Shatsky Rise limestones

Obviously there are major differences between the 13c content of Jamaican chalks altered in the vadose meteoric environment and that of Shatsky Rise limestones. However, as Land (1979b) pointed out, if chemical stabilization of the Jamaican chalks had occurred in the phreatic meteoric environment with little influence from soil CO2, Sr and 180 depletions would be observed with little change in 8l3C. The limestones formed would be more homogeneous and virtually indistinguishable geochemically from Shatsky Rise sediments. 

Figure 8.21. Strontium, 818C, and 8180 composition of Miocene chalk, northern Jamaica. Subaerially exposed chalks are low in Sr, and depleted in 180 and l3C relative to chalks that have never been exposed to subaerial conditions. The line is the Sr-8180 trend for Shatsky Rise limestones recovered by the DSDP program (Matter et al., 1975). Notice the similarity between the Sr-8180 trends for the Shatsky Rise limestones, which have undergone burial diagenesis, and that for the Jamaican chalks, which have been subjected to meteoric processes. (After Land, 1986.)...

---