1. Re: Symplectite Formation (Stephen Haggerty)
 2. Re: Symplectite Formation (Hahn Jr, Timothy Michael)

Dear Tim, I think that the following publication might be of interest to you: Khisina, N R, R Wirth, and M A Nazarov. 2011. “Lamellar Pyroxene-Spinel Symplectites in Lunar Olivine from the Luna 24 Regolith.” /Geochemistry International/ 49 (5). SP MAIK Nauka/Interperiodica: 449–58. doi:10.1134/S0016702911050041. http://dx.doi.org/10.1134/S0016702911050041. Furthermore, you might want to look for the work of Patrick Remmert, how worked on symplectites in his PhD. Good luck, Katharina Marquardt Am 2015-04-29 um 19:10 schrieb msa-talk-request@minlists.org: > Send MSA-talk mailing list submissions to > msa-talk@minlists.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.minlists.org/mailman/listinfo/msa-talk > or, via email, send a message with subject or body 'help' to > msa-talk-request@minlists.org > > You can reach the person managing the list at > msa-talk-owner@minlists.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of MSA-talk digest..." > > > Today's Topics: > > 1. Re: Symplectite Formation (Stephen Haggerty) > 2. Re: Symplectite Formation (Hahn Jr, Timothy Michael) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 29 Apr 2015 16:56:56 +0000 > From: Stephen Haggerty <haggerty@fiu.edu> > To: Robert Tracy <rtracy@vt.edu>, Bob Dymek <bob_d@levee.wustl.edu> > Cc: "msa-talk@minlists.org" <msa-talk@minlists.org> > Subject: Re: [MSA-talk] Symplectite Formation > Message-ID: <1430326616644.13359@fiu.edu> > Content-Type: text/plain; charset="utf-8" > > ?Hi Tim: > > > Enjoyed Bob's comment and am reminded: 1. an 'unpublishable' note from Robin Brett on the matter; and 2. of the heady lunar days & the wonderful UMass encounters with Bob Tracy & colleagues. > > We have looked at a large number of symplectites in mantle xenoliths [Field & Haggerty (1994) CM&P 118, 138-156; and Field (2008) Am Min 93, 618-631], in which many but not all are associated with garnet. Although we invoke a range of reactions [a liberty in the mantle!] the classic goes back to Ian McGregor (1974): > > Ol + Gt = Opx + Sp. One of your BS images looks very much like an advancing Ol-front. However, rather doubt that Larry or Hap would entertain Gt in your ET sample? > > > Best regards, Steve Haggerty > > > ________________________________ > > From: msa-talk-bounces@minlists.org <msa-talk-bounces@minlists.org> on behalf of Robert Tracy <rtracy@vt.edu> > Sent: Wednesday, April 29, 2015 12:30 PM > To: Bob Dymek > Cc: msa-talk@minlists.org > Subject: Re: [MSA-talk] Symplectite Formation > > Tim, > > I worked extensively on 76535 at that time with Steve Haggerty, although no publication resulted, and I agree entirely with Bob that the most reasonable interpretation of the features of the symplectic intergrowths suggest simultaneous crystallization of late-stage magmatic phases in a eutectoid form oin the interstices between larger olivine and plag grains. What he didn't mention, and I suspect he would agree with me on this, is that the proposed olivine-anorthite solid-state reaction was probably to a large extent intended to be a "wishful thinking" bit of evidence for lunar subsolidus metamorphism. > > Bob T. > > Dr. Robert Tracy > Professor of Geosciences > Associate Department Head > Director, Museum of Geosciences > Virginia Tech > Blacksburg VA 24061-0420 > 540-231-5980 > 540-231-3386 (F) > > > > > On Apr 29, 2015, at 11:38 AM, Bob Dymek <bob_d@levee.wustl.edu<mailto:bob_d@levee.wustl.edu>> wrote: > > Dear Tim, > > The "symplectites" in your extraterrestial sample invite a comparison to those found in lunar troctolte sample 76535. The origin of these intergrowths was the subject of a heated debate back in the 1970s (and disagreement continued for a long time afterwards, perhaps to this very day). The symplectites were interpreted originally by Gooley et al. as the products of a solid-state reaction between olivine+plagioclase. We offered the alternative that the symplectites resulted from melt crystallization producing a eutectoid-like intergrowth. Perhaps the information contained in those papers would be of use to you in your studies. Good luck. > > Cheers, > > Bob Dymek > > > > At 05:42 AM 4/29/2015, Hahn Jr, Timothy Michael wrote: > Content-Language: en-US > Content-Type: multipart/alternative; > boundary="_000_B2295C2794A54F66BF07DC0B6525453Dvolsutkedu_" > > Dear all, > > I am a masters student currently working on a research project and I have come across an unusual symplectite. Myself and others have tried multiple explanations for the formation of these symplectites but everything usually ends up as a dead end. I have inserted a link containing two images of the symplectites (images were too large to include in the message). I was wondering if anyone might have some explanation for a formation mechanism? I should also add that these are extraterrestrial sample. Any comments would be greatly appreciated! If anyone is interested I have additional material regarding these symplectites. > > These symplectites are found in Mg-rich olivine and pyroxene (Mg # > 85) clasts that are contained within breccias. The symplectites have sharp boundaries against the adjacent phases and appear to have some type of crystallographic control, which is indicated by the heterogenous nature of the chromite lamellae (this may indicate a polycrystalline precursor). Some of the symplectites contain minor FeNi metal, troilite, and Ca-pyroxene, as well as ???islands??? of orthopyroxene (if the symplectites represent a breakdown textures these could possibly be relict inclusions). I have reconstructed the bulk composition of the symplectites using broad beam analyses, as well as point counting from individual analyses. I have included the bulk composition below from both the broad beam analyses and point count reconstruction. There is a big difference between the two methods and this is probably due to the density consideration when using the point counting method or the errors ass > ociated with broad beam analyses. The stoichometry does not match any known mineral when using either the broad beam or the point count reconstruction as the starting composition. > > > https://docs.google.com/document/d/1wD7sKfAoQrdrXuKjvyTctfslHnDw4zWm8mgijY3GOxA/edit?usp=sharing > > > Thanks, > > Timothy M. Hahn Jr. > > M.S. Geology Candidate > University of Tennessee, Knoxville > 2236 Fisher Place > Knoxville, TN 37920 > (314) 288-7360 > > > > > Point Count Reconstruction > > SiO2 21.98 > TiO2 0.09 > Al2O3 2.19 > V2O3 0.41 > Cr2O3 40.41 > MgO 16.87 > CaO 0.31 > MnO 0.47 > FeO 17.02 > Total 99.76 > > > > Broad Beam > > SiO2 39.6 > TiO2 0.04 > Al2O3 1.2 > V2O3 0.2 > Cr2O3 20.9 > MgO 25.1 > CaO 1.5 > MnO 0.4 > FeO 12.5 > Na2O n.d > Total 101.5 > > > > _______________________________________________ > MSA-talk mailing list > MSA-talk@minlists.org<mailto:MSA-talk@minlists.org> > http://lists.minlists.org/mailman/listinfo/msa-talk > > Robert F. Dymek, Ph.D. > Professor of Geology > Department of Earth & Planetary Sciences > Rudolph Hall > Washington University > St. Louis, MO 63130 > 314-935-5344 (office) > 314-935-7361 (facsimile) > > _______________________________________________ > MSA-talk mailing list > MSA-talk@minlists.org<mailto:MSA-talk@minlists.org> > http://lists.minlists.org/mailman/listinfo/msa-talk > >