Sediment undulations on the Llobregat prodelta: Signs of early slope instability or sedimentary bedforms?
- Author
- Roger Urgeles, Ben De Mol, Camino Liquete, Miquel Canals, Marc De Batist (UGent) , John E Hughes-Clarke, David Amblas, Pedro A Arnau, Antoni M Calafat, José Luis Casamor, Victor Centella, Koen De Rycker (UGent) , Joan Fabres, Jaime Frigola, Sara Lafuerza, Galderic Lastras, Anna Sanchez, Diana Zuniga, Willem Versteeg (UGent) and Veronica Willmott
- Organization
- Abstract
- A field of sediment undulations has been mapped by means of high-resolution multibeam bathymetry and seismic reflection profiles in the Llobregat River prodelta, off the city of Barcelona, Catalonia, Spain. Similar features had previously been recognized in other prodelta environments and interpreted either as downslope sediment deformation or sedimentary structures induced by bottom currents or hyperpycnal flows. Since the study area is undergoing significant offshore development, proper interpretation of such sediment undulations is needed for a correct risk assessment. The occurrence of the sediment undulations is restricted to the prodelta front on slope gradients between 3 and 0.2. The undulations have developed at the edge and atop an area of gas bearing sediments within the Late Holocene high-stand mud wedge. An evaluation is made of the characteristics of the sediment undulations in order to determine the most likely process for the origin of these structures. Among these characteristics are the continuity of the reflections and lack of diffractions in between different undulations, their size distribution (large to small) both from shallow to deep and with depth in section, the asymmetry (decreasing from proximal to distal), the crest to trough vertical distance on the landward side of the undulations (up to 0.5 m), and the lack of features that could indicate a progressive movement such as growth structures and drag folds. These characteristics indicate that the sediment undulations on the Llobregat River prodelta do not result from sediment deformation but rather from the interaction of bottom currents generated by hyperpycnal flows from the Llobregat River with regional sea water circulation. Their identification as sediment waves implies that such features do not pose a major hazard for further offshore development.
Citation
Please use this url to cite or link to this publication: http://hdl.handle.net/1854/LU-369285
- MLA
- Urgeles, Roger, et al. “Sediment Undulations on the Llobregat Prodelta: Signs of Early Slope Instability or Sedimentary Bedforms?” JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, vol. 112, no. B5, AMER GEOPHYSICAL UNION, 2007.
- APA
- Urgeles, R., De Mol, B., Liquete, C., Canals, M., De Batist, M., Hughes-Clarke, J. E., … Willmott, V. (2007). Sediment undulations on the Llobregat prodelta: Signs of early slope instability or sedimentary bedforms? JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 112(B5).
- Chicago author-date
- Urgeles, Roger, Ben De Mol, Camino Liquete, Miquel Canals, Marc De Batist, John E Hughes-Clarke, David Amblas, et al. 2007. “Sediment Undulations on the Llobregat Prodelta: Signs of Early Slope Instability or Sedimentary Bedforms?” JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 112 (B5).
- Chicago author-date (all authors)
- Urgeles, Roger, Ben De Mol, Camino Liquete, Miquel Canals, Marc De Batist, John E Hughes-Clarke, David Amblas, Pedro A Arnau, Antoni M Calafat, José Luis Casamor, Victor Centella, Koen De Rycker, Joan Fabres, Jaime Frigola, Sara Lafuerza, Galderic Lastras, Anna Sanchez, Diana Zuniga, Willem Versteeg, and Veronica Willmott. 2007. “Sediment Undulations on the Llobregat Prodelta: Signs of Early Slope Instability or Sedimentary Bedforms?” JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 112 (B5).
- Vancouver
- 1.Urgeles R, De Mol B, Liquete C, Canals M, De Batist M, Hughes-Clarke JE, et al. Sediment undulations on the Llobregat prodelta: Signs of early slope instability or sedimentary bedforms? JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH. 2007;112(B5).
- IEEE
- [1]R. Urgeles et al., “Sediment undulations on the Llobregat prodelta: Signs of early slope instability or sedimentary bedforms?,” JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, vol. 112, no. B5, 2007.
@article{369285, abstract = {{A field of sediment undulations has been mapped by means of high-resolution multibeam bathymetry and seismic reflection profiles in the Llobregat River prodelta, off the city of Barcelona, Catalonia, Spain. Similar features had previously been recognized in other prodelta environments and interpreted either as downslope sediment deformation or sedimentary structures induced by bottom currents or hyperpycnal flows. Since the study area is undergoing significant offshore development, proper interpretation of such sediment undulations is needed for a correct risk assessment. The occurrence of the sediment undulations is restricted to the prodelta front on slope gradients between 3 and 0.2. The undulations have developed at the edge and atop an area of gas bearing sediments within the Late Holocene high-stand mud wedge. An evaluation is made of the characteristics of the sediment undulations in order to determine the most likely process for the origin of these structures. Among these characteristics are the continuity of the reflections and lack of diffractions in between different undulations, their size distribution (large to small) both from shallow to deep and with depth in section, the asymmetry (decreasing from proximal to distal), the crest to trough vertical distance on the landward side of the undulations (up to 0.5 m), and the lack of features that could indicate a progressive movement such as growth structures and drag folds. These characteristics indicate that the sediment undulations on the Llobregat River prodelta do not result from sediment deformation but rather from the interaction of bottom currents generated by hyperpycnal flows from the Llobregat River with regional sea water circulation. Their identification as sediment waves implies that such features do not pose a major hazard for further offshore development.}}, author = {{Urgeles, Roger and De Mol, Ben and Liquete, Camino and Canals, Miquel and De Batist, Marc and Hughes-Clarke, John E and Amblas, David and Arnau, Pedro A and Calafat, Antoni M and Casamor, José Luis and Centella, Victor and De Rycker, Koen and Fabres, Joan and Frigola, Jaime and Lafuerza, Sara and Lastras, Galderic and Sanchez, Anna and Zuniga, Diana and Versteeg, Willem and Willmott, Veronica}}, issn = {{0148-0227}}, journal = {{JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH}}, language = {{eng}}, number = {{B5}}, publisher = {{AMER GEOPHYSICAL UNION}}, title = {{Sediment undulations on the Llobregat prodelta: Signs of early slope instability or sedimentary bedforms?}}, volume = {{112}}, year = {{2007}}, }