Geothermobarometry in Four-phase Lherzolites II. New Thermobarometers, and Practical Assessment of Existing Thermobarometers

Brey, Gerhard P.; Köhler, Thorsten

doi:10.1093/petrology/31.6.1353

Cited by 2,034 publications

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“…Given that the depth to the Moho in this area is about 37 km, the peridotite xenoliths are likely to have originated in the uppermost 20 km of the mantle beneath Avacha volcano. The xenoliths record temperatures of 800 -1050°C, as indicated by Ca contents in orthopyroxene [Brey and Köhler, 1990]. These temperatures could reflect the temperature gradient of the uppermost mantle beneath the volcanic front [Ishimaru et al, 2007]; consequently, we infer that the peridotite xenoliths were derived from the uppermost part of the low-velocity zone in the mantle.…”

Section: Samples and Methodsmentioning

confidence: 83%

Rock seismic anisotropy of the low‐velocity zone beneath the volcanic front in the mantle wedge

Michibayashi¹,

Oohara²,

Satsukawa³

et al. 2009

Geophysical Research Letters

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Peridotite xenoliths derived from the low velocity zone beneath the Avacha frontal volcano, Kamchatka, preserve a‐axis slip fabrics, comparable with those in xenoliths from the back‐arc region of the NE Japan. Although low‐velocity zones are commonly attributed to zones of partially melted mantle, migration of the melt does not erase the existing olivine fabrics and related seismic anisotropies. These anisotropies may counteract the anisotropies associated with c‐axis slip fabrics, if they exist, along the slab or in the high‐pressure zone.

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Section: Samples and Methodsmentioning

confidence: 83%

Rock seismic anisotropy of the low‐velocity zone beneath the volcanic front in the mantle wedge

Michibayashi¹,

Oohara²,

Satsukawa³

et al. 2009

Geophysical Research Letters

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“…(1) 양휘석 지온계 (Wells, 1977;Bertrand and Mercier, 1985;Brey and Köhler, 1990 (Sun and McDonough, 1989), for clinopyroxenes separated from peridotite xenoliths. Data sources: Arai et al, 2001;Choi et al, 2002Kil, 2006Kil, , 2007Shin et al, 2006.…”

Section: 첨정석 페리도타이트의 광물조합에 적용할 수 있는 지온계는 매우 다양하다 보편적으로 이용되는 것에는mentioning

confidence: 99%

“…첨성석의 Cr#가 높아질수 록 보다 깊은 곳에서 안정할 수 있다 (Robinson and Wood, 1998). Brey and Köhler (1990) for peridotite xenoliths from South Korea. 15 kbar has been used as an input pressure for the temperature estimation.…”

Section: 첨정석 페리도타이트의 광물조합에 적용할 수 있는 지온계는 매우 다양하다 보편적으로 이용되는 것에는mentioning

confidence: 99%

Lithospheric Mantle beneath the Korean Peninsula: Implications from Peridotite Xenoliths in Alkali Basalts

Choi¹

2012

The Journal of the Petrological Society of Korea

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Peridotite xenoliths hosted by alkali basalts from South Korea occur in Baengnyeong Island, Jeju Island, Boeun, Asan, Pyeongtaek and Ganseong areas. K-Ar whole-rock ages of the basaltic rocks range from 0.1 to 18.9 Ma. The peridotites are dominantly lherzolites and magnesian harzburgites, and the constituent minerals are Fo-rich olivine (Fo 88.4-92.0 ), En-rich orthopyroxene, Di-rich clinopyroxene, and Crrich spinel (Cr# = 7.8-53.6). Hydrous minerals, such as pargasite and phlogopite, or garnet have not been reported yet. The Korean peridotites are residues after variable degree of partial melting (up to 26%) and melt extraction from fertile MORB mantle. However, some samples (usually refractory harzburgites) exhibit metasomatic enrichment of the highly incompatible elements, such as LREE. Equilibration temperatures estimated using two-pyroxene geothermometry range from ca. 850 to 1050 o C. Sr and Nd isotopic compositions in clinopyroxene separates from the Korean peridotites show trends between depleted MORB-like mantle (DMM) and bulk silicate earth (BSE), which can be explained by secondary metasomatic overprinting of a precursor time-integrated depleted mantle. The Korean peridotite clinopyroxenes define mixing trends between DMM and EM2 end members on Sr-Pb and Nd-Pb isotopic correlation diagrams, without any corresponding changes in the basement. This is contrary to what we

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“…This reaction took place at similar pressure as formation of mantles of xenocrysts and was followed by the diffusion in clinopyroxene that continued probably until nearly full solidification of the magma ( Figure 8). The spongy-patchy parts of type II phenocrysts are impoverished in Ca compared to spongy-patchy mantles of type I phenocrysts ( Figure 6) pointing to the increase in temperature of crystallisation (Brey and Köhler, 1990), but we suggest that it is rather an effect of disequilibrium reaction with nephelinite. Type III phenocrysts shares cognate origin with type II, but its formation started at significantly lower pressures.…”

Section: Nephelinite Evolution (Conclusion)mentioning

confidence: 66%

Clinopyroxene phenocrysts from the Księginki nephelinite (SW Poland)

et al. 2015

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RecordChemical composition and textures of clinopyroxene phenocrysts from Księginki nephelinite record complex history of melt reacting with mantle rocks and "in situ" crystallisation of the melt. AbstractThe Eocene nephelinite from Księginki quarry (SW Poland) contains five types of clinopyroxene phenocrysts varying by texture and chemical composition. Type I phenocrysts are formed of Mg-rich (mg# = 0.93-0.88) homogenous cores, patchy mantle and zoned rims. Abundant type II is less magnesian (mg# = 0.65-0.88) and consists of spongy or spongy-patchy core surrounded by zoned rims, whilst in type III (mg# = 0.69-0.84), the cores are massive but patchy. The mg# of cores of type IV phenocrysts is slightly lower than that of type I (0.79-0.89), but its cores are either massive or patchy. Type V is very scarce and consist of relatively Mg-poor (mg# = 0.75-0.77) core enveloped by nonpatchy, sometimes zoned mantle and zoned outer rim. Chemical composition of type I and type IV cores suggests that they are xenocrysts introduced into the nephelinite from disintegrated peridotite and clinopyroxenitic xenoliths, respectively. Type V is also of xenocrystic nature, but its source rock was significantly more evolved than mantlederived ones. Types II and III are possibly cognates from the host nephelinite or a melt related to the nephelinite. All the types of phenocrysts suffered from disequilibrium with the nephelinitic (or proto-nephelinitic) melt or dissolution during adiabatic uplift. Linear variation in chemical composition of phenocrysts of Księginki nephelinite suggests its evolution because of fractional crystallisation, without significant influence of other differentiation processes.

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Geothermobarometry in Four-phase Lherzolites II. New Thermobarometers, and Practical Assessment of Existing Thermobarometers

Cited by 2,034 publications

References 0 publications

Rock seismic anisotropy of the low‐velocity zone beneath the volcanic front in the mantle wedge

Rock seismic anisotropy of the low‐velocity zone beneath the volcanic front in the mantle wedge

Lithospheric Mantle beneath the Korean Peninsula: Implications from Peridotite Xenoliths in Alkali Basalts

Clinopyroxene phenocrysts from the Księginki nephelinite (SW Poland)

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