A dynamic marine calcium cycle during the past 28 million years.
Multiple lines of evidence have shown that the isotopic composition and concentration of calcium in seawater have changed over the past 28 million years. A high-resolution, continuous seawater calcium isotope ratio curve from marine (pelagic) barite reveals distinct features in the evolution of the seawater calcium isotopic ratio suggesting changes in seawater calcium concentrations. The most pronounced increase in the delta44/40Ca value of seawater (of 0.3 per mil) occurred over roughly 4 million years following a period of low values around 13 million years ago. The major change in marine calcium corresponds to a climatic transition and global change in the carbon cycle and suggests a reorganization of the global biogeochemical system.
Griffith
Elizabeth M
EM
Department of Geological and Environmental Sciences, Stanford University, Building 320, Room 118, Stanford, CA 94305, USA. egriffith@ucsc.edu
Paytan
Adina
A
Caldeira
Ken
K
Bullen
Thomas D
TD
Thomas
Ellen
E
D000818:Animals; D001466:Barium Sulfate / Q000737:chemistry; D002118:Calcium / Q000032:analysis* / Q000378:metabolism; D002119:Calcium Carbonate / Q000032:analysis; D002127:Calcium Isotopes / Q000032:analysis; D002980:Climate; D019015:Geologic Sediments / Q000737:chemistry; D012623:Seawater / Q000737:chemistry*; D013995:Time
D002127:Calcium Isotopes; D001466:Barium Sulfate; D002119:Calcium Carbonate; D002118:Calcium