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The
Guadalfeo turbidite system in the North Alboran Sea, SW Mediterranean Sea,
is composed of two sub-systems termed System A (also called the Calahonda
Turbidite System) and System B (also named the Sacratif Turbidite System).
(Click here to see schematic map).
System
A is defined by four relatively small canyons (termed V1 to V4), ten channel-levee
complexes and one channelised lobe. System B is characterised by two larger
canyons (called the Eastern and Western canyons), two channel-levee complexes
and one channelised lobe. The recent depositional architecture of both
systems has been governed by lateral and longitudinal migrations.
Recent
sedimentologcal studies (textural analysis, analysis of carbonate content
and sand fraction composition) of 18 gravity cores up to three metres long
have allowed us to define five sedimentary facies within the Guadalfeo
Turbidite System: these are canyon, intercanyon, channel, levee, and channelised
lobe facies. The canyon facies consists of fining-upward
successions from spill-over gravels and sands to turbidite sands and silts
(Ta, Tb, and Tc Bouma divisions), with dispersed patches of biogenic debris.
The intercanyon facies is also defined by fining upward sequences
from spill-over gravels and sands to turbidite sands (Tb). |
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The
channel facies is characterised by alternating intervals of turbidite
sands and silts (Ta, Tb, Tc and Td Bouma divisions), and turbidite sands
(Ta and Tb divisions) and debris flow silts. The levee facies comprises
fining-upward successions from turbidite sands to turbidite silts (Tc and
Td Bouma divisions). The channelised lobe facies contains successions
of turbidite sands and silts (Tb and Tc), and turbidite silts and muds
(Td and Te) alternating with thin intervals of hemipelagic mud.
The spatial and temporal
distribution of the recent sedimentary facies suggest that the development
of System A has been controlled by deposition from turbidity currents
and debris flows in a first phase, and by hemipelagic and low-density turbidity
currents in a second phase. System B has been dominated by spill-over processes
and turbidity current deposition. The occurrence of these processes suggests
that system B is presently active whereas within System A, the sedimentary
activity has decreased with time.
If you require further
information please contact:
Belén Alonso,
Instituto de Ciencias del Mar, CSIC - belen@icm.csic.es
Gemma Ercilla, Instituto
de Ciencias del Mar, CSIC gemma@icm.csic.es |
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