Physical modeling of the impact of changing slope-to-basin morphology on the emplacement, erosion, and transport of sediments by along-slope continuous currents

Abstract

Direct observations of deep-ocean current processes and their resulting deposits continue to be rare, difficult to record, and expensive. Thus, physical experiments give the geologic community a basis for predicting and testing assumptions about the relationships of different geological processes and how they may be expressed in the outcrop, wellbore, or seismic reflection data. Recognized on a global scale, density driven water masses move appreciable amounts of sediment along shelf margins, the continental slope, and the ocean floor. This is of growing importance as hydrocarbon exploration continues to expand beyond the lower slope into the deeper basins. The resultant deposits of these density-driven water masses can preserve high-resolution sedimentological data to aid in the interpretation of palaeoceanographic and paleoclimatic changes. The fundamental understanding of both the erosional and depositional processes and their stratigraphic relationships will greatly inform our understanding of the hydrocarbon potential of these deposits, their role in the petroleum system, and enable us to decipher changes in deep-ocean currents through time.

The current study proposes a better understanding of continuous bottom currents and their resultant deposits in nature through an analogue “similarity of process” laboratory model (Hooke, R.L., 1969) where the laboratory setup is a smaller representation of the natural process. The continuous bottom current flume (CBCF) will reproduce these complex physical interactions, present relatively instant visual feedback, and allow for a high degree of control over the system. This model will be used to investigate how continuous current-related morphologies and deposits are impacted by the degree of changing slope; slope-to-basin transition angles they interact with. While laboratory studies have been conducted looking at continuous current characteristics and flow velocities, no study to date has been conducted in which they imposed continuous current flow parallel to varying transition angles.

This study tested three individual experiments utilizing a 10º slope; 170º slope-to-basin transition angle, a 30º slope; 150º slope-to-basin transition angle, and a 50º slope; 130º slope-to-basin transition angle which all yielded different geomorphological results and led to unique findings. The role of the slope-to-basin transition angle has been determined to be an influential factor in controlling bottom current flow characteristics, sediment distribution and deposition, and slope stability. These experiments will aid in the further understanding of how sediments are moved and molded by continuous bottom current interactions, assist in predicting the distribution of gravity fed sediments through along-slope continuous currents, and study the depositional and erosional geometries of these deep-ocean features as well as lead to more exciting research.