Relationships among basaltic lunar meteorites

During the past two years four meteorites of dominantly mare basalt composition were identified in the Japanese and US Antarctic collections. Basalts represent a much higher proportion of the lunar meteorites than is expected from photogeologic mapping of mare and highland regions. Also, the basaltic lunar meteorites are all described as VLT mare basalt, which is a relatively uncommon type among returned lunar samples. The significance of the basaltic meteorites to the understanding of the lunar crust depends on the evaluation of possible relationships among the individual meteorites. None of the specimens are paired meteorites. They differ from each other in petrography and composition. It is important to determine whether they might be paired ejecta which were ejected from the same mare region by the same impact. The question of paired ejecta must be addressed using a combination of exposure histories and petrographic/compositional characteristics. It is possible that the basaltic lunar meteorites are paired ejecta from the same region of the Moon. However, the relationships among them are more complicated than the basaltic breccias being simply brecciated mare gabbros

Guide to the US collection of antarctic meteorites 1976-1988 (everything you wanted to know about the meteorite collection). Antarctic Meteorite Newsletter, Volume 13, Number 1

The state of the collection of Antarctic Meteorites is summarized. This guide is intended to assist investigators plan their meteorite research and select and request samples. Useful information is presented for all classified meteorites from 1976 to 1988 collections, as of Sept. 1989. The meteorite collection has grown over 13 years to include 4264 samples of which 2754 have been classified. Most of the unclassified meteorites are ordinary chondrites because the collections have been culled for specimens of special petrologic type. The guide consists of two large classification tables. They are preceded by a list of sample locations and important notes to make the tables understandable

Spaceship Earth: A partnership in curriculum writing

As the Apollo astronauts left Earth to venture onto the surface of another planetary body, they saw their home planet in a new global perspective. Unmanned NASA missions have given us a closer look at all the other planets in our solar system and emphasized the uniqueness of Earth as the only place in our solar system that can sustain life as we know it. Spaceship Earth is a new science curriculum which was developed to help students and teachers to explore the Earth, to see it in the global perspective, and to understand the relationships among life, the planet, and the sun. Astronaut photographs, especially shuttle pictures, are used as groundbased studies to help students to understand global Earth Science and integrate various aspects of physical, life, and social science. The Spaceship Earth curriculum was developed at by a team of JSC scientists working in collaboration with teachers from local school districts. This project was done under the auspices of Partner-In-Space, a local non-profit organization dedicated to improving science education and our general knowledge of space. The team met once a month for a year then assembled the curriculum during the summer. The project is now in the testing stage as the teachers try it out in their classrooms. It was supported by the Texas Education Agency and will be offered by the State of Texas as a supplemental curriculum for statewide use. Because the curriculum was developed by teachers, it is self contained and the lessons are easy to implement and give students concrete experiences. The three sub-units follow in a logical order, but may be used independently. If they are used separately, they may be tied together by the teacher returning to the basic theme of the global Earth as each unit is completed

Geochemistry and petrology of a suite of ten Yamato HED meteorites

We have performed petrological characterization and geochemical studies by instrumental neutron activation analysis of a suite of ten Yamato HED samples : Y-74013,Y-74097 and Y-74136 (Type A diogenites); Y-75032 and Y-791199 (Type B diogenites); Y-791195 (cumulate eucrite); Y-793164 and Y-82066 (eucrites); and Y-791192 and Y-82049 (polymict eucrites). The Type A diogenites are essentially identical in composition except for slight differences in Cr, Co, Se and La, which are likely due to inhomogeneous distribution of the minor phases chromite, metal and troilite, and trapped interstitial melt, respectively. The petrology and REE patterns for Type B diogenites show that they are not adcumulate rocks, but rather, contain substantial, perhaps 15%, interstitial liquid trapped in the samples. Y-791195 is a cumulate eucrite intermediate in REE content between Serra de Mage and Moore County, but is more ferroan. Eucrite Y-82066 is similar in composition to trace element-poor main-group eucrites such as Sioux County, and may be a primitive partial melt of the HED parent body. Y-793164 is intermediate in composition between main-group eucrites and Nuevo Laredo in Fe, Cr, Sc and REE, and is an intermediate member of the Nuevo Laredo trend eucrites. Y-793164 is a residual liquid from perhaps 25-30% crystallization of a primitive main-group eucrite like Sioux County or Y-82066. Y-791192 and Y-82049 are classified as polymict eucrites, but major and trace element concentrations indicate that these meteorites contain about 36% and 48% diogenitic material, respectively. These samples are howardites based on our analyses. Y-82049 contains a wide range of pyroxene compositions, from magnesian orthopyroxene similar to Type A diogenite pyroxenes, to ferroan pigeonite similar to basaltic eucrite pyroxenes. Large pyroxene clasts in Y-791192 are dominantly similar to Type B diogenite pyroxenes

Heterogeneity in small aliquots of Apolllo 15 olivine-normative basalt: Implications for breccia clast studies

Most of the recent advances in lunar petrology are the direct result of breccia pull-apart studies, which have identified a wide array of new highland and mare basalt rock types that occur only as clasts within the breccias. These rocks show that the lunar crust is far more complex than suspected previously, and that processes such as magma mixing and wall-rock assimilation were important in its petrogenesis. These studies are based on the implicit assumption that the breccia clasts, which range in size from a few mm to several cm across, are representative of the parent rock from which they were derived. In many cases, the aliquot allocated for analysis may be only a few grain diameters across. While this problem is most acute for coarse-grained highland rocks, it can also cause considerable uncertainty in the analysis of mare basalt clasts. Similar problems arise with small aliquots of individual hand samples. Our study of sample heterogeneity in 9 samples of Apollo 15 olivine normative basalt (ONB) which exhibit a range in average grain size from coarse to fine are reported. Seven of these samples have not been analyzed previously, one has been analyzed by INAA only, and one has been analyzed by XRF+INAA. Our goal is to assess the effects of small aliquot size on the bulk chemistry of large mare basalt samples, and to extend this assessment to analyses of small breccia clasts

Geochemistry and origin of achondritic inclusions in Yamato-75097, -793241 and -794046 chondrites

We have performed instrumental and radiochemical neutron activation analyses of the host L6 chondrite and five splits of the Yamato (Y)-75097 achondritic inclusion, and achondritic inclusions from the Y-793241 (L6) and Y-794046 (H5) chondrites. The troctolitic inclusions from Y-75097 and Y-793241 show numerous compositional similarities, including low Sc contents, fractionated siderophile element patterns at low abundances, and commonly (though not always) depleted trivalent REE abundances but with Eu at near chondritic levels. The REE, however, are highly variable in the Y-75097 inclusion due to variations in modal merrillite. The lack of pyroxene in these inclusions is best explained by assuming the protolith was non-chondritic in bulk composition. However, it is not clear that nebular processes could produce a pyroxene-poor protolith. The siderophile element patterns in these inclusions can be modeled as residual metal left after partial melting of the Fe-FeS system. The Y-794046 inclusion is compositionally and mineralogically different from the other inclusions. Abundances of refractory through moderately volatile lithophile elements are unfractionated relative to mean H chondrites. Similarly, abundances of refractory through moderately volatile siderophile elements are in H chondritic relative proportions, but at ∿10% the abundance of mean H chondrites. This cosmochemical signature is most simply modeled as a result of impact melting of an H chondrite target, with loss of ∿90% of the immiscible Fe-FeS melt

Preliminary examination of the Yamato-86032 lunar meteorite: II. Major and trace element chemistry

The chemical composition of the new lunar meteorite Yamato-86032 has been studied by several laboratories in a consortium study. A preliminary report on the first analytical results from seven laboratories is given in this paper. The meteorite, which is the largest lunar meteorite recovered so far, is more heavily shocked than the other five lunar meteorites, which makes it difficult to classify the rock exactly. Although it may be classified as an anorthositic breccia the trace element composition of Y-86032 is somewhat different from the composition of the other known lunar meteorites. The major element chemistry of Y-86032 is similar to the other lunar meteorites, except for the iron content, which is lower by a factor of about 1. 4. Since the magnesium abundance is nearly identical there is a disparity in the mg ratio. The REE abundances in Y-86032 are very low and comparable to Y-82192/3. There is no evidence of any KREEP component. The abundances of several lithophile and incompatible elements are lower in Y-86032 than in the other lunar meteorites. The siderophile element contents are low and vary between individual chips. Sc, Cr, Mn, and Co have significantly lower abundances than in Y-82192/3. The chemical investigations demonstrate that Y-86032 is a new and important sample from the lunar highlands

Geochemistry of and alteration phases in martian lherzolite Y-793605

We have done preliminary SEM characterization of alteration phases on an exterior and an interior chip of martian lherzolite Yamato-793605,and have performed instrumental and radiochemical neutron activation analyses of a glass-poor and a glass-rich interior sample of the rock for a suite of 31 major and trace elements. To date, we have identified silica (containing minor amounts of S, K, Fe, Al), K-Fe-sulfate (probably jarosite) and Fe-phosphate as alteration phases in Y-793605. Of these, the silica and K-Fe-sulfate are likely terrestrial weathering products. Other evidence of alteration consists of what appear to be partly decomposed Ca-phosphate grains, which were probably originally igneous grains. No carbonates or Ca-sulfates have been identified as yet, and none of the alteration phases we have identified are unambiguously of martian origin. Compositionally, Y-793605 is very similar to the other two martian lherzolites ALHA77005 and LEW 88516. Our sample of Y-793605 is lower in the incompatible lithophile trace elements, such as the REE, than the average of either ALHA77005 or LEW 88516,but is within the ranges of individual analyses for ALHA77005. Y-793605 is a partial cumulate like the other lherzolites, but our sample contained less of a trapped melt component

Geochemistry of Yamato-82192, -86032 and -793274 lunar meteorites

The major and trace element compositions of lunar meteorites Yamato (Y)-82192,Y-86032 and Y-793274 were determined by neutron activation analysis. Y-82192 and Y-86032 are anorthositic lunar meteorites rich in Al_2O_3 and CaO and poor in FeO, MgO and incompatible elements. Although these meteorites are similar in composition to each other and other anorthositic lunar meteorites, they are distinct in several key compositional characteristics. Y-793274 is a basaltic lunar meteorite rich in FeO, MgO, Sc, Cr, Co, and incompatible elements and poor in Al_2O_3 and CaO compared to anorthositic lunar meteorites. It is similar in many ways to lunar meteorite EET87521 which is also a basaltic breccia. It is distinct from EET87521 in its higher proportion of highland material, its meteoritic contamination and regolith glass, and in the composition of its dominant basalt component. Y-793274 contains 65-75% magnesian VLT basalt, while EET87521 consists of ferroan VLT basalt. The eleven lunar meteorites probably represent eight distinct falls. Four are anorthositic and four are basaltic. This 50-50 proportion of highlands-mare material contrasts strongly with the 83-17 proportion derived from photogeologic mapping. The dominance of VLT basalt among lunar meteorites contrasts with its scarcity among Apollo samples. The resolution of these discrepancies awaits further studies of basaltic lunar meteorites and further discoveries of new lunar meteorites

Preliminary report on the Yamato-86032 lunar meteorite: I. Recovery, sample descriptions, mineralogy and petrography

A preliminary consortium examination of the largest lunar meteorite (Y-86032) recovered from the Yamato Mountains revealed that it is a feldspathic breccia, but rather resembles feldspathic fragmental breccias than regolith breccias. Y-86032 is a rugged grayish stone penetrated by numerous compact clast-laden impact melt glassy veins. Distributions of pyroxene and plagioclase chemical compositions are similar to those of Y-82192 and Y-82193,and clast-laden glassy veins and granulitic breccias are abundant. A large light clast in the first consortium sample is another feldspathic fragmental breccia similar to that found in Y-82192