SCARP PROJECT

Canyon and landslide processes of non-tropical carbonate escarpments

The majority of continental margins may be classified as either siliclastic or carbonate. Despite forming some of the largest cliffs on Earth, carbonate slopes are poorly understood features, and the few studies available have been carried out in tropical settings. An improved understanding of non-tropical carbonate slopes is necessary because: (i) they comprise more than half of carbonate slopes worldwide, (ii) they are characterised by very different geological and oceanographic conditions compared to tropical carbonate slopes, (iii) their occurrence in the stratigraphic record is relatively common, (iv) they offer a unique record of past environmental conditions, and (v) they host geohazards, hydrocarbon reservoirs and potentially specialised biological communities.

The aim of SCARP is to characterise the morphology of non-tropical carbonate escarpments in unprecedented detail, investigate the nature and dynamics of canyon and landslide processes responsible for this morphology, understand their role in sediment export and non-tropical carbonate margin development, and determine whether they are significantly different from those of siliclastic and tropical carbonate margins elsewhere.

SCARP will entail the integration of diverse geophysical and sedimentological datasets acquired from the Malta-Sicily Escarpment (Mediterranean Sea) during a number of research cruises, and their analyses using innovative data processing, numerical and statistical techniques, and state-of-the-art sedimentological, geotechnical, and geochoronological methods.

Relevance: An improved understanding of non-tropical carbonate slopes is necessary because: (i) they comprise more than half of carbonate slopes worldwide, (ii) the occurrence of carbonate escarpments in the stratigraphic record is relatively common, (iii) carbonate slopes offer a good record of past environmental conditions, and (iv) they host geohazards, vast hydrocarbon reservoirs and potentially specialised biological communities.

Questions: Two geomorphological elements of continental margins – submarine canyons and landslides – deserve particular attention because of their scale, ubiquity, and the key role they play in transferring sediment and nutrients across continental slopes into deep-water settings.


SCARP PROJECT – FP7:

Marie Curie Career Integration Grant

In spite of their relevance and widespread distribution, the processes leading to the origin and development of canyons are still subject to considerable debate. Their study has always been a challenge due to their complicated morphology and extreme terrain. The best known examples of modern canyons and their ancient counterparts correspond to siliclastic systems. In comparison, studies of modern and ancient carbonate canyons are relatively scarce.

These studies show that canyons incising carbonate escarpments are generally broad and U shaped, with steep amphitheatre heads that have evolved by retrogressive erosion associated with slope instability and density cascading. Fundamental questions still remain about what determines a carbonate canyon to form in a given place, what are the characteristic large- to fine-scale morphologies, and what are the processes and timings involved in the activity, sediment transport dynamics and evolution of canyons incising carbonate escarpments.

In recent years, significant advances have been made in the characterisation and explanation of submarine landslides, but these studies, as for canyons, have mainly focused on siliclastic margins. Because the offshore catalogue of slope failures and their recurrence rates is incomplete, our knowledge of carbonate landslide occurrence is still crude and our ability to estimate the hazard from submarine slope failures is rather low. The few studies carried out in carbonate margins have shown that slope instability can occur as translational/rotational slides, rock falls, debris flows and avalanches, which seem to be triggered by undercutting currents, sea level fluctuations,

Below are links to social media related to CUMECS-2, an oceanographic cruise supported by SCARP in 2014. These links include posts, photographs and videos from the cruise:

https://www.facebook.com/cumecs2

http://cumecs2.blogspot.com/

faulting and seismicity.

We still lack thorough understanding of the geometry, downslope evolution and frequency-magnitude characteristics of submarine landslides on carbonate escarpments, and the role they play in carbonate canyon evolution.

Objectives

SCARP is a research project that will characterise the morphology of non-tropical carbonate escarpments in unprecedented detail, investigate the nature and dynamics of canyon and landslide processes responsible for their morphology, determine their role in sediment export and development of non-tropical carbonate slopes, and understand whether these are significantly different from those of siliclastic and tropical carbonate margins.

The specific objectives of SCARP are:

  • To compile a global geodatabase of submarine canyons and carbonate slope failures, and identify the sources of variations in canyon and landslide distribution, morphology and processes between (i) siliclastic and carbonate margins, and (ii) tropical and non-tropical carbonate slopes.
  • To determine the nature, origin, timing, frequency and extent of processes responsible for submarine canyon development and activity in non-tropical carbonate escarpments.
  • To understand the geometry, nature, pre-conditioning factors, triggers, timing, frequency, extent, and emplacement processes of submarine landslides in non-tropical carbonate escarpments.
  • To develop a spatio-temporal model that highlights the stages, timings and drivers of the evolution of non-tropical carbonate escarpments.

To fulfil these objectives, SCARP will investigate the Malta-Sicily Escarpment (MSE): The MSE is the dominant physiographic element in the central Mediterranean Sea and the principal study area of SCARP. Consisting of a steep, NNW-SSE trending slope that extends southwards from the east coast of Sicily, the escarpment is 250 km long and has a vertical relief of almost 4 km. The MSE is the expression of a passive margin separating the continental crust of the Malta Plateau from the oceanic crust of the Ionian Basin. The age of the MSE remains controversial, with estimates ranging from Late Triassic to Early Cretaceous. Triassic-Neogene shallow-water to basinal carbonate sequences outcrop along the escarpment. The MSE incorporates extensional block faulting and sinistral strike-slip deformation as a result of the different rates of underthrusting between the buoyant Malta Plateau and the Ionian crust. The role of submarine canyons and slope instability in the overall evolution of the MSE is not well-understood. A series of submarine canyons has been mapped from bathymetric data acquired in the late 1970s. Landslide activity across the MSE has mainly been inferred from sediment cores, with turbidites, megaturbidites and debris flows being reported from the base of the MSE. The MSE is a sediment-starved margin (at least since the Messinian), with an estimated post-Messinian sedimentation rate of ~6 cm ka-1, and is characterised by the interplay of numerous processes, such as fluid flow and contouritic deposition.

If you have any questions or would like to request any specific information about this project, please send an email to:

aaron.micallef@um.edu.mt