TY - JOUR
T1 - Further constraints on the diagenetic influences and salinity effect on Globigerinoides ruber (white) Mg/Ca thermometry: Implications in the Mediterranean Sea
AU - Sabbatini, Anna
AU - Bassinot, Franck
AU - Boussetta, Soumaya
AU - Negri, Alessandra
AU - Rebaubier, Hélène
AU - Dewilde, Fabien
AU - Nouet, Julius
AU - Caillon, Nicolas
AU - Morigi, Caterina
PY - 2011/10/1
Y1 - 2011/10/1
N2 - We analyzed Mg/Ca ratios of the planktonic species Globigerinoides ruber
(white) picked from 49 box core samples covering the whole
Mediterranean Sea and 2 core tops from the Atlantic Ocean. Over the
entire data set, we found no significant correlation between Mg/Ca and δ18O-derived
calcification temperatures. This lack of correlation is chiefly due to
the presence of an early diagenetic, Mg-rich calcite coating, which can
constitute up to 20% of the total shell calcite in the central and
eastern Mediterranean basin and result in anomalously high Mg/Ca values
and a high scattering. In the western Mediterranean Sea, however, G. ruber
Mg/Ca scattering shows smaller amplitude and Mg-rich calcite remains
under the XRD detection limit. SEM observations indicate that only a few
samples are affected by trace amounts of post-mortem calcite
overgrowths (most of this calcite being likely removed during the
chemical cleaning for Mg/Ca analyses). Using core top sediments from the
western Mediterranean Sea, we performed an empirical calibration
exercise, which confirms that G. ruber Mg/Ca is not only related
to temperature but it is also significantly affected by sea surface
salinity. This salinity effect is not specific to high salinity
environments such as the Mediterranean Sea, since it appears to be
coherent with recent results obtained on Indo-Pacific and Atlantic
surface sediments, which suggest that a +1 (psu) change in SSS results
in a +1.7°C Mg/Ca-temperature bias. This sensitivity to salinity is
significantly higher than those deduced from culture experiments.
AB - We analyzed Mg/Ca ratios of the planktonic species Globigerinoides ruber
(white) picked from 49 box core samples covering the whole
Mediterranean Sea and 2 core tops from the Atlantic Ocean. Over the
entire data set, we found no significant correlation between Mg/Ca and δ18O-derived
calcification temperatures. This lack of correlation is chiefly due to
the presence of an early diagenetic, Mg-rich calcite coating, which can
constitute up to 20% of the total shell calcite in the central and
eastern Mediterranean basin and result in anomalously high Mg/Ca values
and a high scattering. In the western Mediterranean Sea, however, G. ruber
Mg/Ca scattering shows smaller amplitude and Mg-rich calcite remains
under the XRD detection limit. SEM observations indicate that only a few
samples are affected by trace amounts of post-mortem calcite
overgrowths (most of this calcite being likely removed during the
chemical cleaning for Mg/Ca analyses). Using core top sediments from the
western Mediterranean Sea, we performed an empirical calibration
exercise, which confirms that G. ruber Mg/Ca is not only related
to temperature but it is also significantly affected by sea surface
salinity. This salinity effect is not specific to high salinity
environments such as the Mediterranean Sea, since it appears to be
coherent with recent results obtained on Indo-Pacific and Atlantic
surface sediments, which suggest that a +1 (psu) change in SSS results
in a +1.7°C Mg/Ca-temperature bias. This sensitivity to salinity is
significantly higher than those deduced from culture experiments.
KW - early diagenetic calcite coating
KW - foraminiferal Mg/Ca
KW - Mediterranean Sea
KW - salinity
UR - http://www.scopus.com/inward/record.url?scp=80055014240&partnerID=8YFLogxK
U2 - 10.1029/2011GC003675
DO - 10.1029/2011GC003675
M3 - Article
VL - 12
JO - Geochemistry, Geophysics, Geosystems
JF - Geochemistry, Geophysics, Geosystems
SN - 1525-2027
IS - 10
M1 - Q10005
ER -