JMDMT #1513 Microfossils of Cyanobacteria in Carbonaceous Meteorites

The James M. DuPont Meteorite Collection - cathodoluminescence (CL) characteristic of type A chondrules [3], and this phase is present in the chondrules studied here, although no CL was measured. This clinopyroxene, occurring as isolated crystallites or overgrowths on low-Ca pyroxene, is also rich in Cr and Mn in the present chondrules. Formation of diopside preferentially in the outer, enstatite-rich regions can explain much of the zoning behavior of Ca, Al, and Cr, and possibly the near-surface drop in Mn, implying that diffusional transport in the late-stage melt was very limited. Removal of diopside from the melt would also cause small apparent enrichments in the Na and K in the outer zones, but this effect is not nearly large enough to explain the fourfold or greater enhancements observed