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Global local controls influencing the deposition of the La Luna Formation (Cenomanian-Campanian), western Venezuela

Lookup NU author(s): Dr Paul Farrimond


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Bulk and molecular geochemical, micropalaeontological, and carbon-isotopic data are used to address the different local and global factors influencing the environment of sedimentation of the La Luna Formation (Cenomanian-Campanian, approximate palaeolatitude 15°N) in a single section in western Venezuela. Based on the constructed chronostratigraphic framework, oxygen-depleted bottom-water conditions and black-shale deposition started in western Venezuela well before the widespread occurrence of organic-rich sediments in higher palaeolatitude regions such as the Tethys and the North Atlantic near or at the Cenomanian-Turonian boundary. In the La Luna Formation, palaeoenvironmental conditions that allowed the preservation of organic matter (mainly of marine origin), prevailed until Santonian times in a distal platform facies with very low siliciclastic input. Changes in lithology appear to reflect the local response to eustatic sea-level variations and the presence of a migrating upwelling belt affecting the bioproductivity of silica and carbonate. A marked δ13Corg isotopic excursion is recognised in the middle part of the section, and is apparently unrelated to local palaeoenvironmental changes in bioproductivity and oxygen depletion. Biological marker data show no variations in association with the isotopic excursion, being mainly controlled by local fluctuations in organic-matter input and preservation.

Publication metadata

Author(s): Perez-Infante J, Farrimond P, Furrer M

Publication type: Article

Publication status: Published

Journal: Chemical Geology

Year: 1996

Volume: 130

Issue: 3-4

Pages: 271-288

Print publication date: 27/08/1996

ISSN (print): 0009-2541

ISSN (electronic): 1872-6836

Publisher: Elsevier BV


DOI: 10.1016/0009-2541(96)00019-8


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