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doi:10.2204/iodp.proc.307.204.2009

Conclusions

Challenger Mound sediments are essentially composed of in situ biogenic components and allochthonous siliciclastic components.

The biogenic components are dominated by coldwater coral fragments with a matrix composed of nannofossil (coccoliths) and fine-grained bioclasts (from 10 µm to 2 mm in diameter), foraminifers, sponge spicules, radiolarians, echinoderms, bivalves, and gastropods. Coral fragments originated mainly from L. pertusa and to a lesser extent M. oculata and D. cristagalli. Coral fragments throughout the mound succession show traces of extensive dissolution, bioerosion, and fragmentation.

The siliciclastic components, mainly clay minerals (illite, kaolinite, and chlorite) and fine sand and silt-sized quartz, are immature and allogenic.

Organic matter content is very low (average = 0.2%). Its origin is difficult to determine because the organic matter is mostly oxidized and may be reworked. However, a bacterial origin seems unimportant.

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