Moon basalt 70017

The ilmenite- bearing lunar basalt 70017 is a lunar rock that was picked up in 1972 by Eugene Cernan and Harrison Schmitt during the Apollo 17 mission near the lunar module in the Taurus-Littrow Valley .

description

Moon basalt handpiece 70017

The medium-grain, bubble-rich moon basalt 70017 is a 2957 gram handpiece. It can be described as holocrystalline, uniform-grain, poikilitic plagioclase- bearing basalt with a high titanium content. The rock is composed of around 30 volume percent plagioclase, 59 volume percent pyroxene , 10 volume percent ilmenite and 1 volume percent olivine .

The basalt crystallized about 3700 million years ago BP in the course of the late-Imbrian period . It was exposed to cosmic rays for around 220 million years .

mineralogy

The moon basalt 70017 consists of the following minerals :

Occasionally and in traces:

Petrography

The most common mineral in the moon basalt 70017 with 49.3 to 57.6 percent by volume is clinopyroxene , which appears as 1 to 2 millimeters large, equally sized, hypidiomorphic crystals with ilmenite inclusions. The clinopyroxenes are zonal with subcalcic augite in the core and iron-rich pigeonite in the edge zones. The cores contain up to 3.5 percent TiO ₂ and 4.5% Al ₂ O ₃ . The up to 4 millimeter large plagioclase (19.8 to 26 percent by volume) of the composition An _69-88 show polysynthetic twinning and poikilitisch enclose clinopyroxene, olivine and ilmenite . Late crystallizing cristobalite (1.3 to 1.6 percent by volume) with a characteristic, broken structure is found in the gussets between clinopyroxene and plagioclase . Even-grain olivine (0.4 to 1.0 percent by volume) with a grain size of around 0.1 millimeter has the composition Fo _66-69 and forms inclusions in the core of the clinopyroxene and in the plagioclase. Among the opaque minerals (19.2 to 22.0 percent by volume), ilmenite predominates, which occurs in long chains. It shows segregation of chromite and rutile . Armalcolite was probably present as an early phase, but is now mainly in the form of ilmenite. Relic armalcolite is found in pyroxes. Tiny grains of chromite are present in olivine. There are traces of spinel ( chromium- rich Ulvöspinell ), troilite and metallic iron .

In spandrels of the lunar basalt, a very complex mesostasis (0.3 to 1.4 percent by volume) appears between the phenocrystals , which is composed of brown glass , silica , troilite , whitlockite and traces of tranquilityite . It consists of around 70% SiO ₂ and 5% K ₂ O.

Roedder and Weiblen examined silicate enamel inclusions in ilmenite. They found high and low potassium melts that did not mix.

Chemical composition

The following table gives geochemical analysis values for the lunar basalt 70017:

Oxide wt.%	rock	Trace element ppm	rock	CIPW standard	Weight%
SiO ₂	37.62-38.80	Ni	1-24	q	0
TiO ₂	12.21-13.90	Cr	2950-5400	or	0.41
Al ₂ O ₃	7.40-9.73	Zn	2-4	from	3.47
FeO	17.50-19.60	Sr	127-306	on	22.10
MnO	0.233-0.290	Rb	0.28-1.20	di	31.47
MgO	9.13-10.45	Ba	43-250	hy	25.19
CaO	7.14-13.4	La	3.99-10.0	oil	0.72
Na ₂ O	0.31-0.43	Eu	1.49-1.77	cm	0.80
K ₂ O	0.036-0.070	Nd	12.1-20.0	il	26.40
P ₂ O ₅	0.040-0.052	Zr	138-304	ap	0.09

The moon basalt 70017 is typical of the basalts that are extraordinarily enriched in titanium, iron and magnesium (titanium> 12%, iron> 17%, magnesium> 9%) from the Taurus-Littrow valley, to whose group B he belongs (with samarium < 9 ppm). It is closely related to the basalt samples returned by Apollo 11 . In the rare earths , which are enriched by a factor of 10 to 20 compared to chondrites , a weakly negative europium anomaly can be seen . The sample is undersaturated with quartz and normative for diopside , hypersthene and olivine. Among the standard minerals , in addition to pyroxene and plagioclase, ilmenite and chromite stand out.

Age

With different dating methods, ages between 3670 and 3800 million years BP could be established for the moon basalt 70017, whereby the lower age is to be preferred.

Individual evidence

↑ D. Phinney et al .: 40Ar-39Ar dating of Apollo 16 and 17 rocks . In: Proc. 6th Lunar Sci. Conf . 1975, p. 1593-1608 .
^ J. Longhi et al: The petrology of the Apollo 17 mare basalts . In: Proc. 5th Lunar Sci. Conf . 1974, p. 447-469 .
↑ FN Hodges, I. Kushiro: Apollo 17 petrology and experimental determination of differentiation sequences in model Moon compositions . In: Proc. 5th Lunar Sci. Conf . 1974, p. 505-520 .
↑ E. Roedder, PW Weiblen: Anomalous low-K silicate melt inclusions in ilmenite from Apollo 17 basalts . In: Proc. 6th Lunar Sci. Conf . 1975, p. 147-164 .
↑ C. Meyer: Lunar Sample Compendium: 70017 . 2008.
↑ JB Paces et al: A strontium and neodymium isotopic study of Apollo 17 high-Ti mare basalts: resolution of ages, evolution of magmas and origin of source heterogeneities . In: Geochimica Cosmochimica Acta . tape 55 , 1991, pp. 2025-2043 .
^ LE Nyquist: Lunar Rb-Sr chronology . In: Phys. Chem. Earth . tape 10 , 1977, pp. 103-142 .

[1] D. Phinney et al .: 40Ar-39Ar dating of Apollo 16 and 17 rocks . In: Proc. 6th Lunar Sci. Conf . 1975, p. 1593-1608 .

[2] J. Longhi et al: The petrology of the Apollo 17 mare basalts . In: Proc. 5th Lunar Sci. Conf . 1974, p. 447-469 .

[3] FN Hodges, I. Kushiro: Apollo 17 petrology and experimental determination of differentiation sequences in model Moon compositions . In: Proc. 5th Lunar Sci. Conf . 1974, p. 505-520 .

[4] E. Roedder, PW Weiblen: Anomalous low-K silicate melt inclusions in ilmenite from Apollo 17 basalts . In: Proc. 6th Lunar Sci. Conf . 1975, p. 147-164 .

[5] C. Meyer: Lunar Sample Compendium: 70017 . 2008.

[6] JB Paces et al: A strontium and neodymium isotopic study of Apollo 17 high-Ti mare basalts: resolution of ages, evolution of magmas and origin of source heterogeneities . In: Geochimica Cosmochimica Acta . tape 55 , 1991, pp. 2025-2043 .

[7] LE Nyquist: Lunar Rb-Sr chronology . In: Phys. Chem. Earth . tape 10 , 1977, pp. 103-142 .