A triple oxygen isotope perspective on the origin, evolution, and diagenetic alteration of carbonatites

The18O/16O of calcite fossils increased by ∼8‰ between the Cambrian and present. It has long been controversial whether this change reflects evolution in the δ18O of seawater, or a decrease in ocean temperatures, or greater extents of diagenesis of older strata. Here, we present measurements of the oxygen and ‟clumped” isotope compositions of Phanerozoic dolomites and compare these data with published oxygen isotope studies of carbonate rocks. We show that the δ18O values of dolomites and calcite fossils of similar age overlap one another, suggesting they are controlled by similar processes. Clumped isotope measurements of Cambrian to Pleistocene dolomites imply crystallization temperatures of 15–158 °C and parent waters having δ18OVSMOWvalues from −2 to +12‰. These data are consistent with dolomitization through sediment/rock reaction with seawater and diagenetically modified seawater, over timescales of 100 My, and suggest that, like dolomite, temporal variations of the calcite fossil δ18O record are largely driven by diagenetic alteration. We find no evidence that Phanerozoic seawater was significantly lower in δ18O than preglacial Cenozoic seawater. Thus, the fluxes of oxygen–isotope exchange associated with weathering and hydrothermal alteration reactions have remained stable throughout the Phanerozoic, despite major tectonic, climatic and biologic perturbations. This stability implies that a long-term feedback exists between the global rates of seafloor spreading and weathering. We note that massive dolomites have crystallized in pre-Cenozoic units at temperatures >40 °C. Since Cenozoic platforms generally have not reached such conditions, their thermal immaturity could explain their paucity of dolomites.

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Carbon- and oxygen-isotope records of palaeoenvironmental and carbonate production changes in shallow-marine carbonates (Kimmeridgian, Swiss Jura)

Geological Magazine ◽

10.1017/s0016756810000518 ◽

2010 ◽

Vol 148 (1) ◽

pp. 133-153 ◽

Cited By ~ 35

Author(s):

CLAUDE COLOMBIÉ ◽

CHRISTOPHE LÉCUYER ◽

ANDRÉ STRASSER

Keyword(s):

Oxygen Isotope ◽

High Frequency ◽

Open Ocean ◽

Carbonate Production ◽

Shallow Marine ◽

Diagenetic Alteration ◽

Oxygen Isotope Ratios ◽

Carbon And Oxygen Isotope ◽

Marine Carbonates ◽

Swiss Jura

AbstractCarbon- and oxygen-isotope ratios are commonly used to correlate shallow- and deep-marine successions. Carbon- and oxygen-isotope analyses were performed on bulk-carbonate samples from two Kimmeridgian sections of the Swiss Jura platform in order to correlate them with biostratigraphically well-dated coeval sections in the adjacent basin. On the platform, a general decrease in δ13C and δ18O values from the base to the top of the studied interval is measured, whereas time-equivalent pelagic–hemipelagic carbonates record an increase in carbon- and oxygen-isotope ratios. Moreover, the measured δ13C and δ18O values are generally lower than those indicated for the Kimmeridgian open ocean and show high-frequency variations superimposed on the general trend. Samples were screened for diagenetic alteration using optical and cathodoluminescence petrography and coupled carbon- and oxygen-isotope and trace-element analyses. Some observations favour a role for diagenetic alteration, but isotopic and elemental trends as well as sedimentological evidence suggest that the more negative values of δ13C and δ18O relative to Kimmeridgian seawater are also due to local environmental conditions. High-frequency changes in δ18O and δ13C values most likely result from variations in salinity and carbonate production and accumulation rates. These variations were produced by different water masses that were isolated from the open ocean and developed their own geochemical signatures. Repeated isolation was induced by high-frequency sea-level fluctuations and helped by irregular platform morphology. Consequently, carbon- and oxygen-isotope records in shallow-marine carbonates can be used for stratigraphic correlation only if their origin is well known.

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High-precision triple oxygen isotope analysis of Archean and Proterozoic carbonates

10.5194/egusphere-egu2020-17881 ◽

2020 ◽

Author(s):

Oliver Jäger ◽

Jakub Surma ◽

Nina Albrecht ◽

Chris S. Marien ◽

Wanli Xiang ◽

...

Keyword(s):

Oxygen Isotope ◽

High Precision ◽

Isotope Ratio ◽

Sea Water ◽

Isotope Analysis ◽

Isotopic Shift ◽

Equilibrium Conditions ◽

Mass Spectrom ◽

Diagenetic Alteration ◽

Gas Source

Oxygen isotopes are a widely used tracer in the field of paleoceanography and provide unique information on mineral formation and environmental conditions. Carbonate sediments record a shift in &#948;18O of 10 to 15&#8240; from the Archean towards higher values in the Phanerozoic. Three different scenarios are suggested to explain this observation: (I) hot Archean oceans, (II) depletion of 18O in Archean oceans compared to present day and (III) diagenetic alteration of the primary isotopic signature [1]. Recent advances in high-resolution gas source isotope ratio mass spectrometry provide a new tool that may allow to decipher the origin of this isotopic shift observed in the early rock record. We performed high-precision 18O/16O and 17O/16O measurements on oxygen ion fragments (16O+, 17O+, 18O+) generated in the ion source from CO2 gas [2]. Isobaric interferences on m/z=17 (16OH+) and m/z=18 (H216O+) are separated by means of high mass resolution. The CO2 gas is first liberated from carbonate samples by orthophosphoric acid digestion and then analyzed on a Thermo Scientific Ultra dual-inlet gas source isotope ratio mass spectrometer [3]. By adding the dimension of 17O/16O to the classical 18O/16O system, equilibrium trajectories of carbonates that are defined by the equilibrium fractionation factor (18aeq) and the triple isotope fractionation exponent (&#952;) can be predicted as a function of temperature. Minerals that were altered by or formed in meteoric water can be distinguished from those that precipitated in equilibrium with ambient sea water. Therefore, triple oxygen isotope analysis of carbonates does not only hold the potential for a new single-phase paleothermometer, but may also be used to trace the origin of carbonates. Here, we present high-precision triple oxygen isotope data for carbonates from the Pilbara and the Kaapvaal cratons that cover nearly one billion years from the Paleoarchean to the Paleoproterozoic. Marine carbonates from the Phanerozoic complement the dataset. The carbonates were formed in different marine settings, from shallow marine stromatolites to carbonates grown in the interstitial space of basaltic pillows. Phanerozoic carbonates record equilibrium conditions with modern sea water at moderate temperatures. The majority of Precambrian carbonates plot below the predicted equilibrium curve in the &#948;&#8217;18O-&#916;&#8216;17O space and do not reflect equilibrium conditions with modern sea water at elevated temperatures that were proposed for the Archean oceans. Modeling the triple oxygen isotope composition of carbonates in equilibrium with sea water, that is depleted in 18O also cannot explain the observed isotopic shift. Further modeling of post-depositional alteration suggests that most carbonates interacted and re-equilibrated with meteoric waters at variable water-rock ratios and temperatures.[1] Shields and Veizer, 2002, Geochem., Geophy., Geosyst., 10.1029/2001GC000266 [2] Getachew et al., 2019, Rapid Commun. Mass. Spectrom., 10.1002/rcm.847 [3] Eiler et al., 2013, Int. J. Mass. Spectrom., 335, 45-56.

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Triple oxygen isotope analysis of bioapatite as tracer for diagenetic alteration of bones and teeth

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/j.palaeo.2011.04.014 ◽

2011 ◽

Vol 310 (1-2) ◽

pp. 84-91 ◽

Cited By ~ 35

Author(s):

Alexander Gehler ◽

Thomas Tütken ◽

Andreas Pack

Keyword(s):

Oxygen Isotope ◽

Isotope Analysis ◽

Diagenetic Alteration

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Tsunami sedimentary deposits of Crete records climate during the ‘Minoan Warming Period’ (≈3350 yr BP)

The Holocene ◽

10.1177/0959683617752840 ◽

2018 ◽

Vol 28 (6) ◽

pp. 914-929 ◽

Cited By ~ 6

Author(s):

Christophe Lécuyer ◽

François Atrops ◽

Romain Amiot ◽

Delphine Angst ◽

Valérie Daux ◽

...

Keyword(s):

Oxygen Isotope ◽

Ice Cores ◽

Coastal Sediments ◽

Sedimentary Deposits ◽

Terrestrial Vertebrate ◽

Diagenetic Alteration ◽

Air Temperatures ◽

Incremental Sampling ◽

Geological Timescale ◽

Mollusc Shells

Earthquakes or explosive eruptions generate tsunami, which are at the origin of thick and chaotic coastal sediments. These commonly fossiliferous deposits are formed instantaneously at the historical or geological timescale and therefore have the potential to provide snapshot records of past climates. In Crete, near the city of Palaikastro, crops out a 1- to 9-m-thick sedimentary layer deposited by a huge tsunami that has been previously estimated to be about 9 m high. The presence of volcanic ash, the geometry, the archeological and faunal contents of the sedimentary deposit along with radiocarbon dating converge for interpreting this tsunamite as coeval with the Minoan Santorini (Thera) eruption ≈3350 yr BP. During its drawback, the tsunami deposited rocky blocks and a muddy matrix containing mollusc shells dredged from the seabed as well as cattle skeletal remains and various artifacts belonging to the contemporaneous Minoan civilization. While the oxygen isotope compositions of terrestrial vertebrate bone remains most likely resulted from diagenetic alteration, those of a bovid tooth revealed that air temperatures during MM3 and LM1 periods were about 4°C higher than nowadays. Oxygen isotope measurements of marine mollusc shells also revealed that sea surface temperatures were higher by about 2°C. Those results compare with the 2.5°C temperature difference already estimated according to both δ2H and δ18O values of Greenland ice cores. Incremental sampling of marine gastropods and bovid teeth suggests that the seasonal amplitude was similar to that prevailing during the second half of the 20th century.

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Belemnite-based strontium, carbon and oxygen isotope stratigraphy of the type area of the Maastrichtian Stage

Netherlands Journal of Geosciences – Geologie en Mijnbouw ◽

10.1017/s0016774600001141 ◽

2011 ◽

Vol 90 (2-3) ◽

pp. 259-270 ◽

Cited By ~ 9

Author(s):

H.B. Vonhof ◽

J.W.M. Jagt ◽

A. Immenhauser ◽

J. Smit ◽

Y.W. van den Berg ◽

...

Keyword(s):

Oxygen Isotope ◽

Diagnostic Feature ◽

Time Interval ◽

Sr Isotope ◽

Diagenetic Alteration ◽

Type Area ◽

Carbon And Oxygen Isotope ◽

El Kef ◽

Age Model ◽

Isotope Variation

AbstractBelemnitellid cephalopods from the Maastrichtian stratotype area (southeast Netherlands) are shown to be comparatively well preserved. Although partial diagenetic alteration has been observed, micromilling techniques have permitted the extraction of pristine belemnite calcite, suitable for the reconstruction of strontium (Sr), oxygen (O) and carbon (C) isotope variation of Maastrichtian seawater. A distinct Sr isotope pattern in the Maastricht record can be matched stratigraphically with records from Hemmoor (northern Germany), El Kef (Tunisia) and ODP site 690 (Maud Rise, Antarctica), leading to a new chemostratigraphical age model for the Maastrichtian stratotype section. Our data improve currently applied strontium isotope stratigraphical reference curves by revealing an Sr isotope inflection pattern near the lower/upper Maastrichtian boundary that is a potentially diagnostic feature for intra-Maastrichtian stratigraphical correlation between distant sections. Belemnites further show significant stratigraphical oxygen isotope variation through the Maastrichtian. We interpret this variation to have resulted from palaeoceanographic reorganisations in the Atlantic Ocean during this time interval.

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Raman spectroscopy of fossil bioapatite — A proxy for diagenetic alteration of the oxygen isotope composition

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/j.palaeo.2011.06.016 ◽

2011 ◽

Vol 310 (1-2) ◽

pp. 62-70 ◽

Cited By ~ 41

Author(s):

Daniel B. Thomas ◽

Cushla M. McGoverin ◽

R. Ewan Fordyce ◽

Russell D. Frew ◽

Keith C. Gordon

Keyword(s):

Raman Spectroscopy ◽

Oxygen Isotope ◽

Isotope Composition ◽

Oxygen Isotope Composition ◽

Diagenetic Alteration

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Late diagenetic versus near-primary isotopic compositions in Ordovician carbonate rocks and fossils: A Baltoscandian example

10.5194/egusphere-egu2020-14482 ◽

2020 ◽

Author(s):

Oluwaseun Edward ◽

Christoph Korte ◽

Clemens Vinzenz Ullmann ◽

Christian Mac Ørum Rasmussen

Keyword(s):

Isotopic Composition ◽

Oxygen Isotope ◽

Sea Level ◽

Analytic Description ◽

Geochemical Data ◽

Middle Ordovician ◽

Diagenetic Alteration ◽

Oxygen Isotopic ◽

O Isotope

The Ordovician was an important interval in Earth&#8217;s history, characterized by major sea level fluctuations, carbon cycle and climatic perturbations, as well as a profound increase in marine biodiversity &#8211; the Great Ordovician Biodiversification Event (GOBE) (1-4){Sepkoski, 1981 #6}. Recently, direct links between Ordovician climatic evolution and biotic turnover have been proposed, based on geochemical data obtained from the East Baltic (5). However, the potential impact of late diagenetic modification of the geochemical compositions remains to be evaluated. Based on calcitic fossil brachiopods and bulk rock carbonates, this study documents the Early (Floian) to Late Ordovician (Sandbian) carbon (C) and oxygen (O) isotope evolution on the Swedish island of &#214;land, which was situated in the central part of the Ordovician Palaeobasin on the palaeocontinent of Baltica. The near-primary nature of the carbon and oxygen isotopic trends and its potential palaeoenvironmental significance is evaluated using optical, chemical and statistical methods. The results suggest that diagenetic alteration may have shifted both C and O isotope compositions to higher values, in contrast to classical interpretations. Nevertheless, both long-term and shorter-duration C and O isotope trends of palaeoenvironmental significance are discernible. Carbon isotope compositions suggests that despite the influence of late diagenesis, prominent C isotope perturbations are robust enough to be recorded in both bulk carbonates and calcitic brachiopods. Our Baltic oxygen isotope record reveals a long-term increase in carbonate oxygen isotopic composition during the Ordovician &#8211; consistent with the general O isotope Phanerozoic trend (1, 2, 6), which is most pronounced in the Darriwilian (Middle Ordovician). Therefore, the Ordovician brachiopod fossils, although partially altered, preserve a record of Middle Ordovician climate amelioration; supporting recent suggestions of Middle Ordovician climatic cooling (5, 7).&#160;&#160;REFERENCES<ol><li>J. Veizer et al., 87Sr/86Sr, &#948;13C and &#948;18O evolution of Phanerozoic seawater. Chemical geology 161, 59-88 (1999).</li> <li>H. Qing, J. Veizer, Oxygen and carbon isotopic composition of Ordovician brachiopods: Implications for coeval seawater. Geochimica et Cosmochimica Acta 58, 4429-4442 (1994).</li> <li>A. Munnecke, M. Calner, D. A. Harper, T. Servais, Ordovician and Silurian sea&#8211;water chemistry, sea level, and climate: a synopsis. Palaeogeography, Palaeoclimatology, Palaeoecology 296, 389-413 (2010).</li> <li>J. J. Sepkoski, Jr., A factor analytic description of the Phanerozoic marine fossil record. Paleobiology 7, 36-53 (1981).</li> <li>C. M. &#216;. Rasmussen et al., Onset of main Phanerozoic marine radiation sparked by emerging Mid Ordovician icehouse. Scientific Reports 6, (2016).</li> <li>J. Veizer et al., Oxygen isotope evolution of Phanerozoic seawater. Palaeogeography, Palaeoclimatology, Palaeoecology 132, 159-172 (1997).</li> <li>S. Stouge, G. Bagnoli, J. A. Rasmussen, Late Cambrian (Furongian) to mid-Ordovician euconodont events on Baltica: Invasions and immigrations. Palaeogeography, Palaeoclimatology, Palaeoecology, (2019).</li> </ol>&#160;

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