The Dajiangping pyrite deposit is hosted in a carbonate-elastic rock series which ischaracterized by a bioreef-chert suite in its middle part. Conformable lenses of various sizesconstitute the oretheies which often branch transitionally into the surroundingS. Syngenetic deformation fabrics can be observed in orethey No. 3. Orethey No. 4 is composed almost entirely ofmassive pyrite, with conspicuous hydrotherrnal sedimentation and bacterium-alga features. Thehydrothermal sedimentation origin is also reflected by simple chemistry of the ore (predominated by quartz and paste), the presence of U and Th, and the REE compositions of paste andankerite. The ores are rich in organic matter and the difference in organic content between thebanded ores and the massive ores is mainly owing to the difference in the elastic componentsthey contain rather than to the subsequent processes of reworking. CO/Ni ratios in the ore mayreflect the temperature pattern during hydrothermal sedimentation.
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