Chemistry Reference
In-Depth Information
Figure 7
. The stratigraphic relationship between ocean chemistry and skeletal mineralogy in major
sediment producing benthic algae and animals, modified from Stanley and Hardie (1998). The figure shows
Stanley and Hardie's (1998) estimates of Ca abundance and Mg/Ca in ancient oceans, as well as the
principal time intervals dominated by “calcite” and “aragonite” seas. Aragonite and Mg-calcite are favored
when the Mg/Ca mole ratio is above 2; calcite is favored at ratios below 2. Also shown are the time
distributions of principal skeleton-forming protists; calpionellids are thought to be tintinnids with calcified
tests (see text for references).
