Micrometeorites from Antarctica: Powerful tools to study the formation and evolution of Solar System materials - by Steven Goderis & colleagues

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1. ! ! by Steven Goderis (VUB and UGent) & colleagues Expeditions of 2010-2011 & 2012-2013 Micrometeorites from Antarctica Powerful tools to study the formation and evolution of Solar System materials
2. Chelyabinsk meteorite Airburst over the city of Chelyabinsk at a height of 23.3 km (14.5 miles) ! Bright flash, smaller fragmentary meteorites, and a powerful shock wave (kinetic energy before impact ~ 20-30 x E released from the atomic bomb detonated at Hiroshima ! 1600 people injured - broken glass when shock wave arrived a few minutes later ! ! 17-20 meters in size = largest since 1908 Tunguska event, destroyed wide, remote, forested area of Siberia Wikipedia image
3. Chelyabinsk meteorite Airburst over the city of Chelyabinsk at a height of 23.3 km (14.5 miles) ! Bright flash, smaller fragmentary meteorites, and a powerful shock wave (kinetic energy before impact ~ 20-30 x E released from the atomic bomb detonated at Hiroshima ! 1600 people injured - broken glass when shock wave arrived a few minutes later ! ! 17-20 meters in size = largest since 1908 Tunguska event, destroyed wide, remote, forested area of Siberia Wikipedia image Pierazzo and Artemieva (2012)
4. Micrometeorites: 50 μm-2 mm ! IDP (Brownlee particles): ~5-20 μm (cometary dust) ! Cosmic dust: Micrometeorites + IDP ! Cosmic spherules: Melted micrometeorites Hutchison 2004 Annual global flux of ET material 100 µm
5. Micrometeorites: 50 μm-2 mm ! IDP (Brownlee particles): ~5-20 μm (cometary dust) ! Cosmic dust: Micrometeorites + IDP ! Cosmic spherules: Melted micrometeorites Hutchison 2004 Annual global flux of ET material 100 µm 53Mn produced by solar proton on IDP in ice: location min. snow accumulation & contamination, large ice volume, 3 tons collected (<1952) : ET flux 105 tons/y
6. Where can micrometeorites be found? • Ocean sediments: 1873-1876 expedition of HMS Challenger ! • Terrestrial sediments: ‣ Claystones & hardgrounds (< sedimentation rates) ‣ Salt deposits & limestones (easily dissolved) ‣ Deserts & beach sands ! • Polar depositions: much less weathered (large numbers of glass & unmelted spherules) ‣ Greenland snow ‣ Greenland cryoconite ‣ Antarctic blue ice & aeolian debris ‣ Ice cores ‣ Bottom of the South Pole water well ‣ Present-day Antarctic snow ‣ Antarctic sediment traps Antarctic micrometeorites = AMMs
7. French-Italian team in 2006: AMMs on the tops of Victoria Land Transantarctic Mountains Rochette et al. (2008) Miller Butte (2600 masl) Surface exposure > 1 Ma Images courtesy of L. Folco & P. Rochette
8. Search for Antarctic Meteorites, Belgian Activities: SAMBA Asuka Station (Japan, inactive) Princess
 Elisabeth Station
 (Belgium) 100 km Sør Rondane Mts. Yamato Mts. Mt. Balchen Nansen Icefield 1st find (1969) Japanese team 90°W 0° 90°E 80°S 70°S Syowa Station Yamato Mountains Belgica Mountains Sør Rondane Mountains Asuka Station McMurdo Station
9. Search for Antarctic Meteorites, Belgian Activities: SAMBA Asuka Station (Japan, inactive) Princess
 Elisabeth Station
 (Belgium) 100 km Sør Rondane Mts. Yamato Mts. Mt. Balchen Nansen Icefield 1st find (1969) Japanese team 90°W 0° 90°E 80°S 70°S Syowa Station Yamato Mountains Belgica Mountains Sør Rondane Mountains Asuka Station McMurdo Station
10. • Meteorites easily found (black spots on blue ice) • Good conservation of the meteorites (frozen), limited terrestrial alteration in dry cold climate • Concentration of meteorites in specific ice fields due to glacier movements or accumulation within moraines US: ANSMET ~ yearly expedition since 70s NIPR Japan regular expeditions Occasional contributions from other countries Why is Antarctica so important? Meteorites fall randomly all over the earth
11. Asuka meteorites 3278 specimens found around the Sør Rondane Mountains (6-7% all meteorites worldwide) Field season (Name) Mission Number of meteorites Bare ice field 1986-1987 (Asuka-86) JARE-27 3 Mt. Balchen 1987-1988 (Asuka-87) JARE-29 ~100 ~200 352 total Mt. Balchen Nansen Icefield 1988-1989 (Asuka-88) JARE-29 1597 Nansen Icefield 1990-1991 (Asuka-90) JARE-31 48 Mt. Balchen 2009-10 (Asuka-09) JARE 51-SAMBA 635 Mt. Balchen 2010-11 (Asuka-10) SAMBA 218 Nansen Icefield (NW) 2012-13 (Asuka-12) SAMBA-JARE 54 425 Nansen Icefield
12. Sør Rondane Mts Nansen Icefield Princess Elisabeth
 Station (Belgium) 50 km Mt. Balchen Satellite image of ice fields around the Sør Rondane Mts Asuka Station (Japan, inactive) SAMBA & JARE-54 2012-2013 425 specimens JARE 51 2009 -2010 635 specimens SAMBA 2010-2011 218 specimens NW Nansen
13. Sør Rondane Mts Nansen Icefield Princess Elisabeth
 Station (Belgium) 50 km Mt. Balchen Satellite image of ice fields around the Sør Rondane Mts Asuka Station (Japan, inactive) SAMBA & JARE-54 2012-2013 425 specimens JARE 51 2009 -2010 635 specimens SAMBA 2010-2011 218 specimens NW Nansen
14. High altitude (> 2000 m) outcrops of granite/gneiss, wind-exposed areas, 20 kg of fine material rich in micrometeorites was collected 2012-2013
15. E-SE dominant wind 2012-2013 season: most successful at Widerøfjellet (~2750 masl) Open to the plateau
16. ~1000 MMs (200-800 μm) per kg Protocol • Sieving (3 mm, 800 μm, 400 μm, 200 μm, 125 μm, and below) • Picking under microscope (time consuming) • CT scans • SEM imaging & characterization • Embedding & polishing • EPMA • NanoSIMS & IR fluorination • LA-ICP-MS • Destructive: TIMS & MC-ICP-MS? ! ! ! ! 100 µm 100 µm 100 µm 100 µm Origin? ! Asteroids vs. comets Images courtesy of M. Huber
17. (A) An I-type cosmic spherule dominated by magnetite and wüstite intergrowths. (B) A G-type cosmic spherule dominated by dendritic magnetite. (C) A V-type (vitreous) cosmic spherule (namely a CAT subtype). (D) An S-type (stony) vesicular cryptocrystalline cosmic spherule. (E) S-type microcrystalline cosmic spherule. (F) S-type barred olivine cosmic spherule. (G) S-type porphyritic cosmic spherule with relatively coarse-grained olivine microphenocrysts (H) S-type vesicular porphyritic cosmic spherule with relatively fine-grained olivine microphenocrysts (I) S-type, relict bearing, porphyritic olivine cosmic spherule (J) C1-type unmelted micrometeorite (K) C2-type fine-grained unmelted micrometeorite (L) Partially melted scoriaceous micrometeorite (M) Unmelted coarse-grained micrometeorite consisting of 2 porphyritic chondrules. (N) Unmelted coarse-grained micrometeorite (3D) consisting of a single porphyritic chondrule. (O) Unmelted coarse-grained micrometeorite with a chondritic structure. Classification Transantarctic Mt. collection (Rochette et al., 2008)
18. How do cosmic spherules melt? • “Shooting Stars” • Cosmic spherules are micrometeorites that have been melted • In this study, size is between 200-800 µm • Primarily consist of olivine, some have Fe + Ni metal segments • Studied using X-ray computed tomography (CT) scans at Ghent University: voxel size of 2 μm, up to 50 spherules/scan, processed using in-house software
19. Huber et al. (2014) MetSoc
20. µXRF IRMS FE-SEM/EPMA Raman + ... LA-ICP-MS MC-ICP-MS TIMS Still a lot to be done…
21. Thanks to InBev-Baillet Latour, IPF, BELSPO, FWO, NIPR, VUB, ULB, Matthew Huber (VUB), Vinciane Debaille (ULB), Claudio Ventura Bordenca (VUB), Phil Claeys (VUB), Tim de Kock (UGent), Isabelle Vandaele (VUB) and many others… !