Cenomanian–Turonian facies and sequence stratigraphy, Bahloul Formation, Tunisia

Zagrarni, Mohamed Faouzi; Negra, Mohamed Hédi; Hanini, Amine

doi:10.1016/j.sedgeo.2007.12.007

Cited by 61 publications

(26 citation statements)

References 16 publications

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“…Basinal facies, mainly represented by pelagic marls and argillaceous limestones, are found in the north, such as in the Oued Bazina area [Hanini et al, 2004;Zagrarni et al, 2008].…”

Section: Geographic and Geologic Settingmentioning

confidence: 99%

“…The present study describes filament accumulations within the Cenomanian-Turonian black shales constituting the Bahloul Formation [Burollet, 1956]. The Bahloul Formation and the Cenomanian-Turonian transition have been widely studied Maamouri et al, 1994;Robaszynski et al, 1994;Accarie et al, 2000;Zagrarni, 1999;Abdallah et al, 2000;Hanini et al, 2004;Caron et al, 2006;Zagrarni et al, 2008], and provide the frame for the environmental interpretation of this "filament event". The purpose of this paper is to determine the origin of filaments and to reconstitute their deposition environment at local and global scales.…”

Section: Introductionmentioning

confidence: 96%

“…Mass accumulations of thin bivalve shells ("filaments") occur in several distinct limestone and marly intervals throughout the Mesozoic Tethyan realm [e.g., Robaszynski et al, 1994;Maamouri et al, 1994;Molina et al, 1997;Accarie et al, 2000;Abdallah et al, 2000;Wan et al, 2003;Ettachfini and Andreu, 2004;Caron et al, 2006;Zagrarni et al, 2008;Navarro et al, 2009]. Jurassic filaments are thought to represent protoconchs or juvenile shells of posidoniid bivalves (Bositra, Posidonia), while Triassic occurrences are attributed to halobiid bivalves [Lapparent, 1923;Colom, 1955;Flügel, 2004].…”

Section: Introductionmentioning

confidence: 99%

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The filament event near the Cenomanian-Turonian boundary in Tunisia: filament origin and environmental signification

Negra

Zagrarni

Hanini

et al. 2011

Bulletin De La Société Géologique De France

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Abstract. -Near the Cenomanian-Turonian boundary, the filament event corresponds to the massive occurrence of thin elongate shells, probably bivalves which constitute, in the Bahloul Formation, about 40% of allochems. This biosedimentary event was described in several areas, such as in Tunisia, Algeria, Morocco, North America, Oman and Tibet. In Tunisia, filaments are well represented within well laminated black shales constituting the Bahloul Formation, late Cenomanian -early Turonian in age. These black shales were deposited under anoxic conditions developed in an outer ramp environment. Filaments are particularly abundant in the upper part of the Bahloul Formation, which is topped by a condensation level exhibiting encrusted ammonites associated with frequent burrows, and phosphatic and glauconitic grains. In terms of depositional environments, the filament concentrations announce an evolution towards "normal"-marine conditions, which followed the anoxic conditions favouring black-shale formation. This trend coincided with a deepening that led to maximum flooding at the condensation surface. The petrographic study of samples taken along a N-S transect shows a clear evolution of filament structures from distal to proximal ramp. Limestones deposited in the outer ramp environment mainly contain well preserved "pelagic" bivalve shells showing a thin-shelled structure composed of elongated filaments. Laterally, toward the proximal ramp, the bivalve shells are progressively disintegrated, the filaments being arranged parallel to bedding. In an even more proximal setting, filaments appear finer, highly fragmented and arranged without preferential orientation. The Cenomanian-Turonian "pelagic" bivalves thus probably lived in an outer ramp environment and their thin shells disintegrated progressively into filaments. This happened during high energy conditions generated by storms.The filament event, which is associated to other bio-events expressed by the extinction and the first occurrence of some pelagic species, could be used to establish local to global correlations.When the ammonite Watinoceras, the main early Turonian marker, is rare or absent, the filament-rich facies could indicate the proximity of the Cenomanian-Turonian boundary.At a global scale, the filament event illustrates a sea-level rise in relation with eustatic and climatic changes. The maximum flooding of this transgressive event was identified in several localities and dated about 93 Ma. The very high sea-level conditions are favourable to accumulation and preservation of organic-rich facies such as black shales, which illustrate the anoxic event OAE2.The abundance of filaments near the Cenomanian-Turonian boundary is an indicator of high organic productivity following a climatic change to warmer conditions. The latter have clearly influenced oceanic water-masses circulation, water column stratification and nutrient partitioning. L'événement "à filaments" à la limite Cénomanien -Turonien en Tunisie : origine et milieux de genèse des filamentsMots-c...

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“…Basinal facies, mainly represented by pelagic marls and argillaceous limestones, are found in the north, such as in the Oued Bazina area [Hanini et al, 2004;Zagrarni et al, 2008].…”

Section: Geographic and Geologic Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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The filament event near the Cenomanian-Turonian boundary in Tunisia: filament origin and environmental signification

Negra

Zagrarni

Hanini

et al. 2011

Bulletin De La Société Géologique De France

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“…This surface is sharp and overlain by a (transgressive) lag of reworked bioclasts (mainly echinoderms) from the neighbor platform as well as glauconite and phosphatic grains. These data were not described by Zagrarni et al (2008) although they are expressed in many Bahloul sections. It marks the limit between the SMW and the TST (Figure 5 Figure 6) and represents a fast shore line migration into the continent.…”

Section: Wwwintechopencommentioning

confidence: 90%

“…Nevertheless, this surface occurs when the accommodation space creation is faster than before. In this case there would be no progradation as mentioned by www.intechopen.com Earth and Environmental Sciences 132 Zagrarni et al (2008). On the platform setting, the transgressive interval corresponds to the pelagic fauna limestones unit (Razgallah et al, 1994).…”

Section: Transgressive Systems Tract (Tst)mentioning

confidence: 97%

The Organic-Rich and Siliceous Bahloul Formation: Environmental Evolution Using Facies Analysis and Sr/Ca & Mn Chemostratigraphy, Bargou Area, Tunisia

Soua¹,

Jemia²,

Zaghbib-Turki³

et al. 2011

Earth and Environmental Sciences

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Paleogene of the Huanghekou Sag in the Bohai Bay Basin, NE China: deposition–erosion response to a slope break system of rift lacustrine basins

et al. 2013

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The sequence architecture and depositional systems of the Paleogene lacustrine rift succession in the Huanghekou Sag, Bohai Bay Basin, NE China were investigated based on seismic profiles, combined with well log and core data. Four second-order or composite sequences and seven third-order sequences were identified. The depositional systems identified in the basin include: fan delta, braid delta, meander fluvial delta, lacustrine and sublacustrine fan. Identification of the slope break was conducted combining the interpretation of faults of each sequence and the identification of syndepositional faults, based on the subdivision of sequence stratigraphy and analysis of depositional systems. Multiple geomorphologic units were recognized in the Paleogene of the Huanghekou Sag including faults, flexures, depositional slope break belts, ditch-valleys and sub-uplifts in the central sag. Using genetic division principles and taking into consideration tectonic features of the Paleogene of the Huanghekou Sag, the study area was divided into the Northern Steep Slope/Fault Slope Break System, the Southern Gentle Slope Break System and T10 Tectonic Slope Break System/T10 Tectonic Belt.Responses of slope break systems to deposition-erosion are shown as: (1) basin marginal slope break is the boundary of the eroded area and provenance area; (2) ditch-valley formed by different kinds of slope break belts is a good transport bypass for source materials; (3) shape of the slope break belt of the slope break system controls sediments types; (4) the ditch-valley and sub-sag of a slope break system is an unloading area for sediments; and (5) due to their different origins, association characteristics and developing patterns, the Paleogene slope break belt systems in the Huanghekou Sag show different controls on depositional systems. The Northern Fault Slope Break system controls the deposition of a fan delta-lacustrine-subaqueous fan, the Southern Gentle Slope Break system controls the deposition of a fluvial-deltaicshallow lacustrine and sublacustrine fan, and the T10 Tectonic Slope Break System controls the deposition of shallow lacustrine beach bar sandbodies. The existence of a slope break system is a necessary but not a sufficient condition for studying sandbody development. The formation of effective sandbodies along the slope break depends on the reasonable coupling of effective provenance, necessary association patterns of slope break belt, adequate unloading space and creation of definite accommodation space.

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Cenomanian–Turonian facies and sequence stratigraphy, Bahloul Formation, Tunisia

Cited by 61 publications

References 16 publications

The filament event near the Cenomanian-Turonian boundary in Tunisia: filament origin and environmental signification

The filament event near the Cenomanian-Turonian boundary in Tunisia: filament origin and environmental signification

The Organic-Rich and Siliceous Bahloul Formation: Environmental Evolution Using Facies Analysis and Sr/Ca & Mn Chemostratigraphy, Bargou Area, Tunisia

Paleogene of the Huanghekou Sag in the Bohai Bay Basin, NE China: deposition–erosion response to a slope break system of rift lacustrine basins

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