31 Undergraduate and Graduate Posters with Lightning Talks (Posters)

Monday, 15 April 2024
1:30 PM - 5:30 PM
Grand Ballroom

MICROSTRUCTURAL, MINERALOGICAL, AND CHEMICAL CHARACTERIZATION OF THE HANDYS BEND AND FLAX CREEK METEORITES, KENTUCKY

Paper number: 31-2
Program: Theme Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

Originating in the cores of the solar system’s earliest forming large bodies, iron meteorites remain the only material view into the planetary cores. As a result, much of the scientific knowledge regarding planetary accretion and differentiation is derived from the study of iron meteorites. Despite their scientific relevance, iron meteorites remain relatively rare, exceedingly so in humid climates such as the southeastern United States. In June 2021 and March 2022, the Kentucky Geological Survey received requests to identify metallic specimens discovered by two separate parties in central Kentucky. Hand specimen analyses revealed physical characteristics consistent with iron meteorites, and the specimens were given the provisional names Handys Bend (3175.2 g) and Flax Creek (286.2 g). The goal of this project is to confirm meteoric origin, characterize their structures and chemistry, and if warranted, assign group classifications, and examine possible relations to previously discovered meteorites. Petrographic analysis was conducted using a scanning electron microscope. Dominant mineral phases were examined using X-Ray diffraction crystallography. Major and minor element (Fe, Co, Ni, and Cu) concentrations were determined via energy-dispersive X-Ray fluorescence spectrometry and trace and select minor element (Cr, Co, Cu, Ga, Ge, As, Sb, W, Re, Ir, Pt, and Au) concentrations were determined via instrumental neutron activation analysis. Major and minor concentrations, principal mineral phases, and analysis of Widmanstätten patterns confirmed both specimens to be medium octahedrites. Handys Bend exhibits comprehensive kamacite recrystallization and an absence of Neumann band twinning due to cosmic reheating. The iron contains abundant troilite and daubréelite nodules, some of which exhibit brecciation and local injection into surrounding kamacite. Flax creek contains numerous schreibersite and cohenite macroprecipitates enveloped by swathing kamacite with internal defects. Kamacite bands are knobby, discontinuous and contain abundant rhabdites and Neumann lamellae. Chemical trends reveal group classifications of IIIAB for Handys Bend and IAB for Flax Creek. Structural and chemical analyses verify that both meteorites are unique finds and the first discoveries in Kentucky since 1990.

Geological Society of America Abstracts with Programs. Vol. 56, No. 2

doi: 10.1130/abs/2024SE-398475

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