A revision of the lower Cretaceous stratigraphy of Lebanon

This contribution describes the field geometry, petrography and geochemistry of a well-exposed dolomitization front in Upper Jurassic carbonates, and attempts to highlight the sedimentological, structural and relative sea-level controls on multiphase dolomitization and related diagenetic events. The data presented reflect the superposition of various diagenetic phases which have resulted in a single dolostone body, whose dimensions are well defined in the field. Local microbial intraclastic dolomites of Late Tithonian age accumulated in a hypersaline lagoon during relative sea-level fall. These pre-date beige hydrothermal dolostones (51 to 55 mol% CaCO 3 ; d 18 O: )9AE3 to )4AE0& V-PDB; d 13 C: )1AE5 to +2AE1& V-PDB; 87 Sr/ 86 Sr: 0AE70742; matrix porosity: 6%; Klinkenberg permeability: 0AE5 mD), whose dolomitizing fluid circulated along faults and invaded the nearby facies. First, the burrows were dolomitized, then the bulk rocks, resulting in the investigated 'tongue'shaped dolomite body. Upon Late Jurassic-Early Cretaceous uplift, nearsurface water percolated through -and altered -the underlying beige dolostones. This event was followed by a ferroan dolomite cement phase, which occurred during further burial. This contribution, featuring a welldefined geometric pattern of a dolomitization front with a large petrographic and geochemical data set, may also serve as a case study illustrating the complexity of superimposed diagenetic processes which have to be taken into account in modelling exercises of multiphase hydrothermal dolomitization.

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“…Fluvio‐deltaic sandstones were deposited during periods of regional regression (e.g. Chouf Formation, Barremian; Walley, 1983).…”

Section: Regional Setting and Geological Historymentioning

confidence: 99%

Field geometry, petrography and geochemistry of a dolomitization front (Late Jurassic, central Lebanon)

2007

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“…5, figs 11–12) from the Abeih sandstone in Lebanon. According to Walley (1983), this sandstone is of early Aptian age. Based on the very narrow beaks and pronounced, widely spaced commarginal sculpture of this species, it seems like it belongs to Trigonopis .…”

Section: Discussionmentioning

confidence: 99%

Cretaceous opine bivalves from the Pacific slope of North America and palaeobiogeography of subfamily Opinae Chavan, 1969

Squires

Saul

2009

Palaeontology

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“…72 a.-f. m. abdel-rahman and f. h. nader Figure 3. Summary of the stratigraphy of the Jurassic±Cretaceous sequence of Lebanon according to Dubertret (1955), Saint-Marc (1974) and Walley (1983Walley ( , 1997.…”

Section: Geological Settingmentioning

confidence: 99%

“…The Mesozoic (Jurassic±Cretaceous) stratigraphy of Lebanon has been investigated by a number of authors (Dubertret 1955;Saint-Marc 1974;Walley 1983Walley , 1997. Several other studies were carried out and were focused mainly on detailed stratigraphy and petrology of particular regions.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of the Lebanese Jurassic–Cretaceous carbonate stratigraphic sequence: a geochemical approach

Abdel-Rahman

Nader

2002

Geological Journal

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The Lebanese crustal segment is part of a much larger carbonate platform deposited along the northwestern margin of the Arabian Plate, in the eastern Mediterranean region. It is made up mainly of Jurassic–Cretaceous carbonate rocks. Most of this stratigraphic sequence is exposed in the Nahr Ibrahim canyon and surrounding areas in central Lebanon. The various formations, from the oldest unit (the Lower Jurassic Kesrouane Formation) to the Upper Cretaceous Chekka Formation, are made up of different types of carbonate rocks including micritic limestone, medium‐ to coarse‐grained dolostone, biomicritic (chalk), biosparrudite limestone, micritic dolostone, pelmicrite, marl and marly limestone.Results of this first chemical investigation on the Lebanese carbonate platform show that the micritic limestone of the Kesrouane Formation is relatively enriched in Ca, Na and Sc, and has low rare‐earth element (REE) contents. The marl units of the Hammana Formation are enriched in Al, Fe, K, Ti, Rb, Ga, Nb, U, Th and REE. The chalk of the Chekka Formation shows the highest phosphorus content. A significant increase in P and Sr contents with time (from the Lower Jurassic to the Upper Cretaceous carbonate units) characterizes the Lebanese sequence; this is interpreted to be related to a possible increase in continental weathering rates during the Mesozoic. Enrichment in Ni, Ti and Nb in some formations is interpreted to be linked to Mesozoic volcanism in central Lebanon. The Cretaceous formations are subdivided according to their REE patterns into two distinct groups: limestones (Mdairej, Sannine and Maameltain formations) which are depleted in REE; and marl/chalk (Hammana and Chekka formations) which are significantly enriched in REE. On several geochemical variation diagrams, such as the K–Ti–P triangular plot, the Lebanese Mesozoic carbonate formations are found to occupy distinct compositional fields. Thus, carbonate geochemistry could prove to be a powerful tool (especially when combined with petrographic data) in characterizing and correlating carbonate formations (chemical stratigraphy), particularly in regions where field evidence may be limited. Results of this study have significant implications for the entire carbonate platform that covers a large part of the eastern Mediterranean region. Copyright © 2002 John Wiley & Sons, Ltd.

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A revision of the lower Cretaceous stratigraphy of Lebanon

Cited by 18 publications

References 2 publications

Field geometry, petrography and geochemistry of a dolomitization front (Late Jurassic, central Lebanon)

Field geometry, petrography and geochemistry of a dolomitization front (Late Jurassic, central Lebanon)

Cretaceous opine bivalves from the Pacific slope of North America and palaeobiogeography of subfamily Opinae Chavan, 1969

Characterization of the Lebanese Jurassic–Cretaceous carbonate stratigraphic sequence: a geochemical approach

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