A Geochemical Review of Amphibolite, Granulite, and Eclogite Facies Lithologies: Perspectives on the Deep Continental Crust

Sammon, Laura; McDonough, William F.

doi:10.1002/essoar.10506164.2

Cited by 3 publications

(15 citation statements)

References 83 publications

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“…We can also derive the global distribution of a trace element if that trace element has a quantifiable relationship to one of the thermodynamic components (major oxides) used in our model. We used a geochemical database of samples with both major and trace element concentrations (Sammon & McDonough, 2021) to generate trace element maps as a function of major oxide abundances. We used a bivariate probability analysis to generate trace element distributions from a major oxide abundance, such as SiO 2 , at a specific depth or location.…”

Section: Resultsmentioning

confidence: 99%

“…HPE abundance data are provided in the (Sammon & McDonough, 2021) geochemical data set. Using a joint probability analysis, we derived U abundances with uncertainties from SiO 2 .…”

Section: Discussionmentioning

confidence: 99%

“…We do this to highlight that this is the confidence in the central value, the median. The full range of possible abundances spans five orders of magnitude (Figure 12b) Th abundances could also be generated with a joint Th‐SiO 2 probability analysis, but we use a constant Th/U mass ratio of 3.77 ± 0.1 (Sammon & McDonough, 2021; Wipperfurth et al., 2018) which provides a narrower constraint on Th concentration. K 2 O abundance is calculated directly as a thermodynamic component in our compositional model.…”

Section: Discussionmentioning

confidence: 99%

“…Sammon and McDonough (2021) serves as our geochemical constraint on the deep (middle and lower) continental crust. That study represents a compilation of major and trace element abundances for amphibolite and granulite facies rocks.…”

Section: Methodsmentioning

confidence: 99%

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Compositional Attributes of the Deep Continental Crust Inferred From Geochemical and Geophysical Data

2022

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The deepest parts of Earth's crust are widely inaccessible to traditional geochemical sampling and so their composition is poorly understood. Only in areas where eruptions have brought xenoliths to the surface or where tectonic activity has exhumed medium and high grade metamorphic terrains are we able to partially determine the composition of the deep (middle and lower) continental crust. Even so, these ex situ, aged, weathered, and transported rocks may not adequately represent the overall, current composition of the deep crust. Such inaccessibility has challenged geochemists for decades (Dumond et al., 2018), leading to competing models for continental crust and bulk silicate Earth (BSE) compositions, formation, and evolution (e.g., Javoy et al. (2010);McDonough et al. (2020); Turcotte and Schubert (2014)). Dissonance in the geochemical community stems from known and unknown unknowns; that is, we are mostly certain of the uncertainties in our geochemical and petrological measurements, but we are uncertain if our samples are truly representative of large swathes of the deep crust or if they are merely point samples. Xenoliths and terrains are the sum of the processes that form them, which may cause them to differ from what is presently at 15-45 km and deeper.Seismological techniques, however, provide another piece of the cipher by directly measuring the physical state of large sections of the deep crust. Physical properties (e.g., density, Poisson's ratio, Vp, and Vs) determined from these in situ geophysical experiments can be compared to laboratory experiments on rocks of known compositions, particularly medium to high grade metamorphic lithologies (amphibolite and granulite facies rocks) to

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Section: Resultsmentioning

confidence: 99%

“…HPE abundance data are provided in the (Sammon & McDonough, 2021) geochemical data set. Using a joint probability analysis, we derived U abundances with uncertainties from SiO 2 .…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Compositional Attributes of the Deep Continental Crust Inferred From Geochemical and Geophysical Data

2022

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“…The minimum (Min) and maximum (Max) value of each element is also given. The least outlier-dependent measure of scattering was the interquartile range (IQR), which is the difference between the 75th and 25th percentiles [39].…”

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confidence: 99%

Geochemistry of beryl varieties: comparative analysis and visualization of analytical data by principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE)

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Gavrilchik

Березин

2022

PMI

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A study of the trace element composition of beryl varieties (469 SIMS analyses) was carried out. Red beryls are distinguished by a higher content of Ni, Sc, Mn, Fe, Ti, Cs, Rb, K, and B and lower content of Na and water. Pink beryls are characterized by a higher content of Cs, Rb, Na, Li, Cl, and water with lower content of Mg and Fe. Green beryls are defined by the increased content of Cr, V, Mg, Na, and water with reduced Cs. A feature of yellow beryls is the reduced content of Mg, Cs, Rb, K, Na, Li, and Cl. Beryls of various shades of blue and dark blue (aquamarines) are characterized by higher Fe content and lower Cs and Rb content. For white beryls, increased content of Na and Li has been established. Principal Component Analysis (PCA) for the CLR-transformed dataset showed that the first component separates green beryls from other varieties. The second component divides pink and red beryls. The stochastic neighborhood embedding method with t-distribution (t-SNE) with CLR-transformed data demonstrated the contrasting compositions of green beryls relative to other varieties. Red and pink beryls form the most compact clusters.

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Composition and Evolution of Continental Crust at Orogenic Belts: Constraints From a 3‐D Crustal Model of Southeast China

Sun

Gao

et al. 2022

JGR Solid Earth

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The Earth is a unique planet with highly differentiated continental crust and the knowledge of the crust composition is crucial for deciphering its formation and evolution (Rudnick, 1995;Rudnick & Gao, 2003). Although the estimates for the chemical composition of continental crust vary from each individual study, the consensus of crust composition is reached by featuring an intermediate composition for the bulk crust and a granodioritic composition for the upper crust (Rudnick & Gao, 2003). However, it is difficult to generate a felsic crust if it had only experienced a single-stage melt extraction from the peridotitic mantle (Rudnick, 1995). Therefore, additional processes must contribute to the evolution of crust composition. One of the plausible hypotheses is

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A Geochemical Review of Amphibolite, Granulite, and Eclogite Facies Lithologies: Perspectives on the Deep Continental Crust

Cited by 3 publications

References 83 publications

Compositional Attributes of the Deep Continental Crust Inferred From Geochemical and Geophysical Data

Compositional Attributes of the Deep Continental Crust Inferred From Geochemical and Geophysical Data

Geochemistry of beryl varieties: comparative analysis and visualization of analytical data by principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE)

Composition and Evolution of Continental Crust at Orogenic Belts: Constraints From a 3‐D Crustal Model of Southeast China

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