@article{f2aa271233f64e6290be01764598dcdf,
title = "A record of the δ44/40Ca and [Sr] of seawater over the last 100 million years from fossil elasmobranch tooth enamel",
abstract = "The global geochemical cycles of calcium and strontium in seawater link the chemical composition of the oceans to the global carbon cycle and Earth's climate through the precipitation, diagenetic alteration, and sedimentary recycling of marine carbonate minerals. Here we present a record of calcium isotopic composition and [Sr] of seawater over the last 100 million years using measurements from modern and fossil shark teeth. Although there is significant variability in modern elasmobranch tooth enamel associated with physiology and diet, our record suggests a first-order increase in the average calcium isotopic composition of seawater by 0.5‰ and a decline in Sr/Ca ratios of ∼40% over the last 100 million years. These observations are in agreement with trends seen in other archives. We propose that the observed changes in both the calcium isotopic composition and Sr concentration of seawater can be explained by changes in the partitioning of the global carbonate sink associated with the development of a deep-sea carbonate reservoir in the mid-Mesozoic.",
keywords = "Calcium isotopes, Sr/Ca, elasmobranch teeth, marine calcium cycle, seawater chemistry",
author = "Akhtar, {Alliya A.} and Santi, {Lauren M.} and Griffiths, {Michael L.} and Martin Becker and Eagle, {Robert A.} and Sora Kim and L{\'a}szl{\'o} Kocsis and Yair Rosenthal and Higgins, {John A.}",
note = "Funding Information: We thank Dr. Ted Daeschler (Academy of Natural Sciences of Drexel University), Dr. Hans-Dieter Sues (Smithsonian Institution), Bruce Schumacher (USDA Forest Service), Dr. Christian Shorey (Colorado School of Mines), Robert Kirkham (Geological Solutions, Inc.), Dr. Dewayne Fox (Delaware State University), Dr. Kate Siegfried (NOAA National Marine Fisheries Service), and Calvert Marine Museum for loaning samples. Liz Lundstrom and Nic Slater provided laboratory assistance. Emma Kast, Yuzhen Yan, Michael Bender and Danny Sigman provided helpful discussion and feedback. We would like to thank 2 anonymous reviewers and Lou Derry for constructive comments that improved this manuscript. AAA acknowledges support from the Scott Vertebrate Paleontology Fund ( Princeton University ). This research was supported in part by National Science Foundation Sedimentary Geology and Paleobiology Award to Michael Griffiths, Robert Eagle and Martin Becker ( 1830581 ) and Sora Kim ( 1830480 ), and American Chemical Society Award Petroleum Research Fund Undergraduate New Investigator Grant, PRF–# 54852-UNI2 , to MLG. Funding Information: We thank Dr. Ted Daeschler (Academy of Natural Sciences of Drexel University), Dr. Hans-Dieter Sues (Smithsonian Institution), Bruce Schumacher (USDA Forest Service), Dr. Christian Shorey (Colorado School of Mines), Robert Kirkham (Geological Solutions, Inc.), Dr. Dewayne Fox (Delaware State University), Dr. Kate Siegfried (NOAA National Marine Fisheries Service), and Calvert Marine Museum for loaning samples. Liz Lundstrom and Nic Slater provided laboratory assistance. Emma Kast, Yuzhen Yan, Michael Bender and Danny Sigman provided helpful discussion and feedback. We would like to thank 2 anonymous reviewers and Lou Derry for constructive comments that improved this manuscript. AAA acknowledges support from the Scott Vertebrate Paleontology Fund (Princeton University). This research was supported in part by National Science Foundation Sedimentary Geology and Paleobiology Award to Michael Griffiths, Robert Eagle and Martin Becker (1830581) and Sora Kim (1830480), and American Chemical Society Award Petroleum Research Fund Undergraduate New Investigator Grant, PRF?#54852-UNI2, to MLG. Publisher Copyright: {\textcopyright} 2020 Elsevier B.V.",
year = "2020",
month = aug,
day = "1",
doi = "10.1016/j.epsl.2020.116354",
language = "English (US)",
volume = "543",
journal = "Earth and Planetary Science Letters",
issn = "0012-821X",
publisher = "Elsevier",
}