Preservation of primary lake signatures in alkaline earth carbonates of the Eocene Green River Wilkins Peak-Laney Member transition zone

Murphy, John T.; Lowenstein, Tim K.; Pietras, Jeffrey T.

doi:10.1016/j.sedgeo.2014.09.005

Cited by 34 publications

(15 citation statements)

References 74 publications

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“…Considering that organic matter and clay minerals are abundant on the Earth's crust, they should be commonly found in both modern and ancient shallow-water environments, such as the Eocene Green River Basin (Murphy et al, 2014), the Coroong (Rosen et al, 1988) and Deep Springs Lake (Meister et al, 2011a). This study strongly suggests that the interlayer of clays within an organic matrix could act as a substrate/template for dolomite nucleation.…”

Section: Deep Time Implications For Dolomite Formationmentioning

confidence: 75%

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Nucleation and stabilization of Eocene dolomite in evaporative lacustrine deposits from central Tibetan plateau

Wen

Sánchez‐Román

et al. 2020

Sedimentology

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In past decades, the formation of dolomite at low temperature has been widely studied in both natural systems and cultured experiments, yet the mechanism(s) involved in the nucleation and precipitation of dolomite remains unresolved. Late Eocene dolomitic deposits from core in the upper Niubao Formation (Lunpola Basin, central Tibetan Plateau, China) are selected as a case study to understand the dolomitization process(es) in the geological record. Dolomite formation in Lunpola Basin can be ascribed to a different mechanism forming the large quantities of replacive dolostones in the geological record; and provides a potential fossil analogue for primary dolomite precipitation at low temperature. This analogue consists of an alternation of laminated dolomitic beds, organic‐rich and siliciclastic layers; formed in response to intense evaporation interpreted to take place in a continental shallow lake environment. Mineralogical, textural and stable isotopic evaluations suggest that the dolomite from those dense‐clotted laminated beds is a primary precipitate. At the nanoscale, these dolomitic beds are composed of Ca–Mg carbonate globular nanocrystals (diameter 80 to 100 nm) embedded in an organic matrix and attached to clay flakes. Micro‐infrared spectroscopy analyses have revealed the presence of aliphatic compounds in the organic matrix. Microscopic and elemental compositional studies suggest that clay surfaces may facilitate the nucleation of dolomite at low temperature in the same way as the organic matrix does. The dolomite laminae show values for δ18OVPDB from −3.2 to −1.76‰ and for δ13CVPDB from −2.62 to −3.78‰. Inferred δ18OSMOW values of the lake water reveal typical evaporitic hydrological conditions. These findings provide a potential link to primary dolomite formation in ancient and modern sedimentary environments; and shed new light on the palaeoenvironmental conditions in central Tibet during the Eocene.

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Section: Deep Time Implications For Dolomite Formationmentioning

confidence: 75%

“…(B) Reconstructed d 18 O SMOW of lake water for corresponding primary carbonate precipitation. T = 25°C was used for the Green River Formation calculation (Morrill & Koch, 2002;Ma, 2006;Murphy et al, 2014). calcite as revealed by ATR-FTIR, TEM-EDS and XRD analyses.…”

Section: Primary Dolomite Formation In the Lunpola Basinmentioning

confidence: 99%

Nucleation and stabilization of Eocene dolomite in evaporative lacustrine deposits from central Tibetan plateau

Wen

Sánchez‐Román

et al. 2020

Sedimentology

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“…Lacustrine aragonite is authigenic and/or endogenic because it is a metastable mineral and is never found in ancient carbonate rocks. Lacustrine aragonite is generally found in saline or brackish lakes (Fontes et al, 1996;Digerfeldt et al, 2000;Landmanna et al, 2002;Shapley et al, 2005;Murphy et al, 2014). In the process of seawater evaporation, aragonite begins to precipitate when the solution reaches 2-3 times the concentration of seawater (Warren, 1989).…”

Section: Discussionmentioning

confidence: 99%

Holocene Lake Evolution and Glacial Fluctuations Indicated by Carbonate Minerals and Their Isotopic Compositions in the Sediments of a Glacial Melt Recharge Lake on the Northwestern Tibetan Plateau

Zhu

Wang

et al. 2021

Front. Earth Sci.

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Lakes and glaciers are widely distributed on the Tibetan Plateau and are linked via hydrological processes. They are experiencing rapid changes due to global warming, but their relationships during the Holocene are less well known due to limited coupled geological records. Here, we analyzed the δ13C-VPDB and δ18O-VPDB values and ion content of calcite and aragonite in a 407-cm-long sediment core from Guozha Co, a closed basin on the northwestern Tibetan Plateau supplied by glacial meltwater, in order to understand how the lake responded to glacier changes during the Holocene. Our results indicate that the glacial meltwater lowered the lake’s temperature and the δ18Olake water and δ18Oendogenic + authigenic carbonate values and diluted the ion concentrations in the lake water. Three stages of evolution, 8.7–4.0, 4.0–1.5, and 1.5 kyr BP to present, are distinguished based on the decrease in glacial meltwater recharge. Guozha Co has been a closed basin since at least 8.7 kyr BP, and it has changed from a fresh water lake during 8.7–1.5 kyr BP to a brackish lake from 1.5 kyr BP to present due to several climate events. The famous 4.2 kyr BP cold event was identified in the core at 4.0 kyr BP, while warm events occurred at 6.2, 3.9, 2.2, 0.9, and 0.4 kyr BP. Both glaciers and lakes in this area are controlled by climate, but they exhibit opposite changes, that is, glaciers retreat and lakes expand, and vice versa. Our results provide an accurate interpretation of the cold events based on carbonate minerals and carbon–oxygen isotopes in glacial meltwater–recharged lake sediments.

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“…The chemical conditions that affect the precipitation of aragonite are well-known by experimental research (e.g., [85]). The increase of Mg/Ca ratios can promote the precipitation of aragonite instead of other carbonate minerals [86][87][88]. Aragonite may precipitate from circulating solutions bearing suspended carbonates [89].…”

Section: Fluid Flow and Mineral Processesmentioning

confidence: 99%

“…Aragonite may precipitate from circulating solutions bearing suspended carbonates [89]. Previous experimental studies revealed that the precipitation of calcite and dolomite in natural environments occurs under Mg/Ca ratios of 2/12 [83,88], but aragonite only crystallizes in Mg-rich solutions (Mg/Ca > 50) [90][91][92][93]. The precipitation of aragonite, a mineral with low Mg content, in a high Mg/Ca ratio environment can be explained taking into account some crystal chemical considerations.…”

Section: Fluid Flow and Mineral Processesmentioning

confidence: 99%

Effect of Mineral Processes and Deformation on the Petrophysical Properties of Soft Rocks during Active Faulting

et al. 2020

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We have studied damage zones of two active faults, Baza and Padul faults in Guadix-Baza and Granada basins, respectively, in South Spain. Mineral and microstructural characterization by X-ray diffraction and field emission electron microscopy studies have been combined with structural fieldwork and in situ measurements of rock properties (permeability and Young’s modulus) to find out the relation between deformation behavior, mineral processes, and changes in the soft rock and sediment properties produced by fluid flow during seismic cycles. Our results show that microsealing produced by precipitation of dolomite and aragonite along fractures in the damage zone of Baza Fault reduces the permeability and increases the Young’s modulus. In addition, deformation bands formed in sediments richer in detrital silicates involved cataclasis as deformation mechanism, which hamper permeability of the sediments. In the Granada Basin, the calcarenitic rocks rich in calcite and clays in the damage zone of faults associated to the Padul Fault are characterized by the presence of stylolites without any carbonate cement. On the other hand, marly lithofacies affected by faults are characterized by the presence of disaggregation bands that involve cracking and granular flow, as well as clay smear. The presence of stylolites and deformation bands in these rocks reduces permeability.

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Preservation of primary lake signatures in alkaline earth carbonates of the Eocene Green River Wilkins Peak-Laney Member transition zone

Cited by 34 publications

References 74 publications

Nucleation and stabilization of Eocene dolomite in evaporative lacustrine deposits from central Tibetan plateau

Nucleation and stabilization of Eocene dolomite in evaporative lacustrine deposits from central Tibetan plateau

Holocene Lake Evolution and Glacial Fluctuations Indicated by Carbonate Minerals and Their Isotopic Compositions in the Sediments of a Glacial Melt Recharge Lake on the Northwestern Tibetan Plateau

Effect of Mineral Processes and Deformation on the Petrophysical Properties of Soft Rocks during Active Faulting

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