NTRS - NASA Technical Reports Server

Back to Results
Osmium Isotope Constraints on the Proportion of Bolide Component in Chicxulub Impact MeltsRecent drilling has produced the samples of impact melt breccias examined here. All samples examined here are from the YAX-1 borehole [7]. Two main types of impact breccias have been studied. The first type is a green altered impact meltrock found in the lower portion of the impact sequence. The texture of the rock is microcrystalline and is composed of pyroxene, plagioclase, and alkali feldspars. Its composition is consistent with continental margin rocks. It is generally massive with some flow structure. The rock was brecciated and altered after solidfication and contains small amounts of both shocked and unshocked clasts of the impacted lithologies. These lithologies include lithic quartzite, and isolated feldspar crystals. The compositions of these rocks are similar to those seen in meltrocks sampled by the Yucatan-6 borehole [8-9]. Our study includes samples YAX-1_861.4, YAX-1_863.51, and YAX- 1_876.46, which represent both the top and lower portion of the green impact meltrock. The middle sample in the sequence has the least amount of (mineralogical) alteration [10]. The second type of melt breccia under study is a brown altered impact meltrock. It also has a microcrystalline texture and both shocked and unshocked clasts of the target material. Even though this rock type has been altered, remnant schleiren, metaquartzite, and micritic calcite have been identified. Sample YAX-1_841.32 is representative of this type of rock. It was recovered from a polymict breccia in the middle of the impact sequence.
Document ID
Acquisition Source
Document Type
Conference Paper
Gelinas, A.
(Maryland Univ. College Park, MD, United States)
Walker, R. J.
(Maryland Univ. College Park, MD, United States)
Kring, D. A.
(Arizona Univ. Tucson, AZ, United States)
Zurcher, L.
(Arizona Univ. Tucson, AZ, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Publication Information
Publication: Lunar and Planetary Science XXXIV
Subject Category
Funding Number(s)
Distribution Limits
Public Use Permitted.
Document Inquiry

Available Downloads

There are no available downloads for this record.
No Preview Available