Sedimentary processes in the Discovery Gap (Central–NE Atlantic): An example of a deep marine gateway
Metadata
Show full item recordEditorial
Elsevier
Materia
Deep-water sedimentation Bottom currents Paleocirculation Antarctic bottom water Contourites Deep marine gateways Discovery gap Central-NE Atlantic
Date
2021-11-29Referencia bibliográfica
T. Glazkova... [et al.]. Sedimentary processes in the Discovery Gap (Central–NE Atlantic): An example of a deep marine gateway, Deep Sea Research Part I: Oceanographic Research Papers, Volume 180, 2022, 103681, ISSN 0967-0637, [https://doi.org/10.1016/j.dsr.2021.103681]
Sponsorship
Spanish Government CGL2015-66835-P PID2019-104625RB-100; FEDER Andalucia B-RNM-072-UGR18; Junta de Andalucia P18-RT-4074; SCORE projects CGL2016-80445-R; Russian Science Foundation (RSF) 19-1700246Abstract
Paleoceanographic studies of abyssal bottom currents are often complicated by low current speeds and sedimentation
rates, resulting in sediment condensation or erosion. However, increased rates of erosion and deposition
may occur where bottom current velocities change as they pass through deep marine gaps and gateways.
Despite this, the depositional processes in these gateways and their paleoceanographic implications remain
poorly understood. Based on new sedimentological, hydrological and geophysical (high resolution seismic and
bathymetry) data from Discovery Gap (Azores–Gibraltar Fracture Zone) collected during the 43rd cruise of the R/
V Akademik Nikolaj Strakhov in 2019, the key sedimentary processes occurring in the Late Quaternary have been
determined. Two depressions with depths exceeding 5300 m in the centre and south of Discovery Gap have been
identified, the latter filled with contouritic deposits. These depressions are separated by a roughly N–S trending
central sill at 4860 m and a sediment filled terrace at 4720 m water depth. Elongated NE–SW trending highs and
sills, are present in the north and south of the study area. Their importance in controlling the flow of water
through Discovery Gap is determined by the presence of erosion at the base of these highs with adjacent sheeted
or mounded contourite drifts. Pelagic, hemipelagic, reworked pelagic/hemipelagic and fine-grained contourite
sedimentary facies have been identified. The sedimentary facies associations point to remarkable variability in
the Antarctic Bottom Water (AABW), linked to glacial–interglacial changes, and its intermittent influence in
Discovery Gap during the Quaternary. During glacial intervals (MIS 6, 4 and 2) and at their terminations there
was enhanced bottom current activity coeval with higher terrigenous content, and increased carbonate dissolution.
The results of this study improve our understanding of sedimentary processes in abyssal environments and
highlight the value of the sedimentary record in deep marine gateways for interpreting the interaction of bottom
water with abyssal morphology. Future work in other modern deep gaps is essential to shed more light on how
deep gaps form and to fully reconstruct deep-water paleocirculation within oceanic basins.