Shock barometer using cathodoluminescence of alkali feldspar

Kayama, Masahiro; Nishido, Hirotsugu; Sekine, Toshimori; Nakazato, T.; Gucsik, A.; Ninagawa, K.

doi:10.1029/2011je004025

Cited by 28 publications

(73 citation statements)

References 56 publications

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“…Such a spectral pattern is characteristic of maskelynite and diaplectic feldspar glass, and undetectable in crystalline plagioclase (Kayama et al. , , ). On the other hand, the CL spectroscopy of the dark portion exhibits only a blue emission band at ~410 nm (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…We referred previous data of maskelynite and crystalline feldspar to identify the number and peak position of Gaussian components and emission type (Kayama et al. , ). A chi‐squared test for CL spectral datum of each measured sample was also performed to fit in with the smallest margin of standard error.…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

“…Kayama et al. () developed cathodoluminescence (CL) spectroscopy for estimating the shock pressure condition recorded in the maskelynite of shocked meteorites. Yamato‐790729 L6 ordinary chondrite with a shock‐melt vein is one of the heavily shocked ordinary chondrites.…”

Section: Introductionmentioning

confidence: 99%

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High‐pressure polymorphs in Yamato‐790729 L6 chondrite and their significance for collisional conditions

Kato

Sekine

Kayama

et al. 2017

Meteorit & Planetary Scien

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Shock pressure recorded in Yamato (Y)‐790729, classified as L6 type ordinary chondrite, was evaluated based on high‐pressure polymorph assemblages and cathodoluminescence (CL) spectra of maskelynite. The host‐rock of Y‐790729 consists mainly of olivine, low‐Ca pyroxene, plagioclase, metallic Fe‐Ni, and iron‐sulfide with minor amounts of phosphate and chromite. A shock‐melt vein was observed in the hostrock. Ringwoodite, majorite, akimotoite, lingunite, tuite, and xieite occurred in and around the shock‐melt vein. The shock pressure in the shock‐melt vein is about 14–23 GPa based on the phase equilibrium diagrams of high‐pressure polymorphs. Some plagioclase portions in the host‐rock occurred as maskelynite. Sixteen different CL spectra of maskelynite portions were deconvolved using three assigned emission components (centered at 2.95, 3.26, and 3.88 eV). The intensity of emission component at 2.95 eV was selected as a calibrated barometer to estimate shock pressure, and the results indicate pressures of about 11–19 GPa. The difference in pressure between the shock‐melt vein and host‐rock might suggest heterogeneous shock conditions. Assuming an average shock pressure of 18 GPa, the impact velocity of the parent‐body of Y‐790729 is calculated to be ~1.90 km s−1. The parent‐body would be at least ~10 km in size based on the incoherent formation mechanism of ringwoodite in Y‐790729.

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Section: Resultsmentioning

confidence: 99%

Section: Materials and Experimental Methodsmentioning

confidence: 99%

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High‐pressure polymorphs in Yamato‐790729 L6 chondrite and their significance for collisional conditions

Kato

Sekine

Kayama

et al. 2017

Meteorit & Planetary Scien

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“…The inhomogeneity is not visible under the polarizing microscope. The weak red-violet maskelynite luminescence and the bright blue luminescence of alkali feldspar are related to shock events [48].…”

Section: Datamentioning

confidence: 99%

Validity of the Apatite/Merrillite Relationship in Evaluating the Water Content in the Martian Mantle: Implications from Shergottite Northwest Africa (NWA) 2975

et al. 2017

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Abstract:Phosphates from the Martian shergottite NWA 2975 were used to obtain insights into the source and subsequence differentiation of the melt/melts. The crystallization of two generations of fluorapatite (F > Cl~OH and F-rich), chlorapatite and ferromerrillite-merrillite were reconstructed from TEM (Transmission Electron Microscopy) and geochemical analyses. The research results indicated that the recognized volatiles budget of the two generations of fluorapatite was related to their magmatic origin. The apatite crystals crystallized from an evolved magma during its final differentiation and degassing stage. In turn, chlorapatite replaced ferromerrillite-merrillite and was not related to, mantle-derived shergottite magma. The relationship between merrillite and apatite indicates that apatite is most probably a product of merrillite reacting with fluids. REE (rare earth elements) pattern of Cl-apatite might point to an origin associated with exogenous fluids mixed with fluids exsolved from evolved magma. The study shows that, among the three types of apatite, only the fluorapatite (F > Cl~OH) is a reliable source for assessing the degree of Martian mantle hydration. The occurrence of apatite with merrillite requires detailed recognition of their relationship. Consequently, the automatic use of apatite to assess the water content of the magma source can lead to false assumptions if the origin of the apatite is not precisely determined.

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“…; White ), despite some studies having suggested that feldspar can be just as useful as quartz (e.g., Kayama et al. ; Jaret et al. ).…”

Section: Introductionmentioning

confidence: 99%

Shock effects in plagioclase feldspar from the Mistastin Lake impact structure, Canada

Pickersgill

Osinski

Flemming

2015

Meteorit & Planetary Scien

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-Shock metamorphism, caused by hypervelocity impact, is a poorly understood process in feldspar due to the complexity of the crystal structure, the relative ease of weathering, and chemical variations, making optical studies of shocked feldspars challenging. Understanding shock metamorphism in feldspars, and plagioclase in particular, is vital for understanding the history of Earth's moon, Mars, and many other planetary bodies. We present here a comprehensive study of shock effects in andesine and labradorite from the Mistastin Lake impact structure, Labrador, Canada. Samples from a range of different settings were studied, from in situ central uplift materials to clasts from various breccias and impact melt rocks. Evidence of shock metamorphism includes undulose extinction, offset twins, kinked twins, alternate twin deformation, and partial to complete transformation to diaplectic plagioclase glass. In some cases, isotropization of alternating twin lamellae was observed. Planar deformation features (PDFs) are notably absent in the plagioclase, even when present in neighboring quartz grains. It is notable that various microlites, twin planes, and compositionally different lamellae could easily be mistaken for PDFs and so care must be taken. A pseudomorphous zeolite phase (levyne-Ca) was identified as a replacement mineral of diaplectic feldspar glass in some samples, which could, in some instances, also be potentially mistaken for PDFs. We suggest that the lack of PDFs in plagioclase could be due to a combination of structural controls relating to the crystal structure of different feldspars and/or the presence of existing planes of weakness in the form of twin and cleavage planes.

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Shock barometer using cathodoluminescence of alkali feldspar

Cited by 28 publications

References 56 publications

High‐pressure polymorphs in Yamato‐790729 L6 chondrite and their significance for collisional conditions

High‐pressure polymorphs in Yamato‐790729 L6 chondrite and their significance for collisional conditions

Validity of the Apatite/Merrillite Relationship in Evaluating the Water Content in the Martian Mantle: Implications from Shergottite Northwest Africa (NWA) 2975

Shock effects in plagioclase feldspar from the Mistastin Lake impact structure, Canada

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