Fig. 2: Photomicrographs of Ediacaran iron formations and carbonate fluorapatite (CFA).
From: A phosphate-rich marine reservoir in the redox stratified Ediacaran ocean
a Thin section of iron formations with a typical banded structure, where the red laminae are jasper and the gray laminae are hematite (sample JPG-30, banded IF). b False-color scanning electron microscope (SEM) mineral map of Fig. 2a, where the red-violet color shows CFA, which is mainly distributed in jasper-rich laminae. c SEM photos of fine-grained hematite particles (sample KW-6, IF). d Disseminated CFA grains with a subhedral shape (sample KW-33, IF). e Euhedral CFA grains (sample JPG-30, banded IF). f Rare coarse-grained CFA (sample JPG-28, banded IF). g Hematite inclusions in a CFA particle (sample JPG-26, banded IF). h EDS spectrum from an apatite particle shown in Fig. 2e, using a gold-plated thin section. Peaks for C, O, F, P and Ca confirm the mineral is CFA. Hem-Hematite, Qtz-Quartz.
