Pressure and Temperature Data for Diamonds

Nimis, Paolo

doi:10.2138/rmg.2022.88.10

Cited by 28 publications

(7 citation statements)

References 170 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(2020), who used P estimates from the Carswell (1991) Al‐in‐orthopyroxene geobarometer (modified after Nickel and Green (1985)) for natural xenoliths to correct for P‐underestimation above 4.5 GPa. Although this correction yields improved results on high‐P (>4 GPa) xenoliths relative to the original Nimis and Taylor (2000) calibration (see Figure 6, Nimis, 2022), the uncertainties on P estimates, which undoubtably propagate from the empirical fit, remain poorly understood, but are estimated to be in excess of 0.75 kbar based on the propagation of uncertainties of 0.3 GPa for each of the geobarometers (Carswell, 1991; Nimis & Taylor, 2000). Estimates of equilibration T for pyrope garnet were made using the experimentally calibrated single‐grain Ni‐in‐garnet geothermometer of Sudholz, Yaxley, Jaques, and Chen (2021), using garnet Ni concentrations measured by LA‐ICP‐MS and a recommended olivine Ni concentration of 3,000 ppm.…”

Section: Methodsmentioning

confidence: 99%

Mapping the Structure and Metasomatic Enrichment of the Lithospheric Mantle Beneath the Kimberley Craton, Western Australia

Sudholz,

Jaques,

Yaxley

et al. 2023

Geochem Geophys Geosyst

View full text Add to dashboard Cite

The lithology, geochemistry, and architecture of the continental lithospheric mantle (CLM) underlying the Kimberley Craton of north‐western Australia has been constrained using pressure‐temperature estimates and mineral compositions for >5,000 newly analyzed and published garnet and chrome (Cr) diopside mantle xenocrysts from 25 kimberlites and lamproites of Mesoproterozoic to Miocene age. Single‐grain Cr diopside paleogeotherms define lithospheric thicknesses of 200–250 km and fall along conductive geotherms corresponding to a surface heat flow of 37–40 mW/m2. Similar geotherms derived from Miocene and Mesoproterozoic intrusions indicate that the lithospheric architecture and thermal state of the CLM has remained stable since at least 1,000 Ma. The chemistry of xenocrysts defines a layered lithosphere with lithological and geochemical domains in the shallow (<100 km) and deep (>150 km) CLM, separated by a diopside‐depleted and seismically slow mid‐lithosphere discontinuity (100–150 km). The shallow CLM is comprised of Cr diopsides derived from depleted garnet‐poor and spinel‐bearing lherzolite that has been weakly metasomatized. This layer may represent an early (Meso to Neoarchean?) nucleus of the craton. The deep CLM is comprised of high Cr2O3 garnet lherzolite with lesser harzburgite, and eclogite. The peridotite components are inferred to have formed as residues of polybaric partial mantle melting in the Archean, whereas eclogite likely represents former oceanic crust accreted during Paleoproterozoic subduction. This deep CLM was metasomatized by H2O‐rich melts derived from subducted sediments and high‐temperature FeO‐TiO2 melts from the asthenosphere.

show abstract

Section: Methodsmentioning

confidence: 99%

Mapping the Structure and Metasomatic Enrichment of the Lithospheric Mantle Beneath the Kimberley Craton, Western Australia

Sudholz,

Jaques,

Yaxley

et al. 2023

Geochem Geophys Geosyst

View full text Add to dashboard Cite

show abstract

“…When comparing the experimentally determined P,T parameters of spontaneous diamond formation as a result of reduction of carbonates or CO 2 fluid with the P,T field of natural diamond formation in the lithospheric mantle (review [124]), a significant intersection of these areas was found (Figure 2). This suggests that, despite the fact that the P,T parameters of several reviewed experimental studies [88,89,92] are somewhat higher than those estimated for diamond formation [124], these results provide crucial data for deciphering the diamond genesis in Earth's mantle.…”

Section: Implications Of Experimental Data In the Lithospheric Diamon...mentioning

confidence: 99%

“…[54,[88][89][90][91][92][93][94][95][96][97][98]. Additionally, the estimated parameters of the formation of natural diamond-bearing eclogitic xenoliths as well as lithospheric diamonds are given (modified after [124]).…”

Section: Implications Of Experimental Data In the Lithospheric Diamon...mentioning

confidence: 99%

Diamond Formation via Carbonate or CO2 Reduction under Pressures and Temperatures of the Lithospheric Mantle: Review of Experimental Data

Bataleva

Palyanov

2023

Minerals

View full text Add to dashboard Cite

Existing ideas about the polygenic origin of diamonds in nature involve various processes, mechanisms, and driving forces for diamond crystallization, including redox reactions, changes in P-T conditions, evolution of melt or fluid composition, and others. According to classical models, in the lithospheric mantle, diamond formation occurs at depths of 120–210 km and temperatures of 900–1500 °C as a result of metasomatic processes. The driving forces in these models are considered to be redox reactions leading to the reduction of carbonates, carbonate melts, or CO2 to elemental carbon. In this study, we provide a review and systematization, as well as experimental issues and possible future directions of experimental studies, on diamond crystallization from carbonate carbon through redox reactions at P,T (pressure, temperature) conditions relevant to the lithospheric mantle. These studies have demonstrated that silicon, metals (FeSi, Fe, Fe-Nialloys), carbides (SiC, Fe3C, Fe7C3), reduced components of C-O-H fluid, sulfides/sulfide melts, Fe-S-C melts, and the application of an electric field (potential difference) can act as reducing agents for carbonate/carbonate-bearing melts or CO2 fluid, leading to the formation of diamond and graphite. The experimental data reviewed in this paper not only indicate the fundamental possibility of diamond formation from carbonate carbon through the reduction of carbonate, carbonate-bearing phases, or CO2 in the mantle, but also reveal the characteristic features of the resulting diamonds. Furthermore, the significance of potential reducing agents (fluid, sulfide, silicon, metal, and carbide) in various geodynamic settings, including the lithospheric mantle at depths insufficient for stabilizing iron or carbides, has been identified.

show abstract

“…Unfortunately, a P-dependent Ni-in-Grt geothermometer may not be practical, because an independent estimate of P is rarely available for single-garnet geothermometry. Possible favorable cases are those in which P can be derived by projection onto a model geotherm (Nimis, 2022;Ryan et al, 1996) or inclusions in diamonds for which P is estimated by elastic barometry (Angel et al, 2022). Attempts to calibrate the geothermometer by considering only the cratonic garnets still evidenced a significant P dependence, despite the reduced P range at any given T in the calibration data.…”

Section: Ni-t-p Relationships In Peridotitic Garnetsmentioning

confidence: 99%

A Revision of the Ni-in-Garnet Geothermometer with Special Regard to its Pressure Dependence

Nimis,

Zanetti,

Franz

2023

Preprint

View full text Add to dashboard Cite

Pressure and Temperature Data for Diamonds

Cited by 28 publications

References 170 publications

Mapping the Structure and Metasomatic Enrichment of the Lithospheric Mantle Beneath the Kimberley Craton, Western Australia

Mapping the Structure and Metasomatic Enrichment of the Lithospheric Mantle Beneath the Kimberley Craton, Western Australia

Diamond Formation via Carbonate or CO2 Reduction under Pressures and Temperatures of the Lithospheric Mantle: Review of Experimental Data

A Revision of the Ni-in-Garnet Geothermometer with Special Regard to its Pressure Dependence

Contact Info

Product

Resources

About