Generic autogenic behaviour in fluvial systems: lessons from experimental studies - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 10

(A) Original Profile

Sea Level

Buttress
(Sea Level, Cataract,
Lake level, etc.)

(B)

Effect of Buttress Rise

(C) Effect of Buttress Fall

(D)

Effect of Down-Profile Buttress Shift

(E)

Effect of Local Subsidence

Subsidence

(F) Effect of Up-Stream Uplift

Uplift

Buffer Profile
Instantaneous Profile

Added Preservation Space

Original Preservation Space

Fig. 5. Preservation space added as a result of shifts in initial buffer profiles (A) because of either buttress movement or
tectonic adjustment. Fluvial preservation space may be added as a result of a simple buttress rise (B) or fall (C). Sediments
deposited in added preservation space resulting from a buttress fall (C) are generally sequestered as easily eroded terraces
hanging from the valley wall. They thus tend to have less long-term preservation potential than deposits buried by aggrada-
tion during a buttress rise (B). Movement of the buttress along the trajectory of the original longitudinal profile (D) tends to
lengthen preservation space but otherwise adds minimal room for sediment accumulation. Subsidence beneath reaches of
the lower buffer profile (E) tends to lower sediments deposited within the prior preservation space beneath active erosion.
Long-term preservation potential of these sediments is high. Uplift beneath buffer profiles (F) tends to leave deposits from
previous preservation spaces stranded as terraces where they could potentially be preserved long term but have high prob-
ability of erosion before eventual burial. In each of the above cases B through to F, the total space for potential accumula-
tion of a fluvial unit is the integral of all preservation spaces produced over the period through which the depositing fluvial
system was actively preserving sediment (from Holbrook et al ., 2006).