Calcareous tempestites in pelagic facies (Jurassic, Betic Cordilleras, Southern Spain)

Molina, José Miguel; Ruiz-Ortiz, P. A.; Vera, Jesús

doi:10.1016/s0037-0738(96)00057-7

Cited by 63 publications

(29 citation statements)

References 34 publications

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“…Deposition and burial must have been rapid because the shells do not show any micritisation, bioperforation, or encrustation. In the Middle Jurassic of Spain, Molina et al [1997] and Navarro et al [2009] …”

Section: Linkage Between Filament Shape and Depositional Environmentmentioning

confidence: 99%

“…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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Section: Linkage Between Filament Shape and Depositional Environmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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“…The tempestites may represent organisms washed in from shallower environments (as indicated by reworking). Alternatively, as the deposits coincide with a relative sea-level fall, major storms may have temporarily created a well-aerated environment in which the organisms grew up and were subsequently reworked, as described by Molina et al (1997) for Jurassic calcareous tempestites in a pelagic facies in the Betic Cordillera. The upper surface of the tempestite bed of unit 3 is locally mineralised with iron.…”

Section: Facies Type 3 (Ft3): Light Grey and Red Brachiopodal Limestonesmentioning

confidence: 99%

From carbonate platform to euxinic sea – the collapse of an Early/Middle Devonian reef, Cantabrian Mountains (Spain)

Loevezijn¹,

Raven

2017

Geologos

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The Santa Lucía Formation represents the major phase in Devonian reef development of the Cantabrian Zone (Cantabrian Mountains, northwest Spain). In the present study the transition from the carbonate platform deposits of the Santa Lucía Formation to the overlying euxinic basinal deposits of the Huergas Formation is described. These transitional strata are connected to the Basal Choteč Event and represent a condensed sedimentation of micritic dark-grey and black limestones with an upward increase of dark shale intercalations with iron mineralisation surfaces and storm-induced brachiopod coquinas. The transitional beds are grouped into a new unit, the Cabornera Bed, which consists of limestone, limestone-shale and shale facies associations, representing a sediment-starved euxinic offshore area just below the storm wave base. Four stages in reef decline can be recognised: a reef stage, an oxygen-depleted, nutrient-rich stage, a siliciclastic-influx stage and a pelagic-siliciclastic stage. Additional geochemical and geophysical investigations are needed to verify the results presented herein.

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“…On the tops of several layers, low-angle cross-lamination or hummocky cross-stratification (HCS) is a characteristic feature (Fot. 2, 3), and indicates a high current regime paired with a combination of unidirectional and oscillatory flow during deposition (e.g., [12]- [15]). At quieter and greater water depths, HCS becomes less distinct and is replaced by parallel laminations that may indicate unidirectional flows.…”

Section: Storm Deposits In Microfacies Analysismentioning

confidence: 99%

The Storm Surge Recorded in a Thin Section

Vierek

2015

ILNS

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ABSTRACT. Limestone and sandstone beds deposited by storms are called tempestites, and exhibit much variation in thickness, grain size and internal structures, depending on the proximity and on the intensity of the storm waves. In this paper, diagnostic features of storm beds observed in thin sections, was presented. Characteristic features are investigated on the basis of detailed study in the Upper Devonian carbonates in the western part of the Holy Cross Mountains (Poland).

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Calcareous tempestites in pelagic facies (Jurassic, Betic Cordilleras, Southern Spain)

Cited by 63 publications

References 34 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

From carbonate platform to euxinic sea – the collapse of an Early/Middle Devonian reef, Cantabrian Mountains (Spain)

The Storm Surge Recorded in a Thin Section

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