According to Orange et al. (1999), widespread fluid expulsion on a transtensional margin may cause headless canyons and mass wasting to form. On some of the high-resolution multibeam shaded relief images from the Lofoten-Vesterålen continental margin (Bøe et al., 2013), there is evidence of numerous headless canyons with apparently prograding mass wasting. These may be candidate 'spring sapping' features. On land, 'spring sapping' is the effect of erosion by groundwater in slopes, and it causes ravine and gully formation. May this effect also be occurring on the Lofoten-Vesterålen margin?
Ref: Orange, D., et al., 1999. Widespread fluid expulsion on a translational Continental margin: mud volcanoes, fault zones, headless canyons, and organic-Rich substrates in Monterey Bay, California. Geol. Soc. Am. Bull. 111, 992-1009.
Article The Lofoten-Vesteralen continental margin, North Norway: Can...
Martin
If I remember correctly spring sapping was suggested for canyons on the Rockall Trough Hebridean slope north and south of the Barra / Donegal Fan many years ago ~1985. I will look for papers. However it might have just been flavour of the month. It was being suggested for other canyon systems that did not connect with large fluvial system. e.g. Paull, CK, Spiess FN, Curray JR, Twichell DC. 1990. Origin of Florida Canyon and the Role of Spring Sapping on the Formation of Submarine Box Canyons. Geological Society of America Bulletin. 102:502-515.
All the best
Dave
Thanks, Dave,
for spring sapping to occur, i do not think you need to connect with large fluvial systems, as you (and Charlie Paull et al.) suggest. I think you can get spring sapping in areas where you get an initial 'tear' in a sloping sediment unit, where underground pore-water may gradually leak out, to erode more of the slope. In the end, the erosion may become so severe, that a proper slide develops. Thereafter, the unit of the sediment sequence that is most permeable will start leaking fluids and you get a prograding process, as seen in gully formation.
I do not know if this information can be useful, because it comes from studies deriving from a very different geological context, a carbonate plateau (the Murgia platform, Apulia, Southern Italy).
In this context, the sea level and its variations determined karst tabular morphogenesis and karst horizontal cave network development (Fidelibus D. Et Al, (2013) Reply to the discussion on “Coastal and inland Karst morphologies driven by sea level stands: a GIS based method for their evaluation”. ESPL (2013)Wiley).
Subsequent sea level lowering allowed the vertical evolution of such morphologies either by deepening and upwards by undermining.
Some of these canyons have their head in large dolines far away from their tracks.
Thus, sea level, its variations and the velocity of the downward variations could have played a role in the development of headless canyons.
Yes, certainly, Giuseppe, althogh the features off Norway do have nothing to do With carbonate carstification, the process you are describing, has been proposed for carbonate areas, such as the underwater Florida escarpment.
Yes, specially in the triggering of mass movements (falls, slides or mixed movements).
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