Astronomical time scale for the Middle Oxfordian to Late Kimmeridgian in the Swiss and French Jura Mountains

Abstract

Detailed investigation of facies and sedimentary structures reveals that, during the Middle Oxfordian to Late Kimmeridgian, the shallow carbonate platform of the Swiss and French Jura Mountains recorded high-frequency sea-level fluctuations quite faithfully. The cyclostratigraphic analysis within the established biostratigraphic and sequence-chronostratigraphic framework implies that the resulting hierarchically stacked depositional sequences formed in tune with the orbital cycles of precession (20 kyr) and eccentricity (100 and 400 kyr). The astronomical time scale presented here is based on the correlation of 19 platform sections and 4 hemipelagic sections from south-eastern France where good biostratigraphic control is available. The cyclostratigraphic interpretation suggests that the interval between sequence boundaries Ox4 and Kim1 (early Middle Oxfordian to earliest Kimmeridgian) lasted 3.2 myr and that the Kimmeridgian sensu gallico has a duration of 3.2 to 3.3 myr. The astronomical time scale proposed here is compared to time scales established by other authors in other regions and the discrepancies are discussed. Despite these discrepancies, there is a potential to estimate the durations of ammonite zones and depositional sequences more precisely and to better evaluate the rates of sedimentary, ecological and diagenetic processes.

Jurassic Sea-Level Variations: A Reappraisal

“…Magnetostratigraphy was helpful only in the Bajocian through Tithonian interval (with a hiatus at CallovianOxfordian transition) where the low-amplitude seafloor magnetic anomalies (from Ocean Drilling Program site 801 on the older part of eastern Pacific Plate) could be tied to magnetostratigraphy. The attempts to astronomically fine-tune discrete intervals of the Jurassic (see, e.g., Strasser, 2007, and a summary by Huang in Ogg and Hinnov, 2012) may help with duration of some zonal intervals, but such piecemeal efforts do not alleviate the precision issues of all of the stage boundaries that are exacerbated by the lack of reproducible radiometric control for much of the Middle and Late Jurassic. This implies that, in general, the time scale of the Jurassic and precision of the ages of many biostratigraphic zonal boundaries still remain less than well constrained.…”

Early diagenetic dolomitization and dedolomitization of Late Jurassic and earliest Cretaceous platform carbonates: A case study from the Jura Mountains (NW Switzerland, E France)

“…High-frequency sequences in Kimmeridgian to Berriasian carbonates of the Jura platform probably originated from orbitally forced sea-level changes (Colombié and Strasser, 2005;Rameil, 2005;Colombié and Rameil, 2007;Strasser, 2007). Medium-scale and small-scale sequences would thus represent the long and the short eccentricity cycle of Earth's orbit (400 ka and 100 ka) respectively.…”

Sequence Stratigraphy: Methodology and Nomenclature

“…Towards the top of these sequences, higher energy deposits indicate shallowing towards the following bounding surface (e. g., small-scale sequences 3 and 4 at Péry-Reuchenette). Through their stacking pattern and within the given bio-chronostratigraphic framework it can be shown that these small-scale sequences formed in tune with the orbital short eccentricity cycle of 100 kyr (Colombié 2002;Strasser 2007). The basinal sections of Crussol and Châteauneuf-d'Oze are dominated by limestone-marl alternations.…”