Projects
Mineralogy, Petrology, and Geochemistry of Martian Regolith Breccias
What is the mineralogy in the Martian surficial crust?
How is Mars' mineralogy different from Earth?
Where is the "water" on Mars now?
Nicknamed "Black Beauty", NWA 7034, NWA 8171, and NWA 11220 are polymict brecciated meteorites representing Martian surface regolith [Agee et al., 2013; Humayun et al., 2013]. We present integrated studies of mineralogy, petrology, and geochemistry of a suite of slabs and thin sections of Martian breccias, determined by in situ micro-XRD (μXRD), Raman, optical microscopy, and EPMA.
NWA 7034_small_01_thin in XPL mode
NWA 7034_small_01_thin_optical mode
Shock Metamorphic Effects of Feldspar in Martian Regolith Breccias
How about the shock features of feldspar minerals?
What is the shock range of different feldspar grains?
How to evaluate the shock pressures through measuring the deformation levels in feldspar?
Schematic diagrams: (a) An unstrained single crystal, producing a single diffracted X-ray. (b) A non-uniformly strained single crystal, showing a continuous mosaic spread of grain orientations, producing a continuous dispersion of diffracted X-ray patterns or “streak”. (c) A series of systematically reoriented mosaic blocks or subgrains, producing a row of discrete diffracted X-rays (i.e., asterism).
Micro X-Ray Diffraction Characteristics of Unshocked and Shocked Crystals
How to quantify the shock-induced deformation in minerals using micro-XRD?
What are the deformation features implied in the 2D XRD images?
Schematic of diffractometer geometry and GADDS images (top images).
Single crystal will produce a single diffracted X-ray spot corresponding to the lattice plane Continuous spreading of diffracted X-ray intensity or streak (bottom images).
Shock-induced Deformation of Pyroxene in Martian Regolith Breccias
What about the shock features of pyroxene grains?
What is the range of shock levels in different pyroxene grains (in both Opx and Cpx subgroups)?
How to evaluate the shock pressures preserved in pyroxene minerals by measuring the deformation levels?
Micro X-Ray Diffraction Characteristics of Experimentally Shocked Andesine
Micro-XRD of experimentally shocked andesine samples under shock pressures of 0-56 GPa.
The calibration curve is used to estimate the shock pressures in meteorites and terrestrial impact rocks with plagioclase minerals.
Andesine anorthosite samples were acquired from St. Urbain, Canada. They are initially monomineralic rocks that contain ~ 95% andesine (An36–46), with minor amounts of quartz and potassium feldspar, with grains < 5–10 mm [Johnson, 2012]
