Limestone: Dating & Isotopic Analyses
Limestone is a granular sedimentary rock predominantly composed of
calcium carbonate (CaCO3), which commonly forms along shallow ocean
water beds from fossilized shells and exoskeletons of marine organisms.
Gypsum: Isotopes & Dating
Gypsum is a relatively soft and common mineral made up of hydrous
calcium sulfate (CaSO4-2H2O). Whilst pure gypsum crystals are transparent
(often with a pearly or vitreous luster), they can appear opaque and colored
due to the inclusion of other materials (e.g. sand).
Strontium dating of foraminifera, shells & corals
Strontium dating (as enabled by the 87Sr/86Sr ratio of marine carbonates) can be used to date various marine samples based on the premise that the mixing of oceanic strontium occurs relatively rapidly through time compared to the residence time of oceanic strontium.