High-Resolution trace element studies on Tektites from Maastrichtian/Danian (K/T) Strata
Abstract
The composition, alteration and diagenetic effects of Chicxulub-Impact Ejecta (Spherules and Tektite glasses) has been investigated by Transmission Electron Microscopy, Raster Electron Microscopy, Electron Microscopy, Microprobe and Synchrotron X-ray Fluorescence in order to document glass alteration and to evaluate and understand these processes. Microprobe as well as Transmission Electron Microscope studies of individual glasses (Spherules) show different intra-sample element concentrations and reveal the nature and extend of glass alteration. TEM studies of K/T-boundary samples of impact-derived Ejecta from the Gulf of Mexico has revealed the occurrence of almost fresh and unweathered glasses with only minor alteration. However, altered glasses could be observed in some K/T-sections. Net bulk chemical composition for altered glass includes losses of Si, Mn, Ca, Na and K. This material is redistributed into altered fracture Phyllosilicates. We conclude that the major alteration process is due to undergoing low-temperature hydrothermal processes to produce Phyllosilicates. Various horizons in investigates sites may be alteration products of these impact Ejecta. In general two types of impact glass are described from the investigated sections. These types are Si-Al- (dark) and Si-Ca-rich (light yellow), respectively. Some spherules show the presence of Fe-, Ti- and K-rich schlieren structures.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFM.P51A1184H
- Keywords:
-
- 1065 Major and trace element geochemistry;
- 5420 Impact phenomena;
- cratering (6022;
- 8136);
- 6022 Impact phenomena (5420;
- 8136);
- 8136 Impact phenomena (5420;
- 6022)