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Ichnological analysis of core and outcrop contourite facies: scientific and economic implications

Periodic Reporting for period 1 - ICON-SE (Ichnological analysis of core and outcrop contourite facies: scientific and economic implications)

Berichtszeitraum: 2019-03-01 bis 2021-02-28

Deep water dynamic causes different types of currents (e.g. internal waves, contour currents or deep-water bottom currents among others). All these currents erode and deposit sediments, generating complex depositional systems with a high interest in palaeoenvironment, palaeoceanography and hydrocarbon exploration. These deposits, are called in general terms as contourites and their study has undergone a huge development due to their abundance and importance, being considered as a very hot topic in palaeoceanography. However, they are still poorly understood and some controversial points about their recognition and differentiation from associated sediments remain unsolved. Large-scale contourites drifts can be easily identified based on seismic-reflection data, but their characterization is much more complicated when working at small-scale (outcrops or cores). For this purpose, bioturbation has been proposed as a potential criterion to differentiate contourites deposits from turbidites and hemipelagic/pelagic ones.
Bioturbation was firstly considered as a diagnostic criterion as contourites and mixed systems have significant macrobenthic trace-makers activity. Moreover, during the last years, one of the most used proxies in sedimentary basin to interpret palaeoenvironmental conditions and ocean/atmosphere dynamic is the ichnological analysis. Trace fossils reflect the trace-maker behaviour, recording modifications associated to environmental changes and, consequently being a powerful tool in palaeoenvironmental and palaeoecological studies. Moreover, analysis of bioturbation is also a powerful tool for hydrocarbon exploration as trace fossils can modify porosity and permeability of sediments,affecting the potential reservoir quality.
Considering the scarcity of ichnological studies in contourites, but evidencing the importance of bioturbation as a potential diagnostic criterion, the influence in porosity and permeability values and its economic interest, the ICON-SE project is focused, for the first time, on the detailed ichnological analysis of these deposits, with two main objectives:
1. Ichnological characterization of contourite deposits.
2. Determining the influence of trace fossils in hydrocarbon exploration and its economic implications.
The main purpose of this project is to explore the presence of trace fossils which are commonly underestimated in their importance for the society (based on palaeoenvironmental and hydrocarbon industry applications), that they play a structural function in contourite formations and especially critical in economic implications as potential reservoirs.
The project has fully achieved its objectives and milestones for the period. In terms of training, multiple activities were established in the Description of the Action (DoA) with the aim to improve research skills, teaching experience, communication skills, leadership, and new collaborations (with companies and other researchers). Moreover, the Fellow proposed communication and dissemination activities to promote the research conducted. Most of these objectives and activities were achieved, with the exception of a few adaptations due to pandemic restrictions. Detailed descriptions can be found in the Technical Reoport.

Regarding scientific production, 7 congress contributions and 12 research papers related with the project were published and others submitted are currently under review. All of them provide interesting advances about the ichnological content of contourites, and a number are remarkably innovative, especially those related to 2D and 3D imaging techniques applied to the ichnological study of these deposits (further information below). Owing to all these new findings, the body of knowledge about ichnological contents of contourites and their economic implications has increased substantially, upgrading the state-of-the-art. Secondments in Equinor SA and at the University of Granada enriched discussions with other colleagues working on the same topic and allowed for study of the economic impact of potential reservoirs. Therefore, the main goals of the project were achieved; however, some of them were slightly affected due to pandemic restrictions.

The project has provided a noteworthy advance in the scientific knowledge of contourites and imaging techniques. Just a few problems were encountered, but they were solved and did not cause any relevant modification from the DoA (see section 5 for more details).
Regarding the Fellow’s training, the current project has had a strong impact in different areas. His research skills have benefited from the use of new techniques (porosity quantification, 3D CT data processing), the study of new locations (i.e. Moroccan outcrops), the published contributions, and working within the TDRG framework. The Fellow has moreover established stronger collaborations with colleagues from different international institutions —from academia and private companies— and has participated in periodic workshops and seminars organized by TDRG (e.g. fieldtrip training in Almeria about Deep-sea deposits, periodic virtual seminars, palaeoceanography workshop…). Considering non-research activities, the Fellow has been teaching about trace fossils in the Advanced Sedimentology module from the Department and leaded a workshop about ichnology during the 58th British Sedimentological Research Group Annual General Meeting (BSRG AGM), enhancing his teaching, leading and communicating skills (Fig. 1). Additionally, the present project has given the Fellow strong training in leadership, given the chance to develop a research project, calling for self-management and decision-making to sort out difficulties and arrive at sound results. The Fellow has also been in touch with staff from different oil companies interested in this project due to the Equinor secondment and the Joint Industry Project (JIP) coordinated by Prof. Hernández Molina. The relationship with them has provided for an excellent training experience, to assess the economic implications of the conducted research, to create collaborations between companies and academia, and even to get funding opportunities for his future career. Finally, the Fellow has attended diverse learning courses at RHUL for additional professional development (e.g. Data protection, Freedom of information)
A more dtailed explanation can be found in the submitted Final Technical Report.
Considering the scarcity of ichnological studies of contourite deposits, any result will be a contribution beyond the state of art as soon as they will be published. At this moment for example, we have demonstrated that environmental conditions vary laterally in elongated drifts and this is affecting macro-benthic community, as the most relevant point.
Moreover, I can preliminarily say that trace fossils can be used as a tool to know the oxygenation level during deposition of potential source rocks, which could be a potential feature to be further considered by oil industry. Moreover, any finding about contourites will have an economic and social impact due to the huge interest that these deposits have for the oil industry due to their features to be potential oil and gas reservoirs.
Contourite facies section with bioturbation content (modified from Rebesco et al., 2014)