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The Kimmeridgian-Tithonian boundary in the Central Iberian Basin (Spain): new stratigraphic information
Cristina Sequero, Jorge Val, Marcos Aurell, Beatriz Bádenas, Idoia Rosales

Building: Muséum d'Histoire Naturelle de Genève
Room: Lobby /Hall/
Date: 2018-12-05 11:11 AM – 11:14 AM
Last modified: 2018-11-24

Abstract


The location of the Kimmeridgian-Tithonian boundary in the coastal to shallow marine successions recorded in the central part of the Iberian Basin (NE Spain), has been the subject of discussion over the last years. In this work we report on further data that allows an accurate calibration of the uppermost Kimmeridgian-lowermost Tithonian interval recorded in the Aguilón and Galve sub-basins.

In the Aguilón sub-basin, Jurassic marine sedimentation ends with the up to 80 m-thick succession of the shallow marine carbonates of the Higueruelas Fm. The widespread record of Alveosepta jaccardi all across the succession, the presence of mid-Kimmeridgian ammonites (i.e., Acanthicum/Eudoxus zones) in the underlying open-marine unit and the new isotopic strontium data (belemnites, brachiopods, oyster shells) indicate that the Higueruelas Fm was deposited at the latest Kimmeridgian (upper Eudoxus and Beckeri zones).

In the Galve sub-basin, the overlaying up to 180 m-thick succesion of the shallow lagoon carbonates to coastal/alluvial siliciclastics of the Villar del Arzobispo Fm stacked in four sequences (S1–S4). The lagoonal carbonates of the lower (S1) sequence mark the last presence of Alveosepta jaccardi and therefore it was deposited at the latest Kimmeridgian. On the other hand, the strontium isotope data (oyster shells) indicates that the overlying S2–S4 sequences were deposited at the earliest Tithonian (i.e, Hybonotum Zone). The reported data update previous interpretation on the age of the lower boundary of the Villar del Arzobispo Fm in the Galve sub-basin, which was previously considered to be younger (mid-early Tithonian; Aurell et al., 2016) or older (mid-Kimmeridgian, Campos-Soto et al., 2017).