Report for the Joint Use/Research of the Institute for Planetary Materials,Okayama University
2019 fiscal year first term / second term / others
30/06/2020
Category:

International Joint Research/ General Joint Research/ Joint Use of Facility/ Workshop

Name of the research project: Mineralogy, chemistry and isotope systematics of an Argentinian
meteorite fall
Principal applicant: Dr. Julia Walter-Roszjar
Affiliated institution and department: Department of Mineralogy and Petrography, Natural
History Museum Vienna, Vienna, Austria
Collaborator:
Name: Prof. Ryoji Tanaka
Affiliated institution and department: Institute for Planetary Materials, Okayama University,
827 Yamada, Misasa, Tottori 682-0193, Japan
Research report:
Purpose of this international joint research project was a detailed petrological, chemical andisotopic analysis of a re-discovered differentiated meteorite (achondrite) fall from Argentina,
now termed “Malotas (b)” and classified as a basaltic eucrite and test of its’ potentiallypairing with a type H5 ordinary chondrite found nearby.
Both specimens were recently discovered in the local Cordoba museum, Argentina by Prof.
Maria Varela, which let to this joint research project. In principle, detailed investigations
using state-of the art instrumentations of these meteorites will help further our understandingof meteorite evolution and pairing in general such as the potential polymict (mixedlithologies) character of meteorite parent bodies and the genesis of basaltic eucrite inparticular.
Here, careful sample preparation was conducted and a stable isotope mass spectrometer(Thermo MAT253) and laser fluorination system at the IPM, Okayama University were used
to measure stable oxygen isotopes on representative sample aliquots. These informations,
together with petrological-mineralogical investigation of the meteorite material, made by theapplicant at the NHM Vienna, Austria are required (i) for an official classification of therock(https://www.lpi.usra.edu/meteor/metbull.php?sea=malotas&sfor=names&ants=&nwas=&falls=&

valids=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&categ=All&mblist=Al
l&rect=&phot=&strewn=&snew=0&pnt=Normal%20table&code=67632),(ii)

unambiguous

identification of its provenance, i.e., asteroidal parent body, Moon or Mars, (iii) and proof ofits’ potential pairing with the H5 ordinary chondrite, found 1931 at the same site in Santiagodel Estero, Argentina. First results were presented at the 82nd Annual meeting of theMeteoritical Society, held in Sapporo, Japan in July 2019. A paper, currently in preparation forsubmission to Meteoritics and Planetary Science, will also include trace element analysis of theMalotas (b) meteorite conducted by Prof. Muni Humayun and noble gas analysis of thesemeteorites, currently made by Dr. Henner Busemann.

Collaborations:
Prof. Maria Eugenia Varela and Dr. Marcela Saavedra, ICATE - Instituto de Ciencias Astronómicasde la Tierra, y del Espacio, Facultad de Ciencias Exactas, Fisicas y Naturales, Universidad Nacionalde San Juan, Av. España Sur 1512, J5402DSP, San Juan, Argentina
Prof. Munir Humayun, The National High Magnetic Field Laboratory, Florida State University,
1800 E. Paul Dirac Dr. Tallahassee , FL 32310-3706
Dr. Henner Busemann,, Institute of Geochemistry and Petrology, Clausiusstrasse 25, 8092 Zürich,
Switzerland

Outcome:
Official

classification

ofthemeteoriteintheMeteoritical

Bulletin

Database:https://www.lpi.usra.edu/meteor/metbull.php?sea=malotas&sfor=names&ants=&nwas=&falls=&v
alids=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&categ=All&mblist=All&rect=&phot=&strewn=&snew=0&pnt=Normal%20table&code=67632
Saavedra M. E., Roszjar J., Humayun M., Tanaka R., Varela M. E., Lira R. (2019) Malotas: A new viewof an old (paired?) meteorite fall from Argentina. In preparation for submission to Meteoritics andPlanetary Science.
Saavedra M. E., Roszjar J., Humayun M., Tanaka R., Varela M. E., Lira R. (2019) Malotas: A new viewof an old fall from Argentina. 82nd Annual meeting of the Meteoritical Society, held July 7-12,
Sapporo Japan, #6168.