Oxygen, strontium, and neodymium isotope composition of fossil shark teeth as a proxy for the palaeoceanography and palaeoclimatology of the Miocene northern Alpine Paratethys

Détails

ID Serval
serval:BIB_418734C9F98F
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Oxygen, strontium, and neodymium isotope composition of fossil shark teeth as a proxy for the palaeoceanography and palaeoclimatology of the Miocene northern Alpine Paratethys
Périodique
Palaeogeography, Palaeoclimatology, Palaeoecology
Auteur(s)
Vennemann T.W., Hegner E.
ISSN-L
0031-0182
Statut éditorial
Publié
Date de publication
1998
Peer-reviewed
Oui
Volume
142
Pages
107-121
Langue
anglais
Résumé
The Upper Marine Molasse sediments of southern Germany were deposited
during the Early to Middle Miocene, a period of significant change for
the global Miocene palaeoceanography, palaeoclimate, and the regional
palaeogeography because of the ongoing Alpine-Himalayan orogeny. To
address the influence of the Alpine uplift on climate and oceanography
of the northern Alpine molasse basin, a combined O-, Sr-, and Nd-isotope
study was undertaken on fossil teeth from sharks (Synodontaspis sp.,
Galeocerdo cf. aduncus, Chaenogaleus sp.), and button-like teeth from
the bony fish of the Upper Marine Molasse (Chrysophrys molassica).
Average delta(18)O values for hydroxyapatite of teeth from two sites are
20.3 parts per thousand (l sigma = 0.6) and 21.2 parts per thousand (l
sigma = 0.5), while their average Sr-87/Sr-86 and Nd-143/Nd-144 ratios
are 0.70850 (+/-0.00001, 2 sigma) and 0.70882 (+/-0.00003, 2 sigma), and
0.51220, and 0.51223 (both at +/-0.00001, 2 sigma), respectively. By
comparison to the Sr-evolution curve for the global ocean, the
Sr-isotope compositions suggest ages of about 22 and 17 Ma for the
teeth. These ages are in good agreement with the depositional ages,
which suggests open marine conditions. Open marine conditions are also
compatible with (1) lower average delta(18)O values and 87Sr/86Sr ratios
for the one site compared to higher delta(18)O values and higher
Sr-87/Sr-86 ratios for the other site, (2) estimates for seawater
temperatures which are similar to other estimates from deposits of
similar latitude and age, (3) a comparison of seawater temperatures with
average ambient air temperature estimates deduced from continental
palaeoclimate indicators. Nd-isotope compositions are compatible with an
influence of the North Atlantic on the Paratethys. Assuming constant
salinity and seawater oxygen isotope composition, a 4 degrees C cooling
can be inferred from average delta(18)O values of the teeth between 22
and 17 Ma. This is similar to trends observed for foraminiferal records
from the Mediterranean Tethys, but different from foraminiferal and
molluscan records of the North Atlantic and the North Sea during this
period, and allows for the possibility that the Alpine orogeny had an
influence on the regional, circum-Alpine climate. (C) 1998 Elsevier
Science B.V. All rights reserved.
Création de la notice
29/09/2012 16:23
Dernière modification de la notice
20/08/2019 13:42
Données d'usage