High-pressure phases in a shock-induced melt vein of the Tenham L6 chondrite

Constraints on shock pressure and duration

Zhidong Xie, Thomas Sharp, Paul S. DeCarli

Research output: Contribution to journalArticle

70 Citations (Scopus)

Abstract

The microtexture and mineralogy of a 580-μm-wide melt vein in the Tenham L6 chondrite were investigated using field-emission scanning electron microscopy and transmission electron microscopy to better understand the shock conditions. The melt vein consists of a matrix of silicate plus metal-sulfide grains that crystallized from immiscible melts, and sub-rounded fragments of the host chondrite that have been entrained in the melt and transformed to polycrystalline high-pressure silicates. The melt-vein matrix contains two distinct textures and mineral assemblages corresponding to the vein edge and interior. The 30-μm-wide vein edge consists of vitrified silicate perovskite + ringwoodite + akimotoite + majorite with minor metal-sulfide. The 520-μm-wide vein interior consists of majorite + magnesiowüstite with irregular metal-sulfide blebs. Although these mineral assemblages are distinctly different, the pressure stabilities of both assemblages are consistent with crystallization from similar pressure conditions: the melt-vein edge crystallized at about 23-25 GPa and the vein interior crystallized at about 21-25 GPa. This relatively narrow pressure range suggests that the melt vein either crystallized at a constant equilibrium shock pressure of ∼25 GPa or during a relatively slow pressure release. Using a finite element heat transfer program to model the thermal history of this melt vein during shock, we estimate that the time required to quench this 580-μm-wide vein was ∼40 ms. Because the entire vein contains high-pressure minerals that crystallized from the melt, the shock-pressure duration was at least 40 ms. Using a synthetic Hugoniot for Tenham and assuming that the sample experienced a peak-shock pressure of 25 GPa near the impact site, we estimate that the Tenham parent body experienced an impact with collision velocity ∼2 km/s. Based on a one-dimensional planar impact model, we estimate that the projectile size was >150 m in thickness.

Original languageEnglish (US)
Pages (from-to)504-515
Number of pages12
JournalGeochimica et Cosmochimica Acta
Volume70
Issue number2
DOIs
StatePublished - Jan 15 2006

Fingerprint

chondrite
melt
Silicates
Sulfides
majorite
Minerals
silicate
Metals
sulfide
metal
mineral
ringwoodite
matrix
Mineralogy
parent body
Equilibrium constants
perovskite
Projectiles
Crystallization
Field emission

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

High-pressure phases in a shock-induced melt vein of the Tenham L6 chondrite : Constraints on shock pressure and duration. / Xie, Zhidong; Sharp, Thomas; DeCarli, Paul S.

In: Geochimica et Cosmochimica Acta, Vol. 70, No. 2, 15.01.2006, p. 504-515.

Research output: Contribution to journalArticle

@article{d2429a503de74f87867a8e003d3647f7,
title = "High-pressure phases in a shock-induced melt vein of the Tenham L6 chondrite: Constraints on shock pressure and duration",
abstract = "The microtexture and mineralogy of a 580-μm-wide melt vein in the Tenham L6 chondrite were investigated using field-emission scanning electron microscopy and transmission electron microscopy to better understand the shock conditions. The melt vein consists of a matrix of silicate plus metal-sulfide grains that crystallized from immiscible melts, and sub-rounded fragments of the host chondrite that have been entrained in the melt and transformed to polycrystalline high-pressure silicates. The melt-vein matrix contains two distinct textures and mineral assemblages corresponding to the vein edge and interior. The 30-μm-wide vein edge consists of vitrified silicate perovskite + ringwoodite + akimotoite + majorite with minor metal-sulfide. The 520-μm-wide vein interior consists of majorite + magnesiow{\"u}stite with irregular metal-sulfide blebs. Although these mineral assemblages are distinctly different, the pressure stabilities of both assemblages are consistent with crystallization from similar pressure conditions: the melt-vein edge crystallized at about 23-25 GPa and the vein interior crystallized at about 21-25 GPa. This relatively narrow pressure range suggests that the melt vein either crystallized at a constant equilibrium shock pressure of ∼25 GPa or during a relatively slow pressure release. Using a finite element heat transfer program to model the thermal history of this melt vein during shock, we estimate that the time required to quench this 580-μm-wide vein was ∼40 ms. Because the entire vein contains high-pressure minerals that crystallized from the melt, the shock-pressure duration was at least 40 ms. Using a synthetic Hugoniot for Tenham and assuming that the sample experienced a peak-shock pressure of 25 GPa near the impact site, we estimate that the Tenham parent body experienced an impact with collision velocity ∼2 km/s. Based on a one-dimensional planar impact model, we estimate that the projectile size was >150 m in thickness.",
author = "Zhidong Xie and Thomas Sharp and DeCarli, {Paul S.}",
year = "2006",
month = "1",
day = "15",
doi = "10.1016/j.gca.2005.09.003",
language = "English (US)",
volume = "70",
pages = "504--515",
journal = "Geochmica et Cosmochimica Acta",
issn = "0016-7037",
publisher = "Elsevier Limited",
number = "2",

}

TY - JOUR

T1 - High-pressure phases in a shock-induced melt vein of the Tenham L6 chondrite

T2 - Constraints on shock pressure and duration

AU - Xie, Zhidong

AU - Sharp, Thomas

AU - DeCarli, Paul S.

PY - 2006/1/15

Y1 - 2006/1/15

N2 - The microtexture and mineralogy of a 580-μm-wide melt vein in the Tenham L6 chondrite were investigated using field-emission scanning electron microscopy and transmission electron microscopy to better understand the shock conditions. The melt vein consists of a matrix of silicate plus metal-sulfide grains that crystallized from immiscible melts, and sub-rounded fragments of the host chondrite that have been entrained in the melt and transformed to polycrystalline high-pressure silicates. The melt-vein matrix contains two distinct textures and mineral assemblages corresponding to the vein edge and interior. The 30-μm-wide vein edge consists of vitrified silicate perovskite + ringwoodite + akimotoite + majorite with minor metal-sulfide. The 520-μm-wide vein interior consists of majorite + magnesiowüstite with irregular metal-sulfide blebs. Although these mineral assemblages are distinctly different, the pressure stabilities of both assemblages are consistent with crystallization from similar pressure conditions: the melt-vein edge crystallized at about 23-25 GPa and the vein interior crystallized at about 21-25 GPa. This relatively narrow pressure range suggests that the melt vein either crystallized at a constant equilibrium shock pressure of ∼25 GPa or during a relatively slow pressure release. Using a finite element heat transfer program to model the thermal history of this melt vein during shock, we estimate that the time required to quench this 580-μm-wide vein was ∼40 ms. Because the entire vein contains high-pressure minerals that crystallized from the melt, the shock-pressure duration was at least 40 ms. Using a synthetic Hugoniot for Tenham and assuming that the sample experienced a peak-shock pressure of 25 GPa near the impact site, we estimate that the Tenham parent body experienced an impact with collision velocity ∼2 km/s. Based on a one-dimensional planar impact model, we estimate that the projectile size was >150 m in thickness.

AB - The microtexture and mineralogy of a 580-μm-wide melt vein in the Tenham L6 chondrite were investigated using field-emission scanning electron microscopy and transmission electron microscopy to better understand the shock conditions. The melt vein consists of a matrix of silicate plus metal-sulfide grains that crystallized from immiscible melts, and sub-rounded fragments of the host chondrite that have been entrained in the melt and transformed to polycrystalline high-pressure silicates. The melt-vein matrix contains two distinct textures and mineral assemblages corresponding to the vein edge and interior. The 30-μm-wide vein edge consists of vitrified silicate perovskite + ringwoodite + akimotoite + majorite with minor metal-sulfide. The 520-μm-wide vein interior consists of majorite + magnesiowüstite with irregular metal-sulfide blebs. Although these mineral assemblages are distinctly different, the pressure stabilities of both assemblages are consistent with crystallization from similar pressure conditions: the melt-vein edge crystallized at about 23-25 GPa and the vein interior crystallized at about 21-25 GPa. This relatively narrow pressure range suggests that the melt vein either crystallized at a constant equilibrium shock pressure of ∼25 GPa or during a relatively slow pressure release. Using a finite element heat transfer program to model the thermal history of this melt vein during shock, we estimate that the time required to quench this 580-μm-wide vein was ∼40 ms. Because the entire vein contains high-pressure minerals that crystallized from the melt, the shock-pressure duration was at least 40 ms. Using a synthetic Hugoniot for Tenham and assuming that the sample experienced a peak-shock pressure of 25 GPa near the impact site, we estimate that the Tenham parent body experienced an impact with collision velocity ∼2 km/s. Based on a one-dimensional planar impact model, we estimate that the projectile size was >150 m in thickness.

UR - http://www.scopus.com/inward/record.url?scp=30944452144&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=30944452144&partnerID=8YFLogxK

U2 - 10.1016/j.gca.2005.09.003

DO - 10.1016/j.gca.2005.09.003

M3 - Article

VL - 70

SP - 504

EP - 515

JO - Geochmica et Cosmochimica Acta

JF - Geochmica et Cosmochimica Acta

SN - 0016-7037

IS - 2

ER -