scholarly journals Advances and Challenges in Palaeoenvironmental Studies Based on Oxygen Isotope Composition of Skeletal Carbonates and Phosphates

Geosciences ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 419
Author(s):  
Hubert Wierzbowski
Keyword(s):  
Oxygen Isotope ◽  
Oxygen Isotopes ◽  
Isotope Composition ◽  
Sedimentary Basins ◽  
Sea Level Changes ◽  
Temperature Trends ◽  
Isotope Record ◽  
Vital Effects ◽  
Reliable Temperature ◽  
Clumped Isotope

Oxygen isotopes are widely used in palaeoenvironmental and palaeoclimatic studies as they record variations in the precipitation temperature of biogenic carbonates and phosphates. Problems associated with the preservation state of fossils, selection of the proper temperature equation, vital effects occurring during biomineralization, habitat effects of organisms as well as salinity, bathymetry and water circulation changes limit, however, the applicability of oxygen isotopes to reconstruction of ancient environmental settings. The progress of oxygen isotope studies, temperature calculations and ambiguities of the isotope record are discussed in this paper. The same applies to the methods of retrieving reliable temperature signals and the record of water chemistry changes based on well-preserved calcareous and phosphatic fossils. Sometimes neglected importance of sedimentological and faunistic data associated with sea-level changes and salinity variations is emphasised as an important tool for refinement of the temperature trends of epeiric sedimentary basins. In addition, published case datasets and new laboratory techniques, including micro-area and clumped isotope analyses, are presented to demonstrate examples and prospective ways of extension of the scope of palaeoenvironmental research. The provided information may be used in discussion and a critical review of published oxygen isotope data and their palaeoenvironmental interpretations.

scholarly journals Oxygen isotope composition of waters recorded in carbonates in strong clumped and oxygen isotopic disequilibrium

2019 ◽  
Author(s):  
Caroline Thaler ◽  
Amandine Katz ◽  
Magali Bonifacie ◽  
Bénédicte Ménez ◽  
Magali Ader
Keyword(s):  
Oxygen Isotope ◽  
Isotope Composition ◽  
Isotopic Equilibrium ◽  
Oxygen Isotopic ◽  
Vital Effects ◽  
Biogenic Carbonates ◽  
Clumped Isotope ◽  
Interstitial Waters ◽  
Isotopic Disequilibrium ◽  
Paleoenvironmental Reconstructions

Abstract. Paleoenvironmental reconstructions, which are mainly retrieved from oxygen isotope (δ18O) and clumped isotope (Δ47) compositions of carbonate minerals, are compromised when carbonate crystallization occurs in isotopic disequilibrium. To date, knowledge of these common isotopic disequilibria, known as vital effects in biogenic carbonates, remains limited and the potential information recorded by δ18O and Δ47 offsets from isotopic equilibrium values is largely overlooked. Additionally, in carbonates formed in isotopic equilibrium, the use of the carbonate δ18O signature as a paleothermometer relies on our knowledge of the paleowaters' δ18O value, which is often assumed. Here, we report the largest Δ47 offsets observed to date (as much as −0.270 ‰), measured on microbial carbonates, that are strongly linked to carbonate δ18O offsets (−25 ‰) from equilibrium. These offsets are likely both related to the microorganism metabolic activity and yield identical erroneous temperature reconstructions. Unexpectedly, we show that the δ18O value of the water in which carbonates precipitated, as well as the water-carbonate δ18O fractionation dependence to temperature at equilibrium can be retrieved from these paired δ18O and Δ47 disequilibrium values measured in carbonates. The possibility to retrieve the δ18O value of paleowaters, sediments' interstitial waters or organisms' body water at the carbonate precipitation loci, even from carbonates formed in isotopic disequilibrium, opens long-awaited research avenues for both paleoenvironmental reconstructions and biomineralization studies.

scholarly journals Oxygen isotope composition of waters recorded in carbonates in strong clumped and oxygen isotopic disequilibrium

2020 ◽  
Vol 17 (7) ◽  
pp. 1731-1744 ◽  
Author(s):  
Caroline Thaler ◽  
Amandine Katz ◽  
Magali Bonifacie ◽  
Bénédicte Ménez ◽  
Magali Ader
Keyword(s):  
Oxygen Isotope ◽  
Isotope Composition ◽  
Carbonate Precipitation ◽  
Isotopic Equilibrium ◽  
Oxygen Isotopic ◽  
Vital Effects ◽  
Biogenic Carbonates ◽  
Clumped Isotope ◽  
Isotopic Disequilibrium ◽  
Paleoenvironmental Reconstructions

Abstract. Paleoenvironmental reconstructions, which are mainly retrieved from oxygen isotope (δ18O) and clumped isotope (Δ47) compositions of carbonate minerals, are compromised when carbonate precipitation occurs in isotopic disequilibrium. To date, knowledge of these common isotopic disequilibria, known as vital effects in biogenic carbonates, remains limited, and the potential information recorded by δ18O and Δ47 offsets from isotopic equilibrium values is largely overlooked. Additionally, in carbonates formed in isotopic equilibrium, the use of the carbonate δ18O signature as a paleothermometer relies on our knowledge of the paleowaters' δ18O value, which is often assumed. Here, we report the largest Δ47 offsets observed to date (as much as −0.270 ‰), measured on microbial carbonates that are strongly linked to carbonate δ18O offsets (−25 ‰) from equilibrium. These offsets are likely both related to the microorganism metabolic activity and yield identical erroneous temperature reconstructions. Unexpectedly, we show that the δ18O value of the water in which carbonates precipitated, as well as the water–carbonate δ18O fractionation dependence on temperature at equilibrium, can be retrieved from these paired δ18O and Δ47 disequilibrium values measured in carbonates. The possibility to retrieve the δ18O value of paleowaters, sediments' interstitial waters or organisms' body water at the carbonate precipitation loci, even from carbonates formed in isotopic disequilibrium, opens long-awaited research avenues for both paleoenvironmental reconstructions and biomineralization studies.

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

2008 ◽  
Vol 72 (1) ◽  
pp. 239-242 ◽  
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).

scholarly journals Oxygen isotope composition of the Phanerozoic ocean and a possible solution to the dolomite problem

2018 ◽  
Vol 115 (26) ◽  
pp. 6602-6607 ◽  
Author(s):  
Uri Ryb ◽  
John M. Eiler
Keyword(s):  
Oxygen Isotope ◽  
Isotope Exchange ◽  
Isotope Composition ◽  
Temporal Variations ◽  
Oxygen Isotope Exchange ◽  
Diagenetic Alteration ◽  
Isotope Studies ◽  
Dolomite Problem ◽  
Clumped Isotope

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.

scholarly journals Potential Reference Materials for Hematite Oxygen Isotope Analysis

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 987
Author(s):  
Lianjun Feng ◽  
Hongwei Li ◽  
Tiejun Li
Keyword(s):  
Oxygen Isotope ◽  
Iron Oxides ◽  
Oxygen Isotopes ◽  
Reference Materials ◽  
Isotope Composition ◽  
Isotope Analysis ◽  
Isotope Ratios ◽  
Bulk Rock ◽  
Accurate Analysis ◽  
Oxygen Isotope Ratios

Hematite is a potential mineral for reconstructing the oxygen isotope composition and paleotemperature of paleowater. A highly accurate analysis of oxygen isotopes is essential. However, relative to other oxygenated minerals, we lack hematite reference materials that allow for internationally comparable analyses between different laboratories. To address this issue, we attempted to perform bulk rock oxygen isotope analysis on five hematite reference materials (GBW07223a, GBW07825, YSBC28740-95, YSBC28756-2008, Harvard 92649). Meanwhile, the oxygen isotope ratios of iron oxides (GBW07223a, GBW07825, YSBC28740-95, YSBC28756-2008) were obtained by mass balance involving other oxygen-bearing minerals such as quartz and silicates. In addition, the oxygen isotope ratios of iron oxides in an oolitic hematite (ca. 1.65 billion years ago) are consistent with the results of previous analyses of this class of minerals.

An Oxygen Isotope Study of Seasonal Trends in Jinxiuchuan River of Jinan South Mountain

2014 ◽  
Vol 522-524 ◽  
pp. 954-957 ◽  
Author(s):  
Yong Sen Wang ◽  
Zheng He Xu ◽  
Si Fang Dong
Keyword(s):  
Stable Isotope ◽  
Oxygen Isotope ◽  
River Water ◽  
Oxygen Isotopes ◽  
Water Cycle ◽  
Climatic Factors ◽  
Isotope Composition ◽  
Stable Isotope Composition ◽  
Isotope Study ◽  
Isotopic Variations

The stable isotope composition of river water contains some information of water cycle and climatic factors, such as precipitation, evaporation and temperature. Oxygen isotopes in river water were monitored at one site in Jinxiuchuang basin of Jinan southern mountain.δ18O values of river water show a variation from-7.82 on July 6 to-9.98 on June 6. The result reveals that the river water was mainly supplied by the precipitation. The isotopic variations at Jinxiuchuan river have strong precipitation patterns owning to different rainfall in summer.

Relationship between δ18O and minor element composition of Terebratalia transversa

2007 ◽  
Vol 98 (3-4) ◽  
pp. 443-449 ◽  
Author(s):  
Maggie Cusack ◽  
David Parkinson ◽  
Alberto Pérez-Huerta ◽  
Jennifer England ◽  
Gordon B. Curry ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Isotope Composition ◽  
Seawater Temperature ◽  
Minor Element ◽  
Oxygen Isotope Composition ◽  
Secondary Layer ◽  
Vital Effects ◽  
Stable Oxygen ◽  
Temperature Proxy ◽  
Isotope Equilibrium

ABSTRACTWith their extensive fossil record and shells of stable low-Mg calcite, rhynchonelliform brachiopods are attractive sources of climate information via seawater temperature proxies such as stable oxygen isotope composition. In Terebratalia transversa (Sowerby) there is a progression towards oxygen isotope equilibrium in the calcite of the innermost secondary layer. This study confirms the lack of any vital effects influencing oxygen isotope composition of T. transversa, even in specialised areas of the innermost secondary layer. Calcite Mg/Ca ratio is another potential seawater temperature proxy, that has the advantage of not being influenced by salinity. Mg concentrations measured by electron microprobe analyses indicate that there is no concomitant decrease in Mg concentration towards the inner secondary layer, associated with the progressive shift towards oxygen isotope equilibrium. Mg distribution is heterogeneous throughout the shell and correlates with that of sulphur, which may be a proxy for organic components, suggesting that some of the Mg may not be in the calcite lattice. It is essential therefore, to determine the chemical environment of the magnesium ions to avoid any erroneous temperature extrapolations in brachiopods or any other calcite biomineral.

The Marine Oxygen Isotope Record in Pleistocene Coral, Barbados, West Indies

1978 ◽  
Vol 10 (2) ◽  
pp. 181-196 ◽  
Author(s):  
Richard G. Fairbanks ◽  
R.K. Matthews
Keyword(s):  
Oxygen Isotope ◽  
Sea Level ◽  
Oxygen Isotopes ◽  
Time Range ◽  
Acropora Palmata ◽  
Oxygen Isotope Stage ◽  
Average Temperature ◽  
Time Period ◽  
Oxygen Isotope Record ◽  
Isotope Record

The reef-crest coral Acropora palmata from late Pleistocene reefs on Barbados has recorded the same global variations in oxygen isotopes as planktonic and benthonic foraminifera. Although the record of oxygen isotopes in Acropora palmata is discontinuous, it offers several advantages over the isotope records from deep-sea sediments: (1) the coral grows at water depths of less than 5 m; (2) the samples are unmixed; (3) specimens may be sampled from various elevations of paleo-sea level; and (4) aragonitic corals are suitable for 230Th/234U and He/U dating techniques. The latter advantage means that direct dating of the marine oxygen isotope record is possible. Oxygen isotope stage 5e corresponds to Barbados III, dated at 125,000 ± 6000 yr BP. Petrographic and geochemical evidence from five boreholes drilled into the south coast of Barbados indicates a major eustatic lowering (greater than 100 m below present sea level) occurred between 180,000 and 125,000 yr BP. The age and isotopic data suggest correlation of this change in sea level to Emiliani's oxygen isotope stage 6. Acropora palmata deposited at various elevations of sea level during oxygen isotope stage 6 vary by 0.11 ‰ δ18O for each 10 m of change in sea level. We further hypothesize a minimum drop of 2°C in the average temperature occurred during the regressive phase of oxygen isotope stage 6. These data indicate that temperature lowering of surface water near Barbados lagged behind a major glacial buildup during this time period. Using the δ18O vs sea level calibration herein derived, we estimate the relative height of sea stands responsible for Barbados coral reef terraces in the time range 80,000 to 220,000 yr BP.

Application of combined fluid-inclusion and clumped isotope thermometry to biogenic and inorganic carbonates

2021 ◽  
Author(s):  
Jeroen van der Lubbe ◽  
Cas Nooitgedacht ◽  
Philip Staudigel ◽  
Martin Ziegler
Keyword(s):  
Fluid Inclusion ◽  
Oxygen Isotope ◽  
High Temperatures ◽  
Fluid Inclusions ◽  
Isotope Composition ◽  
A Priori ◽  
Calcium Carbonates ◽  
Oxygen Isotope Exchange ◽  
Calcite Veins ◽  
Clumped Isotope

<p>Biogenic and inorganic carbonates are widely used to reconstruct past temperatures and fluid compositions. For decades, calcification temperatures have been inferred from oxygen isotope composition (δ<sup>18</sup>O) of calcium carbonates (CaCO­<sub>3</sub>) assuming the δ<sup>18</sup>O of the parental fluid and isotopic equilibrium precipitation conditions. The development of the clumped isotope (Δ<sub>47</sub>) thermometer allows for reconstructing equilibrium calcification temperatures without requiring a priori knowledge of the water δ<sup>18</sup>O values.</p><p>Carbonate minerals can also contain several weight percentages of water, which are typically trapped within microscopic pores. These fluid-inclusions may preserve remnants of the parental fluid, which can be analyzed for the δ<sup>18</sup>O as well as hydrogen isotopic (δ<sup>2</sup>H) composition. Subsequently, the δ<sup>18</sup>O of fluid-inclusion and host carbonate may allow for the determination of paleotemperatures by providing constraint on the δ<sup>18</sup>O water value.</p><p>Reasonable equilibrium temperatures can be obtained for speleothem calcites from cave systems. On the contrary, anomalously high temperatures are derived from δ<sup>18</sup>O fluid-inclusion and calcite pairs in soil carbonates possibly suggesting diffusion of trapped water from host CaCO<sub>3</sub>. Deeply-buried and subsequently exhumed (inorganic) calcite veins have yielded discrepant paleotemperature estimates between fluid-inclusion and Δ<sub>47</sub> thermometers. The distinctly lower fluid-inclusion derived temperatures might be attributed to kinetic fraction during initial vein cementation and/or isotopic re-equilibration between fluid-inclusions and CaCO<sub>3</sub> at lower temperatures during uplift.</p><p>Heating experiments demonstrate that the oxygen isotope exchange between fluid inclusions and host carbonate is limited for inorganic calcite and aragonite at high temperatures (175<sup>o</sup>C) for short timescales (90 minutes). In contrast, considerable positive shifts in the δ<sup>18</sup>O of fluid inclusions have been recorded in biogenic aragonites during experimental heating, which coincide with lower carbonate δ<sup>18</sup>O values (albeit to a lesser extent due to the overwhelming amount of oxygen in the CaCO<sub>3</sub>), indicative of re-equilibration between host carbonate and pore fluids. This effect leads to apparently high equilibrium temperatures. In conjunction, the Δ<sub>47</sub> derived temperatures do not change significantly after heating of inorganic aragonite, whereas a considerable higher Δ<sub>47</sub> temperature is derived from aragonitic bivalve samples after heating. The positive shift in both thermometers has interpreted to reflect re-crystallization of CaCO<sub>3</sub> and isotopic re-equilibration between the host carbonate and fluid-inclusions. This exchange might be facilitated by extremely small fluid-inclusions present in biogenic carbonates and/or water associated with organic substances.</p><p>Importantly, these isotopic exchange processes in biogenic aragonites took place in the absence of an external fluid and below the temperature thresholds for solid-state-reordering and the aragonite-to-calcite transition. The novel application of combined fluid-inclusion and clumped isotope thermometry has a proven utility in determining equilibrium precipitation temperatures, monitoring preservation of the primary fluid-inclusions and re-crystallization processes during diagenesis. However, additional experiments and analytical improvements are needed to further constrain the diagenetic behavior of this proxy.</p><p> </p>

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