Reconstruction of mantle sections beneath Yakutian kimberlite pipes using monomineral thermobarometry

Ashchepkov, Igor; Pokhilenko, N. P.; Vladykin, N. V.; Rotman, A. Ya.; Afanasiev, V. P.; Logvinova, A. M.; Kostrovitsky, Sergey; Pokhilenko, L. N.; Karpenko, Mikhail A.; Kuligin, S. S.; Malygina, E. V.; Stegnitsky, Yu.B.; Alymova, Natalia; Khmelnikova, O. S.

doi:10.1144/sp293.15

Cited by 12 publications

(7 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous studies on the lateral and vertical variations of the mantle structure of Siberian platform have shown that a layering exists in the SCLM beneath Udachnaya and other Siberian kimberlite pipes (Ashchepkov et al, 2010;Ashchepkov et al, 2008a;Boyd et al, 1997;Griffin et al, 2005;Griffin et al, 1999b;Nimis et al, 2009). For example, the garnets from kimberlite heavy mineral separates show an increasing depletion of the lower part of the mantle lithosphere northward (Griffin et al, 1999b).…”

Section: Geological Backgroundmentioning

confidence: 96%

Isotopic composition of Mg and Fe in garnet peridotites from the Kaapvaal and Siberian cratons

Huang

Griffin

et al. 2017

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

We present Mg and Fe isotopic data for whole rocks and separated minerals (olivine, clinopyroxene, orthopyroxene, garnet, and phlogopite) of garnet peridotites that equilibrated at depths of 134 -186 km beneath the Kaapvaal and Siberian cratons. There is no clear difference in δ 26 Mg and δ 56 Fe of garnet peridotites from these two cratons. δ 26 Mg of whole rocks varies from -0.243‰ to -0.204‰ with an average of -0.225 ± 0.037‰ (2σ, n = 19), and δ 56 Fe from -0.038‰ to 0.060‰ with an average of -0.003 ± 0.068‰ (2σ, n = 19). Both values are indistinguishable from the fertile upper mantle, indicating that there is no significant Mg-Fe isotopic difference between the shallow and deep upper mantle. The garnet peridotites from ancient cratons show δ 26 Mg similar to komatiites and basalts, further suggesting that there is no obvious Mg isotopic fractionation during different degrees of partial melting of deep mantle peridotites and komatiite formation.The precision of the Mg and Fe isotope data (≤ ±0.05‰ for δ 26 Mg and δ 56 Fe, 2σ) allows us to distinguish inter-mineral isotopic fractionations. Olivines are in equilibrium with opx in terms of Mg and Fe isotopes. Garnets have the lowest δ 26 Mg and δ 56 Fe among the coexisting mantle minerals, suggesting the dominant control of crystal structure on the Mg-Fe isotopic compositions of garnets. Elemental compositions and mineralogy suggest that clinopyroxene and garnet were produced by later metasomatic processes as they are not in chemical equilibrium with olivine or orthopyroxene. This is consistent with the isotopic disequilibrium of Mg and Fe isotopes between orthopyroxene/olivine and garnet/clinopyroxene. Combined with one sample showing slightly heavy δ 26 Mg and much lighter δ 56 Fe, these disequilibrium features in the garnet peridotites reveal kinetic isotopic fractionation due to Fe-Mg inter-diffusion during reaction between peridotites and percolating melts in the Kaapvaal craton.

show abstract

Section: Geological Backgroundmentioning

confidence: 96%

Isotopic composition of Mg and Fe in garnet peridotites from the Kaapvaal and Siberian cratons

Huang

Griffin

et al. 2017

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

show abstract

“…Single-mineral thermometer-barometer pairs, such as those available for peridotitic garnet and clinopyroxene (Ryan et al 1996;Nimis and Taylor 2000;Grütter et al 2006), permit thermobarometric surveys to extend across copious data for mantlederived xenocrysts. Although with some limitations concerning their reliability and applicability (e.g., Cookenboo and Grütter 2010), the single-mineral methods have enabled the vertical and horizontal mapping of the lithospheric mantle to an extent far beyond that achievable with xenoliths alone (e.g., Griffin et al 1999Griffin et al , 2002Griffin et al , 2004Malkovets et al 2007;Ashchepkov et al 2008;Grütter and Tuer 2009;Lehtonen et al 2009;Nimis et al 2009;Zozulya et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Error sources in single-clinopyroxene thermobarometry and a mantle geotherm for the Novinka kimberlite, Yakutia

Ziberna

Nimis

Kuzmin

et al. 2016

American Mineralogist

View full text Add to dashboard Cite

A new suite of 173 clinopyroxene grains from heavy-mineral concentrates of the diamondiferous Novinka kimberlite (Upper Muna field, Yakutia) has been analyzed for major and minor elements with an electron microprobe to perform a thermobarometric study and model the thermal structure of the Archean Upper Muna lithospheric mantle. Scrupulous evaluation of propagation of analytical uncertainties on pressure estimates revealed that (1) the single-clinopyroxene geobarometer can be very sensitive to analytical uncertainties for particular clinopyroxene compositions, and that (2) most clinopyroxenes from Novinka have compositions that are sensitive to analytical uncertainties, notwithstanding their apparent compositional suitability for single-clinopyroxene thermobarometry based on previously proposed application limits. A test on various mantle clinopyroxenes containing different proportions of the sensitive elements Cr, Na, and Al allowed us to identify clinopyroxene compositions that produce unacceptably high propagated errors and to define appropriate analytical conditions (i.e., higher beam currents and longer counting times for specific elements) that allow precise P-T estimates to be obtained for sensitive compositions. Based on the results of our analytical test, and taking into account the intrinsic limitations of the single-clinopyroxene thermobarometer, we have designed a new protocol for optimum thermobarometry, which uses partly revised compositional filters. The new protocol permits precise computation of the conductive paleogeotherm at Novinka with the single-clinopyroxene thermobarometer of Nimis and Taylor (2000). Thermal modeling of the resulting P-T estimates indicates a ~34 mW/m2 surface heat flow, a thermal lithosphere thickness of ~225 km, and an over 100 km thick “diamond window” beneath Novinka in the middle Paleozoic (344–361 Ma). We estimate that appropriate analytical conditions may extend the applicability of single-clinopyroxene thermobarometry to over 90% of clinopyroxene-bearing garnet peridotites and pyroxenites and to ~70% of chromian-diopside inclusions in diamonds. In all cases, application to clinopyroxenes with Cr/(Cr+Al)mol < 0.1 is not recommended. We confirm the tendency of the single-clinopyroxene barometer to progressively underestimate pressure at P > 4.5 GPa

show abstract

“…We have calculated and estimated the P-T parameters with the help of an olivine-spinel (Ol-Sp) geothermometer, provided in [88]. The oxygen fugacity was determined using an Ol-Sp oxybarometer, provided in [89], in accordance with oxybarometers [90,91]. For the chrome spinels I group (high Al′), the calculated temperatures of the Ol-Sp equilibrium are TOl-Sp = 1020-920 °C, and fO2 = (−0.7)-(−1.5) (Table 1); for the chrome spinels II group (medium-, low-Al′), the calculated temperatures are TOl-Sp = 891-1003 °C , and fO2 = (−1.1) − (−4.4); for the chrome spinels III group, these values are TOl-Sp = 846-…”

Section: Spinel and Olivine Geothermometers And Olivine-spinel Oxybarometersmentioning

confidence: 99%

Podiform Chromitites and PGE Mineralization in the Ulan-Sar’dag Ophiolite (East Sayan, Russia)

et al. 2020

View full text Add to dashboard Cite

In this paper, we present the first detailed study on the chromitites and platinum-group element mineralization (PGM) of the Ulan-Sar’dag ophiolite (USO), located in the Central Asian Fold Belt (East Sayan). Three groups of chrome spinels, differing in their chemical features and physical–chemical parameters, under equilibrium conditions of the mantle mineral association, have been distinguished. The temperature and log oxygen fugacity values are, for the chrome spinels I, from 820 to 920 °C and from (−0.7) to (−1.5); for chrome spinels II, 891 to 1003 °C and (−1.1) to (−4.4); and for chrome spinels III, 738 to 846 °C and (−1.1) to (−4.4), respectively. Chrome spinels I were formed through the interaction of peridotites with mid-ocean ridge basalt (MORB)-type melts, and chrome spinels II were formed through the interaction of peridotites with boninite melts. Chrome spinels III were probably formed through the interaction of andesitic melts with rocks of an overlying mantle wedge. Chromitites demonstrate the fractionated form of the distribution of the platinum-group elements (PGE), which indicates a high degree of partial melting at 20–24% of the mantle source. Two assemblages of PGM have been distinguished: The primary PGE assemblage of Os-Ir-Ru alloys-I, (Os,Ru)S2, and IrAsS, and the secondary PGM assemblage of Os-Ir-Ru alloys-II, Os0, Ru0, RuS2, OsS2, IrAsS, RhNiAs with Ni, Fe, and Cu sulfides. The formation of the secondary phases of PGE occurred upon exposure to a reduced fluid, with a temperature range of 300–700 °C, log sulfur fugacity of (−20), and pressure of 0.5 kbar. We have proposed a scheme for the sequence of the formation and transformation of the PGMs at various stages of the evolution of the Ulan-Sar’dag ophiolite.

show abstract

Reconstruction of mantle sections beneath Yakutian kimberlite pipes using monomineral thermobarometry

Cited by 12 publications

References 45 publications

Isotopic composition of Mg and Fe in garnet peridotites from the Kaapvaal and Siberian cratons

Isotopic composition of Mg and Fe in garnet peridotites from the Kaapvaal and Siberian cratons

Error sources in single-clinopyroxene thermobarometry and a mantle geotherm for the Novinka kimberlite, Yakutia

Podiform Chromitites and PGE Mineralization in the Ulan-Sar’dag Ophiolite (East Sayan, Russia)

Contact Info

Product

Resources

About