Publication Date:
2022-05-26
Description:
Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 6 (2005): Q12P07, doi:10.1029/2005GC000974.
Description:
Secondary ion mass spectrometry (SIMS) is useful for measuring Mg/Ca in both primary calcite and diagenetic minerals in planktonic foraminifera. The excellent spatial resolution (〈10 μm) and small amount of material removed (〈2 ng) makes it easy to avoid targets that include obvious embedding material and encrusting or infilling minerals such as secondary calcite and authigenic clays in diagenetically altered samples. Because analyses can be performed on individuals, SIMS is also a viable technique for generating Mg/Ca values from sediment samples in which foraminifera are rare or have low mass. For clean primary calcite samples, Mg/Ca ratios from SIMS compare well to those obtained using inductively coupled plasma mass spectrometry (ICP-MS), while maintaining information regarding the true variability of elemental ratios within individual tests. For samples with secondary calcite or stubbornly adhering clays, SIMS enables us to accurately measure primary calcite compositions and to assess and reconcile contamination problems in bulk samples analyzed by solution-based ICP-MS. We have observed that SIMS is an invaluable and reliable tool for the identification and avoidance of problems of diagenesis and the analysis of rare or delicate planktonic foraminifera. However, because of operator time required to properly target delicate (thin-walled) or contaminated planktonic foraminifera, SIMS may not be feasible for Mg/Ca studies where large numbers (hundreds) of samples must be processed and bulk measurements on multiple individuals will suffice.
Description:
Funding for this research was provided by The Andrew W. Mellon Foundation Endowed Fund for Innovative Research and by the U.S. Science Support Program of the Joint Oceanographic Institutions. This material is also based on work supported by the National Science Foundation under grant OCE-0334598. Partial support for the Northeast National Ion Microprobe Facility was provided by NSF (EAR-0115433). This research used samples and data provided by the Ocean Drilling Program (ODP). ODP is sponsored by the U.S. National Science Foundation and participating countries under management of Joint Oceanographic Institutions, Inc.
Keywords:
Cenomanian
;
Eocene
;
Holocene
;
Mg/Ca
;
Paleoceanography
;
Paleocene
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
539255 bytes
Format:
application/pdf
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