and internal structure of one specific carbonate mound in Porcupine Seabight (SWof Ireland), i.e. ChallengerMound, is successfully unveiled. The mound is built from top to bottom of cold-water coral fragments embedded in an alternating biogenic (carbonate-rich) to terrigenous (siliciclastic) matrix. This creates a cyclicity which is considered to be driven by glacial-interglacial changes. Magnetostratigraphy and datings show that the mound started to grow between ~2.70 and~2.50 Ma. It is nowadays in a stage of decline.In a second phase, the significance of the carbonate mound record is discussed. The comparison of the top of Challenger Mound with another mound in Porcupine Seabight reveals that even on a regional scale, different mounds have different characteristics. Video imagery through Remotely Operated Vehicle (ROV) surveys, providing images of the surface of different carbonate mounds, substantiates the above statement. Small mound structures are occurring between the giant mounds and “dead” mounds are flanked by “live” mounds. The carbonate mounds on the Moroccan margin occur in a different oceanographic and geological setting than the mounds along the Irish margin. So, a wide variety of mounds occur in a wide variety of settings. This calls for an appropriate classification for recent carbonate mound systems and cold-water coral reefs. The role of recent carbonate mounds, such as Challenger Mound, in the global carbonate budget is discussed and appears to be significant but not extraordinary. The way recent carbonate mounds can be seen as analogues of ancient mud mound systems is a whole study on itself. However, at first sight, some significant differences are noted. |
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