Please use this identifier to cite or link to this item: https://hdl.handle.net/10953/3297
Title: Environmental conditions in the pre-Jenkyns event time (late Pliensbachian - early Toarcian) in the South Iberian Palaeomargin (Betic External Zones, Southern Spain)
Authors: Nieto, L.M.
Ayadi, C.
Fraguas, A.
Molina, J.M.
Reolid, M.
Abstract: Three stratigraphic sections of the Betic External Zones were studied, two from the Median Subbetic (PEL and PR) and one from the External Subbetic (CE). The upper Pliensbachian materials and the transition to the lower Toarcian were dated with calcareous nannofossils in PEL and PR in this paper, while in the CE section, previous ammonite and nannofossil biostratigraphies were considered. The dominant facies are alternance of marly limestone—marl, although in the CE section, the Toarcian is represented by marls, where the Jenkyns Event has been recorded. In terms of ichnofossils, in the PEL section Macaronichnus predominates. In the PR and CE sections, the ichnoassemblages are dominated by Planolites, Thalassinoides and Chondrites. The facies and ichnofacies distinguished formed in pelagic or hemipelagic marine environments. Analysis of the correlation between δ13C and δ18O and of each of them with Sr and Fe/Ca and Sr/Ca, as well as the Z-factor, indicate that the geochemical signal has not been modified by diagenesis. In the PEL and PR sections, the δ13C and δ18O ratios do not allow to clearly identify isotopic events, except in CE where the Jenkyns Event was recorded. The proxies used to study detritism (Zr/Rb, Sr/Cu, Chemical Index Alteration, CIA, and C-value) show trends opposite to those detected in other Tethys sections and even between them. These peculiarities in the geochemical data are interpreted as the result of the opening of the Hispanic Corridor, the mixing of Panthalassa and Tethys seawaters and extensional tectonics, which favoured the development of half grabens with significant differential subsidence, especially during the NJT5b Subzone (latest Pliensbachian). These half grabens could be affected by contourite currents according to the Macaronichnus assemblage in some of these sections.
Keywords: Early Jurassic
Southern Iberian Palaeomargin
Ichnofossils
Calcareous nannofossil biostratigraph
Geochemical proxies of detritism
Hispanic Corridor
Contourite currents
Issue Date: 18-Oct-2024
Publisher: Springer
Citation: Nieto et al. 2024. Journal of Iberian Geology
Appears in Collections:DG-Artículos

Files in This Item:
File Description SizeFormat 
Nieto et al., 2024_JIBG.pdf9,89 MBAdobe PDFView/Open


This item is protected by original copyright