Samples were made into thin sections with polished surface. Each spectrum was measure by 10 loops with each one collected for 15 seconds.

Samples were made into thin sections with polished surface. Elements of MgO, SiO2, CaO, FeO, MnO and SrO were measured.

Samples were made into powder. About 1 mg was required for each sample. Results were measured by the standard phosphoric acid method.

The mineral phase of primary marine fibrous carbonate is supposed to be mainly controlled by the Mg/Ca of seawater during precipitation. However, fibrous Mg calcite was...