Origin of sulfide replacement textures in lunar breccias. Implications for vapor element transport in the lunar crust

Shearer, C. K.; Burger, P. V.; Guan, Yunbin; Papike, J. J.; Sutton, S. R.; Atudorei, N.-V.

doi:10.1016/j.gca.2011.11.031

Cited by 53 publications

(91 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is more reducing than crystallization conditions of terrestrial zircons with mantle-like O isotopic signatures (Cavosie et al, 2005(Cavosie et al, , 2006Fu et al, 2008Fu et al, , 2009) but similar to those of lunar zircons (Trail et al, 2011after Taylor et al, 2009) as well as terrestrial metamorphic zircons associated with ilmenite in highly reduced granulites (Harlov and Förster, 2002;Ewing et al, 2013). Furthermore, the estimated f O 2 is consistent with the close association of ulvöspinel-ilmenite-troilite in Agoult, which is suggestive of f O 2 conditions between IW and iron-ilmenite-ulvöspinel buffers (El Goresy and Ramdohr, 1975;Shearer et al, 2012). Overall, mineralogical and geochemical evidence indicate that the Agoult zircon formed at ca.…”

Section: Genesis and Crystallization Conditions Of The Agoult Zirconsupporting

confidence: 67%

Timing of global crustal metamorphism on Vesta as revealed by high-precision U–Pb dating and trace element chemistry of eucrite zircon

Iizuka

Yamaguchi

Haba

et al. 2015

Earth and Planetary Science Letters

View full text Add to dashboard Cite

Non-cumulate eucrites represent basaltic crust that experienced a complex thermal history involving multistage metamorphism and metasomatism, probably on asteroid Vesta. To better constrain the thermal history of these rocks and their parent body, we have integrated high-precision U-Pb age and trace element data for zircon grains with sizes up to 80 μm in the eucrite Agoult. All analyzed zircon grains yielded concordant U-Pb dates that correspond to the precise 207 Pb/ 206 Pb age of 4554.5 ± 2.0 Ma.The Ti contents in these zircon grains indicate their crystallization at subsolidus temperatures of ca. 900 • C, which are similar to the inferred conditions of pyroxene exsolution in most basaltic eucrites that occurred during protracted thermal metamorphism. The zircon crystallization temperatures, together with the presence of baddeleyite needles and variable Zr concentration in Agoult ilmenite grains, indicate metamorphic origin of the Agoult zircon through Zr release from ilmenite followed by reaction with silica. We therefore consider the zircon 207 Pb/ 206 Pb age as the timing of the widespread thermal metamorphism in Vesta's crust. The metamorphic age is coincident with the oldest Mn-Cr date for cumulate eucrites, supporting the view that the thermal metamorphism is a result of burial of basaltic crust and subsequent heating from the hot interior rather than collision of asteroids. The zircon rare earth element patterns with restricted Ce positive anomalies suggest that the metamorphism occurred at an oxygen fugacity below the iron-wüstite buffer, implying the absence of oxidizing agents such as aqueous fluid within the crust at that time.

show abstract

Section: Genesis and Crystallization Conditions Of The Agoult Zirconsupporting

confidence: 67%

Timing of global crustal metamorphism on Vesta as revealed by high-precision U–Pb dating and trace element chemistry of eucrite zircon

Iizuka

Yamaguchi

Haba

et al. 2015

Earth and Planetary Science Letters

View full text Add to dashboard Cite

show abstract

“…These intrusions were probably the source for the S. The process that drove the derivation of the S-rich volatiles from these intrusions was also instrumental in fractionating the isotopic composition of S from 0‰ in the magmas to -5‰ in the vapor phase. This fractionation was not controlled by the proportions of SO 2 2-to H 2 S in the vapor phase, but more likely COS, S 2 , and CS 2 species (Shearer et al 2012b;McCubbin et al in revision).…”

Section: Troilite Replacement Of Olivinementioning

confidence: 96%

“…Alternatively, the veins could be the result of S-rich vapor streaming in the lunar crust. Shearer et al (2012b) invoked S-rich vapor streaming to explain sulfide replacement textures in olivine in other highlands lithologies, and Elardo et al (2012) suggested that a similar process may have acted on 76535, perhaps after its excavation from the lower crust during a period of slow cooling in an ejecta blanket (McCallum et al 2006).…”

Section: Chromite Symplectitesmentioning

confidence: 99%

“…Numerous studies have identified the replacement of mafic silicates with troilite in both magnesian-suite and FAN suite lithologies (Roedder and Weiblen 1974;Norman 1981;Lindstrom and Salpas 1983;Norman et al 1995;Shearer et al 2012aShearer et al , 2012b. In the Mg-suite clasts such as the olivine-rich gabbronorite in 67915, low-Ca pyroxene-troilite intergrowths occur along the perimeter of the olivine and along fractures in the olivine.…”

Section: Troilite Replacement Of Olivinementioning

confidence: 99%

See 1 more Smart Citation

Origin of the lunar highlands Mg-suite: An integrated petrology, geochemistry, chronology, and remote sensing perspective

Shearer

Elardo

Petro

et al. 2014

American Mineralogist

136

154

View full text Add to dashboard Cite

The Mg-suite represents an enigmatic episode of lunar highlands magmatism that presumably represents the first stage of crustal building following primordial differentiation. This review examines the mineralogy, geochemistry, petrology, chronology, and the planetary-scale distribution of this suite of highlands plutonic rocks, presents models for their origin, examines petrogenetic relationships to other highlands rocks, and explores the link between this style of magmatism and early stages of lunar differentiation. Of the models considered for the origin of the parent magmas for the Mg-suite, the data best fit a process in which hot (solidus temperature at ≥2 GPa = 1600 to 1800 °C) and less dense (r ~3100 kg/m 3 ) early lunar magma ocean cumulates rise to the base of the crust during cumulate pile overturn. Some decompressional melting would occur, but placing a hot cumulate horizon adjacent to the plagioclase-rich primordial crust and KREEP-rich lithologies (at temperatures of <1300 °C) would result in the hybridization of these divergent primordial lithologies, producing Mg-suite parent magmas. As urKREEP (primeval KREEP) is not the "petrologic driver" of this style of magmatism, outside of the Procellarum KREEP Terrane (PKT), Mg-suite magmas are not required to have a KREEP signature. Evaluation of the chronology of this episode of highlands evolution indicates that Mg-suite magmatism was initiated soon after primordial differentiation (<10 m.y.). Alternatively, the thermal event associated with the mantle overturn may have disrupted the chronometers utilized to date the primordial crust. Petrogenetic relationships between the Mg-suite and other highlands suites (e.g., alkali-suite and magnesian anorthositic granulites) are consistent with both fractional crystallization processes and melting of distinctly different hybrid sources.

show abstract

“…The second possibility is that these veins represent the impact-related effects on 76535. Shearer et al (2012) documented textures in Apollo 16 impact breccias where olivine grains are replaced by a combination of OPX and troilite, and they attributed this to S-rich vapor streaming in the upper crust or regolith as a result of impact processes. McCallum et al (2006) suggested that 76535 underwent a period of relatively slow cooling in a hot ejecta blanket after excavation from the lower crust, so the CPXtroilite veins could be the result of a similar replacement process while the troctolite cooled after initial excavation.…”

Section: Origin Of Cpx-troilite Veinsmentioning

confidence: 99%

Chromite symplectites in Mg-suite troctolite 76535 as evidence for infiltration metasomatism of a lunar layered intrusion

Elardo

McCubbin

Shearer

2012

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

Origin of sulfide replacement textures in lunar breccias. Implications for vapor element transport in the lunar crust

Cited by 53 publications

References 40 publications

Timing of global crustal metamorphism on Vesta as revealed by high-precision U–Pb dating and trace element chemistry of eucrite zircon

Timing of global crustal metamorphism on Vesta as revealed by high-precision U–Pb dating and trace element chemistry of eucrite zircon

Origin of the lunar highlands Mg-suite: An integrated petrology, geochemistry, chronology, and remote sensing perspective

Chromite symplectites in Mg-suite troctolite 76535 as evidence for infiltration metasomatism of a lunar layered intrusion

Contact Info

Product

Resources

About