Les terrains jurassiques du sondage de Couy (Cher, France). Leur analyse séquentielle détaillée à partir de la description des carottes et des courbes diagraphiques

Gély, Jean-Pierre; Lorenz, C.; Lorenz, Jacqueline

doi:10.2516/ogst:1996027

Cited by 2 publications

(4 citation statements)

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“…Also, our detailed core description during the process of high‐resolution (2 to 4 cm) MS measurements do not show any sedimentological feature, indicator of hiatuses. Despite Peti et al (2017) have suggested potential hard grounds and marine gully erosions (Figures 1 and 2), previous reports on the Sancerre core (Gély et al, 1996) and our sedimentological description do not show significant erosional surfaces or hiatuses over most of the Pliensbachian‐Toarcian interval. One exception is the Pliensbachian–Toarcian transition or rather the top of Pliensbachian, which may be the subject of marine gully erosion, but does not show any biostratigraphic gap (Gély et al, 1996).…”

Section: Discussioncontrasting

confidence: 91%

“…Despite Peti et al (2017) have suggested potential hard grounds and marine gully erosions (Figures 1 and 2), previous reports on the Sancerre core (Gély et al, 1996) and our sedimentological description do not show significant erosional surfaces or hiatuses over most of the Pliensbachian‐Toarcian interval. One exception is the Pliensbachian–Toarcian transition or rather the top of Pliensbachian, which may be the subject of marine gully erosion, but does not show any biostratigraphic gap (Gély et al, 1996). Previous cyclostratigraphic analyses also suggest potential condensation in the uppermost part of Pliensbachian (Boulila et al, 2014; Boulila & Hinnov, 2017), without evidence for hiatuses.…”

Section: Discussioncontrasting

confidence: 91%

“…2). The prominent changes in sedimentation rates along with the sedimentological responses of the Paris Basin to sea-level change does not reveal the occurrence of hiatuses (Gély et al, 1996). Also, our detailed core description during the process of high-resolution (2 to 4 cm) MS measurements does not show any sedimentological feature, indicator of hiatuses.…”

Section: Sedimentological Expression Of Sl Changes In the Paris Basinmentioning

confidence: 65%

“…The very low global SL of −3 m at the Spinatum–Tenuicostaum Zones may be expressed at Sancerre in the paleontological (accumulation of fossil ammonites) and sedimentological (dolostone event) data (Figure 2). The prominent changes in sedimentation rates along with the sedimentological responses of the Paris Basin to sea‐level change do not reveal the occurrence of hiatuses (Gély et al, 1996). Also, our detailed core description during the process of high‐resolution (2 to 4 cm) MS measurements do not show any sedimentological feature, indicator of hiatuses.…”

Section: Discussionmentioning

confidence: 99%

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A 20‐million‐year Early Jurassic cyclostratigraphic record and its implications for the chaotic inner Solar System and sea‐level changes

et al. 2023

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We present high-resolution (every 2 cm) magnetic susceptibility (MS) data from the Sancerre-Couy drill-core (Paris Basin), spanning the latest Sinemurian to the earliest Aalenian (early Jurassic). This record allows to build a 20-million-year cyclostratigraphic interval using the stable 405 kyr (g2-g5) orbital eccentricity cycle and to focus on long-period cyclicities and their potential implications for the chaotic diffusion in the inner Solar System and sea level changes. Time series analysis indicates evidence of two long-period cyclicities of 1.6 and 3.4 Myr. These Early Jurassic cyclicities likely correspond to the Cenozoic orbital cyclicities of 2.4 Myr (g4-g3) and 4.7 Myr eccentricity terms. Shortening of eccentricity terms during the Early Jurassic is potentially related to the chaotic orbital motion of the inner planets expressed in the resonant argument θ = 2(g4 -g3) − (s4 -s3). The 1.6 Myr (g4-g3) cycle matches the third-order eustatic sequences, while the 3.4 Myr cycle has no equivalent in the reference eustatic chart. To these cycles of several million years are superimposed a cyclicity of ~7.5 Myr, which may correspond to the eccentricity term of 9.5 Myr, previously detected in the Cenozoic. Such cyclicity matches the global, "shorter" second order sea level sequences, and is strongly documented in the sedimentological and mineralogical proxy data, hence supporting the potential key role of orbitally paced climate and sea-level changes at this timescale.

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Section: Discussioncontrasting

confidence: 91%