Nacre tablet thickness records formation temperature in modern and fossil shells
Abstract
Nacre, the iridescent outer lining of pearls and inner lining of many mollusk shells, is composed of periodic, parallel, organic sheets alternating with aragonite (CaCO_3) tablet layers. Nacre tablet thickness (TT) generates both nacre's iridescence and its remarkable resistance to fracture. Despite extensive studies on how nacre forms, the mechanisms controlling TT remain unknown, even though they determine the most conspicuous of nacre's characteristics, visible even to the naked eye. Thermodynamics predicts that temperature (T) will affect both physical and chemical components of biomineralized skeletons. The chemical composition of biominerals is well-established to record environmental parameters, and has therefore been extensively used in paleoclimate studies. The physical structure, however, has been hypothesized but never directly demonstrated to depend on the environment. Here we observe that the physical TT in nacre from modern and fossil shallow-water shells of the bivalves Pinna and Atrina correlates with T as measured by the carbonate clumped isotope thermometer. Based on the observed TT vs. T correlation, we anticipate that TT will be used as a paleothermometer, useful to estimate paleotemperature in shallow-water paleoenvironments. Here we successfully test the proposed new nacre TT thermometer on two Jurassic Pinna shells. The increase of TT with T is consistent with greater aragonite growth rate at higher T, and with greater metabolic rate at higher T. Thus, it reveals a complex, T-dependent biophysical mechanism for nacre formation.
Additional Information
© 2016 Elsevier B.V. Received 24 May 2016; Received in revised form 27 September 2016; Accepted 6 November 2016; Available online 15 December 2016. We thank Andreas Scholl and Anthony Young for expert technical help during the experiments. We thank Nami Kitchen, Yunbin Guan and Chi Ma for help with analytical measurements at Caltech. We are indebted to Jessica Cundiff, Susan Butts, Jessica Utrup, Neil Landman, Bushra Hussaini, Robert Hazen, John Nance, Christopher Andrew, and Steven Davies for finding and providing fossil specimens from their museum collections. We thank Jonatahn Erez, Erez Lieberman-Aiden and Lakshmi Narasimhan for discussions, and C. Kevin Boyce for reading the manuscript and suggesting improvements. PUPAG 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 DE-FG02-07ER15899, the Radcliffe Institute for Advanced Study at Harvard University, NSF Grant DMR-1105167, US-Israel Binational Science Foundation Grant BSF-2010065. PEEM and diffraction experiments were done at the ALS, which is a DOE Office of Science User Facility supported by Grant DE-AC02-05CH11231. AHK and CEM acknowledge support from the NASA Astrobiology Institute and the NASA Postdoctoral Program. KDB acknowledges support from the Harvard Society of Fellows.Attached Files
Supplemental Material - mmc1.pdf
Supplemental Material - mmc2.xlsx
Supplemental Material - mmc3.xlsx
Supplemental Material - mmc4.xlsx
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Additional details
- Eprint ID
- 73421
- Resolver ID
- CaltechAUTHORS:20170111-104816530
- DE-FG02-07ER15899
- Department of Energy (DOE)
- Harvard University
- DMR-1105167
- NSF
- BSF-2010065
- Binational Science Foundation (USA-Israel)
- DE-AC02-05CH11231
- Department of Energy (DOE)
- NASA Postdoctoral Program
- Harvard Society of Fellows
- Created
-
2017-01-21Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences