Planktonic foraminifer biostratigraphy as a tool in constraining the timing of flysch deposition: Gurnigel flysch, Voirons massif (Haute-Savoie, France)

Ospina Ostios, Lina Maria; Ragusa, Jeremy; Wernli, Roland; Kindler, Pascal

doi:10.1111/sed.12013

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Title		Planktonic foraminifer biostratigraphy as a tool in constraining the timing of flysch deposition: Gurnigel flysch, Voirons massif (Haute-Savoie, France)
Authors		Ospina Ostios, Lina Maria Ragusa, Jeremy Wernli, Roland Kindler, Pascal
Published in		Sedimentology. 2013, vol. 60, no. 1, p. 225-238
Abstract		New biostratigraphic, sedimentological and petrographic data and a thorough review of existing literature modify existing knowledge on the age, the sedimentology, the petrography and the palaeogeographic origin of the Gurnigel flysch from the Voirons massif (Haute Savoie, France). Planktonic foraminiferal biostratigraphy assigns the flysch to the upper Middle Eocene (zones P12 to P14) through to Lower Oligocene (zones P16 to P20) stages. This result contrasts with previous work, which assigned the unit to the Lower Palaeocene to upper Middle Eocene on the basis of calcareous nannofossil and dinoflagellate assemblages. The following findings suggest that the Voirons massif comprises several stacked flysch units that do not have exactly the same palaeogeographic origin: (i) the occurrence of flysch exposures in reverse stratigraphic order combined with the lack of evidence for bed overturning; (ii) the variability of palaeo‐depositional settings inferred from different flysch outcrops of similar age; (iii) the differences in the heavy mineral content; and (iv) the anomalous superimposition of distal turbidites and/or basinal contourites (Saxel Marls) over proximal turbidites (Vouan Conglomerates). The young age of these kilometre‐sized flysch slices precludes their hitherto postulated locus of deposition in the South‐Penninic Ocean, and rather indicates a provenance from the Ultrahelvetic and/or North‐Penninic (Valais) palaeogeographical domains. Finally, none of the nannofossil assemblages are contemporaneous with the observed planktonic foraminifera associations, suggesting that they have been reworked, dissolved, or just simply diluted and not found by earlier researchers. This study from the Voirons massif shows that planktonic foraminifera associations are a highly reliable biostratigraphic tool for obtaining accurate ages of flysch successions.
Keywords		Biostratigraphy — Contourites — Eocene — Flysch — France — Gurnigel — Haute-Savoie — Oligocene — Planktonic foraminifera — Prealps — Turbidites — Ultrahelvetics — Valais realm
Identifiers		DOI: 10.1111/sed.12013
Full text		Article (Published version) (1.8 MB) - Limited access to UNIGE
Structures		Faculté des sciences / Section des sciences de la Terre et de l'Environnement / Département des sciences de la Terre
Research group		Sedimentology, Biostratigraphy and Micropaleontology
Citation (ISO format)		OSPINA OSTIOS, Lina Maria et al. Planktonic foraminifer biostratigraphy as a tool in constraining the timing of flysch deposition: Gurnigel flysch, Voirons massif (Haute-Savoie, France). In: Sedimentology, 2013, vol. 60, n° 1, p. 225-238. doi: 10.1111/sed.12013 https://archive-ouverte.unige.ch/unige:117858