A procedure for calculating a consistent set of closure temperatures and cooling rate using Dodson’s formula

Maeda, J.; Zeniya, Ryoichi; Kuramoto, Yoshiyuki; Itaya, Tetsumaru; Kagami, Hiroo

doi:10.5575/geosoc.117.99

Cited by 4 publications

(2 citation statements)

References 15 publications

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“…For apatite, this closure temperature is only 400–600°C for the smaller grains found in these meteorites, at slow cooling rates (Fig. S3 in supporting information; Cherniak et al., 1991; Dodson, 1973; Harrison et al., 2002; Maeda et al., 2011). Here, we assume that merrillite too has a similar closure temperature.…”

Section: Discussionmentioning

confidence: 90%

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A detailed record of early solar system melting in the carbonaceous achondrites Northwest Africa 7680 and 6962

Hyde

Moser

Tait

et al. 2022

Meteorit & Planetary Scien

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Detailed textural and geochemical analyses of the carbonaceous achondrites Northwest Africa (NWA) 7680 and NWA 6962 support a rapid progression of thermal events, by similar processes, on the same parent body. The achondrites have olivine compositions of Fa44.8 and Fa47.4 for NWA 7680 and NWA 6962, respectively. Replicate oxygen isotope analyses of grains and bulk powders from NWA 7680 yielded average Δ17O values of −1.04 ± 0.03‰ and −1.00 ± 0.05‰, respectively, which is identical to that reported for NWA 6962. The whole rock ɛ54Cr compositions are also equivalent for NWA 7680 and NWA 6962 (1.36 ± 0.05 and 1.30 ± 0.05, respectively). Both meteorites are plagioclase‐rich, and NWA 7680 is also Fe‐metal‐rich, suggesting they both formed via differentiation processes that resulted in the pooling of partial melt products. Major element geochemical trends show that both rocks could be formed through the melting of chondritic material on a CR chondrite‐like parent body. This is consistent with oxygen isotope and chromium isotope compositions. Intrusion of a late‐stage melt is evident in both meteorites and the crystallization products include silica‐rich, alkali‐deficient nepheline. The late‐stage liquid has partially melted and mixed with primary plagioclase in NWA 6962. In contrast, the late‐stage liquid was often restricted to grain boundaries in NWA 7680, leaving some of the primary plagioclase crystals intact. In situ dating of NWA 7680 phosphate minerals (merrillite and fluorapatite) reveals that it has not experienced long duration thermal metamorphism, or impact‐related Pb loss and age resetting since 4578 ± 17 Ma (207Pb/206Pb age ± 2σ, within error of solar system age). Phosphates associated with the late‐stage melt in NWA 6962 yield a 207Pb/206Pb age of 4556.6 ± 8.0 Ma (2σ) within 2σ of the NWA 7680 age. These early dates indicate that the observed chromium isotope signatures in these meteorites were not introduced by a later high‐temperature event, such as late impact accretion processes. These data are consistent with a rapid separation of inner and outer solar system chemical reservoirs, planetesimal melting, differentiation, and cooling, all within several million years of calcium‐aluminum‐rich inclusion formation.

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Section: Discussionmentioning

confidence: 90%

“…S3. Calculated closure temperatures for grains in NWA 7680 and NWA 6962 following the methods of Dodson (1973), Cherniak et al (1991), andMaeda et al (2011). The calculated temperatures span a range of slow cooling rates.…”

Section: Supporting Informationmentioning

confidence: 99%

A detailed record of early solar system melting in the carbonaceous achondrites Northwest Africa 7680 and 6962

Hyde

Moser

Tait

et al. 2022

Meteorit & Planetary Scien

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U–Pb age constraints on the protolith, cooling and exhumation of a Variscan middle crust migmatite complex from the Central Iberian Zone: insights into the Variscan metamorphic evolution and Ediacaran palaeogeographic implications

Ferreira

Pereira

Santos

et al. 2022

JGS

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The Figueira de Castelo Rodrigo – Lumbrales Anatectic Complex (FCR-LAC) located in the Central Iberian Zone of the European Variscan Belt is delimited by two shear zones, which have been interpreted as constraining its exhumation. New U-Pb zircon and apatite ages for the migmatites allowed to obtain a peak metamorphic age of the anatectic complex (316.8±2.0 Ma), and to estimate fast cooling (7-54 °C/Ma) and fast exhumation (0.2-1.3 mm.a-1) after a vertical displacement of ca. 6-9 km.Our results show a similar zircon age distribution between migmatites and the Excomungada Formation from the host Ediacaran-Cambrian Douro-Beiras Supergroup (DBSG), but the existence of an inherited zircon population with ca. 500 Ma, absent in the metasedimentary units, suggests the contribution of Ollo de Sapo magmatic rocks during the Lower-Middle Pennsylvanian melting events.Detrital zircon ages of the Pinhão Formation (Douro Group) have contrasting sources to units from the Beiras Group, which may indicate the presence of a barrier that prevented older detrital components from reaching the Douro basin. However, at odds with what has been postulated before, such barrier must have been placed farther south of the FRC-LAC, and thus not coincident with the Juzbado-Penalva do Castelo shear zone.Supplementary material:https://doi.org/10.6084/m9.figshare.c.6002006

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Prompt K-Ar and Ar-Ar analysis and its application to Orogeny

徹丸¹

2012

Japanese Magazine of Mineralogical and Petrological Sciences

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A procedure for calculating a consistent set of closure temperatures and cooling rate using Dodson’s formula

Cited by 4 publications

References 15 publications

A detailed record of early solar system melting in the carbonaceous achondrites Northwest Africa 7680 and 6962

A detailed record of early solar system melting in the carbonaceous achondrites Northwest Africa 7680 and 6962

U–Pb age constraints on the protolith, cooling and exhumation of a Variscan middle crust migmatite complex from the Central Iberian Zone: insights into the Variscan metamorphic evolution and Ediacaran palaeogeographic implications

Prompt K-Ar and Ar-Ar analysis and its application to Orogeny

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