Climatic fluctuations and seasonality during the Late Jurassic (Oxfordian-Early Kimmeridgian) inferred from d super(1) super(8)O of Paris Basin oyster shells

Oxygen isotope data from biostratigraphically well-dated oyster shells from the Late Jurassic of the eastern Paris Basin are used to reconstruct the thermal evolution of western Tethyan surface waters during the Early Oxfordian-Early Kimmeridgian interval. Seventy eight oyster shells were carefully...

Full description

Saved in:
Bibliographic Details
Published in:Earth and planetary science letters 2008-08, Vol.273 (1-2), p.58-67
Main Authors: Brigaud, B, Puceat, E, Pellenard, P, Vincent, B, Joachimski, M M
Format: Article
Language:English
Subjects:
Cymodoce
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Oxygen isotope data from biostratigraphically well-dated oyster shells from the Late Jurassic of the eastern Paris Basin are used to reconstruct the thermal evolution of western Tethyan surface waters during the Early Oxfordian-Early Kimmeridgian interval. Seventy eight oyster shells were carefully screened for potential diagenetic alteration using cathodoluminescence microscopy. Isotope analyses were performed on non-luminescent parts of shells (n=264). Intra-shell d super(1) super(8)O variability was estimated by microsampling along a transect perpendicular to the growth lines of the largest oyster shell. The sinusoidal distribution of the d super(1) super(8)O values along this transect and the dependence of the amplitude of variations with bathymetry suggest that intra-shell variability reflects seasonal variations of temperature and/or salinity. Average amplitudes of about 5 super(o)C in shallow water environments and of about 2-3 super(o)C in deeper offshore environments are calculated. These amplitudes reflect minimum seasonal temperature variation. Our new data allow to constrain existing paleotemperature trends established from fish tooth and belemnite d super(1) super(8)O data and are in better agreement with paleontological data. More specifically, a warming trend of about 3 super(o)C is reconstructed for oceanic surface waters during the Early to Middle Oxfordian transition, with maximum temperatures reaching 24 super(o)C in the transversarium Zone (late Middle Oxfordian). From the transversarium Zone to the bimmamatum Zone, a cooling of about 7 super(o)C is indicated, whereas from the bimmamatum Zone, temperatures increased again by about 7 super(o)C to reach 24 super(o)C in average during the cymodoce Zone (Early Kimmeridgian).
ISSN:0012-821X
DOI:10.1016/j.epsl.2008.06.015