Textural and compositional analysis of Fe-Ni metallic spherules in impact melt from Monturaqui Crater, Chile

• Main Author: Cukierski, Daniel Owen
• Other Authors: Peate, David W.
• Format: Others
• Language: English
• Published: University of Iowa 2013
• Subjects: Fe-Ni spherules; Hexahedrite; Monturaqui; Ni-rich rims; Geology
• Online Access: https://ir.uiowa.edu/etd/2467; https://ir.uiowa.edu/cgi/viewcontent.cgi?article=4595&context=etd

The scope of this project is to collect and interpret geochemical and textural data of iron-nickel (Fe-Ni) spherules in impact melt from the Monturaqui Impact Crater, Chile to investigate the processes accounting for the compositional variations. Major element data are collected on in situ spherules in one thin section and three epoxy rounds by electron microprobe and major element, trace element, and platinum group element data are collected by inductively coupled plasma mass spectrometry on spherules separated from impact glass by electric pulse disintegration (Figure 1C-1D). Major element, trace element, and platinum group element data are collected on a piece of iron shale from Monturaqui by using both instruments. Though the variation of the major elements within Fe-Ni spherules has been well documented, the variations of trace elements have not been rigorously investigated. This study aims to document the variations seen in major elements, trace elements, and platinum group elements in the Fe-Ni spherules relative to the iron impactor. The impactor was originally classified as a group I coarse octahedrite based on the Ni content of Fe-Ni spherules in the impact melt as well as the morphology of the iron shale (Bunch and Cassidy, 1972; Buchwald, 1975). For this study, major element, trace element, and platinum group element data were collected on a piece of iron shale from Monturaqui to provide a more robust classification.