{"title":"Scale-dependent effects of growth rate on temperature reconstruction in a marine biogenic carbonate","authors":"Ronald E. Thresher","doi":"10.1016/j.epsl.2025.119391","DOIUrl":null,"url":null,"abstract":"<div><div>Analyses of a temperature proxy—Mg/Ca ratios—in the calcitic skeletons of bamboo corals (Octocorallia: Keratoisididae and Mopseidae) show that the effects of ambient temperature and growth rate on Mg/Ca (and oxygen isotope ratios) differ depending on the scale of the analysis. At the whole-of-specimen scale, Mg/Ca ratios are canonically positively correlated with temperature and influenced by growth rate-dependent entrapment and diffusion. However, within specimens, Mg/Ca is much more steeply positive with temperature and correlates negatively with growth rate. Within specimens, the slope of the (Mg/Ca)/temperature relationship itself varies with growth rate, which is hypothesized to result from micro-scale shifts in the relative abundance of slow and fast growing crystal types that, in turn, differ in their affinity for Mg++. This variable slope critically affects proxy-based temperature reconstruction, can underlie frequent mis-matches in marine calcifiers between environmental records and proxy-based reconstructions, and suggests cautious application within-specimens of proxies developed and calibrated using geographic “core top” comparisons.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"662 ","pages":"Article 119391"},"PeriodicalIF":4.8000,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Earth and Planetary Science Letters","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0012821X25001906","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
Analyses of a temperature proxy—Mg/Ca ratios—in the calcitic skeletons of bamboo corals (Octocorallia: Keratoisididae and Mopseidae) show that the effects of ambient temperature and growth rate on Mg/Ca (and oxygen isotope ratios) differ depending on the scale of the analysis. At the whole-of-specimen scale, Mg/Ca ratios are canonically positively correlated with temperature and influenced by growth rate-dependent entrapment and diffusion. However, within specimens, Mg/Ca is much more steeply positive with temperature and correlates negatively with growth rate. Within specimens, the slope of the (Mg/Ca)/temperature relationship itself varies with growth rate, which is hypothesized to result from micro-scale shifts in the relative abundance of slow and fast growing crystal types that, in turn, differ in their affinity for Mg++. This variable slope critically affects proxy-based temperature reconstruction, can underlie frequent mis-matches in marine calcifiers between environmental records and proxy-based reconstructions, and suggests cautious application within-specimens of proxies developed and calibrated using geographic “core top” comparisons.
期刊介绍:
Earth and Planetary Science Letters (EPSL) is a leading journal for researchers across the entire Earth and planetary sciences community. It publishes concise, exciting, high-impact articles ("Letters") of broad interest. Its focus is on physical and chemical processes, the evolution and general properties of the Earth and planets - from their deep interiors to their atmospheres. EPSL also includes a Frontiers section, featuring invited high-profile synthesis articles by leading experts on timely topics to bring cutting-edge research to the wider community.