Applying Oxygen Isotope Paleothermometry in Deep Time

Oxygen isotope paleotemperature studies of the Mesozoic and Paleozoic are based mainly on conodonts, belemnite guards, and brachiopod shells—material resistant to diagenesis and generally precipitated in oxygen isotope equilibrium with ambient water. The greatest obstacle to accurate oxygen isotope paleothermometry in deep time is uncertainty in the oxygen isotopic composition of the ambient seawater. The second greatest obstacle is fossil diagenesis. Useful application of the oxygen isotope method to brachiopod shells requires extreme care in sample screening and analyses, and is best done with scanning-electron microscopy, and petrographic and cathodoluminescence microscopy, and trace-element analysis. Correct interpretation of oxygen isotope data is greatly aided by thorough understanding of the paleolatitude, paleoecology, and depositional environment of the samples. The oxygen isotope record for the Triassic, based on brachiopod shells, is too sparse to show any distinct isotopic features. Jurassic and Early Cretaceous δ18O records, based on belemnites, show a Toarcian (Jurassic) decline (warming), a Callovian-Oxfordian acme, and an Early Cretaceous increase (cooling) to a Valanginian-Hauterivian maximum, followed by a decline (warming) to a middle Barremian minimum. Deep-time applications to oxygen isotope thermometry provide evidence for cooling and glaciation in the Ordovician, Carboniferous, and Permian. The δ18O values from Silurian and Devonian brachiopod shells and conodonts average lower than those of the remaining Phanerozoic because of the absence of continental glaciers and possibly higher temperatures (~37°?), although slightly lower (≤2%o) seawater δ18O cannot be ruled out. The hypothesis of high temperatures in the early Paleozoic implies a relatively constant hydrospheric δ18O, which is supported by clumped isotope paleotemperatures. However, more research is needed to develop methods for evaluating clumped isotope reordering in fossils. Ongoing and future research in oxygen isotope and clumped isotope thermometry hold the promise of resolving deep-time temperatures, seawater δ18O, and salinity with heretofore unavailable accuracy (±2°, ±0.4%o, and ±2 psu), providing the environmental setting for the evolution of metazoan life on Earth.

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Carbonate clumped isotope evidence for latitudinal seawater temperature gradients and the oxygen isotope composition of Early Cretaceous seas

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/j.palaeo.2020.109777 ◽

2020 ◽

Vol 552 ◽

pp. 109777 ◽

Cited By ~ 2

Author(s):

Gregory D. Price ◽

David Bajnai ◽

Jens Fiebig

Keyword(s):

Oxygen Isotope ◽

Early Cretaceous ◽

Isotope Composition ◽

Seawater Temperature ◽

Oxygen Isotope Composition ◽

Temperature Gradients ◽

Isotope Evidence ◽

Clumped Isotope

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Oxygen isotope equilibrium in brachiopod shell fibres in the context of biological control

Mineralogical Magazine ◽

10.1180/minmag.2008.072.1.239 ◽

2008 ◽

Vol 72 (1) ◽

pp. 239-242 ◽

Cited By ~ 1

Author(s):

M. Cusack ◽

A. Pérez-Huerta ◽

P. Chung ◽

D. Parkinson ◽

Y. Dauphin ◽

...

Keyword(s):

Oxygen Isotope ◽

Isotope Composition ◽

Seawater Temperature ◽

Environmental Data ◽

Ambient Seawater ◽

Secondary Layer ◽

Vital Effect ◽

Vital Effects ◽

Stable Oxygen ◽

Isotope Equilibrium

With their long geological history and stable low-Mg calcite shells, Rhynchonelliform brachiopods are attractive sources of environmental data such as past seawater temperature (Buening and Spero, 1996; Auclair et al., 2003; Brand et al., 2003; Parkinson et al., 2005). Concerns about the influence of vital effects on the stable isotope composition of brachiopod shells (Popp et al., 1986), led to isotope analyses of different parts of brachiopod shells in order to identify those parts of the shell that are influenced by any vital effect and those parts that may be suitable recorders of seawater temperature via stable oxygen isotope composition (Carpenter and Lohmann, 1995; Parkinson et al., 2005). Such detailed studies demonstrated that the outer primary layer of acicularcalcite is isotopically light in both δ18O and δ13C while the secondary layer, composed of calcite fibres, is in oxygen-isotope equilibrium with ambient seawater(Fig. 1) (Parkinson et al., 2005).

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Evaluation of two genera of benthic foraminifera for down-core paleotemperature studies in the western south atlantic

Brazilian Journal of Oceanography ◽

10.1590/s1679-87592006000100007 ◽

2006 ◽

Vol 54 (1) ◽

pp. 75-84 ◽

Cited By ~ 9

Author(s):

Karen B. Costa ◽

Felipe A. L. Toledo ◽

Maria A.G. Pivel ◽

Cândido A.V. Moura ◽

Farid Chemale Jr.

Keyword(s):

Isotopic Composition ◽

Water Temperature ◽

Benthic Foraminifera ◽

Small Difference ◽

Oxygen Isotopic Composition ◽

South Atlantic ◽

Ambient Seawater ◽

Oxygen Isotopic ◽

Isotope Equilibrium ◽

Equilibrium Oxygen

In this study we have compared the oxygen isotopic composition of two genera of benthic foraminifera (Uvigerina and Cibicidoides) from core-top samples with modern oxygen isotopic composition of seawater (delta18O). Based on a new relationship between delta18O and salinity for the mid-latitude western South Atlantic, we estimated the isotopic composition of equilibrium calcite (delta18Oeq) using two different equations: (1) O'Neil et al. (1969), modified by McCorkle et al. (1997) and (2) Kim & O'Neil (1997). When using (1), the small difference between delta18Oeq and delta18O of Uvigerina suggests that this genus precipitates its shell close to equilibrium with ambient seawater. The delta18O Cibicidoides data are 0.82 ‰ lower than the predicted (equilibrium) oxygen isotopic composition. Conversely, using (2) the Cibicidoides delta18O data show excellent agreement with the oxygen isotopic composition predicted from delta18O and water temperature while Uvigerina delta18O data are 0.69 ‰ higher than predicted oxygen isotope equilibrium values. Based on the evidences presented here and on the results from previous studies we suggest using the genus Cibicidoides and applying Kim & O'Neil's (1997) equation for down-core paleotemperature investigations. In the absence of enough Cibicidoides specimens we suggest using Uvigerina delta18O data and applying a correction factor of -0.69 ‰.

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Unraveling the histories of Proterozoic shales through in situ Rb-Sr dating and trace element laser ablation analysis

Geology ◽

10.1130/g49187.1 ◽

2021 ◽

Author(s):

Darwinaji Subarkah ◽

Morgan L. Blades ◽

Alan S. Collins ◽

Juraj Farkaš ◽

Sarah Gilbert ◽

...

Keyword(s):

Laser Ablation ◽

Trace Element ◽

Inductively Coupled Plasma ◽

Trace Element Analysis ◽

Reaction Cell ◽

Element Analysis ◽

Deep Time ◽

Novel Approach ◽

Depositional Age

Authigenic components in marine sediments are important archives for past environment reconstructions. However, defining reliable age constraints and assessing the effects of post-depositional overprints in Precambrian sequences are challenging. We demonstrate a new laser-based analytical approach that has the potential to rapidly and accurately evaluate the depositional and alteration histories of Proterozoic shales. Our study employs a novel application of in situ Rb-Sr dating coupled with simultaneous trace-element analysis using reaction-cell laser ablation–inductively coupled plasma–tandem mass spectrometry (LA-ICPMS/MS). We present results from shales sourced from two wells in the Proterozoic McArthur Basin, northern Australia. These rocks have been widely used by previous studies as a key section for ancient biogeochemical and paleo-redox reconstructions. Shales from well UR5 yielded initial 87Sr/86Sr ratios, Rb-Sr ages, and rare earth element plus yttrium (REEY) patterns similar to those of a dolerite sampled from the same core. We propose that the UR5 samples chronicle hydrothermal alteration instigated by the dolerite intrusion. In contrast, a correlative shale from well UR6 yielded an age consistent with the expected depositional age (1577 ± 56 Ma) with REEY and initial 87Sr/86Sr ratios similar to ca. 1.5 Ga seawater. We suggest that this sample records the minimum depositional age and early marine diagenetic history for this unit. This new technique can date Proterozoic shales quickly, cheaply, and with minimum sample preparation. Importantly, ages are triaged to differentiate between those recording primary marine versus secondary processes. This novel approach provides a potentially powerful tool for dating and fingerprinting the vast array of ancient marine shales for further studies of Earth systems through deep time.

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Oxygen isotope ratios in the shell of <i>Mytilus edulis</i>: archives of glacier meltwater in Greenland?

Biogeosciences Discussions ◽

10.5194/bgd-9-12019-2012 ◽

2012 ◽

Vol 9 (9) ◽

pp. 12019-12046 ◽

Cited By ~ 1

Author(s):

E. A. A. Versteegh ◽

M. E. Blicher ◽

J. Mortensen ◽

S. Rysgaard ◽

T. D. Als ◽

...

Keyword(s):

Oxygen Isotope ◽

Mytilus Edulis ◽

Blue Mussel ◽

Full Range ◽

Greenland Ice Sheet ◽

Future Research ◽

Ambient Seawater ◽

Glacier Meltwater ◽

Prehistoric Settlements ◽

Global Sea Level

Abstract. Melting of the Greenland Ice Sheet (GrIS) is accelerating and will contribute significantly to global sea level rise during the 21st century. Instrumental data on GrIS melting only cover the last few decades, and proxy data extending our knowledge into the past are vital for validating models predicting the influence of ongoing climate change. We investigated a potential meltwater proxy in Godthåbsfjord (West Greenland), where glacier meltwater causes seasonal excursions with lower oxygen isotope water (δ18Ow) values and salinity. The blue mussel (Mytilus edulis) potentially records these variations, because it precipitates its shell calcite in oxygen isotopic equilibrium with ambient seawater. As M. edulis shells are known to occur in raised shorelines and kitchen middens from previous Holocene warm periods, this species may be ideal in reconstructing past meltwater dynamics. We investigate its potential as a palaeo-meltwater proxy. First, we confirmed that M. edulis shell calcite oxygen isotope (δ18Oc) values are in equilibrium with ambient water and generally reflect meltwater conditions. Subsequently we investigated if this species recorded the full range of δ18Ow values occurring during the years 2007 to 2010. Results show that δ18Ow values were not recorded at very low salinities (< ~19), because the mussels appear to cease growing. This implies that M. edulis δ18Oc values are suitable in reconstructing past meltwater amounts in most cases, but care has to be taken that shells are collected not too close to a glacier, but rather in the mid region or mouth of the fjord. The focus of future research will expand on the geographical and temporal range of the shell measurements by sampling mussels in other fjords in Greenland along a south-north gradient, and by sampling shells from raised shorelines and kitchen middens from prehistoric settlements in Greenland.

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Oxygen isotope ratios in the shell of <i>Mytilus edulis</i>: archives of glacier meltwater in Greenland?

Biogeosciences ◽

10.5194/bg-9-5231-2012 ◽

2012 ◽

Vol 9 (12) ◽

pp. 5231-5241 ◽

Cited By ~ 18

Author(s):

E. A. A. Versteegh ◽

M. E. Blicher ◽

J. Mortensen ◽

S. Rysgaard ◽

T. D. Als ◽

...

Keyword(s):

Oxygen Isotope ◽

Mytilus Edulis ◽

Blue Mussel ◽

Full Range ◽

Greenland Ice Sheet ◽

Future Research ◽

Shell Middens ◽

Ambient Seawater ◽

Glacier Meltwater ◽

Prehistoric Settlements

Abstract. Melting of the Greenland Ice Sheet (GrIS) is accelerating and will contribute significantly to global sea level rise during the 21st century. Instrumental data on GrIS melting only cover the last few decades, and proxy data extending our knowledge into the past are vital for validating models predicting the influence of ongoing climate change. We investigated a potential meltwater proxy in Godthåbsfjord (West Greenland), where glacier meltwater causes seasonal excursions with lower oxygen isotope water (δ18Ow) values and salinity. The blue mussel (Mytilus edulis) potentially records these variations, because it precipitates its shell calcite in oxygen isotopic equilibrium with ambient seawater. As M. edulis shells are known to occur in raised shorelines and archaeological shell middens from previous Holocene warm periods, this species may be ideal in reconstructing past meltwater dynamics. We investigate its potential as a palaeo-meltwater proxy. First, we confirmed that M. edulis shell calcite oxygen isotope (δ18Oc) values are in equilibrium with ambient water and generally reflect meltwater conditions. Subsequently we investigated if this species recorded the full range of δ18Ow values occurring during the years 2007 to 2010. Results show that δ18Ow values were not recorded at very low salinities (< ~ 19), because the mussels appear to cease growing. This implies that Mytilus edulis δ18Oc values are suitable in reconstructing past meltwater amounts in most cases, but care has to be taken that shells are collected not too close to a glacier, but rather in the mid-region or mouth of the fjord. The focus of future research will expand on the geographical and temporal range of the shell measurements by sampling mussels in other fjords in Greenland along a south–north gradient, and by sampling shells from raised shorelines and archaeological shell middens from prehistoric settlements in Greenland.

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Combining clumped isotope and trace element analysis to constrain potential kinetic effects in calcite

Geochimica et Cosmochimica Acta ◽

10.1016/j.gca.2020.12.024 ◽

2021 ◽

Author(s):

Adhipa Herlambang ◽

Cédric M. John

Keyword(s):

Trace Element ◽

Trace Element Analysis ◽

Element Analysis ◽

Kinetic Effects ◽

Clumped Isotope

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An improved interference correction for trace element analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100132868 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1646-1647

Author(s):

John J. Donovan ◽

Donald A. Snyder ◽

Mark L. Rivers

Keyword(s):

Trace Element Analysis ◽

Accurate Estimate ◽

Simple Expression ◽

Standard Reference Materials ◽

Characteristic Line ◽

Analytical Line ◽

Element Analysis ◽

Electron Probe Analysis ◽

Calculated Concentration ◽

X Ray

We present a simple expression for the quantitative treatment of interference corrections in x-ray analysis. WDS electron probe analysis of standard reference materials illustrate the success of the technique.For the analytical line of wavelength λ of any element A which lies near or on any characteristic line of another element B, the observed x-ray counts at We use to denote x-ray counts excited by element i in matrix j (u=unknown; s=analytical standard; ŝ=interference standard) at the wavelength of the analytical line of A, λA (Fig. 1). Quantitative analysis of A requires an accurate estimate of These counts can be estimated from the ZAF calculated concentration of B in the unknown C,Bu measured counts at λA in an interference standard of known concentration of B (and containing no A), and ZAF correction parameters for the matrices of both the unknown and the interference standard at It can be shown that:

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