# Upwelling-driven reworking of a MTD's fine-grained plume: an example at the Cariaco Basin/Cariaco Gulf connection.

Iliana Aguilar, Christian Beck, Franck Audemard, Christian Crouzet, Pierre Sabatier, Anne-Lise Develle, Mohammed Boussafir, Corina Campos

► To cite this version:

Iliana Aguilar, Christian Beck, Franck Audemard, Christian Crouzet, Pierre Sabatier, et al. Upwelling-driven reworking of a MTD's fine-grained plume: an example at the Cariaco Basin/Cariaco Gulf connection. EGU General Assembly 2016, 2016, Vienne, Austria. hal-03551953

HAL Id: hal-03551953

https://hal.science/hal-03551953

Submitted on 2 Feb 2022

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_2.png" /></figure>

# Upwelling-driven reworking of a MTD's fine-grained plume: an example at the Cariaco Basin/Cariaco Gulf connection.

Iliana Aguilar (1), Christian Beck (1), Franck Audemard (2), Christian Crouzet (1), Pierre Sabatier (3), Anne-Lise Develle (3), Mohammed Boussafir (4), and Corina Campos (5)

(1) CNRS ISTerre, Savoie Mont Blanc University, Le Bourget du Lac, France (beck@univ-savoie.fr), (2) Venezuelan Foundation for Seismological Research / FUNVISIS, El Llanito, Caracas, Venezuela, (3) CNRS EDYTEM, Savoie Mont Blanc University, F-73376, Le Bourget du Lac, France, (4) Institut des Sciences de la Terre d'Orléans, CNRS / BRGM / Université d'Orléans, F-45071 Orléans Cedex, France, (5) Earth Sciences Department, Simón Bolívar University, Sartenejas, Caracas, Venezuela

The Cariaco Basin is a 1400 m-deep and 90 km-wide pull-apart basin, in the south-eastern corner of the Caribbean Sea. To the East, it is connected to the Cariaco Gulf, a 60 km-long, 15 km-wide, and 90 m-deep appendix. Both are E-W elongated and developed upon the south-eastern transform boundary of the Caribbean Plate, an active limit here mainly represented by the El Pilar Fault. The Gulf of Cariaco entrance is a 55 m-deep, and 5 km-wide sill mainly controlled by the large Manzanares River delta, which western foreset slope is facing the Basin's eastern edge. Within this connection area, two particular sedimentary processes have been previously documented:

1) strong seasonal upwelling responsible for the transfer of deep particulate organic matter from the Basin into the Gulf;

2) the recent occurrence, in the Basin, of a fine-grained suspension related to a submarine landslide; this event was detected after the 1997 Cariaco earthquake (Thunell et al., 1999; Lorenzoni et al., 2012) and was related to a slope failure of the Manzanares delta western foreset.

From short gravity cores retrieved in the Gulf, we analysed the last millennium of sedimentation (components, transport and settling processes) using classical proxies and physical properties. All parameters led to underline:

- a permanent mixed provenance of particulate Organic Matter in the main part of the Gulf: i) in situ and ii) allochtonous;

- the occurrence of coarse siliciclastic layers related to flooding from the southern edge of the Gulf;

- the occurrence of one peculiar fine-grained siliciclastic layer with a widespread distribution, dated around 1850 AD;

- an abrupt increase of open marine influence just after the above-mentioned layer.

Concerning the “background” permanent sedimentation, these results confirm the importance of upwelling through the connection between the Gulf and the Basin (transfer of the “allochtonous” O.M.). For the fine-grained siliciclastic “event”, we could discard a consequence of flooding from the Manzanares River. We rather envisage an upwelling-driven suspension brought from the Basin and dispersed into the Gulf. We tentatively relate the genesis of this peculiar load to a mechanism similar to what was described for the 1997 event.

A major earthquake-triggered tsunami occurred in 1853 in the concerned area, related to a MTD. We thus propose to correlate this peculiar layer with the 1853 event. Due to this earthquake and the associated tsunami, the upwelling transported fine-grained siliciclastics removed from the western slope of the Manzanares delta. Such a combination of a MTD-generated plume with the permanent upwelling may have occurred several times since the establishment of the connection during the post-MIS2 sea-level rise (Van Daele et al., 2011). The resulting specific layers may thus be used for paleo-earthquakes/paleo-tsunamis detection; furthermore, several major MTDs were imaged on high resolution seismic profiles across the concerned connecting area (Aguilar et al., 2015).

Ref.: Aguilar, I., et al., 2015. Comptes Rendus Geoscience, in press.

Lorenzoni, L., et al., 2012. Marine Geology, 307:105-110.

Thunell, R., 1999. Nature, 398:233-236.

Van Daele, M., et al., 2011, Marine Geology 279:37-51.