Biogeochemical contrasts between mid-Cretaceous carbonate platforms and Cenozoic reefs

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4 Citations (Scopus)

Abstract

Carbonate sediments of mid-Cretaceous platforms on Allison and Resolution Guyots, Mid-Pacific Mountains (ODP Leg 143, Sites 865, 866, 867 and 868) and those of upper Oligocene to Pliocene reefs of the Kita-daito-jima Borehole were studied. The mid-Cretaceous platforms abound with abiotic (?) precipitates (ooids) and microbial carbonate grains/sediments (oncoids and 'algal' laminites), whereas the Cenozoic reefs consist mainly of coral and non-geniculate coralline algae, major frame-builders, benthic foraminifers and codiacean alga (Halimeda). There exists a remarkable difference in a mode of calcification between the mid-Cretaceous platforms and Cenozoic reefs. The major reef-builders of Cenozoic reefs precipitated carbonates within closed to semiclosed spaces within their bodies. In contrast, the mid-Cretaceous platforms contain abundant grains/sediments formed by chemical (?) precipitations and biotic extracellular calcification. This contrasting feature reflects different modes of biogeochemical cycles between the mid-Cretaceous and Cenozoic. Increased CO2 (degassed by active volcanism) and resultant high temperature and intensive weathering may have brought high concentration of Ca2+ and HCO3- into the mid-Cretaceous sea, which enhanced abiotic and extracellular calcification. Inverse processes are true for the Cenozoic.

Original languageEnglish
Pages (from-to)475-490
Number of pages16
JournalIsland Arc
Volume8
Issue number4
DOIs
Publication statusPublished - 1999 Dec 1

Keywords

  • Biogeochemical cycle
  • Carbonate platform
  • Cenozoic
  • Cretaceous
  • Reef

ASJC Scopus subject areas

  • Geology

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