TY - JOUR
T1 - Sedimentary model for mixed depositional systems along the Pacific margin of the Antarctic Peninsula
T2 - decoding the interplay of deep-water processes
AU - Rodrigues, Sara
AU - Hernández-Molina, F. J.
AU - Larter, Robert
AU - Rebesco, Michele
AU - Hillenbrand, Claus-Dieter
AU - Lucchi, Renata
AU - Rodríguez-Tovar, Francisco J.
PY - 2022/3
Y1 - 2022/3
N2 - Mixed depositional systems offer potential new findings on the interplay of deep-water processes. An evaluation of their morphological elements and their lateral and spatial distribution is crucial to decode the interplay of depositional processes, involving along-slope bottom currents and down-slope turbidity currents. This work investigates extensive and still active mixed depositional systems developed along the Pacific margin of the Antarctic Peninsula, which comprise large asymmetric mounded drifts, dendritic channel-complex systems and wide trunk channels. These systems offer a unique setting to investigate diverse morphological elements at a high-resolution scale, using multibeam bathymetry and acoustic sub-bottom profiles. Four main seismic units define distinct evolutionary stages for the Pleistocene to present day record: a) 1.3 – 1 Ma, characterized by aggradational mounded drifts built by a dominant along-slope bottom current; b) 1 – 0.6 Ma, built by synchronous interactions between a SW-flowing bottom current and NW-directed turbidity currents; c) 0.6 – 0.2 Ma, characterized by deposition of thick gravitational deposits across the margin under a weak SW-flowing bottom current comprising the Lower Circumpolar Deep Water (LCDW); and d) 0.2 Ma – present, when synchronous interactions between the bottom current, characterized by flow speed fluctuations, and ephemeral turbidity currents led to intercalations of turbidites, contourites, reworked turbidite deposits and hemipelagites. Alternations in the stratigraphic stacking pattern suggest cyclic spatial and temporal variations of gravity-driven down-slope processes and along-slope bottom currents, which were responsible for the construction of these modern mixed depositional systems and which themselves were controlled by glacial-interglacial changes. The present results are compared with similar mixed depositional systems to decode the main processes involved in their formation, explore their interactions at short- and long-term time scales, and propose a conceptual sedimentary model.
AB - Mixed depositional systems offer potential new findings on the interplay of deep-water processes. An evaluation of their morphological elements and their lateral and spatial distribution is crucial to decode the interplay of depositional processes, involving along-slope bottom currents and down-slope turbidity currents. This work investigates extensive and still active mixed depositional systems developed along the Pacific margin of the Antarctic Peninsula, which comprise large asymmetric mounded drifts, dendritic channel-complex systems and wide trunk channels. These systems offer a unique setting to investigate diverse morphological elements at a high-resolution scale, using multibeam bathymetry and acoustic sub-bottom profiles. Four main seismic units define distinct evolutionary stages for the Pleistocene to present day record: a) 1.3 – 1 Ma, characterized by aggradational mounded drifts built by a dominant along-slope bottom current; b) 1 – 0.6 Ma, built by synchronous interactions between a SW-flowing bottom current and NW-directed turbidity currents; c) 0.6 – 0.2 Ma, characterized by deposition of thick gravitational deposits across the margin under a weak SW-flowing bottom current comprising the Lower Circumpolar Deep Water (LCDW); and d) 0.2 Ma – present, when synchronous interactions between the bottom current, characterized by flow speed fluctuations, and ephemeral turbidity currents led to intercalations of turbidites, contourites, reworked turbidite deposits and hemipelagites. Alternations in the stratigraphic stacking pattern suggest cyclic spatial and temporal variations of gravity-driven down-slope processes and along-slope bottom currents, which were responsible for the construction of these modern mixed depositional systems and which themselves were controlled by glacial-interglacial changes. The present results are compared with similar mixed depositional systems to decode the main processes involved in their formation, explore their interactions at short- and long-term time scales, and propose a conceptual sedimentary model.
KW - mixed systems
KW - turbidite
KW - contourite
KW - sub-bottom profiles
KW - Antarctic Peninsula
KW - Quaternary record
KW - glacial-interglacial
U2 - 10.1016/j.margeo.2022.106754
DO - 10.1016/j.margeo.2022.106754
M3 - Article
SN - 0025-3227
VL - 445
JO - Marine Geology
JF - Marine Geology
M1 - 106754
ER -