Fig. 7: Crystal growth microstructures in foliated listvenites.
From: Ductile deformation during carbonation of serpentinized peridotite
a Scanning-electron microscopy cathodoluminescence (SEM-CL) image of magnesite (Mgs) ellipsoids with Fe-magnesite (black) cores and aligned magnesite dendrites, in a quartz (Qtz) matrix with euhedral crystal growth zoning (CL filter optimized for quartz). b SEM-CL image of magnesite ellipsoids with concentric zoning and dendritic rims, and concentric spherulitic to botryoidal growth zoning of quartz (CL filter optimized for magnesite). c Euhedral magnesite with Fe-oxide inclusions and dendritic rims; quartz in the matrix has a crystallographic preferred orientation (c.f. Fig. 4c) (crossed polarized light image). d Electron backscatter diffraction (EBSD) orientation map of magnesite (color scale see Fig. 4) with corresponding crystal shapes overlay of rhombohedral magnesite (crystallographic axes see inset). e Secondary electron (SE) image of dendritic rim on euhedral magnesite. Sub-micron scale crystal facets of quartz (Qtz*) and magnesite (Mgs*) are visible in the related porosity. f High resolution SE image of a nano-porous magnesite dendrite showing a 100−400 nm wide SiO2 rim at the contact to quartz. (a, b: sample BT1B_14-3_77-80; c - f: sample BT1B_16-3_28-31). Scale bars in a–c are 50 µm, in d 200 µm (black bar), in e 10 µm and in f 2.5 µm.
