Unravelling Middle to Late Jurassic palaeoceanographic and palaeoclimatic signals in the Hebrides Basin using belemnite clumped isotope thermometry

Madeleine Vickers*, Alvaro Fernandez, Stephen P. Hesselbo, Gregory D. Price, Stefano M. Bernasconi, Stefanie Lode, Clemens Vinzenz Ullmann, Nicolas Thibault, Iben Winther Hougård, Christoph Korte

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Clumped isotope based temperature estimates from exceptionally well-preserved belemnites from Staffin
Bay (Isle of Skye, Scotland) reveal that seawater temperatures throughout the Middle-Late Jurassic
were significantly warmer than previously reconstructed by conventional oxygen isotope thermometry.
We demonstrate here that this underestimation by oxygen isotope thermometry was likely due to a)
using the incorrect calcite thermometry equation for belemnite temperature reconstructions and b) by
incorrectly estimating the seawater δ18O (δ18Osw) for the Hebrides Basin. Our data suggests that the
fractionation factor for oxygen isotopes in belemnites from seawater was closer to that of slow-growing
abiogenic calcites than that of other marine calcifying organisms. Our clumped isotope temperatures
are used to reconstruct δ18Osw trends across the Callovian–Kimmeridgian in the Hebrides Basin. The
δ18Osw varied significantly in the Hebrides Basin throughout this interval, possibly as a result of changing
currents through the Laurasian seaway. Trends in temperature and δ18Osw are compared to published
palaeoceanographic studies to shed light on changing palaeoceanography in the Tethyan and Boreal
realms throughout the Middle–Late Jurassic.
Original languageEnglish
Article number116401
Pages (from-to)1-10
JournalEarth and Planetary Science Letters
Volume546
DOIs
Publication statusPublished - 15 Sept 2020

Keywords

  • Jurassic palaeoclimate
  • belemnites
  • palaeoceanography
  • clumped isotopes

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