Comment 2 on “Ultra-high pressure and ultra-reduced minerals in ophiolites may form by lightning strikes”
Affiliations | Corresponding Author | Cite as | Funding information
Published by the European Association of Geochemistry
under Creative Commons License CC BY-NC-ND 4.0
Keywords: ophiolite-hosted diamond, super-reduced minerals, UHP minerals, mantle rocks, chromitite
- Share this article
Article views:3,494Cumulative count of HTML views and PDF downloads.
- Download Citation
- Rights & Permissions
top
Comment
We read with great interest the paper by Ballhaus and coauthors (2017)
Ballhaus, C., Wirth, R., Fonseca, R.O.C., Blanchard, H., Pröll, W., Bragagni, A., Nagel, T., Schreiber, A., Dittrich, S., Thome, V., Hezel, D.C., Below, R., Cieszynski, H. (2017) Ultra-high pressure and ultra-reduced minerals in ophiolites may form by lightning strikes. Geochemical Perspectives Letters 5, 42-46.
reporting on electrical discharge experiments that showed how SiC and other phases found in mantle-derived rocks can potentially form by lightning strikes (Ballhaus et al., 2017Ballhaus, C., Wirth, R., Fonseca, R.O.C., Blanchard, H., Pröll, W., Bragagni, A., Nagel, T., Schreiber, A., Dittrich, S., Thome, V., Hezel, D.C., Below, R., Cieszynski, H. (2017) Ultra-high pressure and ultra-reduced minerals in ophiolites may form by lightning strikes. Geochemical Perspectives Letters 5, 42-46.
). The experiments are technically innovative and challenging and the results make fascinating reading. In a comment paper, Griffin et al. (2018)Griffin, W.L., Howell, D., Gonzalez-Jimenez, J.M., Xiong, Q., O’Reilly, S.Y. (2018) Comment on “Ultra-high pressure and ultra-reduced minerals in ophiolites may form by lightning strikes”. Geochemical Perspectives Letters 7, 1-2.
noted several lines of evidence that ultra-high pressure (UHP) and super reduced (SuR) minerals in ophiolites do not form by lightning strikes. Here, we add additional comments relating to the geological and mineralogical data from ophiolites that are not compatible with the model of Ballhaus et al. (2017)Ballhaus, C., Wirth, R., Fonseca, R.O.C., Blanchard, H., Pröll, W., Bragagni, A., Nagel, T., Schreiber, A., Dittrich, S., Thome, V., Hezel, D.C., Below, R., Cieszynski, H. (2017) Ultra-high pressure and ultra-reduced minerals in ophiolites may form by lightning strikes. Geochemical Perspectives Letters 5, 42-46.
.(1) Not all of the samples of podiform chromitite and peridotite hosting UHP and SuR minerals were collected from surface outcrops exposed to lightning; many come from active mines 30-50 m below the surface, from the interiors of large blocks of ore, and/or from deep drill cores (Zhang et al., 2016
Zhang, R.Y., Yang, J.S., Ernst, W.G., Jahn, B.M., Iizuka, Y., Guo, G.L. (2016) Discovery of in situ super-reducing, ultrahigh-pressure phases in the Luobusa ophiolitic chromitites, Tibet: New insights into the deep upper mantle and mantle transition zone. American Mineralogist 101, 1245-1251.
, 2017Zhang, R.Y., Shau, Y.H., Yang, J.S., Liou, J.G. (2017) Discovery of clinoenstatite in the Luobusa ophiolitic mantle peridotite recovered from a drill hole, Tibet. Journal of Asian Earth Sciences 145, 605-612.
). Fulgurites are near-surface features, typically consisting of highly shattered and brecciated rock, which rarely extend more than a few meters below the surface. Furthermore, many of the same UHP and SuR minerals are routinely found in kimberlites sampled by deep mining operations (Shiryaev et al. 2011Shiryaev, A.A., Griffin, W.L., Stoyanov, E. (2011) Moissanite (SiC) from kimberlites: Polytypes, trace elements, inclusions and speculations on origin. Lithos 122, 152-164.
) leaving no question of their presence in the deeper mantle.(2) Although lightning strikes can produce SuR minerals such as silicon carbide (moissanite), native metals and metal silicides (e.g., Essene and Fisher, 1986
Essene, E.J., Fisher, D.C. (1986) Lightning strike fusion: extreme reduction and metal-silicate liquid immiscibility. Science 234, 189-193.
; Rodgers et al., 1989Rodgers, K.A., Courtney, S.R, Seelye, R., Mcculloch, B.A., Mulholland, I. (1989) An occurrence of "moissanite" (SiC) from Seddonville, West Coast, New Zealand. New Zealand Natural Sciences 16: 105-108.
; Sheffer et al., 2003Sheffer A.A., Melosh, H.J., Jarnot, B.M., Lauretta, D.S. (2003) Reduction of silicates at high temperature: fulgurites and thermodynamic modeling. 34th Annual Lunar and Planetary Science Conference, March 17-21, 2003, League City, Texas. Abstract no. 1467.
), no UHP minerals have been reported from fulgurites; yet both moissanite and diamond grains occur together in ophiolite samples (Yang et al., 2014Yang, J.S., Robinson, P.T., Dilek, Y. (2014) Diamonds in ophiolites. Elements 10, 127-130.
, 2015aYang, J.S., Meng, F., Xu, X., Robinson, P.T., Dilek, Y., Makeyev, A. B., Wirth, R., Wiedenbeck, M., Cliff, J. (2015a) Diamonds, native elements and metal alloys from chromitites of the Ray-Iz ophiolite of the Polar Urals. Gondwana Research 27, 459-485.
; Zhang et al., 2016Zhang, R.Y., Yang, J.S., Ernst, W.G., Jahn, B.M., Iizuka, Y., Guo, G.L. (2016) Discovery of in situ super-reducing, ultrahigh-pressure phases in the Luobusa ophiolitic chromitites, Tibet: New insights into the deep upper mantle and mantle transition zone. American Mineralogist 101, 1245-1251.
). These grains are mostly 200-300 μm in size and typically have euhedral to subhedral morphologies, whereas the experiments by Ballhaus et al. (2017)Ballhaus, C., Wirth, R., Fonseca, R.O.C., Blanchard, H., Pröll, W., Bragagni, A., Nagel, T., Schreiber, A., Dittrich, S., Thome, V., Hezel, D.C., Below, R., Cieszynski, H. (2017) Ultra-high pressure and ultra-reduced minerals in ophiolites may form by lightning strikes. Geochemical Perspectives Letters 5, 42-46.
produced SiC crystals 100 times smaller, all of which are anhedral. In situ diamonds in ophiolites are typically well-formed crystals enclosed in small (1 mm) spheres of amorphous carbon.(3) No solid inclusions were reported from the minerals produced in Ballhaus
Ballhaus, C., Wirth, R., Fonseca, R.O.C., Blanchard, H., Pröll, W., Bragagni, A., Nagel, T., Schreiber, A., Dittrich, S., Thome, V., Hezel, D.C., Below, R., Cieszynski, H. (2017) Ultra-high pressure and ultra-reduced minerals in ophiolites may form by lightning strikes. Geochemical Perspectives Letters 5, 42-46.
' experiments, nor have mineral inclusions been reported in any known fulgurite phases. In contrast, diamonds in ophiolites contain a wide range of UHP and SuR mineral inclusions, including SiC, NiMnCo and other alloys, Mn-silicates (olivine, garnet), Mn-oxides, chromite and coesite; some even have fluid inclusions (Yang et al., 2015aYang, J.S., Meng, F., Xu, X., Robinson, P.T., Dilek, Y., Makeyev, A. B., Wirth, R., Wiedenbeck, M., Cliff, J. (2015a) Diamonds, native elements and metal alloys from chromitites of the Ray-Iz ophiolite of the Polar Urals. Gondwana Research 27, 459-485.
; Moe et al., 2018Moe, K.S., Yang, J.S., Johnson, P., Xu, X., Wang, W. (2018) Spectroscopic analysis of microdiamonds in ophiolitic chromitite and peridotite. Lithosphere 10, 133-141.
; Wu et al., 2017Wu, W.W., Yang, J.S., Ma, C.Q., Milushi, I., Lian, D.Y., Tian, Y.Z. (2017) Discovery and Significance of Diamonds and Moissanites in Chromitite within the Skenderbeu Massif of the Mirdita Zone Ophiolite, West Albania. Acta Geologica Sinica (English Edition) 91, 882-897.
). These features are inconsistent with instantaneous shock metamorphism. Besides, there are well-documented exsolution lamellae of coesite and clinopyroxene in some chromite grains that require a high-pressure residence of SiO2 in the grains (Yamamoto et al., 2009Yamamoto, S., Komiya, T., Hirose, K., Maruyama, S. (2009) Coesite and clinopyroxene exsolution lamellae in chromites: In-situ ultrahigh-pressure evidence from podiform chromitites in the Luobusa ophiolite, southern Tibet. Lithos 109, 314-322.
), and this phenomenon should not be observed in fulgurite either.(4) Barren, high-elevation terranes such as those in Tibet might be ideal locations for abundant lightning strikes, as suggested by Ballhaus et al. (2017)
Ballhaus, C., Wirth, R., Fonseca, R.O.C., Blanchard, H., Pröll, W., Bragagni, A., Nagel, T., Schreiber, A., Dittrich, S., Thome, V., Hezel, D.C., Below, R., Cieszynski, H. (2017) Ultra-high pressure and ultra-reduced minerals in ophiolites may form by lightning strikes. Geochemical Perspectives Letters 5, 42-46.
, but there is nothing unique about the UHP and SuR occurrences in Tibet. These minerals have been confirmed in more than 10 different ophiolites in China, India, Russia, Myanmar, Albania, and Turkey, areas with different elevations and different climates (Yang et al., 2015bYang, J.S., Robinson, P.T., Dilek, Y. (2015b) Diamond-bearing ophiolites and their geological occurrence. Episodes 38, 344-364.
；Das et al., 2017Das, S., Basu, A.R., Mukherjee, B.K. (2017) In situ peridotitic diamond in Indus ophiolite sourced from hydrocarbon fluids in the mantle transition zone. Geology 45, 755-758.
; Lian et al., 2017Lian, D., Yang, J., Dilek, Y., Wu, W., Zhang, Z., Xiong, F., Liu, F., Zhou, W. (2017) Deep mantle origin and ultra-reducing conditions in podiform chromitite: Diamond, moissanite, and other unusual minerals in podiform chromitites from the Pozanti-Karsanti ophiolite, southern Turkey. American Mineralogist 102, 1101-1113.
; Wu et al., 2017Wu, W.W., Yang, J.S., Ma, C.Q., Milushi, I., Lian, D.Y., Tian, Y.Z. (2017) Discovery and Significance of Diamonds and Moissanites in Chromitite within the Skenderbeu Massif of the Mirdita Zone Ophiolite, West Albania. Acta Geologica Sinica (English Edition) 91, 882-897.
).The discovery of UHP and SuR minerals in rocks from the oceanic mantle has led to a variety of models for their formation (Arai et al., 2013
Arai, S. (2013) Conversion of low-pressure chromitites to ultrahigh-pressure chromitites by deep recycling: a good inference. Earth and Planetary Science Letters 379, 81-87.
; Zhou et al., 2014Zhou, M.F., Robinson, P.T., Su, B.X., Gao, J.F., Li, J.W., Yang, J.S., Malpas, J. (2014) Compositions of chromite, associated minerals, and parental magmas of podiform chromite deposits: The role of slab contamination of asthenospheric melts in suprasubduction zone environments. Gondwana Research 26, 262-283.
; Robinson et al., 2015Robinson, P.T., Trumbull, R.B., Schmitt, A., Yang, J.S., Li, J.W., Zhou, M.F., Erzinger, J., Dare, S., Xiong, F. (2015) The origin and significance of crustal minerals in ophiolitic chromitites and peridotites. Gondwana Research 27, 486-506.
; Griffin et al., 2016Griffin, W.L., Afonso, J.C., Belousova, E.A., Gain, S.E., Gong, X.H., Gonzalez-Jimenez, J.M., Howell, D., Huang, J.X., Mcgowan, N., Pearson, N.J., Satsukawa, T., Shi, R., Williams, P., Xiong, Q., Yang, J.S., Zhang, M., O’Reilly, S.Y. (2016) Mantle recycling: transition zone metamorphism of Tibetan ophiolitic peridotites and its tectonic implications. Journal of Petrology 57, 655-684.
; Rollinson, 2016Rollinson, H., (2016) Surprises from the top of the mantle transition zone. Geology Today 32, 58-64.
; Ballhaus et al., 2017Ballhaus, C., Wirth, R., Fonseca, R.O.C., Blanchard, H., Pröll, W., Bragagni, A., Nagel, T., Schreiber, A., Dittrich, S., Thome, V., Hezel, D.C., Below, R., Cieszynski, H. (2017) Ultra-high pressure and ultra-reduced minerals in ophiolites may form by lightning strikes. Geochemical Perspectives Letters 5, 42-46.
; Butler and Beaumont, 2017Butler, J.P., Beaumont, C. (2017) Subduction zone decoupling/retreat modeling explains south Tibet (Xigaze) and other supra-subduction zone ophiolites and their UHP mineral phases. Earth and Planetary Science Letters 463, 101–117.
), none of which fully explain these occurrences. We emphasise that the presence of UHP and SuR phases in ophiolites is difficult to reconcile with the overwhelming geologic evidence that the host bodies form in the upper mantle. What now seems clear to us is that many ophiolites are composite bodies, which had a complex history involving subduction of crustal material at least to the transition zone, mixing of such material with mantle peridotites, partial melting and recrystallisation followed by upward migration to shallow levels where mantle slabs were trapped in suprasubduction zone wedges and modified by reaction with fluids and melts. The result is a mixture of crustal and mantle material which appears to exist metastably in ophiolitic chromitites and peridotites. Therefore, we do not consider lightning strikes to be an important source of UHP and SuR minerals in ophiolites, but the geologic processes leading to their formation are still poorly understood.top
Acknowledgements
This study was supported by the NSFC (No. 41720104009) and the CGS (No. DD20160023-01) and MLR (201511022).
Editor: Graham Pearson
top
References
Arai, S. (2013) Conversion of low-pressure chromitites to ultrahigh-pressure chromitites by deep recycling: a good inference. Earth and Planetary Science Letters 379, 81-87.
Show in context The discovery of UHP and SuR minerals in rocks from the oceanic mantle has led to a variety of models for their formation (Arai et al., 2013; Zhou et al., 2014; Robinson et al., 2015; Griffin et al., 2016; Rollinson, 2016; Ballhaus et al., 2017; Butler and Beaumont, 2017), none of which fully explain these occurrences.
View in article
Ballhaus, C., Wirth, R., Fonseca, R.O.C., Blanchard, H., Pröll, W., Bragagni, A., Nagel, T., Schreiber, A., Dittrich, S., Thome, V., Hezel, D.C., Below, R., Cieszynski, H. (2017) Ultra-high pressure and ultra-reduced minerals in ophiolites may form by lightning strikes. Geochemical Perspectives Letters 5, 42-46.
Show in context We read with great interest the paper by C. Ballhaus and coauthors (2017) reporting on electrical discharge experiments that showed how SiC and other phases found in mantle-derived rocks can potentially form by lightning strikes (Ballhaus et al., 2017).
View in article
Here, we add additional comments relating to the geological and mineralogical data from ophiolites that are not compatible with the model of Ballhaus et al. (2017).
View in article
These grains are mostly 200-300 μm in size and typically have euhedral to subhedral morphologies, whereas the experiments by Ballhaus et al. (2017) produced SiC crystals 100 times smaller, all of which are anhedral.
View in article
No solid inclusions were reported from the minerals produced in Ballhaus' experiments, nor have mineral inclusions been reported in any known fulgurite phases.
View in article
Barren, high-elevation terranes such as those in Tibet might be ideal locations for abundant lightning strikes, as suggested by Ballhaus et al. (2017), but there is nothing unique about the UHP and SuR occurrences in Tibet.
View in article
The discovery of UHP and SuR minerals in rocks from the oceanic mantle has led to a variety of models for their formation (Arai et al., 2013; Zhou et al., 2014; Robinson et al., 2015; Griffin et al., 2016; Rollinson, 2016; Ballhaus et al., 2017; Butler and Beaumont, 2017), none of which fully explain these occurrences.
View in article
Butler, J.P., Beaumont, C. (2017) Subduction zone decoupling/retreat modeling explains south Tibet (Xigaze) and other supra-subduction zone ophiolites and their UHP mineral phases. Earth and Planetary Science Letters 463, 101–117.
Show in context The discovery of UHP and SuR minerals in rocks from the oceanic mantle has led to a variety of models for their formation (Arai et al., 2013; Zhou et al., 2014; Robinson et al., 2015; Griffin et al., 2016; Rollinson, 2016; Ballhaus et al., 2017; Butler and Beaumont, 2017), none of which fully explain these occurrences.
View in article
Das, S., Basu, A.R., Mukherjee, B.K. (2017) In situ peridotitic diamond in Indus ophiolite sourced from hydrocarbon fluids in the mantle transition zone. Geology 45, 755-758.
Show in context These minerals have been confirmed in more than 10 different ophiolites in China, India, Russia, Myanmar, Albania, and Turkey, areas with different elevations and different climates (Yang et al., 2015b；Das et al., 2017; Lian et al., 2017; Wu et al., 2017).
View in article
Essene, E.J., Fisher, D.C. (1986) Lightning strike fusion: extreme reduction and metal-silicate liquid immiscibility. Science 234, 189-193.
Show in contextAlthough lightning strikes can produce SuR minerals such as silicon carbide (moissanite), native metals and metal silicides (e.g., Essene and Fisher, 1986; Rodger et al., 1989; Sheffer et al., 2003), no UHP minerals have been reported from fulgurites; yet both moissanite and diamond grains occur together in ophiolite samples (Yang et al., 2014, 2015a; Zhang et al., 2016).
View in article
Griffin, W.L., Afonso, J.C., Belousova, E.A., Gain, S.E., Gong, X.H., Gonzalez-Jimenez, J.M., Howell, D., Huang, J.X., Mcgowan, N., Pearson, N.J., Satsukawa, T., Shi, R., Williams, P., Xiong, Q., Yang, J.S., Zhang, M., O’Reilly, S.Y. (2016) Mantle recycling: transition zone metamorphism of Tibetan ophiolitic peridotites and its tectonic implications. Journal of Petrology 57, 655-684.
Show in contextThe discovery of UHP and SuR minerals in rocks from the oceanic mantle has led to a variety of models for their formation (Arai et al., 2013; Zhou et al., 2014; Robinson et al., 2015; Griffin et al., 2016; Rollinson, 2016; Ballhaus et al., 2017; Butler and Beaumont, 2017), none of which fully explain these occurrences.
View in article
Griffin, W.L., Howell, D., Gonzalez-Jimenez, J.M., Xiong, Q., O’Reilly, S.Y. (2018) Comment on “Ultra-high pressure and ultra-reduced minerals in ophiolites may form by lightning strikes”. Geochemical Perspectives Letters 7, 1-2.
Show in context In a comment paper, Griffin et al. (2018) noted several lines of evidence that ultra-high pressure (UHP) and super reduced (SuR) minerals in ophiolites do not form by lightning strikes.
View in article
Lian, D., Yang, J., Dilek, Y., Wu, W., Zhang, Z., Xiong, F., Liu, F., Zhou, W. (2017) Deep mantle origin and ultra-reducing conditions in podiform chromitite: Diamond, moissanite, and other unusual minerals in podiform chromitites from the Pozanti-Karsanti ophiolite, southern Turkey. American Mineralogist 102, 1101-1113.
Show in contextThese minerals have been confirmed in more than 10 different ophiolites in China, India, Russia, Myanmar, Albania, and Turkey, areas with different elevations and different climates (Yang et al., 2015b；Das et al., 2017; Lian et al., 2017; Wu et al., 2017).
View in article
Moe, K.S., Yang, J.S., Johnson, P., Xu, X., Wang, W. (2018) Spectroscopic analysis of microdiamonds in ophiolitic chromitite and peridotite. Lithosphere 10, 133-141.
Show in contextIn contrast, diamonds in ophiolites contain a wide range of UHP and SuR mineral inclusions, including SiC, NiMnCo and other alloys, Mn-silicates (olivine, garnet), Mn-oxides, chromite and coesite; some even have fluid inclusions (Yang et al., 2015a; Moe et al., 2018; Wu et al., 2017).
View in article
Robinson, P.T., Trumbull, R.B., Schmitt, A., Yang, J.S., Li, J.W., Zhou, M.F., Erzinger, J., Dare, S., Xiong, F. (2015) The origin and significance of crustal minerals in ophiolitic chromitites and peridotites. Gondwana Research 27, 486-506.
Show in context The discovery of UHP and SuR minerals in rocks from the oceanic mantle has led to a variety of models for their formation (Arai et al., 2013; Zhou et al., 2014; Robinson et al., 2015; Griffin et al., 2016; Rollinson, 2016; Ballhaus et al., 2017; Butler and Beaumont, 2017), none of which fully explain these occurrences.
View in article
Rodgers, K.A., Courtney, S.R, Seelye, R., Mcculloch, B.A., Mulholland, I. (1989) An occurrence of "moissanite" (SiC) from Seddonville, West Coast, New Zealand. New Zealand Natural Sciences 16: 105-108.
Show in context Although lightning strikes can produce SuR minerals such as silicon carbide (moissanite), native metals and metal silicides (e.g., Essene and Fisher, 1986; Rodgers et al., 1989; Sheffer et al., 2003), no UHP minerals have been reported from fulgurites; yet both moissanite and diamond grains occur together in ophiolite samples (Yang et al., 2014, 2015a; Zhang et al., 2016).
View in article
Rollinson, H., (2016) Surprises from the top of the mantle transition zone. Geology Today 32, 58-64.
Show in context The discovery of UHP and SuR minerals in rocks from the oceanic mantle has led to a variety of models for their formation (Arai et al., 2013; Zhou et al., 2014; Robinson et al., 2015; Griffin et al., 2016; Rollinson, 2016; Ballhaus et al., 2017; Butler and Beaumont, 2017), none of which fully explain these occurrences.
View in article
Sheffer A.A., Melosh, H.J., Jarnot, B.M., Lauretta, D.S. (2003) Reduction of silicates at high temperature: fulgurites and thermodynamic modeling. 34th Annual Lunar and Planetary Science Conference, March 17-21, 2003, League City, Texas. Abstract no. 1467.
Show in contextAlthough lightning strikes can produce SuR minerals such as silicon carbide (moissanite), native metals and metal silicides (e.g., Essene and Fisher, 1986; Rodger et al., 1989; Sheffer et al., 2003), no UHP minerals have been reported from fulgurites; yet both moissanite and diamond grains occur together in ophiolite samples (Yang et al., 2014, 2015a; Zhang et al., 2016).
View in article
Shiryaev, A.A., Griffin, W.L., Stoyanov, E. (2011) Moissanite (SiC) from kimberlites: Polytypes, trace elements, inclusions and speculations on origin. Lithos 122, 152-164.
Show in contextFurthermore, many of the same UHP and SuR minerals are routinely found in kimberlites sampled by deep mining operations (Shiryaev et al. 2011) leaving no question of their presence in the deeper mantle.
View in article
Wu, W.W., Yang, J.S., Ma, C.Q., Milushi, I., Lian, D.Y., Tian, Y.Z. (2017) Discovery and Significance of Diamonds and Moissanites in Chromitite within the Skenderbeu Massif of the Mirdita Zone Ophiolite, West Albania. Acta Geologica Sinica (English Edition) 91, 882-897.
Show in context In contrast, diamonds in ophiolites contain a wide range of UHP and SuR mineral inclusions, including SiC, NiMnCo and other alloys, Mn-silicates (olivine, garnet), Mn-oxides, chromite and coesite; some even have fluid inclusions (Yang et al., 2015a; Moe et al., 2018; Wu et al., 2017).
View in article
These minerals have been confirmed in more than 10 different ophiolites in China, India, Russia, Myanmar, Albania, and Turkey, areas with different elevations and different climates (Yang et al., 2015b；Das et al., 2017; Lian et al., 2017; Wu et al., 2017).
View in article
Yamamoto, S., Komiya, T., Hirose, K., Maruyama, S. (2009) Coesite and clinopyroxene exsolution lamellae in chromites: In-situ ultrahigh-pressure evidence from podiform chromitites in the Luobusa ophiolite, southern Tibet. Lithos 109, 314-322.
Show in context Besides, there are well-documented exsolution lamellae of coesite and clinopyroxene in some chromite grains that require a high-pressure residence of SiO2 in the grains (Yamamoto et al., 2009), and this phenomenon should not be observed in fulgurite either.
View in article
Yang, J.S., Robinson, P.T., Dilek, Y. (2014) Diamonds in ophiolites. Elements 10, 127-130.
Show in context Although lightning strikes can produce SuR minerals such as silicon carbide (moissanite), native metals and metal silicides (e.g., Essene and Fisher, 1986; Rodger et al., 1989; Sheffer et al., 2003), no UHP minerals have been reported from fulgurites; yet both moissanite and diamond grains occur together in ophiolite samples (Yang et al., 2014, 2015a; Zhang et al., 2016).
View in article
Yang, J.S., Meng, F., Xu, X., Robinson, P.T., Dilek, Y., Makeyev, A. B., Wirth, R., Wiedenbeck, M., Cliff, J. (2015a) Diamonds, native elements and metal alloys from chromitites of the Ray-Iz ophiolite of the Polar Urals. Gondwana Research 27, 459-485.
Show in context Although lightning strikes can produce SuR minerals such as silicon carbide (moissanite), native metals and metal silicides (e.g., Essene and Fisher, 1986; Rodger et al., 1989; Sheffer et al., 2003), no UHP minerals have been reported from fulgurites; yet both moissanite and diamond grains occur together in ophiolite samples (Yang et al., 2014, 2015a; Zhang et al., 2016).
View in article
In contrast, diamonds in ophiolites contain a wide range of UHP and SuR mineral inclusions, including SiC, NiMnCo and other alloys, Mn-silicates (olivine, garnet), Mn-oxides, chromite and coesite; some even have fluid inclusions (Yang et al., 2015a; Moe et al., 2018; Wu et al., 2017).
View in article
Yang, J.S., Robinson, P.T., Dilek, Y. (2015b) Diamond-bearing ophiolites and their geological occurrence. Episodes 38, 344-364.
Show in context These minerals have been confirmed in more than 10 different ophiolites in China, India, Russia, Myanmar, Albania, and Turkey, areas with different elevations and different climates (Yang et al., 2015b；Das et al., 2017; Lian et al., 2017; Wu et al., 2017).
View in article
Zhang, R.Y., Yang, J.S., Ernst, W.G., Jahn, B.M., Iizuka, Y., Guo, G.L. (2016) Discovery of in situ super-reducing, ultrahigh-pressure phases in the Luobusa ophiolitic chromitites, Tibet: New insights into the deep upper mantle and mantle transition zone. American Mineralogist 101, 1245-1251.
Show in context Not all of the samples of podiform chromitite and peridotite hosting UHP and SuR minerals were collected from surface outcrops exposed to lightning; many come from active mines 30-50 m below the surface, from the interiors of large blocks of ore, and/or from deep drill cores (Zhang et al., 2016, 2017).
View in article
Although lightning strikes can produce SuR minerals such as silicon carbide (moissanite), native metals and metal silicides (e.g., Essene and Fisher, 1986; Rodger et al., 1989; Sheffer et al., 2003), no UHP minerals have been reported from fulgurites; yet both moissanite and diamond grains occur together in ophiolite samples (Yang et al., 2014, 2015a; Zhang et al., 2016).
View in article
Zhang, R.Y., Shau, Y.H., Yang, J.S., Liou, J.G. (2017) Discovery of clinoenstatite in the Luobusa ophiolitic mantle peridotite recovered from a drill hole, Tibet. Journal of Asian Earth Sciences 145, 605-612.
Show in contextNot all of the samples of podiform chromitite and peridotite hosting UHP and SuR minerals were collected from surface outcrops exposed to lightning; many come from active mines 30-50 m below the surface, from the interiors of large blocks of ore, and/or from deep drill cores (Zhang et al., 2016, 2017).
View in article
Zhou, M.F., Robinson, P.T., Su, B.X., Gao, J.F., Li, J.W., Yang, J.S., Malpas, J. (2014) Compositions of chromite, associated minerals, and parental magmas of podiform chromite deposits: The role of slab contamination of asthenospheric melts in suprasubduction zone environments. Gondwana Research 26, 262-283.
Show in context The discovery of UHP and SuR minerals in rocks from the oceanic mantle has led to a variety of models for their formation (Arai et al., 2013; Zhou et al., 2014; Robinson et al., 2015; Griffin et al., 2016; Rollinson, 2016; Ballhaus et al., 2017; Butler and Beaumont, 2017), none of which fully explain these occurrences.
View in article