Sign on

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Electronic Refereed Journal Article (HTML)
· References in the article
· Citations to the Article (24) (Citation History)
· Refereed Citations to the Article
· Reads History
·
· Translate This Page
Title:
Composition of impact melt particles and the effects of post-impact alteration in suevitic rocks at the Yaxcopoil-1 drill core, Chicxulub crater, Mexico
Authors:
Hecht, Lutz; Wittmann, Axel; Schmitt, Ralf-Thomas; Stöffler, Dieter
Affiliation:
AA(Institut für Mineralogie, Museum für Naturkunde, Humboldt-Universität zu Berlin, Invalidenstrasse 43, D-10115 Berlin, Germany ), AB(Institut für Mineralogie, Museum für Naturkunde, Humboldt-Universität zu Berlin, Invalidenstrasse 43, D-10115 Berlin, Germany), AC(Institut für Mineralogie, Museum für Naturkunde, Humboldt-Universität zu Berlin, Invalidenstrasse 43, D-10115 Berlin, Germany), AD(Institut für Mineralogie, Museum für Naturkunde, Humboldt-Universität zu Berlin, Invalidenstrasse 43, D-10115 Berlin, Germany)
Publication:
Meteoritics & Planetary Science, Vol. 39, No. 7, p.1169-1186
Publication Date:
07/2004
Origin:
M&PS
DOI:
10.1111/j.1945-5100.2004.tb01135.x
Bibliographic Code:
2004M&PS...39.1169H

Abstract

Petrographical and chemical analysis of melt particles and alteration minerals of the about 100 m-thick suevitic sequence at the Chicxulub Yax-1 drill core was performed. The aim of this study is to determine the composition of the impact melt, the variation between different types of melt particles, and the effects of post-impact hydrothermal alteration. We demonstrate that the compositional variation between melt particles of the suevitic rocks is the result of both incomplete homogenization of the target lithologies during impact and subsequent post-impact hydrothermal alteration. Most melt particles are andesitic in composition. Clinopyroxene-rich melt particles possess lower SiO2 and higher CaO contents. These are interpreted by mixing of melts from the silicate basement with overlying carbonate rocks. Multi-stage post-impact hydrothermal alteration involved significant mass transfer of most major elements and caused further compositional heterogeneity between melt particles. Following backwash of seawater into the crater, palagonitization of glassy melt particles likely caused depletion of SiO2, Al2O3, CaO, Na2O, and enrichment of K2O and FeOtot during an early alteration stage. Since glass is very susceptible to fluid-rock interaction, the state of primary crystallization of the melt particles had a significant influence on the intensity of the post impact hydrothermal mass transfer and was more pronounced in glassy melt particles than in well crystallized particles. In contrast to other occurrences of Chicxulub impactites, the Yax-1 suevitic rocks show strong potassium metasomatism with hydrothermal K-feldspar formation and whole rock K2O enrichment, especially in the lower unit of the suevitic sequence. A late stage of hydrothermal alteration is characterized by precipitation of silica, analcime, and Na-bearing Mg-rich smectite, among other minerals. This indicates a general evolution from a silica-undersaturated fluid at relatively high potassium activities at an early stage toward a silica-oversaturated fluid at relatively high sodium activities at later stages in the course of fluid rock interaction.
Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)
  New!

Find Similar Abstracts:

Use: Authors
Title
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
Physics
arXiv e-prints