--> ABSTRACT: Architectural Elements in Sandy Experimental Turbidity Currents: The Case of Incipient Levees, by Eggenhuisen, Joris T.; Cartigny, Matthieu ; de Leeuw, Jan; Postma, George; Basani, Riccardo ; Hansen, Ernst; #90142 (2012)

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Architectural Elements in Sandy Experimental Turbidity Currents: The Case of Incipient Levees

Eggenhuisen, Joris T.*1; Cartigny, Matthieu 1; de Leeuw, Jan 1; Postma, George 1; Basani, Riccardo 2; Hansen, Ernst 2
(1) Earth Sciences, Utrecht University, Utrecht, Netherlands.
(2) Complex Flow Design AS, Trondheim, Norway.

Recent developments in the Eurotank Laboratory have led to the establishment of experimental procedures in which turbidity currents can efficiently by-pass predominantly sandy sediment at slope angles down to 5 degrees. This allows operating experiments with turbidity currents that hover on and around the point of deposition. Such experiments are a more effective analogue to the interaction between turbidity currents and aggrading deposits than previous experimental approaches. This analogy allows experimental investigations of architectural development in experiments in order to test and develop conceptual and hydraulic models of architectural element evolution in channels, around channel-lobe transitions, on unconfined slopes, and on basin floors.

We illustrate the benefits of the new approach with the experimental deposit architectures on and around break-of-slopes, at channel-unconfined transitions, and on unconfined slopes.

Previous studies of confined-unconfined transitions dominantly resulted in arcuate depositional bodies surrounding a region of scour or non-deposition immediately in front of the confinement exit. While this architecture has never been shown to develop into a lenticular channel with encompassing levees, it has often been speculatively referred to as “incipient channelization”, with references to the two curved sections of the deposit lateral to the scour hole as “incipient levees”. Here we show that such architectures are typical of complete loss of capacity by flows that exit confinements, in analogy to incised channels on steep, active slopes from which flows exit directly into plunge-pools onto basin-floors.

In contrast, where dominantly by-passing experimental turbidity currents flow over unconfined slopes, they develop two parallel depositional ridges alongside the by-passing high-velocity core of the current. We suggest that these are the first experimental turbidity current deposits that truly warrant the term “incipient levees”. Their recognition leads to new arguments in the debate regarding the relative roles of incision and aggradation in deep marine channel initiation.  

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California