Extensive, uplift-related and non-fault-controlled spar precipitation in the Permian Capitan Formation

Loyd, S. J.; Dickson, J. A. D.; Scholle, Peter A.; Tripati, Aradhna

doi:10.1016/j.sedgeo.2013.10.001

Cited by 17 publications

(21 citation statements)

References 34 publications

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“…6). Such late-stage, uplift-related spar precipitation has been proposed in non-concretionary carbonate units (Loyd et al 2013). These new data suggest that uplift-related spar formation might be more common than previously thought and specifically related to spar precipitation in septarian concretions.…”

Section: Implications For Formation Models Of Septarian Concretionssupporting

confidence: 64%

Clumped-Isotope Constraints On Cement Paragenesis In Septarian Concretions

Loyd¹,

Dickson²,

Boles³

et al. 2014

Journal of Sedimentary Research

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Septarian concretions exhibit multiple generations of cements that include body, fringe, and spar phases. Classic paragenetic interpretations include initial precipitation of the body followed by fringe(s) and then by spar in more or less discrete events. Traditional approaches (e.g., carbon and oxygen isotope analyses) are generally unable to distinguish paragenetic trends as they relate to specific formation environments (e.g., precipitation during burial or with meteoric influx O fluid compositions of , 214 to +4% (VSMOW). In stable-isotope cross-plots, specific cement phases group together and confirm the paragenesis indicated by superposition. In some cases, samples analyzed from concretion bodies yield temperature and d18 O fluid values that indicate formation at shallow depths, consistent with independent data (e.g., high minus-cement porosity, external laminae deflection). In contrast, other concretion-body analyses indicate relatively high body temperatures that conflict with shallow-formation indices. Petrographic and backscatter scanning electron microscopy (SEM) reveal that concretion bodies partially consist of a secondary, replacement phase, which could explain the higher temperatures expressed in bulk body samples. Based on data for different phases in these septarian concretions, we suggest that initial body-cement precipitation occurred at relatively shallow depths from unmodified seawater, followed by fringe formation at elevated temperatures that likely coincided with the emplacement of the secondary body phase. When considered together, late-stage spar phases exhibit temperatures and d18 O fluid values supportive of spar precipitation from fluids with a significant meteoric component, possibly during uplift.

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Section: Implications For Formation Models Of Septarian Concretionssupporting

confidence: 64%

Clumped-Isotope Constraints On Cement Paragenesis In Septarian Concretions

Loyd¹,

Dickson²,

Boles³

et al. 2014

Journal of Sedimentary Research

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“…Clumped isotope-derived temperatures can be combined with ␦ 18 O carb to uniquely determine ␦ 18 O w through application of an appropriate carbonate-water oxygen isotope fractionation factor (Kim and O'Neil, 1997;Vasconcelos et al, 2005). The tool has been used for a range of applications including the study of primary and diagenetic processes in terrestrial and marine samples of a wide range of ages (Came et al, 2007;Affek et al, 2008;Dennis and Schrag, 2010;Eagle et al, 2010Eagle et al, , 2011Eagle et al, , 2013Passey et al, 2010;Tripati et al, 2010Tripati et al, , 2014Bristow et al, 2011;Ferry et al, 2011;Finnegan et al, 2011;Huntington et al, 2011;Keating-Bitonti et al, 2011;Loyd et al, 2012aLoyd et al, , 2013aLoyd et al, , 2014Passey and Henkes, 2012;Swanson et al, 2012;Dale et al, 2014).…”

Section: Figmentioning

confidence: 99%

Evolution of Neoproterozoic Wonoka–Shuram Anomaly-aged carbonates: Evidence from clumped isotope paleothermometry

Loyd

Corsetti

Eagle

et al. 2015

Precambrian Research

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a b s t r a c tThe Wonoka-Shuram Anomaly represents the largest negative carbon isotope excursion recognized in the geologic record and is associated with the emergence and diversification of metazoan life ca. 580 million years ago (Ma). The origin of the anomaly is highly debated, with interpretations ranging from primary to diagenetic, each having unique and potentially transformative implications for early life. Here, we apply carbonate clumped isotope thermometry to three sections expressing the anomaly in order to constrain mineral formation temperatures and thus directly calculate water oxygen isotope compositions (␦ 18 O w ) with which carbonate minerals equilibrated. With ␦ 18 O w known, it is possible to address previous hypotheses for the origin of the anomaly. In each section, precipitation temperatures correlate positively with reconstructed ␦ 18 O w . Previous hypotheses, based on the covariance of ␦ 18 O carb vs. ␦ 13 C carb (uncorrected for temperature effects), suggested a meteoric diagenetic origin for the anomaly. However, reconstructed ␦ 18 O w values do not covary with carbon isotope compositions (␦ 13 C carb ) within anomaly facies. Rather, the oxygen isotope and temperature data are consistent with carbonate recrystallization and equilibration under increasingly rock-buffered conditions. Based on simple modeling and comparison to modern formation fluids, recrystallization may have occurred in an environment far removed from the initial depositional or early diagenetic regime. In addition, although clumped isotope temperatures vary significantly and reach elevated values consistent with burial diagenesis, it is unclear to what degree, if at all, carbon isotope values were reset during recrystallization. Ultimately, these new data indicate that Wonoka-Shuram-aged carbonates experienced equilibration with fluids under increasingly closedsystem conditions. The clumped isotope data do not provide a means to distinguish previous hypotheses outright, but provide additional context for the evaluation of geochemical signatures within these ancient carbonate rocks.

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“…Clumped isotope thermometry has emerged as a powerful tool in the geosciences Came et al, 2007;Eagle et al, 2010Eagle et al, , 2011Eagle et al, ,2013aPassey et al, 2010;Csank et al, 2011;Loyd et al, 2012Loyd et al, , 2013Tripati et al, 2010Tripati et al, , 2014. The geothermometer exploits systematic changes in the occurrence of multiple rare-isotope substitutions ( 13 C-18 O bonds) in carbonate minerals with temperature.…”

Section: Introductionmentioning

confidence: 99%

Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

Tripati

Hill

Eagle

et al. 2015

Geochimica et Cosmochimica Acta

120

201

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Clumped-isotope" thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of 13 C and 18 O isotopes bound to each other within carbonate minerals in 13 C 18 O 16 O 2 2À groups (heavy isotope "clumps"). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solution chemistry), several factors other than temperature, including dissolved inorganic carbon (DIC) speciation may influence mineral isotopic signatures. Therefore we used a combination of approaches to understand the potential influence of different variables on the clumped isotope (and oxygen isotope) composition of minerals.We conducted witherite precipitation experiments at a single temperature and at varied pH to empirically determine 13 C-18 O bond ordering (D 47 ) and d 18 O of CO 3 2À and HCO 3 À molecules at a 25°C equilibrium. Ab initio cluster models based on density functional theory were used to predict equilibrium 13 C- 18 O bond abundances and d 18 O of different DIC species and minerals as a function of temperature. Experiments and theory indicate D 47 and d 18 O compositions of CO 3 2À and HCO 3 À ions are significantly different from each other. Experiments constrain the D 47 -d 18 O slope for a pH effect (0.011 ± 0.001; 12 P pH P 7). Rapidly-growing temperate corals exhibit disequilibrium mineral isotopic signatures with a D 47 -d 18 O slope of 0.011 ± 0.003, consistent with a pH effect. Our theoretical calculations for carbonate minerals indicate equilibrium lattice calcite values for D 47 and d 18 O are intermediate between HCO 3 À and CO 3 2À. We analyzed synthetic calcites grown at temperatures ranging from 0.5 to 50°C with and without the enzyme carbonic anhydrase present. This enzyme catalyzes oxygen isotopic exchange between DIC species and is present in many natural systems. The two types of experiments yielded statistically indistinguishable results, and these measurements yield a calibration that overlaps with our theoretical predictions for calcite at equilibrium. The slow-growing Devils Hole calcite exhibits D 47 and d 18 O values consistent with lattice equilibrium.Factors influencing DIC speciation (pH, salinity) and the timescale for DIC equilibration, as well as reactions at the mineral-solution interface, have the potential to influence clumped-isotope signatures and the d 18 O of carbonate minerals. In fast-growing carbonate minerals, solution chemistry may be an important factor, particularly over extremes of pH and salinity. If a crystal grows too rapidly to reach an internal equilibrium (i.e., achieve the value for the temperature-dependent mineral lattice equilibrium), it may record the clumped-isotope signature of a DIC species (e.g., the temperature-dependent equilibrium of HCO 3 À ) or a mixture of DIC species, and hence record a disequilibrium mineral composition. For extremely slow-growing cry...

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Extensive, uplift-related and non-fault-controlled spar precipitation in the Permian Capitan Formation

Cited by 17 publications

References 34 publications

Clumped-Isotope Constraints On Cement Paragenesis In Septarian Concretions

Clumped-Isotope Constraints On Cement Paragenesis In Septarian Concretions

Evolution of Neoproterozoic Wonoka–Shuram Anomaly-aged carbonates: Evidence from clumped isotope paleothermometry

Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

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