Calcite sea

A calcite sea is one in which low-magnesium calcite is the primary inorganic marine calcium carbonate precipitate. An aragonite sea is the alternate seawater chemistry in which aragonite and high-magnesium calcite are the primary inorganic carbonate precipitates. The Early Paleozoic and the Middle to Late Mesozoic oceans were predominantly calcite seas, whereas the Middle Paleozoic through the Early Mesozoic and the Cenozoic (including today) are characterized by aragonite seas (Wilkinson et al., 1985; Wilkinson and Given, 1986; Morse and Mackenzie, 1990; Lowenstein et al., 2001; Palmer and Wilson, 2004).

The most significant geological and biological effects of calcite sea conditions include rapid and widespread formation of carbonate hardgrounds (Palmer, 1982; Palmer et al., 1988; Wilson and Palmer, 1992), calcitic ooids (Sandberg, 1983; Wilkinson et al., 1985), calcite cements (Wilkinson and Given, 1986), and the contemporaneous dissolution of aragonite shells in shallow warm seas (Cherns and Wright, 2000; Palmer and Wilson, 2004). Hardgrounds were very common, for example, in the calcite seas of the Ordovician and Jurassic, but virtually absent from the aragonite seas of the Permian (Palmer, 1982).