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

Nader, F.H., Swennen, R. and Ellam, R.M. (2007) Field geometry, petrography and geochemistry of a dolomitization front (Late Jurassic, central Lebanon). Sedimentology, 54(5), pp. 1093-1120. (doi: 10.1111/j.1365-3091.2007.00874.x)

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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% CaCO3; δ18O: −9·3 to −4·0‰ V-PDB; δ13C: −1·5 to +2·1‰ V-PDB; 87Sr/86Sr: 0·70742; matrix porosity: ≈6%; Klinkenberg permeability: ≈0·5 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, near-surface 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 well-defined 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.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Ellam, Professor Rob
Authors: Nader, F.H., Swennen, R., and Ellam, R.M.
Subjects:G Geography. Anthropology. Recreation > GE Environmental Sciences
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Sedimentology
ISSN (Online):1365-3091
Published Online:21 June 2007

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