XCT, SEM, and LA-ICP-MS map investigation of chondrule FGRS in CM2 Aguas Zarcas

This study of CM2 Aguas Zarcas investigates the formation of fine-grained rims (FGRs) and their relationship to the matrix in CM2 Aguas Zarcas (AZ), combining scanning electron microscopy (SEM), X-ray computed tomography (XCT), and laser-ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) analyses, enabling a novel investigation into early solar system processes, providing insights into FGR formation and trace element patterns across FGR and matrix to investigate their genetic relationships and alteration history. We performed shape and volume analyses of chondrule cores and FGRs using XCT. LA-ICP-MS analysis was also conducted on one calcium-aluminum-rich inclusion (CAI) to compare trace element patterns with non-CAIs. FGRs in AZ most likely formed in either a single reservoir of weakly turbulent nebula, or two chemically similar but turbulently distinct ones. Chondrules in AZ exhibit a weak foliation and lineation fabric like that observed in the Murchison meteorite as the result of impact processing. No deformation significant enough to displace material across shear boundaries was observed in the sample. Many large FGRs exhibit S-rich banding around their cores indicative of an evolving chemistry in the solar nebula throughout FGR formation. LA-ICP-MS analysis reveals that the studied CAI’s FGR and matrix in their immediate vicinity deviate significantly from non-CAIs in trace element composition, particularly in Eu and Tm, likely either due to aqueous mobilization sourced from the CAI, or that the CAI was mobilized from a chemically distinct pocket of nebula. FGRs deviate more strongly from the mean matrix than from the matrix in their immediate vicinity. All non-CAI FGRs are chemically similar, and distinct from matrix. The studied cores, FGRs, and matrix most likely acquired their ~100µm-scale trace element heterogeneity due to either aqueous mobilization, particularly in the vicinity of CAIs or that the studied CAI was sourced from different region of the parent body. S-rich banding indicates chemical evolution in the nebula during FGR production. Our results in FGR volume to core radius relationship and S-rich banding support the nebular accretion model of FGR production.

Name thesis:degree_name

Master of Science in Geological Sciences

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Geological Sciences

Grantor

The University of Texas at Austin

Year dc:date.issued

2025

Author dc:creator

• Redman, Paul Clark, III

Advisors dc:contributor.advisor

• Ketcham, Richard Alan, 1965-
• Hanna, Romy Darlene

Committee member dc:contributor.committeemember

• Craig Martin

• Chondrule
• CM2
• Raster
• XCT
• FGR
• Fine grained rim
• Formation
• Solar nebula
• SEM
• LA-ICP-MS
• Aguas Zarcas
• Chondrite
• Matrix

Language dc:language.iso

English

Identifier URI

https://doi.org/10.26153/tsw/63163

OAI identifier oai:identifier

oai:repositories.lib.utexas.edu:2152/135849