A secondary ionization mass spectrometry calibration of Cibicidoides pachyderma Mg/Ca with temperature

作者：Curry W B^*; Marchitto T M

来源：Geochemistry Geophysics Geosystems, 2008, 9(4): Q04009.

DOI：10.1029/2007GC001620

• magnesium
• benthic foraminifera
• temperature
• ion probe

[ 1] An evaluation of C. pachyderma Mg/Ca using a new suite of warm water multicores from the Florida Straits shows that the slope of Mg/Ca with temperature is shallower than previously thought. Using secondary ionization mass spectrometry, we have documented that the distribution of magnesium within the polished walls of foraminiferal tests is Gaussian, suggesting that the Mg/Ca in these samples is not affected by the addition of a secondary high-magnesium calcite in the walls. The Mg/Ca within a typical C. pachyderma test varies by about +/- 20% ( 1 sigma/mu center dot 100), and the variability increases slightly in tests with higher Mg/Ca. The regression of C. pachyderma Mg/Ca with temperature has a slope of 0.13 +/- 0.05 mmol mol(-1) per degrees C, indistinguishable from the slope observed in inductively coupled plasma-mass spectrometry measurements from a different subset of the same multicores, but about one half the slope of previously published calibrations. The largest differences between the calibrations comes at the warm water end of the regression, where previously published C. pachyderma Mg/Ca values from Little Bahama Bank are at least 3 mmol mol(-1) higher than observed in these new cores. The reasons for this difference are not fully known but are most likely related to diagenesis at Little Bahama Bank.

• 出版日期2008-4-4