Randy L. Korotev

Research Associate Professor
Ph.D., University of Wisconsin-Madison, 1976

Lunar Geochemistry

Dr. Korotev uses the chemical composition of lunar material as a tool to understand lunar geology.  He is mainly interested in the impact history of the Moon, how the Moon’s surface has been affected by meteorite impacts, and the nature of the early lunar crust.  

Lunar regolith at the Apollo 16 site.  Left: Astronaut Charles Duke about to chip a sample off a large rock in the regolith.  Middle: The rock after the sample was removed (right site; photos by John Young).  Right: The sample, known as 60018, in the curatorial facility at the NASA Johnson Space Center.  Sample 60018 is an impact-melt breccia.  Click on images for an enlargement.  (NASA images AS 16-116-18689, AS 16-116-18691, and S-72-36995)

  

With colleagues Brad Jolliff and Ryan Zeigler, Dr. Korotev measures and models the compositions of samples from the Apollo and Luna missions and from lunar meteorites. He also uses mineralogical and compositional data obtained by the Clementine (1994) and Lunar Prospector (1998-1999) missions.  He has developed techniques for precisely determining the chemical composition of large batches of lunar samples using instrumental neutron activation analysis.   

Small rock fragments from the Apollo 11 regolith. The image includes mare basalts, crystalline impact-melt breccias, regolith breccias, anorthosites, and glass fragments and spherules. The background grid spacing is 2 mm. Click on image for enlargement (566 kbytes). For more information about this photo, click here. Photo by Randy Korotev

The lunar surface is covered by a blanket of rock debris produced by more than 4 billion years of impacts. All of the samples collected on the Moon came from that regolith, which consists of material ranging in size from fine powder to large blocks. Measurements made by orbiting instruments such as those aboard Clementine and Prospector mainly obtained data from and about the regolith.  Lunar “soils” (regolith fines) consist of material that has been mixed and transported by many impacts, both large and small, local and distant. Mixing is not complete, however, and compositional differences occur among the landing sites and among soil samples taken at different depths and from different locations at a given landing site because of variable proportions of component rocks. These variations largely reflect the local bedrock geology, but also the nature and efficiency of the impact-mixing process.

Lunar soils from the Apollo sites (e.g., A12 = Apollo 12) are mixtures of three types of material: (1) feldspathic (anorthositic) material of the Feldspathic Highlands Terrane, (2) mafic impact- melt breccias rich in incompatible elements (KREEP) from the Procellarum KREEP Terrane, and (3) volcanic basalt and glass from the maria.

The study of soils complements the study of rocks because the soils give a more representative estimate of the distribution of different rock types at a site than does the study of any reasonable number of large rocks. The compositions of soils can be modeled as mixtures of rock types observed to occur in the soil. However, many of these rocks types are themselves polymict breccias and glasses composed of more primitive rock types that have been melted, shocked, and relithified by numerous impacts; unbrecciated fragments of the original lunar crust are rare. Thus, in principal, it is also possible to account for the composition of a soil or breccia as mixture of igneous rocks of the earliest lunar crust even though those rocks are no longer easily identifiable components of the polymict samples. By combining data for samples with compositional data obtained by remote sensing of the lunar surface, the composition and mineralogy of the lunar crust can be inferred, and this imposes constraints on models for lunar crust formation and redistribution of material by large impacts.  Dr. Korotev and his colleagues are also using the data from the Clementine and Lunar Prospector missions to put data obtained lunar samples into a regional and global context.

Lunar meteorite Queen Alexandra Range (QUE) 93069/94269, a regolith breccia. Read more here.

Lunar meteorites are being found in remarkable numbers. They originate from 40 or more unknown locations on the Moon. Many are breccias composed of regolith. Several are unlike any rocks collected on the Apollo missions. Dr. Korotev and his colleagues study the geochemistry and petrology of lunar meteorites as a means of understanding the geological complexity of the Moon.

See also: Alter ego Randy L. Korotev | Washington University News & Information, February 2, 2006

Hudgins, J. A., Spray J. G., Kelley S. P, Korotev R. L., and Sherlock S. C. (in press) A laser probe 40Ar/39Ar and INAA investigation of four Apollo granulitic breccias. Geochimica et Cosmochimica Acta.

Korotev R. L. (2006) Larry A. Haskin (1934–2005) Geochimica et Cosmochimica Acta 70, 5899-5903.

Korotev R. L., Zeigler R. A., and Jolliff B. L. (2006) Feldspathic lunar meteorites Pecora Escarpment 02007 and Dhofar 489: Contamination of the surface of the lunar highlands by post-basin impacts. Geochimica et Cosmochimica Acta 70, 5935-5956.

Barra F., Swindle T. D., Korotev R. L., Jolliff B. L., Zeigler R. A., and Olson E. (2006) ⁴⁰Ar-³⁹Ar dating on Apollo 12 regolith: Implications on the age of Copernicus and the source of non-mare materials. Geochimica et Cosmochimica Acta 70, 6016-6031.

Zeigler R. A., Korotev R. L., Jolliff B. L., L Haskin. A., and Floss C. (2006) The geochemistry and provenance of Apollo 16 mafic glasses. Geochimica et Cosmochimica Acta 70, 6050-6067.

Lucey P., Korotev R. L., Gillis J. J., Taylor L. A., Lawrence D., Elphic R., Feldman B., Hood L. L., Hunten D., Mendillo M., Noble S., Papike J. J., and Reedy R. C. (2006) Chapter 2. Understanding the lunar surface and space-moon interactions. In New Views of the Moon, pp. 83–219. Reviews in Mineralogy and Geochemistry, Volume 60 (Jolliff, B. L. M. A. Wieczorek, C. K. Shearer, and C. R. Neal, eds.). Mineralogical Society of America, Washington, DC.

Wang A., Korotev R. L., Jolliff B. L., Haskin L. A., Crumpler L., Farrand W. H., Herkenhoff K. E., de Souza P. Jr., Kusack A. G., Hurowitz J. A., and Tosca N. J. (2006) Evidence of phyllosilicate in Wooly Patch, an altered rock encountered at West Spur, Columbia Hills, by the Spirit rover. Journal of Geophysical Research 111, E02S16, doi:10.1029/2005JE002516.

Zeigler R. A., Korotev R. L., Haskin L. A., Jolliff B. L., and Gillis J. J. (2006) Petrology and geochemistry of five new Apollo 16 mare basalts and evidence for post-basin deposition of basaltic material at the site. Meteoritics & Planetary Science 41, 263-284.

Korotev R. L. (2005) Lunar geochemistry as told by lunar meteorites. Chemie der Erde 65, 297–346.

Zeigler R. A., Korotev R. L., Jolliff B. L., and Haskin L. A. (2005) Petrology and geochemistry of the LaPaz icefield basaltic lunar meteorite and source-crater pairing with Northwest Africa 032. Meteoritics & Planetary Science 40, 1073–1102.

Korotev R. L. (2004) A unique chunk of the Moon. Science 305, 622–623.

Gillis J. J., Jolliff B. L., and Korotev R. L. (2004) Lunar surface geochemistry: Global concentrations of Th, K, and FeO as derived from Lunar Prospector and Clementine data. Geochimica et Cosmochimica Acta 68, 3791–3805. Erratum: 69, 5147–5148.

Korotev R. L., Jolliff B. L., Zeigler R. A., Gillis J. J., and Haskin L. A. (2003) Feldspathic lunar meteorites and their implications for compositional remote sensing of the lunar surface and the composition of the lunar crust.Geochimica et Cosmochimica Acta 67, 4895-4923.

Jolliff B. L., Korotev R. L., Zeigler R. A., Floss C., and Haskin L. A. (2003) Northwest Africa 773: Lunar mare breccia with a shallow-formed olivine-cumulate component, very-low-Ti (VLT) heritage, and a KREEP connection. Geochimica et Cosmochimica Acta 67, 4857–4879.

Kitts B. K., Podosek F. A., Nichols R. H. Jr., Brannon J. C., Ramezani J., Korotev R. L., and Jolliff B. L. (2003) Isotopic composition of surface-correlated chromium in Apollo 16 lunar soils. Geochimica et Cosmochimica Acta 67, 4881–4893.

Korotev R. L., Jolliff B. L., Zeigler R. A., and Haskin L. A. (2003) Compositional constraints on the launch pairing of three brecciated lunar meteorites of basaltic composition. Antarctic Meteorite Research 16, 152-175, Nat. Inst. Polar Res., Tokyo.

Fagan T. J., Taylor G. J., Keil K., Bunch T. E., Wittke J. H., Korotev R. L., Jolliff B. L., Gillis J. J., Haskin L. A., Jarosewich E., Clayton R. N., Mayeda T. K., Fernandes V. A., Burgess R., Turner G., Eugster O., and Lorenzetti S. (2002) Northwest Africa 032: Product of lunar volcanism. Meteoritics & Planetary Science 37, 371-394.

See also Department Publications

background image: Apollo 16 landing site

314-935-5637 Please don't call me if you think you have found a meteorite. Send me an e-mail message. Read this and this first.	korotev@wustl.edu
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