The sulfur content of the Martian mantle is critical to understanding volcanic volatiles supplied to the surface of Mars and possibly climate. In the absence of Martian mantle rocks, sulfur content of the mantle has been inferred from S contents of Martian meteorites or from sedimentary sulfate abundances. Estimates of the sulfur content of the Martian mantle vary from 390-2,000 ppm, all of which are higher than that of the terrestrial mantle (~250 ppm;). Residual sulfide in the Martian mantle controls the distribution of chalcophile elements during partial melting. In this study, we report new analyses of Martian meteorites, and use the incompatible behavior of As, Tl and Pb to infer the sulfide mode of the Martian mantle using a different set of assumptions than those of prior studies

Hewins, R. H.

Humayun, M.

Irving, A. J.

Righter, K.

Yang, S.

Zanda, B.

English

NASA Technical Reports Server

CHALCOPHILE ELEMENT CONSTRAINTS ON THE SULFUR CONTENT OF THE MARTIAN 
MANTLE.  S. Yang1, M. Humayun1, K. Righter2, A. J. Irving3, R. H. Hewins4,5 and B. Zanda4,6. 1Florida State Uni-
versity, Tallahassee, FL 32310, USA (syang@magnet.fsu.edu); 2NASA Johnson Space Center, Mail code XI2, Hou-
ston, TX 77058, USA; 3Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, 
USA; 4IMPMC, Sorbonne Université, MNHN-UPMC, 75005 Paris, France; 5Rutgers University, Piscataway, NJ 
08854, USA; 6IMCCE, Observatoire de Paris - CNRS UMR 8028, 75014 Paris, France. 
 
Introduction:  The sulfur content of the Martian 
mantle is critical to understanding volcanic volatiles 
supplied to the surface of Mars and possibly climate 
[1-5]. In the absence of Martian mantle rocks, sulfur 
content of the mantle has been inferred from S contents 
of Martian meteorites [1, 3, 4] or from sedimentary 
sulfate abundances [5]. Estimates of the sulfur content 
of the Martian mantle vary from 390-2,000 ppm, all of 
which are higher than that of the terrestrial mantle 
(~250 ppm; [6]). Residual sulfide in the Martian man-
tle controls the distribution of chalcophile elements 
during partial melting. In this study, we report new 
analyses of Martian meteorites, and use the incompati-
ble behavior of As, Tl and Pb to infer the sulfide mode 
of the Martian mantle using a different set of assump-
tions than those of prior studies.  
Analytical Methodology:  The abundances of 69 
elements in eleven shergottites (ALHA 77005, DaG 
670, Lar 12011, NWA 2975, NWA 7397, NWA 7635, 
NWA 8159, NWA 8657, QUE 94201, RBT 04261 and 
SaU 005), two nakhlites (NWA 10159 and NWA 
6148), two chassignites (NWA 2737 and NWA 8694) 
and the Martian breccia (NWA 7533) were analyzed 
with an Elemental Scientific Lasers New Wave™ 
UP193FX excimer (193 nm) laser ablation system 
coupled to a Thermo Element XR™ ICP-MS at the 
Plasma Analytical Facility, FSU [7-8].  All sample 
sections were rastered using a 75 µm beam spot, at 15 
µm s-1, 50 Hz repetition rate, over about 4 mm2 surface 
area. USGS glasses (BCR-2g, BHVO-2g and BIR-1g) 
were used as the external standards for major elements, 
and most of the lithophile elements. Two synthetic 
glass standards (GSD-1g and  NIST SRM 610) were 
used as the external standards for elements that were  
poorly constrained in USGS glasses, e.g., As, Mo, Sn, 
W, Tl and Pb. The reproducibility of this technique is 
better than 5% for major elements, REEs and most of 
the lithophile elements and is better than 10% for As, 
Sn, Tl and Pb if their abundances are above 10-1 ng/g 
in samples [8].  
Results:  In a log-log plot, a pair of elements with 
identical partition yields a correlation with a slope of 
unity [9]. In Fig.1(a-d), Log[Pb] of Martian meteorites 
analyzed in this study and [7] were plotted against 
Log[Th], Log[Ce], Log[Sm] and Log[Gd] with com-
patibilities changing from highly incompatible (Th) to 
moderately incompatible (Gd). The following samples 
were excluded because of surficial Pb-contamination 
(Shergotty, Los Angeles and Zagami [7]), sulfide as-
similation (NWA 7635 and NWA 8159) and extreme 
fractionation (QUE 94201). The data from a recent 
study of nakhlites and chassignites [10] were also plot-
ted for comparison. Terrestrial MORB data analyzed 
by the same methods [8] are shown in Fig. 1 for com-
parison with Martian igneous rocks. The slopes of the 
correlations were calculated from York regression [11] 
of Martian data (n=24) and MORB data (n=234) sepa-
rately where errors in contents of both elements were 
taken into account.  
 
Fig. 1(a-d): Correlations of Pb vs. Th, Ce, Sm and 
Gd for Martian meteorites analyzed in this study and 
[7, 11]. Terrestrial MORB glasses from [8] are shown 
for comparison.  
 
Fig. 2 compares the mutual compatibilities of As, 
Tl and Pb. Fig. 2(a) shows that the slopes of the corre-
lations between Log[Pb] and Log[As] or Log[Tl] are 
close to unity for both MORB and Martian trends, in-
dicating the partitioning of As and Tl are the same as 
that of Pb during the partial melting of both Martian 
mantle and MORB mantle. Two depleted shergottites 
(SaU 005 and DaG 670) plot off the Log[Pb]-Log[As] 
trend with both being higher in As. This observation is 
not an artifact of our analytical method, since the As 
contents of SaU 005 and DaG 670 obtained in this 
study agree well with literature values [12, 13].  
-2
-1
0
1
2
-2 -1 0 1 2
-2
-1
0
1
-2 -1 0 1 2
-2
-1
0
1
-2
-1
0
1
2
Lo
g 
[T
h]
M
ar
tia
n 
slo
pe
 =
 1
.6
7±
 0
.2
4
1:1
 lin
e
1:1
 lin
e
1:1
 lin
e
1:1
 lin
e
Ma
rtia
n s
lop
e =
 1.
38
± 0
.20
Ma
rtia
n s
lop
e =
 0.
97±
 0.
15
Ma
rtia
n s
lop
e =
 0.
64±
 0.
13
a
Literature data: Global MORB  Nakhlites & Chassignites 
This study: Enriched shergottites  Intermediate shergottites  Depleted shergottites 
 Nakhlites  Chassignites  Martian crust
Lo
g 
[G
d]
d
Lo
g 
[C
e]
Log [Pb]
MO
RB
 slo
pe 
= 0
.96
± 0.
02
Log [Pb]
b
MO
RB
 slo
pe
 = 
1.3
7±
 0.
02
Lo
g 
[S
m
]
MO
RB 
slop
e = 
0.66
± 0.
03
MOR
B slo
pe =
 0.46
± 0.0
5
c
https://ntrs.nasa.gov/search.jsp?R=20200001834 2020-05-24T04:12:25+00:00Z
Discussion:  The compatibilities of a series of lith-
ophile trace elements (Rb, Th, U, Nb, Ta, K, Sn, Zr, 
Hf, Ti, Na and REE) were tested to ascertain if the 
relative compatibilities of these elements are consistent 
between Martian and terrestrial igneous processes. The 
higher relative uncertainties on the correlations for 
Martian rocks relative to terrestrial MORB glasses [8] 
is likely due to the coarse-grained nature of Martian 
igneous rocks. The REE and Y are principally in phos-
phates, and the correlations between two adjacent REE 
(e.g., La and Ce) are better than 5%. The relative un-
certainties on the correlations of Nb vs. Ta and Zr vs. 
Hf are also similar to those observed for MORB glass-
es, but inter-group correlations, e.g. La vs. Nb, are less 
precise due to the distinct hosts for each of these ele-
ments not being representatively sampled. 
Fig. 1 shows that Pb is about as compatible as Sm 
in Martian igneous rocks, with a slope of  0.97 ± 0.15 
(Fig. 1c). For MORBs, Pb is best correlated with Ce 
with a slope of  0.96 ± 0.15 (Fig. 1b), consistent with 
other studies [8, 14], and the correlation for Pb with 
Sm in terrestrial rocks is distinctly poorer (slope: 0.66). 
Thus, Pb, As and Tl are all more compatible during 
melt extraction from the Martian mantle than from the 
terrestrial mantle. 
It has been shown for terrestrial rocks, that Pb be-
haves more compatibly (like Ce rather than Th) than 
cpx-silicate melt partitioning would indicate due to the 
presence of sulfide in the source [14]. Similarly, Tl has 
been shown to be more compatible for the same reason 
[9]. Experimental partitioning of various chalcophile 
elements between liquid sulfide and silicate melts [14-
16] shows that As and Pb are both compatible in sul-
fide melt, and the presence of small quantities of sul-
fide (~0.1 %) in the terrestrial source accounts for the 
higher compatibilities of both elements. The only 
available partitioning of Tl between liquid sulfide and 
liquid silicate [15] indicates that Tl is not sufficiently 
compatible in sulfide liquid to fully explain the com-
patibility of Tl in terrestrial rocks [9]. Thus, it is inter-
esting that Tl follows Pb on Mars like Earth (Fig. 2), 
even though the reasons for this are not fully under-
stood. 
Knowing that the partition coefficient for Pb is 
comparable to that of Sm, and assuming that Sm parti-
tioning between basaltic melts and silicate mantles is 
the same for Earth and Mars, we calculated the abun-
dance of sulfide needed to make Pb (and As) as com-
patible as Sm. This calculation yielded a Martian man-
tle sulfur content of 1,050 ± 250 ppm. This sulfur con-
tent is applicable to sources of shergottites, nakhlites-
chassignites and of the breccias precursors, i.e. gener-
ally applicable to the entire Martian mantle. 
 
 
Fig. 2: Correlations of Pb vs. As and Tl in Martian 
meteorites analyzed in this study and [7, 11]. Terrestri-
al MORB glasses from [8] are shown for comparison. 
Fig. 3: Sulfur contents estimated in this study com-
pared with literature estimates for Martian and terres-
trial mantles. 
References: [1] Ding S. et al. (2015) EPSL 409, 
157-167. [2] Righter K. et al. (2009) EPSL 288, 235-
243. [3] Halevy I. et al. (2007) Science 318, 1903-
1907. [4] Wang Z. and Becker H. (2017) EPSL 463, 
56-68. [5] Gaillard F. et al. (2013) Space Sci. Rev. 174, 
251-300. [6] McDonough W. F. and Sun S.-s. (1995) 
Chem. Geol. 120, 233-253. [7] Yang S. et al. (2015) 
MaPS 50, 694-714 [8] Yang S. et al. (2018) G3 19, 
4236-4259. [9] Nielsen S. et al. (2014) G3 15, 4905-
4919. [10] Udry A. and Day J. M. D. (2018) GCA 238, 
292-315. [11] York D. et al. (2004) Am. J. Phys. 72, 
367-375. [12] Zipfel J., et al. (2000) MaPS 35, A178. 
[13] Dreibus G., et al. (2000) MaPS 35, A49. [14] Hart 
S. and Gaetani G. (2016) GCA 185, 9-20. [15] Kiseeva 
E. and Wood B. J. (2015) EPSL 383, 68-81. [16] Li Y. 
and Audetat A. (2015) EPSL 355-356, 327-340. [17] 
Lodders J. and Fegley B. (1997) Icarus 126, 373–394. 
[18] Sanloup C. et al. (1999) PEPI 112, 43-54. [19] 
Salters V. J. M and Stracke A. (2004) G3 5, 
doi:10.1029/2003GC000597.  
-1 0 1
-3
-2
-1
0
1
SaU 005
DaG 670
Literature data: Global MORB 
This study:
Enriched shergottites  Intermediate shergottites  Depleted shergottites 
 Nakhlites  Chassignites  Martian crust
a
Mar
tian
 slo
pe =
 0.9
5 ± 
0.15
As
Tl
MO
RB 
slop
e = 
1.04
 ± 0
.02
MO
RB
 slo
pe 
= 0
.90
 ± 0
.10
Mar
tian
 slo
pe =
 0.9
4 ± 
0.15
Log [Pb]
Lo
g 
[A
s,
 T
l]
0 500 1000 1500 2000
S (ppm)
Primitive mantle [6]
MORB mantle [19]
MORB mantle (this study)
[18]
[17]
[5]
(this study)
[1]
[4]
Terrestial mantle estimates 
Martian mantle estimates 


Chalcophile Element Constraints on the Sulfur Content of the Martian Mantle

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