Clumped isotopes of paired dolomite and calcite constraining alteration histories of ancient carbonate successions

Lu, Chaojin; Zou, Huayao; Wang, Guangwei; Cong, Fuyun; Quan, Yongbin; Swart, Peter K.

doi:10.1016/j.chemgeo.2022.121264

Cited by 6 publications

(7 citation statements)

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“…This similarity can be attributed to (i) the dissemination of small rhombohedral dolomite found in the micrite matrix of the Permian limestone [37], which obscures the actual ∆ 47 of the calcite, or (ii) the lack of ∆ 47 reordering, because the strata were not buried deep enough to attain the high temperatures required (Figure 7). In contrast to our study, a study in the Sichuan Basin showed that the ∆ 47 temperatures of calcite are higher than co-located and coeval dolomites [114]. In this study, the dolomite and calcite were collected from the same rock specimen.…”

Section: This Studycontrasting

confidence: 73%

“…For context, the results are compared to other studies in the Central Oman High [37] and the Sichuan Basin, China [114] (Figure 7). A study on co-located and coeval Permian dolomites and calcite in Central Oman High showed that the ∆ 47 values between the two minerals are similar [37].…”

Section: This Studymentioning

confidence: 99%

“…In this study, the dolomite and calcite were collected from the same rock specimen. To separate the minerals, the dolomite was isolated from calcite using an iterative chemical leaching process, which selectively dissolved calcite, leaving the dolomite in the residual sample [114,115]. However, such cleaning methods have the potential to cause alteration to the geochemical signal, mainly Mg/Ca and δ 18 O [116].…”

Section: This Studymentioning

confidence: 99%

“…Furthermore, the calcite and dolomites used in the Sichuan Basin study were collected from the same rock matrix [114], thus raising the question of the isotopic interaction between minerals during burial and recrystallisation (dissolution and precipitation). Thus, the acquisition timing for the ∆ 47 values of these minerals is uncertain, as the isotopic exchange between calcite and dolomite was not explained in the study.…”

Section: This Studymentioning

confidence: 99%

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Clumped Isotope Reordering and Kinetic Differences in Co-Hosted Calcite and Dolomite Minerals throughout Burial Diagenesis and Exhumation

Adlan,

Kaczmarek,

John

2023

Minerals

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The clumped isotope paleo-thermometer has become a valuable proxy for the burial history reconstruction of carbonate formations. To maximise the accuracy of these reconstructions, post-depositional alterations, such as recrystallisation and Δ47 isotope exchange reactions, must be understood. In this study, we examine the isotopic behaviour of calcites and early dolomite samples from the same stratigraphic intervals, and thus with similar burial history. This approach provides additional constraints on the kinetics of Δ47 reordering in dolomite during exhumation. Clumped isotope measurements were performed on 19 calcites and 15 early dolomites from the Permian, Jurassic, and Cretaceous periods from four locations in Oman spanning different burial regimes. The calcite and dolomite samples were collected from the rock matrix, based on the assumption that fine material was more susceptible to recrystallisation. Our results show that calcites and dolomites record different Δ47 values despite being subjected to the same thermal history. The maximum Δ47 temperature recorded in dolomites (181 ± 13 °C) corresponds to the oldest and most deeply buried Permian rock. This value is approximately 35 °C higher than those measured in the co-located and coeval calcite matrix (145 ± 14 °C). This discrepancy suggests that calcite and dolomite have different kinetic parameters. Our data confirm (1) that dolomite Δ47 values are more resistant to alteration during burial and exhumation than Δ47 calcite values, and (2) that dolomite has a higher Δ47 closing temperature than calcite during cooling. The presence of two mineral phases with distinct kinetic parameters in the same stratigraphic unit provides additional constraints on models of burial and uplift. In addition, mineralogical data coupled with Δ47 and burial depths suggest that the progressive development of dolomite cation ordering is driven by temperature elevation, as previously suggested.

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Section: This Studycontrasting

confidence: 73%

Section: This Studymentioning

confidence: 99%

Section: This Studymentioning

confidence: 99%

Section: This Studymentioning

confidence: 99%

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Clumped Isotope Reordering and Kinetic Differences in Co-Hosted Calcite and Dolomite Minerals throughout Burial Diagenesis and Exhumation

Adlan,

Kaczmarek,

John

2023

Minerals

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“…Three composite patterns, including the ‘early‐Cambrian hydrothermal + deep burial’, ‘middle‐Silurian hydrothermal + deep burial’ and ‘late‐Permian hydrothermal + deep burial’ histories, have been modelled to examine the influence on the Δ 47 values during the Ediacaran. Previous studies suggested that the interval of the hydrothermal pulse ranged from 10 3 to 10 4 years (Chang et al ., 2020; Lu et al ., 2023). Therefore, in the composite model, the hydrothermal event is assumed to reach 250°C and last over 10 3 to 10 4 years.…”

Section: Samples and Methodsmentioning

confidence: 99%

A clumped isotope diagenetic framework for the Ediacaran dolomites: Insights to fabric‐specific geochemical variabilities

Lu,

Koeshidayatullah,

et al. 2023

Sedimentology

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While marine dolomites formed under near surface conditions have been considered to be potentially reliable archives of past oceanic conditions, this interpretation comes with significant challenges because diagenetic alteration frequently produces diverse fabrics with large geochemical variability. It has been suggested that the Ediacaran dolomites in South China (Hamajing Member, Dengying Formation) recorded the oceanic conditions present at the time they formed, yet these dolomites are composed of five different fabrics (stromatolitic, micritic, oolitic, saddle dolomites and fibrous–radial dolomite cements) and show large variations in multiple geochemical isotope proxies (carbon, oxygen, clumped, magnesium and the sulphur of carbonate‐associated sulphate). This study establishes a paragenetic sequence for these dolomites by combining the clumped and the oxygen isotopic compositions, thereby assessing whether they are geochemically representative of the original seawater. Using this diagenetic framework, the micritic and stromatolitic dolomites show a closed‐system behaviour (low water–rock ratios; <0.3) and are largely resistant to the hydrothermal alteration during late diagenesis. In contrast, the ooid and cement fabrics have been affected by the hydrothermal fluid precipitating saddle dolomite in the open‐system condition with the high stimulated water–rock ratios (>1). Furthermore, in a closed‐system environment, the elevated δ24Mg and δ34S values in the stromatolitic dolomite reflect the isotopic Rayleigh fractionation that enriches the 26Mg and 34S through rock‐buffered recrystallization, coupled with microbial sulphate reduction. These results demonstrate that the complex signals in early marine dolomite should be carefully evaluated when used as a palaeoproxy.

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What is the source of magnesium in hydrothermal dolomites? New insights from coupling δ26Mg - ∆47 isotopes

Muñoz-López,

Lu,

et al. 2024

Earth and Planetary Science Letters

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Clumped isotopes of paired dolomite and calcite constraining alteration histories of ancient carbonate successions

Cited by 6 publications

References 84 publications

Clumped Isotope Reordering and Kinetic Differences in Co-Hosted Calcite and Dolomite Minerals throughout Burial Diagenesis and Exhumation

Clumped Isotope Reordering and Kinetic Differences in Co-Hosted Calcite and Dolomite Minerals throughout Burial Diagenesis and Exhumation

A clumped isotope diagenetic framework for the Ediacaran dolomites: Insights to fabric‐specific geochemical variabilities

What is the source of magnesium in hydrothermal dolomites? New insights from coupling δ26Mg - ∆47 isotopes

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