Stable isotope composition of smectite in suevites at the Ries crater, Germany: Implications for hydrous alteration of impactites

Détails

ID Serval
serval:BIB_060C91206BA3
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Stable isotope composition of smectite in suevites at the Ries crater, Germany: Implications for hydrous alteration of impactites
Périodique
Earth and Planetary Science Letters
Auteur(s)
Muttik N., Kirsimaee K., Vennemann T.W.
ISSN-L
0012-821X
Statut éditorial
Publié
Date de publication
2010
Peer-reviewed
Oui
Volume
299
Pages
190-195
Langue
anglais
Résumé
The 24-km diameter Ries crater, Germany, exhibits well-preserved crater
filling and surficial melt-rich breccia deposits that are believed to
have been altered by post-impact hydrothermal fluids. The alteration
mineralogy of the crater filling breccias is characterized by clay
(smectite, chlorite) and a zeolite assemblage, and secondary clay phases
(smectite, minor halloysite) in surficial melt-bearing breccia deposits.
Using stable isotope analysis of secondary smectitic clay fractions,
evidence of significant hydrous alteration of impactites at large
water/rock ratios was found. The estimated fluid temperatures, using
data derived by delta(18)O and delta D fractionation, suggest smectite
precipitation in surficial breccias in equilibrium with meteoric fluids
at temperatures 16 +/- 5 degrees C in agreement with the long-term
variation of modern precipitation in the area. The stable isotope
composition of smectite in crater-fill breccia, however, suggests a
trend of monotonously increasing temperatures from 43 to 112 degrees C.
with increasing depth through the breccia sequence. This demonstrates a
different origin of alteration and temperature distribution for the
surficial and crater filling melt-bearing impact breccias in the Ries
crater. Our results suggest that the inverted structure of hydrothermal
systems observed in some terrestrial impact craters, including the Ries
crater, could indicate the initial configuration of a thermal anomaly in
the crater filling sequence, but which is replaced with a normal
hydrothermal convection in crater proper, during the course of
post-impact cooling. (C) 2010 Elsevier B.V. All rights reserved.
Création de la notice
29/09/2012 16:22
Dernière modification de la notice
20/08/2019 12:28
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