Near-ultrahigh pressure processing of continental crust: Miocene crustal xenoliths from the Pamir

Bradley Hacker, Peter Lufffi, Valery Lutkov, Vladislav Minaev, Lothar Ratschbacher, Terry Plank, Mihai N Ducea, Alberto Patiño-Douce, Michael McWilliams, Jim Metcalf

Research output: Contribution to journalArticle

133 Citations (Scopus)

Abstract

Xenoliths of subducted crustal origin hosted by Miocene ultrapotassic igneous rocks in the southern Pamir provide important new information regarding the geological processes accompanying tectonism during the Indo-Eurasian collision. Four types have been studied: sanidine eclogites (omphacite, garnet, sanidine, quartz, biotite, kyanite), felsic granulites (garnet, quartz, sanidine and kyanite), basaltic eclogites (omphacite and garnet), and a glimmerite (biotite, clinopyroxene and sanidine). Apatite, rutile and carbonate are the most abundant minor phases. Hydrous phases (biotite and phengite in felsic granulites and basaltic eclogites, amphiboles in mafic and sanidine eclogites) and plagioclase form minor inclusions in garnet or kyanite. Solid-phase thermobarometry reveals recrystallization at mainly ultrahigh temperatures of 1000-1100°C and near-ultrahigh pressures of 2·5-2·8 GPa. Textures, parageneses and mineral compositions suggest derivation of the xenoliths from subducted basaltic, tonalitic and pelitic crust that experienced high-pressure dehydration melting, K-rich metasomatism, and solid-state re-equilibration. The timing of these processes is constrained by zircon ages from the xenoliths and 40Ar/39Ar ages of the host volcanic rocks to 57-11 Ma. These xenoliths reveal that deeply subducted crust may undergo extensive dehydration-driven partial melting, density-driven differentiation and disaggregation, and sequestration within the mantle. These processes may also contribute to the alkaline volcanism observed in continent-collision zones.

Original languageEnglish (US)
Pages (from-to)1661-1687
Number of pages27
JournalJournal of Petrology
Volume46
Issue number8
DOIs
StatePublished - Aug 2005

Fingerprint

sanidine
garnets
continental crust
Garnets
crusts
biotite
Miocene
garnet
kyanite
Processing
omphacite
Quartz
dehydration
Dehydration
quartz
melting
Melting
Amphibole Asbestos
collisions
amphiboles

Keywords

  • High-pressure
  • Pamir
  • Subduction
  • Tibet
  • Xenolith

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

Hacker, B., Lufffi, P., Lutkov, V., Minaev, V., Ratschbacher, L., Plank, T., ... Metcalf, J. (2005). Near-ultrahigh pressure processing of continental crust: Miocene crustal xenoliths from the Pamir. Journal of Petrology, 46(8), 1661-1687. https://doi.org/10.1093/petrology/egi030

Near-ultrahigh pressure processing of continental crust : Miocene crustal xenoliths from the Pamir. / Hacker, Bradley; Lufffi, Peter; Lutkov, Valery; Minaev, Vladislav; Ratschbacher, Lothar; Plank, Terry; Ducea, Mihai N; Patiño-Douce, Alberto; McWilliams, Michael; Metcalf, Jim.

In: Journal of Petrology, Vol. 46, No. 8, 08.2005, p. 1661-1687.

Research output: Contribution to journalArticle

Hacker, B, Lufffi, P, Lutkov, V, Minaev, V, Ratschbacher, L, Plank, T, Ducea, MN, Patiño-Douce, A, McWilliams, M & Metcalf, J 2005, 'Near-ultrahigh pressure processing of continental crust: Miocene crustal xenoliths from the Pamir', Journal of Petrology, vol. 46, no. 8, pp. 1661-1687. https://doi.org/10.1093/petrology/egi030
Hacker, Bradley ; Lufffi, Peter ; Lutkov, Valery ; Minaev, Vladislav ; Ratschbacher, Lothar ; Plank, Terry ; Ducea, Mihai N ; Patiño-Douce, Alberto ; McWilliams, Michael ; Metcalf, Jim. / Near-ultrahigh pressure processing of continental crust : Miocene crustal xenoliths from the Pamir. In: Journal of Petrology. 2005 ; Vol. 46, No. 8. pp. 1661-1687.
@article{056f65407a8d4314898099cc443774d2,
title = "Near-ultrahigh pressure processing of continental crust: Miocene crustal xenoliths from the Pamir",
abstract = "Xenoliths of subducted crustal origin hosted by Miocene ultrapotassic igneous rocks in the southern Pamir provide important new information regarding the geological processes accompanying tectonism during the Indo-Eurasian collision. Four types have been studied: sanidine eclogites (omphacite, garnet, sanidine, quartz, biotite, kyanite), felsic granulites (garnet, quartz, sanidine and kyanite), basaltic eclogites (omphacite and garnet), and a glimmerite (biotite, clinopyroxene and sanidine). Apatite, rutile and carbonate are the most abundant minor phases. Hydrous phases (biotite and phengite in felsic granulites and basaltic eclogites, amphiboles in mafic and sanidine eclogites) and plagioclase form minor inclusions in garnet or kyanite. Solid-phase thermobarometry reveals recrystallization at mainly ultrahigh temperatures of 1000-1100°C and near-ultrahigh pressures of 2·5-2·8 GPa. Textures, parageneses and mineral compositions suggest derivation of the xenoliths from subducted basaltic, tonalitic and pelitic crust that experienced high-pressure dehydration melting, K-rich metasomatism, and solid-state re-equilibration. The timing of these processes is constrained by zircon ages from the xenoliths and 40Ar/39Ar ages of the host volcanic rocks to 57-11 Ma. These xenoliths reveal that deeply subducted crust may undergo extensive dehydration-driven partial melting, density-driven differentiation and disaggregation, and sequestration within the mantle. These processes may also contribute to the alkaline volcanism observed in continent-collision zones.",
keywords = "High-pressure, Pamir, Subduction, Tibet, Xenolith",
author = "Bradley Hacker and Peter Lufffi and Valery Lutkov and Vladislav Minaev and Lothar Ratschbacher and Terry Plank and Ducea, {Mihai N} and Alberto Pati{\~n}o-Douce and Michael McWilliams and Jim Metcalf",
year = "2005",
month = "8",
doi = "10.1093/petrology/egi030",
language = "English (US)",
volume = "46",
pages = "1661--1687",
journal = "Journal of Petrology",
issn = "0022-3530",
publisher = "Oxford University Press",
number = "8",

}

TY - JOUR

T1 - Near-ultrahigh pressure processing of continental crust

T2 - Miocene crustal xenoliths from the Pamir

AU - Hacker, Bradley

AU - Lufffi, Peter

AU - Lutkov, Valery

AU - Minaev, Vladislav

AU - Ratschbacher, Lothar

AU - Plank, Terry

AU - Ducea, Mihai N

AU - Patiño-Douce, Alberto

AU - McWilliams, Michael

AU - Metcalf, Jim

PY - 2005/8

Y1 - 2005/8

N2 - Xenoliths of subducted crustal origin hosted by Miocene ultrapotassic igneous rocks in the southern Pamir provide important new information regarding the geological processes accompanying tectonism during the Indo-Eurasian collision. Four types have been studied: sanidine eclogites (omphacite, garnet, sanidine, quartz, biotite, kyanite), felsic granulites (garnet, quartz, sanidine and kyanite), basaltic eclogites (omphacite and garnet), and a glimmerite (biotite, clinopyroxene and sanidine). Apatite, rutile and carbonate are the most abundant minor phases. Hydrous phases (biotite and phengite in felsic granulites and basaltic eclogites, amphiboles in mafic and sanidine eclogites) and plagioclase form minor inclusions in garnet or kyanite. Solid-phase thermobarometry reveals recrystallization at mainly ultrahigh temperatures of 1000-1100°C and near-ultrahigh pressures of 2·5-2·8 GPa. Textures, parageneses and mineral compositions suggest derivation of the xenoliths from subducted basaltic, tonalitic and pelitic crust that experienced high-pressure dehydration melting, K-rich metasomatism, and solid-state re-equilibration. The timing of these processes is constrained by zircon ages from the xenoliths and 40Ar/39Ar ages of the host volcanic rocks to 57-11 Ma. These xenoliths reveal that deeply subducted crust may undergo extensive dehydration-driven partial melting, density-driven differentiation and disaggregation, and sequestration within the mantle. These processes may also contribute to the alkaline volcanism observed in continent-collision zones.

AB - Xenoliths of subducted crustal origin hosted by Miocene ultrapotassic igneous rocks in the southern Pamir provide important new information regarding the geological processes accompanying tectonism during the Indo-Eurasian collision. Four types have been studied: sanidine eclogites (omphacite, garnet, sanidine, quartz, biotite, kyanite), felsic granulites (garnet, quartz, sanidine and kyanite), basaltic eclogites (omphacite and garnet), and a glimmerite (biotite, clinopyroxene and sanidine). Apatite, rutile and carbonate are the most abundant minor phases. Hydrous phases (biotite and phengite in felsic granulites and basaltic eclogites, amphiboles in mafic and sanidine eclogites) and plagioclase form minor inclusions in garnet or kyanite. Solid-phase thermobarometry reveals recrystallization at mainly ultrahigh temperatures of 1000-1100°C and near-ultrahigh pressures of 2·5-2·8 GPa. Textures, parageneses and mineral compositions suggest derivation of the xenoliths from subducted basaltic, tonalitic and pelitic crust that experienced high-pressure dehydration melting, K-rich metasomatism, and solid-state re-equilibration. The timing of these processes is constrained by zircon ages from the xenoliths and 40Ar/39Ar ages of the host volcanic rocks to 57-11 Ma. These xenoliths reveal that deeply subducted crust may undergo extensive dehydration-driven partial melting, density-driven differentiation and disaggregation, and sequestration within the mantle. These processes may also contribute to the alkaline volcanism observed in continent-collision zones.

KW - High-pressure

KW - Pamir

KW - Subduction

KW - Tibet

KW - Xenolith

UR - http://www.scopus.com/inward/record.url?scp=26444509860&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=26444509860&partnerID=8YFLogxK

U2 - 10.1093/petrology/egi030

DO - 10.1093/petrology/egi030

M3 - Article

AN - SCOPUS:26444509860

VL - 46

SP - 1661

EP - 1687

JO - Journal of Petrology

JF - Journal of Petrology

SN - 0022-3530

IS - 8

ER -