Abstract:Submarine fans are important components of continental margins; they contain a stratigraphic record of environmental changes and host large accumulations of oil and gas. The grain size and volume of sediment supply to fans is thought to control the heterogeneity of deep-water deposits; predicting spatial variability of sandy and muddy deposits is an important applied challenge in the characterization of fans. Here, we use DionisosFlow stratigraphic-forward models to evaluate the sensitivity of submarine-fan de… Show more
“…3 | DATASETS AND METHODOLOGY 3.1 | DionisosFlow forward stratigraphic model DionisosFlow software is a 4-D process-based deterministic multi-lithology forward stratigraphic model that simulates the first-order evolution of depositional systems at the spatial scale of 10 2 -10 3 m and temporal resolution of 10 3 -10 5 yr (e.g. Granjeon, 2014;Hawie et al, 2019). For each time step, DionisosFlow is able to numerically calculate three main physical processes, namely the creation of accommodation space (i.e.…”
Section: Middle Miocene Pearl River Delta-tofan S2s Couplingmentioning
confidence: 99%
“…where Q s is the sediment discharge (km 3 /Myr); K s and K w are, respectively, the gravity-and water-driven diffusion coefficients (km 2 /kyr); Q w is the water discharge (m 3 /s); n and m are exponents that affect sediment transport capacity related to slope-and water-driven transport, with values ranging from 1 to 2 (Tucker & Slingerland, 1994); h is the topographic elevation (m); �� ⃗ ∇ h is the local topographic gradient or slope (dimensionless) (Harris et al, 2020); and S is the dimensionless gradient of the basin (Granjeon, 2014). All of these sediment-transport input values are listed in Table 1, and were also utilized in many other DionisosFlow forward stratigraphic experiments (Harris et al, 2016(Harris et al, , 2018(Harris et al, , 2020Hawie et al, 2018Hawie et al, , 2019.…”
Section: D Seismic Data and Boreholesmentioning
confidence: 99%
“…DionisosFlow 3D stratigraphic forward model is widely used to explore the interplay of geological factors related to the volume and architecture of depositional systems (e.g. tectonism, sea level, water and sediment supply) (Harris et al, 2016(Harris et al, , 2018(Harris et al, , 2020Hawie et al, 2018Hawie et al, , 2019. It has been employed herein to explore physical and conceptual linkages of delta to deep-water fan systems and their role in the modulation of deep-water sand delivery beyond the shelf edge.…”
Section: Middle Miocene Pearl River Delta-tofan S2s Couplingmentioning
confidence: 99%
“…Irrespective of what brings the delivery system to a shelf-edge position and whether accommodation, supply or shelf-edge process regime is the more influential, it is by no means guaranteed that shelf-edge deltaic sands will automatically pass down to toe-of-slope submarine fans (e.g. Dixon et al, 2012;Fisher et al, 2021;Hawie et al, 2019;Kim et al, 2013) (Figure 1). There remains significant uncertainty and debate regarding the transport, erosion and deposition of when and how terrestrial sands are delivered into deepwater (e.g.…”
We propose that a more readily studied, secondary source-to-sink (S2S) systems can be formed on direct-fed margins, in which shelf-edge deltas are 'sources' and deep-water fans are terminal depositional 'sinks', with channels working as delivery 'conduits' in between. DionisosFlow stratigraphic-forward model, coupled to seismic and borehole data from middle Miocene Pearl River margin, are used to explore physical and conceptual linkages of delta-to-fan S2S systems, with a focus on the predictability of when and how coarse clastics are delivered from the deltas down to the submarine fans. Middle Miocene Pearl River delta-to-fan S2S coupling was stratigraphically enacted in three main ways: (a) deltas that lack downdip fans: high sea level or low sediment supply caused coarse clastics to be stored mainly on inner to outer shelf areas; (b) deltas that are linked downdip to fans: coarse clastics were funneled to submarine fans through slope channels, via direct delta-to-fan S2S linkages created by delta overreach at shelf break or channels extending back to shelf-margin prodeltas; (c) fans that lack updip, coeval deltas: coarse shelf clastics were carried laterally by longshore or other shelf currents, but eventually captured by canyon heads, and then delivered directly to the basin floor. Moreover, our DionisosFlow stratigraphic-forward models suggest that an oscillation in sea-level behaviour from slowly falling to rapidly falling would result in a within-system tract surface occurring within the falling-stage systems tract. This surface is identified as a significant lower-order unconformity in its proximal reaches and as a correlative conformity distally. Within-system tract surfaces are identified by a change in shelfedge trajectory regimes from flat to slight falling to moderately falling and in architecture from mixed progradation and degradation to dominant degradation. They are coeval with the onset of the deposition of submarine fans linked updip to deltas or lacking updip deltas, highlighting that sandy deposits can be compartmentalized even within a single systems tract.
K E Y W O R D Sdelta-to-fan S2S coupling, forward stratigraphic model, sequence stratigraphy, source-to-sink system, within-system tract surface F I G U R E 1 (a) Topographic map showing the geographical location and context of the Pearl River S2S systems and map-view locations of seismic lines shown in Figures 1b and 2. Larger study area signifies the domain of DionisosFlow forward numerical modelling (white box). (b-d) Depositional dip-oriented seismic transects and borehole data showing cross-sectional seismic manifestations and lithologies of late Quaternary Pearl River delta-to-fan S2S linkages. T dr and T dp are two basinwide unconformities interpreted to have formed during the middle Pleistocene marine oxygen isotope stage (MIS) 20 (814 ka) and MIS 12 (478 ka) periods of the most pronounced sea-level fall, respectively (see Gong et al., 2018 for full details) F I G U R E 3 (a) Regional seismic line (see line location in Figure 2) a...
“…3 | DATASETS AND METHODOLOGY 3.1 | DionisosFlow forward stratigraphic model DionisosFlow software is a 4-D process-based deterministic multi-lithology forward stratigraphic model that simulates the first-order evolution of depositional systems at the spatial scale of 10 2 -10 3 m and temporal resolution of 10 3 -10 5 yr (e.g. Granjeon, 2014;Hawie et al, 2019). For each time step, DionisosFlow is able to numerically calculate three main physical processes, namely the creation of accommodation space (i.e.…”
Section: Middle Miocene Pearl River Delta-tofan S2s Couplingmentioning
confidence: 99%
“…where Q s is the sediment discharge (km 3 /Myr); K s and K w are, respectively, the gravity-and water-driven diffusion coefficients (km 2 /kyr); Q w is the water discharge (m 3 /s); n and m are exponents that affect sediment transport capacity related to slope-and water-driven transport, with values ranging from 1 to 2 (Tucker & Slingerland, 1994); h is the topographic elevation (m); �� ⃗ ∇ h is the local topographic gradient or slope (dimensionless) (Harris et al, 2020); and S is the dimensionless gradient of the basin (Granjeon, 2014). All of these sediment-transport input values are listed in Table 1, and were also utilized in many other DionisosFlow forward stratigraphic experiments (Harris et al, 2016(Harris et al, , 2018(Harris et al, , 2020Hawie et al, 2018Hawie et al, , 2019.…”
Section: D Seismic Data and Boreholesmentioning
confidence: 99%
“…DionisosFlow 3D stratigraphic forward model is widely used to explore the interplay of geological factors related to the volume and architecture of depositional systems (e.g. tectonism, sea level, water and sediment supply) (Harris et al, 2016(Harris et al, , 2018(Harris et al, , 2020Hawie et al, 2018Hawie et al, , 2019. It has been employed herein to explore physical and conceptual linkages of delta to deep-water fan systems and their role in the modulation of deep-water sand delivery beyond the shelf edge.…”
Section: Middle Miocene Pearl River Delta-tofan S2s Couplingmentioning
confidence: 99%
“…Irrespective of what brings the delivery system to a shelf-edge position and whether accommodation, supply or shelf-edge process regime is the more influential, it is by no means guaranteed that shelf-edge deltaic sands will automatically pass down to toe-of-slope submarine fans (e.g. Dixon et al, 2012;Fisher et al, 2021;Hawie et al, 2019;Kim et al, 2013) (Figure 1). There remains significant uncertainty and debate regarding the transport, erosion and deposition of when and how terrestrial sands are delivered into deepwater (e.g.…”
We propose that a more readily studied, secondary source-to-sink (S2S) systems can be formed on direct-fed margins, in which shelf-edge deltas are 'sources' and deep-water fans are terminal depositional 'sinks', with channels working as delivery 'conduits' in between. DionisosFlow stratigraphic-forward model, coupled to seismic and borehole data from middle Miocene Pearl River margin, are used to explore physical and conceptual linkages of delta-to-fan S2S systems, with a focus on the predictability of when and how coarse clastics are delivered from the deltas down to the submarine fans. Middle Miocene Pearl River delta-to-fan S2S coupling was stratigraphically enacted in three main ways: (a) deltas that lack downdip fans: high sea level or low sediment supply caused coarse clastics to be stored mainly on inner to outer shelf areas; (b) deltas that are linked downdip to fans: coarse clastics were funneled to submarine fans through slope channels, via direct delta-to-fan S2S linkages created by delta overreach at shelf break or channels extending back to shelf-margin prodeltas; (c) fans that lack updip, coeval deltas: coarse shelf clastics were carried laterally by longshore or other shelf currents, but eventually captured by canyon heads, and then delivered directly to the basin floor. Moreover, our DionisosFlow stratigraphic-forward models suggest that an oscillation in sea-level behaviour from slowly falling to rapidly falling would result in a within-system tract surface occurring within the falling-stage systems tract. This surface is identified as a significant lower-order unconformity in its proximal reaches and as a correlative conformity distally. Within-system tract surfaces are identified by a change in shelfedge trajectory regimes from flat to slight falling to moderately falling and in architecture from mixed progradation and degradation to dominant degradation. They are coeval with the onset of the deposition of submarine fans linked updip to deltas or lacking updip deltas, highlighting that sandy deposits can be compartmentalized even within a single systems tract.
K E Y W O R D Sdelta-to-fan S2S coupling, forward stratigraphic model, sequence stratigraphy, source-to-sink system, within-system tract surface F I G U R E 1 (a) Topographic map showing the geographical location and context of the Pearl River S2S systems and map-view locations of seismic lines shown in Figures 1b and 2. Larger study area signifies the domain of DionisosFlow forward numerical modelling (white box). (b-d) Depositional dip-oriented seismic transects and borehole data showing cross-sectional seismic manifestations and lithologies of late Quaternary Pearl River delta-to-fan S2S linkages. T dr and T dp are two basinwide unconformities interpreted to have formed during the middle Pleistocene marine oxygen isotope stage (MIS) 20 (814 ka) and MIS 12 (478 ka) periods of the most pronounced sea-level fall, respectively (see Gong et al., 2018 for full details) F I G U R E 3 (a) Regional seismic line (see line location in Figure 2) a...
“…Coarse-and fine-grained sediments began to be deposited in the slope area and formed the basin floor fan orientated from a southwest to northeast direction, possibly during the mid-Middle Eocene. Coarse-grained sediments were transported and deposited when the energy decreased at the proximal fan, while fine-grained sediments were transported to the distal fan (e.g., Hawie et al, 2019).…”
Globally, a wide range of pockmarks have been identified onshore and offshore. These features can be used as indicators of fluid expulsion through unconsolidated sediments within sedimentary basin-fills. The Great South Basin, New Zealand, is one such basin where paleo-pockmarks are observed at around 1,500 m below the seabed. This study aims to describe the characteristics of paleo-pockmarks in the Great South Basin. Numerous paleo-pockmarks are identified and imaged using three-dimensional seismic reflection data and hosted by fine-grained sediments of the Middle Eocene Laing Formation. The paleo-pockmarks are aligned in a southwest to northeast direction to form a fan-shaped distribution with a high density of around 67 paleo-pockmarks per square kilometre in the centre of the study area. The paleo-pockmarks in this area have a similar shape, varying from sub-rounded to a rounded planform shape, but vary in size, ranging from 138 to 481 m in diameter, and 15–45 ms (TWT) depth. The origin of the fluids that contributed to the paleo-pockmark formation is suggested, based on seismic observations, to be biogenic methane. The basin floor fan deposits beneath the interval hosting the paleo-pockmark might have enhanced fluid migration through permeable layers in this basin-fill. This model can help to explain pockmark formation in deep water sedimentary systems, and may inform future studies of fluid migration and expulsion in sediment sinks.
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