Joris Eggenhuisen (Utrecht) and Jake Covault (Chevron) convened the Deepwater research Group meeting on the subject of
"Autogenic and allogenic controls on deep-water depositional systems".
Four speakers were invited, they were chosen for a balance between different approaches and perspectives, stage in their relative careers, and academic vs. industry profile:
- Fluvial/upstream controls on deep-water sediment delivery: Mike Blum (Exxon)
- Outcrop and/or marine geology perspective: Brian Romans (Virginia Tech)
- Experimental perspective: Kyle Straub (Tulane)
- Numerical modeling perspective: Ashley Harris (Chevron)
It was a pleasant surprise to see/hear that the speakers all led similar lines of discussion regarding allogenic and autogenic controls. Here are some highlights from our incomplete notes:
General goals, outlined by Eggenhuisen during the beginning of the meeting:
On reflection during the past few days, we interpret that these goals were more-or-less addressed, although in a slightly disorganized fashion:
- Definitions of autogenic and allogenic controls (touched by Blum, stressed by Romans, Straub, Harris);
- Specification of mechanisms by which the controls act on the system, and resulting deposit characteristics;
- Differentiating controls from the stratigraphic record (touched by all);
- Future Directions (potentially overlooked, with some lip service paid to integration of data/expertise and more robust chronostratigraphy of measurable/observable patterns).
Blum - Focus on connection of sediment routing segments and delivery of load to deep water. Focus on sediment budgets and sediment load prediction (e.g., BQART). The discussion boiled down to upstream delivery/Qs control on deep-water stratigraphy.
Romans - Focus on recognition of patterns and placing them into a chronostratigraphic framework. Focus on definitions of allogenic and autogenic controls, with a discussion of different scales and locations of avulsions. Like Blum, focus on sediment budgets and sediment load prediction (Qs). Focus on characterization of sediment routing systems (e.g., buffered vs. reactive end members), with implications for signal propagation and interpreting controls.
Straub - Focus on autogenics. Focus on high temporal resolution. Like Romans, focus on definitions of allogenic and autogenic controls, with a discussion of different scales and locations of avulsions- for example, do we consider terrestrial autogenics a boundary condition? Like Romans, focus on characterization of sediment routing systems, with implications for signal propagation and interpreting controls.
Harris - Focus on false dichotomy of autogenic vs. allogenic controls- when does autogenic become allogenic and vice versa? This was reminiscent of Romans/Straub focus on different scales and locations of avulsions. Like Blum, focus on sediment budgets and sediment load prediction (Qs). Focus on deep, geologic time and often overlooked impact of dynamic topography.
- One of the topics that emerged from the entire evening is that scale seems to determine the nature of the control: in a source-to-sink perspective of the system, the variations of fluvial sediment supply to the coastline are internal, and dynamics such as delta-lobe switching may be autogenic, while the same switching could be regarded as an external forcing of sediment supply pulses to the slope environment. This is reminiscent of, though not entirely parallel to the classical paper of Schumm and Lichty (1965) that discusses the time-scale dependent nature of controlling parameters on fluvial systems.
- A key missing piece during virtually the entire evening was the impact of controls on architecture and facies of deepwater deposits. Some points/questions were raised by the audience and the speakers, but nowhere did we get a feeling for well-defined consequences of the different controls for deposit characteristic distribution.
- The plus side of this omission was that the contributions were all very much aligned along the sediment supply control to and within the deepwater depositional system.
- In retrospect, it is surprising that recent developments of the concept of "Sediment-mass-extraction", with implications for applied challenges of sediment partitioning and reservoir quality were not addressed. Folks who address sediment mass extraction include John Martin, Chris Paola, Sean Connell, Ron Steel and disciples, including Cristian Carvajal, Andy Petter, and Dave Mohrig, among others, and Imperial College researchers Allen and Whittaker, among others.
- As an aside, we have received a lot of positive feedback following the meeting, and many have commended the speakers, their presentations, and the general topic of controls.
- The level of attendance was considered a success by the conveners.