Geodynamic Framework of Saline Systems in Eastern Tunisia: Saline Depressions Inherited from the Triassic Intrusions and/or the Messinian Salinity Crisis
Based on the geodynamic context, two hypotheses of origin of salt in the subsurface of the Sahel area are worth being defended. The first suggests that the halokinesis activities, namely, of the Triassic evaporitic sedimentation, may still be until now influencing the functioning of the saline systems in the Sahel. The second integrates the Sahel area geodynamic evolution in the framework of the convergence between African and Eurasian plates. It suggests a link between the blockage of the subduction between African and Eurasian plates in North Tunisia, the Messinian Salinity Crisis, and eventually the concrete opening and evolution of the playa during the Quaternary. Such a suggestion is materialized by a geodynamic model relating successively these events. This scenario suggests that the Messinian Salinity Crisis constituted huge quantities of salt and/or salty water. This saline subsurface reserve is until now influencing the Sahel behavior as a whole. Through groundwater convergence, huge quantities of salt are accumulated within depressions of the Sahel area. Currently, the convergence of the plate between African and Eurasian plates results in a tectonic activity within these saline systems materialized by the formation of fault spring mounds along preferential orientation ensuring the surface-subsurface connectivity. 1. Introduction Though structures of the previous tectonic activities in the Sahel area are covered by a thick Plio-Quaternary series, geological and geophysical studies (e.g., [1–7]) gave a lot of data on the deep tectonic structures and the salt tectonics that was enhanced by the intrusion of the Triassic domes [3, 4]. The geodynamic inheritance in the subsurface of this region is still until now controlling the geology of its surface. For instance, the genesis and evolution of saline depressions in the Tunisian Sahel were strongly controlled by its subsurface, which controlled their formation and evolution [1] and is still until now feeding them with huge quantities of salt through aquifers convergence toward their surfaces [8–11]. The aim in this paper is to examine the geodynamic context that controlled the genesis and evolution of saline systems in Tunisian Sahel such as the Mechertate-Chrita-Sidi El Hani system, not only during the geomorphologic shaping and real opening of their depressions but also during previous geological events that had provided a salty context to the subsurface of the Sahel area. This work aims also to study geochemical traces of this salty geodynamics, which may be detected in aquifers. Based on these
References
[1]
A. Amari and M. Bedir, “Les bassins quaternaires du sahel central de la Tunisie. Genèse et évolution des sebkhas en contexte décrochant compressif et distensif,” Géodynamqiue, vol. 4, no. l, pp. 49–65, 1989.
[2]
M. Bedir, Gedynamics of the sedimentary bassin of the Sahel of Mahdia (eastern Tunisia) from the Aptian to the present: sismo-stratigraphy, sismo-tectonic and structural [Ph.D. thesis], University of El Manar Tunis, El Manar, Tunisia, 1989.
[3]
S. Khomsi, M. Bédir, and M. G. Ben Jemia, “Mise en évidence d’un nouveau front de chevauchement dans l’Atlas tunisien oriental de Tunisie par sismique réflexion. Contexte structural régional et r？le du Trias salifère,” Comptes Rendus Geoscience, vol. 336, pp. 1401–1408, 2004.
[4]
S. Khomsi, M. Bédir, M. Soussi, M. G. Ben Jemia, and K. Ben Ismail-Lattrache, “Mise en évidence en subsurface d’événements compressifs Eocène moyen-supérieur en Tunisie orientale (Sahel): généralité de la phase atlasique en Afrique du Nord,” Comptes Rendus Geoscience, vol. 338, pp. 41–49, 2006.
[5]
H. Gabtni, “Apport de la gravimétrie à l’étude des structures profondes du Sahel de Tunisie (cas de la région de Kairouan-Sousse-Monastir),” Comptes Rendus Geoscience, vol. 337, no. 16, pp. 1409–1414, 2005.
[6]
R. Ghribi, Morpho-structural study and evolution of paleo-fields of constraints of the Tunisian Sahel: geodynamic implcations [Ph.D. thesis], Faculty of Sciences of Sfax, Sfax, Tunisia, 2010.
[7]
T. Zouaghi, M. Bédir, F. Melki et al., “Neogene sediment deformations and tectonic features of northeastern Tunisia: evidence for paleoseismicity,” Arabian Journal of Geosciences, vol. 4, no. 7-8, pp. 1301–1314, 2011.
[8]
E. Essefi, Multidisciplinary study of Sidi El Hani Saline environment: the history and the climatic variability [M.S. thesis], Faculty of Sciences of Sfax, University of Sfax, Sfax, Tunisia, 2009.
[9]
E. Essefi, J. Touir, M. A. Tagorti et al., “Modeling of the chaotic behavior of Sidi El Hani discharge playa, Tunisian Sahel: which exogenous factor commands this saline environment? The subsurface flow or variability?” in Proceedings of the International Congress Geotunis, 2009.
[10]
E. Essefi, J. Touir, M. A. Tagorti, and C. Yaich, “Effect of the groundwater contribution, the climatic change, and the human induced activities on the hydrological behavior of discharge playas: a case study Sidi El Hani discharge playa, Tunisian Sahel,” Arabian Journal of Geoscience, vol. 6, no. 10, pp. 3997–4009, 2013.
[11]
M. A. Tagorti, E. Essefi, J. Touir, R. Guellala, and C. Yaich, “Geochemical controls of groundwaters upwelling in saline environments: case study the discharge playa of Sidi El Hani (Sahel, Tunisia),” Journal of African Earth Sciences, vol. 86, pp. 1–9, 2013.
[12]
L. Chihi and H. Philip, “Le bloc atlasopélagien: place et évolution géodynamique dans le contexte subduction-collision de la Méditerranée centrale (Afrique du nord-Sicile) du miocène au quaternaire,” Notes du Service Géologique de Tunisie, vol. 65, pp. 49–61, 1999.
[13]
E. Essefi, G. Komatsu, A. G. Fairén, M. A. Chan, and C. Yaich, “Groundwater influence on the aeolian sequence stratigraphy of the Mechertate-Chrita-Sidi El Hani system, Tunisian Sahel: analogies to the wet-dry aeolian sequence stratigraphy at Meridiani Planum, Terby crater, and Gale crater, Mars,” Planetary and Space Science, 2013.
[14]
E. Essefi, M. A. Tagorti, J. Touir, and C. Yaich, “Hydrocarbons migration through groundwater convergence toward saline depressions: a case study, Sidi El Hani discharge playa, Tunisian Sahel,” ISRN Environmental Chemistry, vol. 2013, Article ID 709190, 14 pages, 2013.
[15]
P. Haller, Structure profonde du Sahel tunisien: interprétation géodynamique [Ph.D. thesis], La Faculté des Sciences et Technologies, Université de Franche-Comté, Paris, France, 1983.
[16]
H. Ben Jmaa, The endorheic system of Sidi El Hani, Chrita and Mechertate: paleoenvironment and recent dynamics [Ph.D. thesis], University of Tunis, Tunis, Tunisia, 2008.
[17]
E. Essefi, M. A. Tagorti, and J. Touir, “Sensitivity of Sidi El Hani discharge playa to groundwater and climatic variability,” in Proceedings of the 22nd Colloquium of African Geology, Hammamet, Tunisia, 2008.
[18]
E. Essefi, G. Komatsu, A. G. Fairén, H. Ben Jmaa, F. Rekhiss, and C. Yaich, “Spring mounds at Sidi El Hani saline environment, eastern Tunisia: terrestrial analog for Mars,” in Proceedings of the 43rd Lunar and Planetary Science Conference, Houston, Tex, USA, 2012.
[19]
E. Essefi, A. G. Fairén, G. Komatsu, F. Rekhiss, and C. Yaich, “Study of cores from a spring mound at the Mars analog of Boujmal, eastern Tunisia: coring martian spring mounds as potential efficient tool for a geologic exploration of early Mars,” in Proceedings of the 3rd Conference on Early Mars, Lake Tahoe, Nev, USA, 2012.
[20]
E. Essefi, G. Komatsu, A. G. Fairén, M. A. Chan, and C. Yaich, “Alignment of fault spring mounds at El-Guetiate, Southeast Tunisia: terrestrial analogue implications for martian tectonics,” in Proceedings of the 44th Lunar and Planetary Science Conference, The Woodlands, Tex, USA, 2013.
[21]
E. Essefi, Wet aeolian sedimentology and sequence stratigraphy within the terrestrial analogues of Mechertate-Chrita-Sidi El Hani and Boujmal, eastern Tunisia: implications for wet aeolian sedimentology and sequence stratigraphy on Mars [Ph.D. thesis], National Engineering School of Sfax, University of Sfax, Sfax, Tunisia, 2013.
[22]
M. Bedir, “Tectonic and basin structuring of eastern Tunisia seismogenic sites,” 2010, http://www.docstoc.com.
[23]
R. Ghribi, A. Sghari, and S. Bouaziz, “Tectonic evolution of the oriental Tunisian platform from miocene to quaternary,” in Proceedings of the 22nd Colloquium of African Geology, Hammamet, Tunisia, 2008.
[24]
W. F. Ryan, K. J. Hsü, M. B. Cita, et al., Leg 13. Initial Reports of The Deep Sea Drilling Project, vol. 13, US Government Printing Office, Washington, DC, USA, 1973.
[25]
K. J. Hsü, M. B. Cita, and W. B. F. Ryan, “The origin of the Mediterranean evaporites,” in Reports of the Deep Sea Drilling Project, W. B. F. Ryan and K. J. Hsü, Eds., vol. 13, pp. 1203–1231, US Government Printing Office, Washington, DC, USA, 1973.
[26]
S. Duggen, K. Hoernie, P. van den Bogaard, L. Rüpke, and J. P. Morgan, “Deep roots of the Messinian salinity crisis,” Nature, vol. 422, no. 6932, pp. 602–606, 2003.
[27]
J.-J. Cornée, J.-P. S. Martin, G. Conesa et al., “Correlations and sequence stratigraphic model for Messinian carbonate platforms of the western and central Mediterranean,” International Journal of Earth Sciences, vol. 93, no. 4, pp. 621–633, 2004.
[28]
W. Krijgsman, F. J. Hilgen, I. Raffi, F. J. Sierro, and D. S. Wilson, “Chronology, causes and progression of the Messinian salinity crisis,” Nature, vol. 400, no. 6745, pp. 652–655, 1999.
[29]
P. Guennoc, C. Gorini, and A. Mauffret, “Histoire géologique du Golfe du Lion et cartographie du rift oligo-aquitanien et de la surface messinienne,” Géologie de la France, vol. 3, pp. 67–97, 2000.
[30]
A. Sghari and J. L. Mercier, “Le Messinien de la formation “Ségui” du Sahel Tunisien un équivalent des ‘Gilbert deltas’,” in Proceedings of the 22nd Colloquium of African Geology, Hammamet, Tunisia, 2008.
[31]
N. El-Euch-El-Kondi, S. Ferry, J. P. Suc, G. Clauzon, and F. Zargouni, “La crise messénienne en Tunisie du nord: réinterprétation des données de Sicile,” Communication orale, 2008.
[32]
N. Bahrouni, S. Bouaziz, A. Soumaya et al., “Neotectonic and seismotectonic investigation of seismically active regions in Tunisia: a multidisciplinary approach,” Journal of Seismology, vol. 18, no. 2, pp. 235–256, 2014.
[33]
Y. Kamoun, Etude néotectonique dans la région deMonastir-Mahdia (Tunisie orientale) [Ph.D. thesis], Université d’Orsay, Paris, France, 1981.
[34]
M. Gueddiche, Analysis of sismicity in Tunisia, seismic, seismo-tectonic and neotectonic study of septentrional Tunisia [Ph.D. thesis], Paris University, Paris, France, 1992.
[35]
M. Dlala and S. Reba？, “Relation compression-extension Miocène supérieur à quaternaire en Tunisie: implication sismotectonique,” Comptes Rendus de l'Académie des Sciences, vol. 319, no. 8, pp. 945–950, 1994.
[36]
L. Chihi, N. Gaaloul, and S. Razgallah, “Paleoseismic events in Eastern Tunisia (Cap Bon, Sahel): seismites associated with Miocene-Pliocene and quaternary sediments,” Africa Geoscience Review, vol. 7, no. 3, pp. 307–314, 2000.
[37]
M. A. Tagorti, Rapport d’étude Bibliographique sur le Secteur de la Sebkha de Sidi El Hani, Annales des Mines et de la Géologie, Tunis, Tunisia, 1995.
[38]
L. Marquer, S. Pomel, A. Abichou, E. Schulz, D. Kaniewski, and E. van Campo, “Late Holocene high resolution palaeoclimatic reconstruction inferred from Sebkha Mhabeul, southeast Tunisia,” Quaternary Research, vol. 70, no. 2, pp. 240–250, 2008.
[39]
E. Essefi, G. Komatsu, A. G. Fairén, F. Rekhiss, and C. Yaich, “Identification of tephra layers in spring mounds at the terrestrial analog of Boujmal, eastern Tunisia: repercussions and limits of tephrostratigraphy application on martian stratigraphy and paleoclimatology,” in Proceedings of the 3rd Conference on Early Mars, Lake Tahoe, Nev, USA, 2012.
[40]
S. Ferhi, E. Essefi, R. Barbieri, and C. Yaich, “Study of the terrestrial analogue of Chott El Gharsa, southwestern Tunisia: implications for martian study,” The 5th Tunisian Days of Applied Geology, 2013.
[41]
N. Ben Ayed and F. Zargouni, Carte Sismotectonique de la Tunisie a l’échelle 1/1000 000, Fondation Nationale de la Recherche Scientifique, 1990.
