@article{64bea54901b54f7fa1479113a68d02f7,
title = "The origin of carbonate mud and implications for global climate",
abstract = "Carbonate mud represents one of the most important geochemical archives for reconstructing ancient climatic, environmental, and evolutionary change from the rock record. Mud also represents a major sink in the global carbon cycle. Yet, there remains no consensus about how and where carbonate mud is formed. Here, we present stable isotope and trace-element data from carbonate constituents in the Bahamas, including ooids, corals, foraminifera, and algae. We use geochemical fingerprinting to demonstrate that carbonate mud cannot be sourced from the abrasion and mixture of any combination of these macroscopic grains. Instead, an inverse Bayesian mixing model requires the presence of an additional aragonite source. We posit that this source represents a direct seawater precipitate. We use geological and geochemical data to show that “whitings” are unlikely to be the dominant source of this precipitate and, instead, present a model for mud precipitation on the bank margins that can explain the geographical distribution, clumped-isotope thermometry, and stable isotope signature of carbonate mud. Next, we address the enigma of why mud and ooids are so abundant in the Bahamas, yet so rare in the rest of the world: Mediterranean outflow feeds the Bahamas with the most alkaline waters in the modern ocean (>99.7th-percentile). Such high alkalinity appears to be a prerequisite for the nonskeletal carbonate factory because, when Mediterranean outflow was reduced in the Miocene, Bahamian carbonate export ceased for 3-million-years. Finally, we show how shutting off and turning on the shallow carbonate factory can send ripples through the global climate system.",
keywords = "Bahamas, carbonates, climate, geochemistry, pCO",
author = "Geyman, {Emily C.} and Ziman Wu and Nadeau, {Matthew D.} and Stacey Edmonsond and Andrew Turner and Purkis, {Sam J.} and Bolton Howes and Blake Dyer and Ahm, {Anne Sofie C.} and Nan Yao and Deutsch, {Curtis A.} and Higgins, {John A.} and Stolper, {Daniel A.} and Maloof, {Adam C.}",
note = "Funding Information: This material is based on work supported by NSF Division of Earth Sciences Grant 1410317, the High Meadows Environmental Institute, the Geological Society of America Stephen G. Pollock Student Research Grant, the Evolving Earth Foundation, and the Princeton Geosciences Student Research Fund. E.C.G. thanks the NSF Graduate Research Fellowships Program and the Fannie and John Hertz Foundation. D.A.S. acknowledges support from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, under Award Number DE-AC02-05CH11231. We acknowledge the use of Princeton{\textquoteright}s Imaging and Analysis Center, which is partially supported through the Princeton Center for Complex Materials, an NSF Materials Research Science and Engineering Centers program (DMR-2011750). We thank Liam O{\textquoteright}Connor and Tano Humes for field assistance in the Bahamas. Thank you to John Valley, Jon Husson, Nadir Jeevanjee, Blair Schoene, Amanda Oehlert, Peter Swart, and John Grotzinger for insightful conversation. Linda Kah, Nick Tosca, and an anonymous reviewer provided valuable feedback. Finally, thank you to Jeff Birch, the Small Hope Bay Lodge staff, and the Bahamas Environment, Science & Technology Commission for making work possible on Andros Island. Funding Information: ACKNOWLEDGMENTS. This material is based on work supported by NSF Division of Earth Sciences Grant 1410317, the High Meadows Environmental Institute, the Geological Society of America Stephen G. Pollock Student Research Grant, the Evolving Earth Foundation, and the Princeton Geosciences Student Research Fund. E.C.G. thanks the NSF Graduate Research Fellowships Program and the Fannie and John Hertz Foundation. D.A.S. acknowledges support from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, under Award Number DE-AC02-05CH11231.Weacknowledgetheuseof Princeton{\textquoteright}sImagingandAnal-ysisCenter,whichispartiallysupportedthroughthePrincetonCenterforComplex Materials, an NSF Materials Research Science and Engineering Centers program (DMR-2011750). We thank Liam O{\textquoteright}Connor and Tano Humes for field assistance in the Bahamas. Thank you to John Valley, Jon Husson, Nadir Jeevanjee, Blair Schoene, Amanda Oehlert, Peter Swart, and John Grotzinger for insightful conversation. Linda Kah, Nick Tosca, and an anonymous reviewer provided valuable feedback. Finally, thank you to Jeff Birch, the Small Hope Bay Lodge staff, and the Bahamas Environment, Science & Technology Commission for making work possible on Andros Island. Publisher Copyright: {\textcopyright} 2022 the Author(s). Published by PNAS.",
year = "2022",
month = oct,
day = "25",
doi = "10.1073/pnas.2210617119",
language = "English (US)",
volume = "119",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
publisher = "National Academy of Sciences",
number = "43",
}