Clinopyroxene megacrysts from Marion Island, Antarctic Ocean: evidence for a late stage shallow origin
R. James Roberts, Keabetswe D. Lehong, Andries E.J. Botha, Gelu Costin, Frikkie C. De Beer, Willem J. Hoffman, Callum J. Hetherington
Clinopyroxene megacrysts (up to 5 cm) from a scoria cone on Marion Island, Antarctic Ocean are zoned, with compositionally distinct low (Al + Ti) and high (Al + Ti) patches arranged haphazardly throughout crystals. Inclusions of olivine, pyrrhotite, oxides, sulphides, and rounded inclusions with euhedral micro-crystals interpreted as former melt inclusions are observed. Olivine inclusions have variable compositions, ranging from primary Ti-poor crystals to Ti-rich crystals hosting secondary haematite crystals formed by hydrogenation. The crystals contain voids that are concentrated in the middle of each crystal indicating that the initial crystal growth was skeletal. Subsequent crystallisation filled in the skeletal framework creating the patchy zoning in the crystals. The Marion Island megacrysts are not homogenous, but the combination of crustal clinopyroxene compositions, primary and hydrogenated olivine, and the mode of eruption in scoria eruptions indicates that these crystals most likely formed in a shallow magma chamber. Primary olivines crystallised from a mafic magma and secondary altered olivines were incorporated into a rapidly growing megacryst in a super-saturated, fluid-rich environment, prior to being ejected onto surface in a scoria eruption.
Mineralogy and Petrology
https://doi.org/10.1007/s00710-018-00651-x
Ankaramites
Clinopyroxene megacrysts
Late stage eruption
Marion Island
Dive into the research topics of 'Clinopyroxene megacrysts from Marion Island, Antarctic Ocean: evidence for a late stage shallow origin'. Together they form a unique fingerprint.
Antarctic Ocean Physics & Astronomy 100%
megacryst Earth & Environmental Sciences 58%
clinopyroxene Earth & Environmental Sciences 44%
olivine Physics & Astronomy 31%
crystal Earth & Environmental Sciences 30%
crystals Physics & Astronomy 21%
volcanic eruptions Physics & Astronomy 17%
inclusions Physics & Astronomy 15%
Roberts, R. J., Lehong, K. D., Botha, A. E. J., Costin, G., De Beer, F. C., Hoffman, W. J., & Hetherington, C. J. (2019). Clinopyroxene megacrysts from Marion Island, Antarctic Ocean: evidence for a late stage shallow origin. Mineralogy and Petrology, 113(2), 155-167. https://doi.org/10.1007/s00710-018-00651-x
Roberts, R. James ; Lehong, Keabetswe D. ; Botha, Andries E.J. et al. / Clinopyroxene megacrysts from Marion Island, Antarctic Ocean : evidence for a late stage shallow origin. In: Mineralogy and Petrology. 2019 ; Vol. 113, No. 2. pp. 155-167.
@article{dafae4b63e4848668f3daa2e1e7402f7,
title = "Clinopyroxene megacrysts from Marion Island, Antarctic Ocean: evidence for a late stage shallow origin",
abstract = "Clinopyroxene megacrysts (up to 5 cm) from a scoria cone on Marion Island, Antarctic Ocean are zoned, with compositionally distinct low (Al + Ti) and high (Al + Ti) patches arranged haphazardly throughout crystals. Inclusions of olivine, pyrrhotite, oxides, sulphides, and rounded inclusions with euhedral micro-crystals interpreted as former melt inclusions are observed. Olivine inclusions have variable compositions, ranging from primary Ti-poor crystals to Ti-rich crystals hosting secondary haematite crystals formed by hydrogenation. The crystals contain voids that are concentrated in the middle of each crystal indicating that the initial crystal growth was skeletal. Subsequent crystallisation filled in the skeletal framework creating the patchy zoning in the crystals. The Marion Island megacrysts are not homogenous, but the combination of crustal clinopyroxene compositions, primary and hydrogenated olivine, and the mode of eruption in scoria eruptions indicates that these crystals most likely formed in a shallow magma chamber. Primary olivines crystallised from a mafic magma and secondary altered olivines were incorporated into a rapidly growing megacryst in a super-saturated, fluid-rich environment, prior to being ejected onto surface in a scoria eruption.",
keywords = "Ankaramites, Clinopyroxene megacrysts, Late stage eruption, Marion Island",
author = "Roberts, {R. James} and Lehong, {Keabetswe D.} and Botha, {Andries E.J.} and Gelu Costin and {De Beer}, {Frikkie C.} and Hoffman, {Willem J.} and Hetherington, {Callum J.}",
note = "Publisher Copyright: {\textcopyright} 2019, Springer-Verlag GmbH Austria, part of Springer Nature.",
doi = "10.1007/s00710-018-00651-x",
journal = "Mineralogy and Petrology",
Roberts, RJ, Lehong, KD, Botha, AEJ, Costin, G, De Beer, FC, Hoffman, WJ & Hetherington, CJ 2019, 'Clinopyroxene megacrysts from Marion Island, Antarctic Ocean: evidence for a late stage shallow origin', Mineralogy and Petrology, vol. 113, no. 2, pp. 155-167. https://doi.org/10.1007/s00710-018-00651-x
Clinopyroxene megacrysts from Marion Island, Antarctic Ocean : evidence for a late stage shallow origin. / Roberts, R. James; Lehong, Keabetswe D.; Botha, Andries E.J. et al.
In: Mineralogy and Petrology, Vol. 113, No. 2, 04.04.2019, p. 155-167.
T1 - Clinopyroxene megacrysts from Marion Island, Antarctic Ocean
T2 - evidence for a late stage shallow origin
AU - Roberts, R. James
AU - Lehong, Keabetswe D.
AU - Botha, Andries E.J.
AU - Costin, Gelu
AU - De Beer, Frikkie C.
AU - Hoffman, Willem J.
AU - Hetherington, Callum J.
N1 - Publisher Copyright: © 2019, Springer-Verlag GmbH Austria, part of Springer Nature.
N2 - Clinopyroxene megacrysts (up to 5 cm) from a scoria cone on Marion Island, Antarctic Ocean are zoned, with compositionally distinct low (Al + Ti) and high (Al + Ti) patches arranged haphazardly throughout crystals. Inclusions of olivine, pyrrhotite, oxides, sulphides, and rounded inclusions with euhedral micro-crystals interpreted as former melt inclusions are observed. Olivine inclusions have variable compositions, ranging from primary Ti-poor crystals to Ti-rich crystals hosting secondary haematite crystals formed by hydrogenation. The crystals contain voids that are concentrated in the middle of each crystal indicating that the initial crystal growth was skeletal. Subsequent crystallisation filled in the skeletal framework creating the patchy zoning in the crystals. The Marion Island megacrysts are not homogenous, but the combination of crustal clinopyroxene compositions, primary and hydrogenated olivine, and the mode of eruption in scoria eruptions indicates that these crystals most likely formed in a shallow magma chamber. Primary olivines crystallised from a mafic magma and secondary altered olivines were incorporated into a rapidly growing megacryst in a super-saturated, fluid-rich environment, prior to being ejected onto surface in a scoria eruption.
AB - Clinopyroxene megacrysts (up to 5 cm) from a scoria cone on Marion Island, Antarctic Ocean are zoned, with compositionally distinct low (Al + Ti) and high (Al + Ti) patches arranged haphazardly throughout crystals. Inclusions of olivine, pyrrhotite, oxides, sulphides, and rounded inclusions with euhedral micro-crystals interpreted as former melt inclusions are observed. Olivine inclusions have variable compositions, ranging from primary Ti-poor crystals to Ti-rich crystals hosting secondary haematite crystals formed by hydrogenation. The crystals contain voids that are concentrated in the middle of each crystal indicating that the initial crystal growth was skeletal. Subsequent crystallisation filled in the skeletal framework creating the patchy zoning in the crystals. The Marion Island megacrysts are not homogenous, but the combination of crustal clinopyroxene compositions, primary and hydrogenated olivine, and the mode of eruption in scoria eruptions indicates that these crystals most likely formed in a shallow magma chamber. Primary olivines crystallised from a mafic magma and secondary altered olivines were incorporated into a rapidly growing megacryst in a super-saturated, fluid-rich environment, prior to being ejected onto surface in a scoria eruption.
KW - Ankaramites
KW - Clinopyroxene megacrysts
KW - Late stage eruption
KW - Marion Island
U2 - 10.1007/s00710-018-00651-x
DO - 10.1007/s00710-018-00651-x
JO - Mineralogy and Petrology
JF - Mineralogy and Petrology
Roberts RJ, Lehong KD, Botha AEJ, Costin G, De Beer FC, Hoffman WJ et al. Clinopyroxene megacrysts from Marion Island, Antarctic Ocean: evidence for a late stage shallow origin. Mineralogy and Petrology. 2019 Apr 4;113(2):155-167. doi: 10.1007/s00710-018-00651-x