Al-rich chondrules (ARCs) are a rare constituent of chondrites. They have relatively high bulk Al_2O_3 content (> 10 wt%), which is due to the presence of Al-rich phases, such as plagioclase, spinel, Al-rich glass etc. [1]. ARCs share some chemical and petrologic characteristics with Ca, Al-rich inclusions (CAis), and may represent a genetic link between ferromagnesian chondrules and CAis

Bannister, M. T.

Beshore, E.

Brown, M. E.

Garradd, G.

Larson, S.

McNaught, R.

Schmidt, B. P.

English

The population of icy objects beyond Neptune provide dynamical and compositional insight into the early history and subsequent evolution of the Solar System. The past several years have seen the completion of major surveys of this population across the Northern Hemisphere sky and the introduction of surveys in the South. We present the results of our archival search of more than ten thousand

square degrees of sky south of the ecliptic observed over five years, with an approximate limiting flux of m(clear)~19.5. We detail our innovative survey technique, its null detection, and our modelling of the survey's sensitivity via a synthetic population of trans-Neptunian objects (TNOs)

Caltech Authors - Main

75th Annual Meteoritical Society Meeting (2012) 
THE DETECTION LIMITS FOR TRANS-NEPTUNIAN 
DWARF PLANETS OF THE SIDING SPRING SURVEY. 
M. T. Bannister (1), M. E. Brown (2), B. P. Schmidt (1), R. 
McNaught (3), G. Garrad (3), S. Larson (4) and E. Beshore (4) 
(1) Mt Stromlo Observatory, the Australian National Universi-
ty (2) GPS, Caltech (3) Siding Spring Observatory, ANU (4) 
University of Arizona. E-mail: michele@mso.anu.edu.au 
Introduction: The population of icy objects beyond 
Neptune provide dynamical and compositional insight into 
the early history and subsequent evolution of the Solar Sys-
tem. The past several years have seen the completion of major 
surveys of this population across the Northern Hemisphere 
sky and the introduction of surveys in the South. We present 
the results of our archival search of more than ten thousand 
square degrees of sky south of the ecliptic observed over five 
years, with an approximate limiting flux of m(clear)- 19.5. 
We detail our innovative survey technique, its null detection, 
and our modelling of the survey's sensitivity via a synthetic 
population of trans-Neptunian objects (TNOs). 
Survey: The Siding Spring Survey is an ongoing survey 
for near-Earth asteroids that has been operating at the 0.5 m 
Uppsala telescope at Siding Spring Observatory since 2004. 
In the five years to late 2009, it observed each of - 2300 4.55 
square degree fields on between 30 and 90 nights. These 
fields span approx. -15 to -70 dec! ination and the full range 
in right ascension, avoiding the galactic plane by I 0 degrees 
either side. Although this Uppsala observing cadence is much 
more widely spaced than that of a purpose-designed 1NO 
survey, its dense temporal coverage was sufficient to allow 
any bright dwarf planets to be detected many tim on each field 
in the course of each year. This would provide high-quality 
orbits with multiple oppositions to any discoveries. 
Algorithm: We extracted the transient sources from these 
images and permute all sets of three sources (triplets) generat-
ed from observations of the same field made within a 180-day 
period centred on opposition. We overcome the computation-
al demands of fitting orbits to these abundant triplets 
through a prefilter for bound, plausible outer Solar System 
orbits, then fully fit the selection through the orbfit package 
[1]. Arcs are created by linking all permutations of two 
triplets and refitting for valid orbits, then visually inspecting 
for false positives. This proved highly parsimonious and left 
no dwarf planet detections. 
Efficiency limits: We simulate the observation of [2]'s 
synthetic Centaur, Kuiper belt and scattered disk populations 
according to their sky positions throughout the five years of 
Uppsala surveying. We apply a range of absolute magnitudes 
to each observable object, evaluate each against the visible 
magnitude limit of its corresponding observation, and orbit-
fit triplets and arcs of the successful detections. From this we 
compute our detection efficiencies as a function of 1NO 
orbital parameter space. 
Results: We detect no new dwarf planets. We note that all 
known dwarf planets, including Pluto, fall outside our survey 
coverage in its temporal span. (Recently discovered 2012 
DR30 moved onto northerly fields with too few nights to be 
considered in this survey only after our survey period had 
concluded). This result places constraints on the bright end of 
the trans-Neptunian population, and models of 1NO size 
distribution. 
References: [1] Bernstein G. and Khushalani B. 2000. 
Astronomical Journal 120:3323. [2] Grav T. et a!. 2011. 
Publications of the Astronomical Society of the Pacific 123 
(902):423-447. 
5385.pdf 


The Detection Limits for Trans-Neptunian Dwarf Planets of the Siding Spring Survey

Hsu, W.

Guan, Y.

Jiang, Y.

Wang, Y.

75th Annual Meteoritical Society Meeting (2012) 
OXYGEN ISOTOPES OF AL-RICH CHONDRULES 
FROM UNEQUILIBRATED ORDINARY CHONDRITES. 
W. Hsu1, Y. Guan2, Y. Jiang 1, andY. Wang 1• 1Purple Mountain 
Observatory, Nanjing, China. E-mail: wbxu@pmo.ac.cn. 2GPS, 
Caltech, Pasadena, CA 91125. 
Al-rich chondrules (ARCs) are a rare constituent of chon-
drites. They have relatively high bulk Al20 3 content(> 10 wt%), 
which is due to the presence of Al-rich phases, such as plagioc-
lase, spinel, Al-rich glass etc. [1]. ARCs share some chemical 
and petrologic characteristics with Ca, Al-rich inclusions (CAis), 
and may represent a genetic link between ferromagnesian chon-
drules and CAis. 
Twelve ARCs were found in unequilibrated ordinary chon-
drites (UOCs) GRV 022410 (H4), GRV 052722 (H3 .7), GRV 
020104 (H3.4), GRV 050016 (H3.7), GRV 050009 (H3.6), and 
Julesburg (L3.6) [2]. They contain bulk Al20 3 - 16-33 wt% and 
exhibit igneous textures comprised of olivine, diopside, plagioc-
lase, spinel, and glass. In situ SIMS analyses show that ARCs 
have oxygen isotopic compositions (1i 180 -6.1 %o - 7.1 %o; 1i 170-
4.5%o- 5.1%o) close to ferromagnesian chondrules but far more 
depleted in 160 than CAis (1i 180 - - 40%o; 1i 170 - -40%o). Most 
ARCs plot close to the TF line, and a few between the TF and 
CCAM lines. All ARCs define a line with a slope of- 0.79 ± 
0.07. They are 160 -poor relative to their counterparts in [3] but 
similar to those in [4]. The oxygen isotope data indicate that 
ARCs from UOCs do not represent a simple mixing product of 
ferromagnesian chondrules and CAis. Instead, they probably ex-
perienced higher-degree oxygen isotopes exchange with 160 -poor 
nebular gas reservoir during multiple heating events. 
References: [1] MacPherson G. J. and Huss G. R. 2005. 
Geochim. Cosmochim. Acta 69:3099-3127. [2] Jiang Y. and Hsu 
W. 2009. Chinese J. Polar Sci. , 20:135-150. [3] RussellS. S. et 
al. 2000. Earth Planet. Sci. Lett. 184:57-74. [4] Nagahara H., et 
al. 2009. Geochim. Cosmochim. Acta 72:1442-1465. 
Acknowledgement: Samples used in this study are provided 
by the Polar Research Institute of China. This work was sup-
ported by the National NSF of China (Grant No. 41173076 and 
10921 063) and by the Minor Planet Foundation of China. 
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5165.pdf 


Oxygen Isotopes of Al-Rich Chondrules from Unequilibrated Ordinary Chondrites

The Moon has been thought to have a bulk planetary water content < 1 ppb [1]. Recent ion microprobe analyses have shown that lunar samples contain up to 7000±1000 ppm OR (reported as equivalent H_20) in apatite and 4-46 ppm in

igneous glass [2-6]. These studies suggest that the mantle

sources of at least some lunar magmas contain from 64 ppb to

200 ppm [4-6]. Sharp et al. [6] report an apparently

contradictory observation -that ^(37)Cl values of lunar samples vary from -1 to 24%o, with an upper extreme they argue demands devolatilization of anhydrous melts. We examine this issue further through measurements of water content, δ^(37)Cl, and δD of apatite from lunar meteorites MIL 05035, NWA 2977, and Dhofar 458

Eiler, J. M.

75th Annual Meteoritical Society Meeting (2012) 
WATER CONTENT, CHLORINE AND HYDROGEN 
ISOTOPE COMPOSITIONS OF LUNAR APATITE. 
Y. Wang1•2, Y. Guan2, W. Hsu 1, and J. M. Eiler2• 1Purple 
Mountain Observatory, Nanjing, China. E-mail: 
y_wang@pmo.ac.cn. 2GPS, Caltech, Pasadena, CA 91125 . 
Introduction: The Moon has been thought to have a bulk 
planetary water content < 1 ppb [I]. Recent ion microprobe 
analyses have shown that lunar samples contain up to 7000±1000 
ppm OR (reported as equivalent H20) in apatite and 4-46 ppm in 
igneous glass [2-6]. These studies suggest that the mantle 
sources of at least some lunar magmas contain from 64 ppb to 
200 ppm [4-6]. Sharp et al. [6] report an apparently 
contradictory observation -that 37Cl values of lunar samples 
vary from -1 to 24%o, with an upper extreme they argue demands 
devolatilization of anhydrous melts. We examine this issue 
further through measurements of water content, 837 Cl, and oD of 
apatite from lunar meteorites MIL 05035, NWA 2977, and 
Dhofar 458. 
Results: Nine apatite grains were examined with the Cameca 
NanoSIMS SOL and 7f Geo at Cal tech. Apatite grains from two 
basaltic meteorites (MIL 05035 and NWA 2977) yielded o37CI 
values from 3.8±3.1 (2cr) to 26.2±1.8 %o and water contents from 
1100±120 to 5200±280 ppm, comparable with those previously 
reported for lunar apatite [ 4-7]. One apatite grain from a 
feldspathic breccia (Dhofar 458) has extreme ly high o37Cl of 
67.2±2.0 to 81.1±2.0 %o, and a relatively low water content 
averaging 240±40 ppm. oD of apatite varies from -11 0±30 %o in 
NWA 2977 to 400±80 %o in MIL 05035, and to 510±130 %o in 
Dhofar 458, showing no correlation with water content or o37CI. 
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Discussion: Our study shows that lunar apatite exhibits a 
large range of o37CI even in individual crystals that contain 
significant amounts of water. These findings appear to be 
inconsistent with the interpretations of Cl isotope data presented 
in Sharp et al. [6]. We suggest our observations for lunar basalts 
might be explained if the major volatile species responsible for 
degassing of Cl from lunar magmas are metal chlorides, which 
could account for the large fractionation of Cl isotopes [7]. 
Uncorrelated oD and o37CI values of apatite indicate that the 
fractionations of H and Cl isotopes were decoupled in the lunar 
samples we examined. The high o37CI values of the apatite in 
Dhofar 458 are exceptional compared to our and previous data 
for apatites in basaltic rocks. We suggest such extreme values in 
this impact breccia reflect sampling a reservoir of extremely 
heavy Cl isotopes on the lunar surface, possibly produced by 
repeated 35CI loss during multiple shocks events or gardening 
processes. 
References: [1] TaylorS. R. et a l. 2006. In New Views of the 
Moon: 657- 704. [2] Saal A. E. et al. 2008. Nature 454: 192- 195. 
[3] Hauri et al. 201 1. Science 333: 213- 215. [4] Boyce J. W. et 
al. 2010. Nature 466: 466-469. [5] McCubbin F. M. et al. 2010. 
PNAS 107: 11223- 11228. [6] Greenwood J. P. et al. 20 11. 
Nature Geo. 4: 79- 82. [7] Sharp Z . D. et al. 2010. Science 329: 
1050-1053. 
This work was supported by Chinese National and Jiangsu 
NSF ( 41003026, BK20 11891 ), and the minor planet foundation. 
5170.pdf 


Water Content, Chlorine and Hydrogen Isotope Compositions of Lunar Apatite

Oxygen isotopes measured by MegaSIMS on

Genesis Concentrator samples indicate a solar wind (SW) oxygen isotope composition that is related to the ^(16)O-enriched CAI composition by a large mass dependent fractionation [I]. Isotope fractionation during acceleration of the solar wind is expected to create

such a large mass fractionation, but a direct test of the presence of mass fractionation in the solar wind has not been possible with sufficient precision. Unlike O and Ne, Mg isotopes are sufficiently uniform in chondrites, terrestrial samples, and other meteoritic and planetary materials from the inner solar system [2], and so offer the best opportunity for a precise (±1‰) test of the Coulomb Drag mechanism for solar wind isotope fractionation

Humayun, M.

Jurewicz, A. J. G.

Olinger, C.

Burnett, D. S.

75th Annual Meteoritical Society Meeting (2012) 
EVIDENCE FOR UNFRACTIONA TED MAGNESIUM 
ISOTOPES IN GENESIS SOS WAFERS. 
M. Humayun 1, A. J. G. Jurewicz2, C. Olinger3, and D. S. 
Bumett4• 1Florida State University, Tallahassee, FL 32310, USA, 
E-mail: humayun@magnet.fsu.edu; 2Arizona State University, 
Tempe, AZ 85287, USA; 3Los Alamos National Laboratory, Los 
Alamos, NM 87545, USA; 4Caltech, Pasadena, CA 91125, USA. 
Introduction: Oxygen isotopes measured by MegaSIMS on 
Genesis Concentrator samples indicate a solar wind (SW) oxygen 
isotope composition that is related to the 160-enriched CAl com-
position by a large mass dependent fractionation [I]. Isotope frac-
tionation during acceleration of the solar wind is expected to cre-
ate such a large mass fractionation, but a direct test of the pres-
ence of mass fractionation in the solar wind has not been possible 
with sufficient precision. Unlike 0 and Ne, Mg isotopes are suf-
ficiently unifonn in chondrites, terrestrial samples, and other me-
teoritic and planetary materials from the inner solar system [2], 
and so offer the best opportunity for a precise (±1%o) test of the 
Coulomb Drag mechanism for solar wind isotope fractionation. 
We have previously reported Mg isotopes from flight Si-on-
Sapphire (SoS) wafer #20403 fractionated by --4%o w.r.t. Mg 
isotope standard DSM-3 [3, 4]. Backside depth profiling of Mg 
isotopes in Si wafers by SIMS yielded possibly fractionated SW 
Mg with large errors [5]. Interpretations of the measurements we 
reported earlier [3] were complicated by a lack of knowledge on 
whether the aggressive acid cleaning procedures employed at 
FSU were removing some of the SW layer. Since then, SIMS Mg 
profiles performed on Si wafers cleaned in the same batch of 
samples as SoS #20304 provide confirmation that the FSU clean-
ing technique preserves the depth profile of SW Mg in the Si wa-
fers. Below, we consider the implications of the SIMS data and 
SRIM calculations for SoS wafers. 
Discussion: The epitaxially grown Si layer on Genesis flight 
SoS wafers has a thickness (170-200 nm) less than the original 
design specification of 300 nm, so that SW ions are not com-
pletely stopped within the extractable Si layer. Therefore, SRIM 
calculations were performed to assess the isotope fi·actionation 
induced by the different stopping ranges of Mg isotopes. The SW 
Mg ion velocity profiles of [6] were used. A backscatter conec-
tion is applied. About 95% of the Mg is stopped by the Si layer 
with an isotopic composition of 625Mg- -5%o, with the heavier 
Mg implanted preferentially in the sapphire layer. Thus, isotopi-
cally unfractionated SW Mg (w.r.t. chondrites) would be meas-
ured at -5%o by our method. SW Mg fractionated by Coulomb 
Drag should appear as -15%o. SoS wafer #20304 and four other 
wafers plot on a mixing line defined between UTTR dirt Mg iso-
tope composition (-0.3%o) and -5%o, with #20304 exhibiting a Mg 
fluence of - 2£12 atoms/cm 2, expected of the solar wind. Its 
625Mg= -3.6±1.5%o (2o) indicates that the solar wind as measured 
by Genesis SoS wafers is consistent with no fractionation of the 
SW during acceleration. This result is surprising in view ofO and 
noble gas results [1 , 5]. A new set of measurements on Si wafers 
is in progress to better establish the SW Mg isotope composition. 
References: [1] McKeegan K. D. et al. 2011. Science 332: 
1528-1532. [2] Teng F.-Z. et al. 2010. Geochimica et Cosmo-
chimica Acta 47: 4150-4166. [3] Humayun M. et al. 2011. Ab-
stract #121 1. 42th Lunar & Planetary Science Conference. [4] 
Galy A. et al. 2003. Journal of Analytical Atomic Spectrometly 
18: 1352-1356. [5] Heber V. S. et al. 20 12. Abstract #2921. 43rd 
Lunar & Planetary Science Conference. [6] Reisenfeld D. B. et 
al. 2007 Space Sci. Rev . 130: 79-86. 
5353.pdf 


Evidence for Unfractionated Magnesium Isotopes in Genesis SOS Wafers

During a nano-mineralogy investigation of the Vigarano CV3 meteorite, eringaite Ca_3(Sc,Y,Ti)_2Si_3O_(12) was

identified in a cluster of ultra-refractory inclusion fragments within a shattered amoeboid olivine aggregate in VCM3. Eringaite is a newly-discovered garnet-group mineral in metasomatic rodingite-like rocks from the Wiluy River, Sakha-Yakutia Republic, Russia [I]. Reported here is the second natural occurrence of eringaite, as a new ultra-refractory mineral in a primitive meteorite, among the earliest solids formed in the solar nebula. Field-emission SEM, electron back-scatter diffraction (EBSD) and electron microprobe were used to characterize its composition and structure and associated phases

Ma, Chi

75th Annual Meteoritical Society Meeting (2012) 
DISCOVERY OF METEORITIC ERINGAITE, 
Ca3(Sc,Y,Ti)2Si30 12, THE FIRST SOLAR GARNET? 
Chi Ma. Division of Geological and Planetary Sciences, Califor-
nia Institute of Technology, Pasadena, CA 91125, USA. E-mail: 
chi@gps.caltech.edu 
Introduction: During a nano-mineralogy investigation of the 
Vigarano CV3 meteorite, eringaite Ca3(Sc,Y,Ti)2Si30 12 was 
identified in a cluster of ultra-refractory inclusion fragments 
within a shattered amoeboid olivine aggregate in VCM3. Erin-
gaite is a newly-discovered garnet-group mineral in metasomatic 
rodingite-like rocks from the Wiluy River, Sakha-Yakutia Re-
public, Russia [I]. Reported here is the second natural occurrence 
of eringaite, as a new ultra-refractory mineral in a primitive me-
teorite, among the earliest solids formed in the solar nebula. 
Field-emission SEM, electron back-scatter diffraction (EBSD) 
and electron microprobe were used to characterize its composi-
tion and structure and associated phases. 
Occurrence, Chemistry, and Crystallography: Eringaite 
occurs as irregular or subhedral grains, 0.5- 2 Jlm in size, along 
with tazheranite, hexaferrum and MgAl-spinel within davisite 
and Sc-bearing diopside in a cluster of ultra-refractory inclusion 
fragments . The mean chemical composition of the eringaite is 
(wt%) Si02 28.93, CaO 25 .26, Y20 3 12.37, Sc20 3 11.04, Ti02 
5.33, Ti20 3 4.43, MgO 4.36, Alz03 4.34, Zr02 2.38, FeO 0.63 
V20 3 0.42, sum 99.49, showing an empirical formula 
(Ca23 1Mgo 56 Yo o9Feoos)(Sco 82 Yo48 Ti3+o.J2 Ti4+o zsZro1o Yo 03Cro ol) 
(Siz47Alo44Ti
4+o o9)0 12, where Ti
3+ is calculated base on stoichio-
metry. EBSD analysis reveals that the eringaite has a garnet Ia3d 
structure, identical to that of synthetic Ca3Sc2Si30 12 [2], showing 
a = 12.25 A, V = 1838.27 A3, Z=8. 
Associated tazheranite (71 wt% ZrO) is a special cubic zirco-
nia with a formula (Zr0 6oSco 18 Yo.o8 Tio o?CaoozMgo ozA looi)OLBo, 
maybe expressed as (Sc,Y,Ti,Ca,Mg)2Zr30 9. Fine-grained eu-
hedral hexaferrum shows Fe0_550so.1slro_13 Mo0_o8 Wo_o4Nio.DJ Ruo.oz, 
or Feo.6zMOozoRu0 o80s0.o4Iro ozNio 02 W o.oz. Davisite (I 0 wt% 
Sc20 3) and diopside (6 wt% Sc20 3) are surrounded by forsterite. 
Origin and Significance: Eringaite is a new Sc-rich ultra-
refractory silicate and likely the first garnet fonned in the solar 
system. Eringaite is Ti3+-rich, indicating highly reducing envi-
ronments. Texturally, eringaite, tazheranite , spinel and hexa-
ferrum formed early in this Vigarano ultra-refractory inclusion 
before the appearance of davisite and Sc-rich diopside. Molar 
Sc/Zr of eringaite (- 8.2), tazheranite (- 0.3), davisite (-3.6) and 
diopside ( - 7. 7), are consistent with conservation of Sc/Zr in a 
reaction among eringaite, tazheranite, spinel and/or vapor to pro-
duce davisite and Sc-rich diopside. Forsterite condensed around 
the refectory inclusion at a later stage in the nebula. 
Thortveitite (Sc2Si20 7) identified in the Murchison ultra-
refractory inclusion MURl , is probably the first solar silicate, as 
an early condensate [3]. This discovery implies that eringaite 
may be the second solar si licate, followed by davisite. 
References: [I] Galuskin l. O. eta!. 20 10. Miner. Mag 74, 
365-373. [2] Quartieri S. eta!. 2006. Am. Miner. 91, 1240-1 248. 
[3] MaC. eta!. 2011. MAPS 46, Sl , Al44. 
5015.pdf 


Discovery of Meteoritic Eringaite, Ca_3(Sc,Y,Ti)_2Si_3O_(12), the First Solar Garnet?

http://authors.library.caltech.edu/34634/1/A9R90FF.pdf

Oxygen Isotopes of Al-Rich Chondrules from Unequilibrated Ordinary Chondrites

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