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Trace fossils as diagnostic indicators of deep-marine environments, Middle Eocene Ainsa-Jaca basin, Spanish Pyrenees

Heard, TG; Pickering, KT; (2008) Trace fossils as diagnostic indicators of deep-marine environments, Middle Eocene Ainsa-Jaca basin, Spanish Pyrenees. SEDIMENTOLOGY , 55 (4) 809 - 844. 10.1111/j.1365-3091.2007.00922.x.

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Abstract

A quantitative study of trace fossil abundance in the Middle Eocene deep-marine clastic systems, Ainsa-Jaca basin, Spanish Pyrenees, shows that they are powerful discriminators of submarine fan and related environments. Sixteen fan and related environments are recognized from upper-slope gully to the distal basin-floor. For each environment, the degree of bioturbation (density), trace-fossil diversity, number of pre-depositional and post-depositional trace fossils, as well as the number of graphoglyptid ichnospecies were quantified. In the more laterally confined and channel-dominated Ainsa basin, there is a trend of increasing bioturbation intensity and trace-fossil diversity away from channel-axis to off-axis environments. In the more unconfined and distal Jaca basin, there is a trend of increasing trace-fossil diversity and number of pre-depositional trace fossils including graphoglyptids from the channel-lobe transition to the fan-fringe. The trace-fossil assemblages of the Ainsa-Jaca basin are characteristic of a number of sub-ichnofacies of the Nereites ichnofacies. In the distal Jaca basin, the Paleodictyon sub-ichnofacies occurs in the lobe-fringe and fan-fringe, whereas the distal basin-floor has a trace-fossil assemblage typical of the Paleodictyon sub-ichnofacies, but with a high proportion of post-depositional fodinichnia. Trace-fossil assemblages of proximal basin, axial, environments are characteristic of the Ophiomorpha rudis sub-ichnofacies, whilst proximal off-axis environments, have a mixed Paleodictyon-Ophiomorpha rudis sub-ichnofacies trace-fossil assemblage.

Type:Article
Title:Trace fossils as diagnostic indicators of deep-marine environments, Middle Eocene Ainsa-Jaca basin, Spanish Pyrenees
DOI:10.1111/j.1365-3091.2007.00922.x
Keywords:clastic, deep-marine, ichnofacies, trace fossils, SOUTH-CENTRAL PYRENEES, SPAIN, STRATA, FLYSCH, COLONIZATION, COMMUNITIES, TURBIDITES, EVOLUTION, SEDIMENTS, BULGARIA
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Earth Sciences

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