期刊
EARTH AND PLANETARY SCIENCE LETTERS
卷 460, 期 -, 页码 281-292出版社
ELSEVIER
DOI: 10.1016/j.epsl.2016.11.012
关键词
paleo-climate; proxy; biomineral; mollusk; PEEM; iridescence
资金
- U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division [DE-FG02-07ER15899]
- Radcliffe Institute for Advanced Study at Harvard University
- NSF [DMR-1105167]
- US-Israel Binational Science Foundation [BSF-2010065]
- DOE Office of Science User Facility [DE-AC02-05CH11231]
- NASA Astrobiology Institute
- NASA Postdoctoral Program
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [1603192] Funding Source: National Science Foundation
Nacre, the iridescent outer lining of pearls and inner lining of many mollusk shells, is composed of periodic, parallel, organic sheets alternating with aragonite (CaCO3) 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. (C) 2016 Elsevier B.V. All rights reserved.
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