Honisch et al., 2012 (The geological record of ocean acidification DOI: 10.1126/science.1208277 ) might be helpful.

Thanks Shannon

This is a model approach rather than basic bulk calcite sedimentation rates per Ma.

I ll keep digging - should be something out there

Best

Alan

Dear Alan

see

Article Foraminifera promote calcification by elevating their intracellular pH

Thanks Massih!