Here, we compare Sm-147-Nd-143 and Sm-146-Nd-142 data for lunar norite 78236 to those for approximately 4.54-4.56 Ga old cumulate eucrite Yamato 980318/433 and show that the norite data are compatible with its derivation from an isotopic reservoir similar to that from whence the eucrite pair came. Thus, lunar-like Sm-Nd isotopic systematics are not unique to the Earth-Moon system

Nyquist, L. E.

Reese, Y. D.

Shih, C-Y.

NASA Technical Reports Server

Sm-Nd FOR NORITE 78236 AND EUCRITE Y980318/433: IMPLICATIONS FOR PLANETARY AND 
SOLAR SYSTEM PROCESSES.  L. E. Nyquist1, C-Y. Shih2, and Y. D. Reese3, 1Mail Code KR, NASA Johnson 
Space Center, Houston, TX 77058, laurence.e.nyquist@nasa.gov, 2Mail Code JE-23, ESCG/Jacobs Sverdrup, P.O. 
Box 58477, Houston, TX 77058, chi-yu.shih@nasa.gov,  3Mail Code JE-23, ESCG/Muniz Engineering, Houston, 
TX 77058, young.reese@.nasa.gov. 
 
Introduction:  Nyquist et al. [1] estimated lunar 
mantle formation to be 238(+56/-40) Ma later than 
formation of angrite LEW86010, and bulk present-day 
ε142Nd = -0.01±0.03 relative to terrestrial standards, 
assumed equivalent to CHUR (Chondritic Uniform 
Reservoir [2]). Boyet and Carlson [3] reported a mean 
value of 142Nd/144Nd of -0.20±0.14 ε-units for several 
chondrites relative to a terrestrial standard. They sug-
gested that material of sub-chondritic Sm/Nd ratio oc-
curs within inaccessible regions of Earth’s mantle.  
New, high precision data for lunar samples by Boyet 
and Carlson [4] agree with those of [1], and imply that 
if Earth and Moon formed in a Giant Impact, then it 
occurred after segregation of material of sub-
chondritic Sm/Nd ratio into Earth’s mantle. Ranken-
burg et al. [5], report a chondritic 142Nd abundance for 
the Moon, implying either that the impact occurred 
before terrestrial differentiation, or that the moon in-
herited its Nd from an undifferentiated impactor. Man-
tle formation ages of 254(+30/-25) and 215(+23/-21) 
Ma, respectively, were reported by [4] and [5] in 
agreement with [1]. The “mean chondrite” 147Sm/144Nd 
and 143Nd/144Nd values of [3] yield initial ε143Nd at 
4567 Ma ago that is ~+0.6 ε-units higher than obtained 
from the widely accepted CHUR value [2] also 
adopted by [4]. 
Here, we compare 147Sm-143Nd and 146Sm-142Nd 
data for lunar norite 78236 to those for ~4.54-4.56 Ga 
old cumulate eucrite Yamato 980318/433 and show 
that the norite data are compatible with its derivation 
from an isotopic reservoir similar to that from whence 
the eucrite pair came. Thus, lunar–like Sm-Nd isotopic 
systematics are not unique to the Earth-Moon system.  
Samples and analytical procedures:  Sm-Nd 
analyses of lunar highland rocks suggest the rocks 
were derived from reservoirs with higher 143Nd/144Nd 
ratios than expected for evolution from CHUR. Sm-Nd 
analyses of eucrites also show that while the isotopic 
systematics of many are disturbed, those giving reli-
able ages indicate initial 143Nd/144Nd higher than 
CHUR. For example, cumulate eucrite Yamato 980318 
gave a Sm-Nd age of 4567±24 Ma, and εNd,CHUR = 
1.36±0.53[6]. To verify these results, we repeated the 
Sm-Nd analyses on paired sample Y980433. We also 
concurrently re-analysed lunar norite 78236 to provide 
a direct comparison between the Nd-isotopic systemat-
ics of these two samples, which are similar petrologi-
cally, and well-suited for Nd-isotopic analysis. Ana-
lytical procedures were standard for our group, except 
that Ce was quantitatively removed from Nd prior to 
isotopic analysis by a solvent extraction method [7]. 
147Sm-143Nd results:  147Sm-143Nd isochrons are 
shown for both norite 78236 and eucrite Y980433 in 
Fig. 1. The data for Y980433 reproduces the earlier 
data for Y980318. Analyses of 78236 are incomplete 
at this writing, but the isochron age is in agreement 
with earlier analyses of this norite and paired sample 
78238. Fig. 1 shows that the Sm-Nd ages of Y980433 
and 78236 are similar, but distinguishable. 
Fig. 2 shows data useful for defining a “meteoritic” 
value of 143Nd/144Nd at 4568 Ma ago. In addition to the 
results for Y980318/433, Fig. 2 shows JSC data for  
“non-eucrite” Ibitira, the Efremovka CAI E38, and 
eucrite analyses from [3]. These data are used to define 
ε143Nd for the HED Reservoir, HEDR, = +0.87±0.25 
147Sm/144Nd
0.10 0.15 0.20 0.25 0.30 0.35
14
3 N
d/
14
4 N
d
0.508
0.510
0.512
0.514
0.516
Norite 78236 & Eucrite Y980433
Px
Px
Plag Plag
WR
WR
Norite 78236,3
T=4.320±0.087 Ga
εNd,CHUR= +0.11±0.30
Eucrite Y980433
T=4.542±0.042 Ga
εNd,CHUR= +1.53±1.14
CHUR
HEDR
Figure 1. 147Sm-143Nd isochrons for norite 78236 and 
eucrite Y 980433. Isochron regressions by Isoplot [11].
Eucrites Y980318 & Y980433
Time before Present (Ga)
4.4 4.5 4.6 4.7
ε  (1
43
N
d)
-1
0
1
2
3
4
5
Eucrite
Y980433
Eucrite
Y980318
Efremovka
(E-38)
Ibitira
4.568Ga
Eucrites
DTM
CHUR HEDR
+0.87±0.25ε
Figure 2. Initial ε143Nd for the Y98 pair, Ibitira, and 
Efremovka CAI E-38 (JSC) and DTM data for 
eucrites (Boyet and Carlson, [3]). 
https://ntrs.nasa.gov/search.jsp?R=20080013410 2019-08-30T04:12:45+00:00Z
for ε143Nd relative to CHUR. This value is essentially 
unchanged from [6], which shows an earlier data base. 
We call it HEDR because HED meteorites make up the 
majority of meteorites used in its definition, but data 
for other meteorite types are consistent with it (Fig. 2). 
146Sm-142Nd results:  Fig. 3 shows a 146Sm-142Nd 
isochron for Y980433. Several of the data are for 
spiked samples, a customary procedure in our group 
for less-critical samples. The data for spiked and un-
spiked samples are in complete agreement. The 
isochron (Isoplot regression) determines  initial 
146Sm/144Sm = 0.0057±0.0005 in agreement with  
146Sm/144Sm = 0.0060±0.0008 for Y980318 [8]. For 
the more carefully and precisely determined value for 
Y980433, the calculated 146Sm/144Sm for CHUR at 
4568 Ma  is 0.0069±0.0005. Fig. 4 compares the 
146Sm-142Nd isochron obtained for norite 78236 to that 
for Y980433. Using 146Sm/144Sm = 0.0069 at 4568 Ma 
ago, the 146Sm-142Nd age for 78236 is ~4.31 Ga, in 
agreement with its 147Sm-143Nd age. Determined 
ε142Nd values are +0.11±0.04 (HEDR) and -0.16±0.05 
relative to terrestrial standards at CHUR 147Sm/144Nd = 
0.1967. 
Discussion: Fig. 5 compares ε143Nd and ε142Nd for 
lunar norite 78236, FAN 60025, and Y86032 anortho-
sitic lithologies (“An93 and An97 anorthosites” [9]) to 
HEDR and CHUR reference values. The simplest in-
terpretation is that the lunar data are consistent with 
single-stage evolution from HEDR values between 
4568 and ~4430 Ma ago for crustal anorthosites. Al-
ternatively, for evolution from CHUR, two (or more) 
stages of Nd-isotopic evolution in a super-chondritic 
Sm/Nd reservoir are required by both the ε143Nd and 
ε142Nd data.  For a two stage model, a value of 
μ (147Sm/144Nd) >~ 0.22 is required. This lower limit is 
constrained by the necessity to evolve from  CHUR to 
the 60025 ε143Nd and ε142Nd values in ~140 Ma, and is 
similar to μ = 0.21 inferred for the EDR [3]. The upper 
limit shown in the figure is the maximum μ-value in-
ferred for the lunar mantle for basalt Asuka 881757 by 
[1]. Its growth curve intersects the lunar evolution 
lines at ~50 Ma post-CAI, consistent with the Hf-W 
age for lunar formation of 62(+90/-10 Ma) [10].  
Conclusions: Either (a) The Moon, HED meteor-
ites, and accessible terrestrial samples came from res-
ervoirs of super-chondritic Sm/Nd ratios, or (b) the 
CHUR reference values need revision, or (c) both of 
the above.  Super-chondritic Sm/Nd ratios may result 
from solar system rather than terrestrial processes. 
References: [1] Nyquist L. E. et al. (1995) GCA, 59, 
2817-2837. [2] Jacobsen S. B. and Wasserburg G. J. (1984) 
EPSL 67, 137-150. [3] Boyet M. and Carlson R. W. (2005) 
Science 309, 576-580. [4] Boyet M. and Carlson R. W. 
(2007) EPSL, 262, 505-516. [5] Rankenburg K. et al. (2006) 
Science 312, 1369-1372. [6] Nyquist L. E. et al. (2004) 28th 
Symp. Antartic. Met. 66-67. [7] Rehkaemper M. et al. (1996) 
Chemical Geology, 129, 201-208. [8] Nyquist L. E. et al. 
(2007) 31st Symp. Antartic. Met. 80-81.  [9] Nyquist L. et al. 
(2006) GCA 70, 5990-6015. [10] Touboul M. et al. (2007) 
Nature 450, 1206-1209. [11]Ludwig K. (2003) Isoplot soft-
ware package. 
Norite 78236 & Eucrite Y980433
147Sm/144Nd
0.10 0.15 0.20 0.25 0.30 0.35
ε  14
2 N
d
-2
-1
0
1
2
Norite 78236,3
I(Sm)=0.0012±0.0025
εNd,Earth= -0.16±0.05
Px
Px
WR
WR
Plag
Plag
CHUR
Eucrite Y980433
I(Sm)=0.0057±0.0005
εNd,Earth= +0.11±0.04
Earth
T=4.31Ga
T=4.54Ga
Figure 4. ε142Nd for Y980318 (yellow), Y980433 
(green), and lunar norite 78236 (red). 
Figure 5. Initial ε143Nd and ε142Nd in  lunar highlands 
rocks and model Nd-isotopic ingrowth curves. 
Nd Evolution Model for Lunar Norite & FAN
ε 143Nd
-1.5
-1.0
-0.5
0.0
0.5
1.0
Time before Present (Ga)
4.2 4.3 4.4 4.5 4.6
ε 142Nd
-0.6
-0.4
-0.2
0.0
0.2
0.4
μ=147Sm/144Nd
CHUR
CHUR
(DTM)
HED-PB
(~Y98)
Norite 78236
Eucrite
Y980433
Norite source
μ=0.174
μ=0.16
60025
Y86032
60025
Y86032
4.568 Ga
HED
~Earth ?
μ=0.18 Earth
μ=0.32
μ=0.32
μ=0.22
μ=0.22
Eucrites
Y980318
Y980433
Figure 3. ε142Nd analyses for spiked (red) and un-
spiked (yellow) samples of Y980433. 
Eucrite Y980433
147Sm/144Nd
0.10 0.15 0.20 0.25 0.30 0.35
ε  14
2 N
d
-2
-1
0
1
2
WR
Plag(r)
Px
leach
Px(r)
Plag CHUR
Earth
146Sm/144Sm=0.0057±0.0005
ε (142Nd)Earth=+0.11±0.04
T(Sm-Nd)=4.54±0.04 Ga


Sm-Nd for Norite 78236 and Eucrite Y980318/433: Implications for Planetary and Solar System Processes

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