The Golo Submarine Turbidite System (east Corsica Margin): Morphology And Processes Of Terrace Formation From High-resolution Seismic Reflection Profiles

The Golo submarine turbidite system (east Corsica margin):

morphology and processes of terrace formation

from high-resolution seismic reflection profiles

Received: 13 September 2002 / Accepted: 16 July 2003 / Published online: 2 September 2003

Springer-Verlag 2003

Abstract New high-resolution seismic reflection data

collected along the eastern margin of Corsica have

been analysed to describe the morphology of the turbidite

systems located seaward of the Golo River

mouth. The boomer data reveal that there is not only

one turbidite system directly associated with the river,

but four additional, non-coalescing systems which grew

simultaneously. In the south, the system has the typical

morphology of a turbidite deposit rich in mud and

sand with a well-developed meandering canyon and

channel morphology. In the north, they have the

morphology of sand-rich turbidite systems with shorter

straight channels. The southernmost deposits are

interpreted to represent a more advanced stage of

turbidite system development. Terraces, recognised by

their particular seismic facies on boomer profiles which

clearly differs from the surrounding levee facies, are

observed in the channel meanders. They are interpreted

as confined levees built by vertical accretion due

to deposition from low-energy flows. Despite limited

penetration, boomer seismics are demonstrated to be a

useful complement to lower-resolution sparker data.

The boomer data are superior (1) for the characterisation

of fine-grained turbidite deposits by extending

seawards the limits of the turbidite systems commonly

defined by the acoustic response of sands, (2) in

demonstrating the persistence of turbiditic processes

farther towards the basin, and (3) for proposing conceptual

models for the formation of terraces in fan

valleys.

Introduction

The three-dimensional structure of turbidite systems is

rarely observed in continuity in ancient turbidite systems.

Conversely, modern turbidite systems suitable for

the study of such 3D geometry usually lie in water depth

greater than 1,000 m, making data acquisition difficult.

In recent years, improvements in multibeam echosounding

and high- or very high-resolution seismic

techniques have added a new quality to the data, as a

result of which numerous investigations of modern turbidite

systems have been undertaken. The main objectives

were: (1) to define the global extent of turbiditic

systems and their morphology from the continental shelf

to the deep ocean, (2) to determine the physical processes

controlling their development, and (3) to compare

their structure and evolution with conceptual models

developed for the interpretation of ancient counterparts.

Turbidite systems may develop sandy channels and

lobes, and are thus considered to be good exploration

models for hydrocarbon reservoirs, in particular because

of their high connectivity and low heterogeneity

(Shanmugam and Moiola 1991).

Up to about 10 years ago, bathymetric, seismic and

sedimentologic data from the eastern margin of Corsica

were insufficient to allow an accurate definition of the

nature of the surficial sedimentary layers. Bathymetric

surveys using a multibeam echo-sounder during the

MESSIM cruise of the N/O Atalante in 1991 (for location

of study area see Fig. 1) for the first time provided

evidence of the presence of small turbidite systems, but

the data were not accurate enough to define their morphology

and structure in detail (Bellaiche et al. 1993).

These turbidite systems were found to be small (<20 km

in extent) and rich in sand. The small size of these

Geo-Mar Lett (2003) 23: 117–124

DOI 10.1007/s00367-003-0131-4

L. Pichevin Æ T. Mulder Æ B. Savoye Æ A. Gervais

M. Cremer Æ D. J. W. Piper

L. Pichevin (&) Æ T. Mulder Æ A. Gervais Æ M. Cremer

De´partement de Ge´ologie et Oce´anographie,

UMR 5805 EPOC, Universite´ Bordeaux 1,

Avenue des Faculte´ s, 33405 Talence cedex, France

E-mail: [e-mail]

B. Savoye

Ifremer, Centre de Brest, DRO/GM, BP70, 29280

Plouzane´