Kevin Righter, NASA-JSC
This newsletter reports 238 new meteorites from the 2010 and 2012 ANSMET seasons from the Buckley Island (BUC10), Dominion Range (DOM10), La Paz Ice Field (LAP10), Graves Nunatak (GRA12) Larkman Nunatak (LAR12) and Szabo Bluff (SZA12) areas. There are some exciting samples many of which reflect the ongoing diversity of meteorites coming from the Larkman Nunatak area. Detailed descriptions are provided for three new shergottites (one likely paired with LAR 06319, and two others that are paired with each other), 9 HED meteorites, 10 carbonaceous chondrites (CK, CO, CR, and CV), one L3.5 chondrite, and several impact melt breccias (L and LL). We also have updated descriptions for 6 shock blackened L chondrites from Buckley Island previously announced in AMN 36,1.
New rules for PIs: loan agreements and annual inventories
This summer we will start two new policies regarding the loans of Antarctic meteorites from the US collection at NASA-JSC. We will start with annual inventories for all scientists holding samples from our collection. Following the release of the Fall 2013 newsletter, all scientists currently holding or wishing to request samples from our collection will need to have a valid loan agreement on file.
First, we will be initiating an annual inventory of samples that are on loan. The inventory will be emailed to each scientist. We will require an update for every sample that is on loan; for example, if a thin section has been loaned, we would like verification that that section is still held in the possession of the scientist. If a chip is on loan, we would like verification that that chip is still held by the scientist. If there are any changes to that status, such as a chip has been dissolved or consumed for chemical analysis, we require that information to be filled out on the inventory. The inventories are designed to be brief and non-intrusive, and anyone who does not return an inventory summary to the JSC curation office cannot continue to receive meteorite samples. This is also a good opportunity to return any meteorite samples on loan that are no longer being used, or for which the loan period has expired. When you receive your Antarctic meteorite inventory by email, please fill it out and return it to us (by email) as soon as you can. Delays on your end will just cause delays in getting samples out to you.
Second, we will be requiring loan agreements to be completed for each scientist currently holding or requesting meteorites on loan from us. The loan agreements will last five years and must be renewed and kept current as long as the scientist wishes to continue to study samples from our collection. Any scientist who does not have a valid/current loan agreement filed with us at JSC cannot receive meteorite samples. Loan Agreements can be downloaded from our website, and once filled out and signed by the PI and an institution official (department chair, dean, provost, etc.) can be scanned and emailed, or mailed to us. You may do this anytime starting immediately.
These two new policies are explained in detail in our new Antarctic Meteorite Sample Investigators Guidebook.
Meteorite reclassifications / corrections
In light of new information collected and published recently by D.W. Mittlefehldt, the following samples are reclassified:
LEW 87002: LEW 87002, initially classified as a Eucrite, Mg-rich (Antarctic Meteorite Newsletter 11(2), page 29, 1988), is a fragmental breccia containing mm-sized clasts of low-Ca pyroxene, a mafic clast with subophitic texture, and a matrix composed mostly of low-Ca pyroxene and plagioclase. Low-Ca pyroxenes in the matrix, the margins of orthopyroxene clasts, and from the margin of the mafic clast are relatively uniform in Fe/Mg and have compositions of Wo2.5-3.5En64.4-66.3Fs31.0-32.1. High-Ca pyroxene compositions in the same petrologic settings are Wo40.4-42.0En43.4-45.4Fs14.3-15.3. The most magnesian orthopyroxene in the core of a mm-sized clast is Wo0.8En77.0Fs22.2, the most ferroan low-Ca and high-Ca pyroxenes from the mafic clast core are Wo2.5En58.1Fs39.4 and Wo43.0En41.2Fs15.8. Olivine compositions are Fo60.6, plagioclase compositions range from AnAb5.2Or0.2 to An87.0Ab12.4Or0.6. The bulk rock composition determined by Warren et al. (2009; GCA 73:5918) has a subchondritic Eu/Sm and ma94.6jor element composition consistent with a mixture of diogenite:basaltic eucrite of ~65:35. LEW 87002 is a howardite exhibiting an exceptional degree of post-assembly metamorphism that caused large-scale Fe-Mg exchange.
QUE 97002: QUE 97002, initially classified as a howardite, (Antarctic Meteorite Newsletter 21(2), page 18, 1998), is a fragmental breccia with a matrix composed mostly of ferroan low-Ca pyroxene and plagioclase, and containing mm-sized mafic clasts with subophitic/ophitic textures. The most magnesian pyroxene given in the initial description has a composition of Wo2En44Fs54, within the range of cumulate eucrites. The most magnesian pyroxene in section ,34 is Wo5.4En62.0Fs32.6 which is just within the ranges of the most ferroan diogenites and the most magnesian cumulate eucrites. Other coarse pyroxene fragments have compositions of Wo16.5-22.0En30.5-35.1Fs46.5-48.8, within the ranges of basaltic eucrites. Five whole rock samples have compositions consistent with mixtures of >90 wt% basaltic eucrite. QUE 97002 is a polymict eucrite.
Fieldwork news for Fall, 2013: Same Great Products at the Same Great Price!
Ralph Harvey, Case Western Reserve University
The Antarctic Search for Meteorites program (ANSMET) is now officially “Under New Management ”. Many of you are aware that in 2012 NSF decided they would no longer directly fund ANSMET fieldwork. NASA immediately began working with us to continue the Antarctic meteorite recovery efforts, and I'm happy to announce a successful transition. Just a few days after NSF funding officially expired at the end of July, NASA approved support for the 2013-2014 and 2014-2015 field seasons, ensuring continuity for the near term.
Our plans for the 2013-2014 field season include a return to the icefields of the Miller Range in the central Transantarctic Mountains, high on the polar plateau and situated between the drainages of the Beardmore and Nimrod glaciers. Four previous seasons of systematic searching (2005-2006, 2007-2008, 2009-2010 and 2011-2012 as well as several shorter reconnaissance visits (in 1985, 1999 and 2003) have resulted in the recovery of nearly 2400 meteorite specimens from these icefields, including many rare meteorites such as martian and lunar samples. The MIL meteorites come from a variety of icefields in different settings distributed across almost 60 km of the Miller Range, and the areas remaining to be searched sit at both ends. Some of our plans for the current season are recycled from the 2011-2012 season, when an overabundance of snow made us less productive than we had hoped. We’ll start at the northern end of the range where a few small blue ice patches in valleys facing out on the Nimrod yielded surprising numbers of specimens. When that work is done, we'll traverse southward (into the wind and uphill) to the other end of the Miller Range where a large icefield represents the last major challenge to completion of our work in the region. Seven seasons in the Miller Range have taught us that the weather can vary dramatically from season to season so we know better than to predict how things will go; but if good conditions prevail we hope to complete a large part of the searching that remains.
As in previous seasons, we plan to update our weblog daily; visit us at http://Case.edu/ansmet to see how we're doing.
Systematic searching on the southern Miller Range icefield (courtesy Anne Peslier, JSC / ANSMET)
Report from the Smithsonian
Cari Corrigan, Geologist (Dept. of Mineral Sci.)
This newsletter announces the classification of 238 meteorites from the 2010 and 2012 ANSMET seasons. Since the last newsletter, we have said goodbye to Sheri Singerling. Sheri has moved to Albuquerque, New Mexico to begin a Ph.D. with Dr. Adrian Brearley at the University of New Mexico. We wish her all the best and thank her for all of her hard work over the past year! We have recently welcomed a new volunteer, Norman Burr, who will be helping us in the meteorite collection, and have also welcomed post doc Dr. Kathryn Gardner-Vandy (Ph.D. 2012, University of Arizona).