The projects EMeRG undertakes are supported by four main pillars of research:
- Fluid flow
- Salt tectonics
- Regional tectonics
- Erosional and depositional processes
1. Fluid flow
In the context of EMeRG’s research, fluid flow refers to the primarily upwards migration of fluids (pore water and gas) through the subsurface. Interpreting evidence of fluid flow in seismic reflection data allows the interpretation of various root, migration, storage and outlet components that when analysed holistically combine to build the basins ‘hydrocarbon plumbing system’.
Conceptual diagram illustrating the different types and context of focused fluid flow features in the main sub-basins of the Eastern Mediterranean (from Bertoni et al., 2017).
Interpretation of the basins hydrocarbon plumbing system is important for our understanding of:
- Petroleum systems – secondary hydrocarbon migration can be important in identifying and de-risking prospects.
- Overpressure – interpreting palaeo overpressure release events associated with regional drivers and identifying regions of potentially hazardous present day overpressure.
- Seal integrity – evaluating the seal-breach risk and the circumstances under which the Messinian salt is bypassed.
The seismic expression of a pipe-like mud volcano conduit (C) that roots to a crest at the base of the salt (N) and extends to a seafloor mud volcano (MV) (from Kirkham et al., 2018).
2. Salt tectonics
The offshore Mediterranean is underlain by a thick and aerially extensive unit of evaporites deposited during the Messinian Salinity Crisis. Under gravitational and tectonic forces salt deforms over geological time having a dramatic impact on basin architecture and the surface morphology. Analysing how the salt in the Mediterranean has deformed is important for basin reconstruction, interpretation of deformations associated with leakage pathways through the salt, pre-salt plays and our understanding or changes in thermal gradient and pre-salt overpressure.
Map of the structural domains and features along the Levant Margin associated with deformation on the Messinian evaporites, interpreted from regional seismic reflection data (from Cartwright et al., 2008).
A new branch of salt tectonics analysis employed by EMeRG involves interpreting the relationship between fluid flow features and salt. It has recently been demonstrated that fluids flow features that transect the Messinian salt can be interpreted in 3D seismic reflection data and present natural strain markers for its deformation. Through this novel method we have shown that it is possible to obtain several fundamental details about deforming salt sheets including flow direction, cumulative strain, average flow velocity and viscosity.
3D visualization of a linear trail of fluids escape pipes and pockmarks in the Levant Basin, formed by hydraulic fracturing through the salt and displaced from above the pre-salt leakage point by the flow of the salt (from Cartwright et al., 2018).
3. Regional tectonics
The Mediterranean is a region of active convergence between the African and Arabian continents in the south, and Eurasia in the north. Various stages in the closure of the Oceanic basin are present within the Mediterranean region, leading to a widespread and varied record of faulting related to continental collision, both thin and thick-skinned crustal deformation, as well as Oceanic subduction. The distribution and styles of faulting have played important roles in controlling sediment sources in adjacent mountain ranges, accommodation space in the deep and shallow basins, and the routing of sediment between source and sink. The active faulting also constitutes a substantial and widespread source of natural hazards.
Our aim in EMeRG is to unravel the distribution, evolution, and present-day behaviour of the active tectonics and faults of the Mediterranean by combining expertise, observations, and techniques from both onshore and offshore realms. Many of our tectonic studies of the Mediterranean are from onshore regions, and combine remote-sensing and field investigation of active faults and earthquakes around the Mediterranean margins We have had a particular focus on the lands east of the Mediterranean, which are defined by the continental collision of Arabia and Eurasia, and the formation of widespread fold-and-thrust belts combined with major through-going zones of strike-slip deformation. We have worked extensively in the collisional belts of Iran, and have field experience in the Levant, Turkey, Cyprus, Greece and Italy.
A particular challenge in the study of natural hazards in the Mediterranean is that many of the active faults are underwater, and their potential for failure in earthquakes cannot be assessed using standard field-based techniques. It is likely that numerous faults exist within the Mediterranean, with intervals of thousands of years between successive ruptures on each. This means that instrumental catalogues, and even the relatively long historical records that exist in this part of the world, are insufficient to identify the full distribution of potentially hazardous faults. Several devastating tsunamis are recorded in Mediterranean history, (e.g. in 365CE, 551CE, 1303CE), which, if repeated in the modern setting, would have widespread destructive effects.
In a project funded by the Leverhulme Trust we are using high-quality industrial seismic data to map and characterise active faults across the Mediterranean basin, and to assess whether those faults break the sea-floor – in which case they constitute particular tsunami hazard. This project is titled NEPTUNE (Neotectonics, Earthquakes, Palaeoseismology & Tsunami in the Eastern Mediterranean). Our current foci for this work is in the offshore Levant and Cyprus, and also in the Western Mediterranean offshore Spain. We aim, eventually, to extend the project across the central Mediterranean, Aegean, and North African coast.
4. Erosional and depositional processes
The Messinian Salinity Crisis and associated erosional and depositional processes in the Eastern Mediterranean are prominent research topics in our group. In the late Miocene, the Salinity Crisis led to the deposition of vast evaporite deposits in the Mediterranean, in a variety of tectonic configurations. In the Eastern Mediterranean we observe the infill of depocentres with salt in the deep basin, and widespread erosional surfaces, both at the margins and within the Salinity Crisis sedimentary sequences (Bertoni et al., 2006). Dissolution plays also an important part in this system (Bertoni et al., 2005).
3D visualisation of a collapse structure (CS1) in the Levant Basin, formed by submarine dissolution of buried Messinian evaporites. The source of undersaturated and vertically focused fluids is in sediment pockets within the underlying Afiq Canyon. A feedback effect among fluid circulation, salt dissolution and deformation can enhance pathways, forming features such as dissolution moats at the evaporitic basins edge (linear depression). TES – Top erosional surface; BES – Base erosional surface; Me20 – Intra-salt horizon (Bertoni & Cartwright 2005).
Within the Neptune project, we study the interaction of active convergence with evaporite deposition, through the analysis of syn-depositional deformation and sediment supply into the Levant-Nile area during the late Miocene. This sediment/tectonics interaction is reflected in the depositional patterns of three large river systems that dominated sediment supply at that time: Nile, Nahr Menashe and Eo-Sahabi.
Compiled from proprietary research, and Madof et al. (2019), Lofi et al. (2019), Aal et al. (2000), Bowman (2012), Fiduk (2009), Radeff et al,( 2017).
The Nahr Menashe (Madof et al., 2019) extends for >300km into the deep Levant basin and was comparable in size to the Nile system, its catchment being located in the north/eastern hinterlands. This river system provided a source of terrestrially derived clastic sediments into the deep Levant basin, in addition to the Nile River and coeval to the Abu Madi Fm. The top-salt Nahr Menashe developed within a relatively short time window (5.55-5.33 My) and therefore it can be used as a time-marker, and as a tool to understand the relative timing of anticline development and thrust faulting in the area. The complex plate tectonic configuration of the region, at the intersection between the Dead Sea Fault System, the Cyprus arc and Anatolian fault zone, strongly influenced the sediment routing and the thickness of the Nahr Menashe fluvial deposit, up the most distal parts of the Levant basin (Bertoni et al. 2019, EAGE).
A: Thickness map of the Nahr Menashe (green shaded areas, see Figure 1), of the salt (brown shaded areas, see Figure 1) and tectonic lineaments from Maillard et al. (2011). Thick black lines: main thrusts, thick red lines: folds at horizons IES, BES and TES. B: Seismic section showing examples of confined Nahr Menashe (between horizons BES and TES) in the eastern part of the Latakia Ridge. UC: Upper Cretaceous. C: Seismic section showing unimpeded Nahr Menashe (between horizons IES and TES) on the crest of anticlines/thrusts in the western part of the Latakia Ridge (Bertoni et al. 2019, EAGE).