Content uploaded by Sara Rodrigues
Author content
All content in this area was uploaded by Sara Rodrigues on Oct 30, 2020
Content may be subject to copyright.
Sedimentary Model for Mixed Depositional Systems: Conceptual Implications
1
Sara Rodrigues1*, F. Javier Hernández-Molina1, Renata Giulia Lucchi2, Robert Larter3, Claus-
2
Dieter Hillenbrand3, Michele Rebesco2, Karyna Rodriguez4, Neil Hodgson4
3
1 Department of Earth Sciences, Royal Holloway University of London, Egham Surrey, TW20 0EX, UK,
4
*Sara.Rodrigues.2017@live.rhul.ac.uk
5
2 Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Borgo Grotta Gigante, Trieste, 42/c
6
34010, Italy.
7
3 British Antarctic Survey, High Cross Madingley Road, Cambridge, CB3 0ET, UK.
8
4 Spectrum Geo Ltd, Dukes Court, Duke Street, Woking Surrey, GU21 5BH, UK.
9
10
Along- and down-slope processes are fairly common processes along continental margins. The
11
aforementioned processes and their interaction can build large mixed / hybrid (turbiditic-contouritic)
12
depositional systems. These systems are characterized by a variability and complexity of features.
13
Globally, several mixed systems have been identified on the Cenozoic, however their representation in
14
the Mesozoic remains severely understated. This issue is aggravated if we consider that the diagnostic
15
criteria for mixed systems is not fully defined and, therefore, not used to improve the examples already
16
described in the literature.
17
This work aims to contribute to a better understanding of the dynamics between along- and down-
18
slope processes, by identifying significant modifications in physiographic features and stacking
19
architectures, and by discriminating the mechanisms responsible for the formation of each feature and
20
how they operate through time. To approach these objectives, we are studying two key areas: 1) a
21
modern example on the Pacific Margin of the Antarctic Peninsula, characterized by a remarkable
22
depositional system with several contourite mounded drifts and turbidite channels in the continental
23
lower slope and continental rise; and 2) the Cretaceous record on the Argentine Margin, which
24
comprises an extensive mixed system on the continental slope. This study is based on a compilation of
25
swath multibeam bathymetry, high- and low-resolution seismic reflection datasets, well borehole data
26
and sediment cores.
27
The two examples share similar downslope elongated mounds along the lower slope and rise with
28
asymmetric morphologies, marked by a smooth, aggradational side and a steep, eroded side with signs
29
of mass movements. However, while the Antarctic Peninsula has a dendritic network of gullies and
30
channels on the upper continental slope that converge into single turbidite channels on the lower slope
31
and rise, the Argentine Margin is characterized by individual large channels that start at the continental
32
shelf / upper slope and cut through the topography. The interpretation and integration of these results
33
aims to propose a conceptual model for depositional mixed systems that will clarify the role and
34
influence of bottom currents versus turbidity currents.
35
36