Constraints on the Depth and Thermal Vigor of Melting in the Martian Mantle

PUBLICATIONS

Journal of Geophysical Research: Planets

RESEARCH ARTICLE Constraints on the depth and thermal vigor 10.1002/2014JE004745 of melting in the Martian mantle Key Points: Justin Filiberto1 and Rajdeep Dasgupta2 • Mantle potential temperature calculated for Gale Crater rocks 1Department of Geology, Southern Illinois University, Carbondale, Illinois, USA, 2Department of Earth Science, Rice • 1450 ± 70°C may represent global Noachian mantle temperature University, Houston, Texas, USA • Consistent with simple convective cooling of the interior of Mars Abstract Studies of rocks in Gale Crater and clasts within the Martian meteorite breccia Northwest Africa (NWA) 7034 (and paired stones) have expanded our knowledge of the diversity of igneous rocks that make up the Martian crust beyond those compositions exhibited in the meteorite collection or Correspondence to: J. Filiberto, analyzed at any other landing site. Therefore, the magmas that gave rise to these rocks may have been fi[email protected] generated at significantly different conditions in the Martian mantle than those derived from previously studied rocks. Here we build upon our previous models of basalt formation based on rocks analyzed in Citation: Gusev Crater and Meridiani Planum to the new models of basalt formation for compositions from Gale Filiberto, J., and R. Dasgupta (2015), Crater and a clast in meteorite NWA 7034. Estimates for the mantle potential temperature, TP based on Constraints on the depth and thermal vigor of melting in the Martian mantle, Noachian age rock analyses in Gale Crater, Gusev Crater, and Bounce Rock in Meridiani Planum, and a J. Geophys. Res. Planets, 120, vitrophyre clast in NWA 7034 are within error, which suggests that the calculated average TP of 1450 ± 70°C doi:10.1002/2014JE004745. may represent an average global mantle temperature during the Noachian. The TP estimates for the Hesperian and Amazonian, based on orbital analyses of the chemistry of the crust, are lower in temperature Received 17 OCT 2014 Accepted 1 DEC 2014 than our estimates for the Noachian, which is consistent with simple convective cooling of the interior of Accepted article online 10 OCT 2014 Mars.However,theTP estimates from the young meteorites are significantly higher than the estimates based on surface chemistry and are consistent with localized “hot spot” melting and not heating up of the interior.

1. Introduction Recent investigations of Mars rocks at Gale Crater and meteorite Northwest Africa (NWA) 7034 (and pairs) have expanded our knowledge of the variability of igneous compositions that make up the Martian crust. These rocks may have experienced signiﬁcantly different formation conditions in the Martian mantle than those previously studied. Mars Science Laboratory examined four rocks in Gale Crater, dubbed the Bradbury assemblage (Jake_M, Bathurst Inlet, Et_Then, and Rocknest), which are more silica- and alkali-rich compositions than rocks in the meteorite collection or those analyzed at other landing sites [Stolper et al., 2013; Schmidtetal., 2014]. Three out of the four rocks show chemical similarities and may be related [Schmidtetal., 2014]; the other rock, Jake_M, is a silica-undersaturated mugearite and potentially unrelated to the other rocks analyzed in Gale Crater [Stolperetal., 2013; Schmidt et al., 2014]. NWA 7034 (and paired stones), a Martain regolith breccia, contains clasts of mugearite and other similarly silca- and alkali-rich compositions [Agee et al., 2013; Santos et al., 2013, 2014b; Udry et al., 2014b]. These rocks extend thecompositionalspacetomoreevolvedcompositions than exhibited in the meteorite collection or analyzed at any other landing site [Agee et al., 2013; Humayun et al., 2013; Santos et al.,2013;Stolperetal., 2013; Schmidtetal.,2014;Udry et al., 2014b]. Therefore, they may represent magmas that tapped a previously unstudied source region (P and/or T). Here we build upon our previous models of basalt formation based on rocks analyzed in Gusev Crater and Meridiani Planum [Filiberto et al., 2010a; Filiberto and Dasgupta, 2011]. We compare our new results on rocks from Gale Crater and a clast in meteorite NWA 7034 to the similarly ancient rocks from Gusev Crater and Meridiani Planum to calculate an average mantle potential temperature for ancient Mars. We then compare the results for Noachian Mars to estimates for formation conditions of younger rocks (Hesperian and Amazonian surface regions [Baratoux et al., 2011] and Amazonian Martian meteorites [Musselwhite et al., 2006; Filiberto et al., 2010b; Gross et al., 2011]) to investigate how the mantle potential temperature of Mars may have changed through time.

2. Samples and Previous Estimates on the Conditions of Mantle Melting 2.1. Gale Crater The rocks Jake_M, Et_Then, Rocknest_3, Bathurst_Inlet, Coronation, and Mara have been investigated at Bradbury Rise, Gale Crater, giving us our first glimpse of the diversity of rocks at Gale Crater [e.g., Grotzinger, 2013; Stolper et al., 2013; Sautter et al., 2014; Schmidt et al., 2014]. Schmidt et al. [2014] and Sautter et al. [2014] discuss the possible igneous origin of rocks within the Bradbury Rise, while Stolper et al. [2013] discuss the origin of Jake_M. Jake_M is the first Martian mugearite analyzed on the surface or in the meteorite collection. Since its discovery, there have been mugearite clasts found in meteorite NWA 7034 (and paired stones) [Agee et al., 2013; Santos et al., 2013]. Therefore, rocks similar to Jake_M may not be uncommon on the Martian surface. Bathurst_Inlet is a very fine grained rock with a smooth, dusty surface. It is a floatrockthatis surrounded by pieces of similar rocks and is thought to represent relatively in place bedrock [Sautter et al., 2013; Schmidtetal., 2014]. Bathurst_Inlet has an igneous-like bulk composition, CIPW norm calculated mineralogy similar to the Martian meteorites (with the exception of anorthoclase content) and is thought to represent a near igneous composition [Sautteretal.,2013;Schmidtetal.,2014].Coronation-type rocks are dark gray rocks with variable grain size, flat facets, and undulating breakage patterns, which have been interpreted as basalt fragments [Sautteretal., 2014]. Coronation has 2.1 ± 3 wt % MgO and is quartz normative [Sautteretal., 2014]; therefore, Coronation-class rocks represent evolved magmas and are not appropriate to use for this work where least fractionated, near-primary basalts should be used to estimate mantle-equilibrated melt compositions. Et_Then and Rocknest_3 represent two rocks of the Rocknest suite. They are rough/vuggy and smooth/blocky/finely laminated, respectively [Schmidt et al., 2014]. Et_Then is a dark-toned, angular rock, while Rocknest_3 is a dark, fine-grained, blocky rock. Similar to Bathurst_Inlet, Rocknest_3 has an igneous-like bulk composition with a reasonable CIPW norm calculated mineralogy and is suggested to be a near-igneous composition. However, Rocknest_3 major element composition plots between Jake_M and Bathurst_Inlet suggesting that it may represent a mechanical mixture of those two rock types [Schmidt et al., 2014]. Et_Then has the highest concentration of Fe among the Bradbury rocks, while having the lowest Mg and Cr concentrations, possibly suggesting the presence of Fe3+-bearing oxide cements and the least igneous composition studied [Schmidt et al., 2014]. However, there is debate among the Mars Science Laboratory team as to the origin of these rocks (sedimentary versus igneous) [e.g., Bridges et al., 2013; Minitti et al., 2013; Sautteretal., 2013; Blaney et al., 2014; Edgett et al., 2014; Schmidtetal., 2014]. We will rely on those rocks (Jake_M and Bathhurst_Inlet), which have been suggested to be near igneous compositions [Stolperetal., 2013; Sautteretal., 2014; Schmidtetal., 2014]. We will include other compositions (Rocknest_3 and Et_Then) with the caveat that they may represent broadly volcanic compositions with isochemical alteration [Schmidtetal., 2014] suggestive of volcaniclastic rocks [Sautteretal., 2013], increasing the uncertainty in our calculations and similar to assumptions made by previous studies [e.g., Balta and McSween, 2013a; Schmidtetal., 2014; Treiman and Filiberto, 2014]. We will discuss the effects of alteration and their calculated parental magmas in more details below. While no age date has been obtained for the Bradbury Assemblage, we have two constraints on the age of Gale Crater, placing an estimate on the age of the Bradbury Assemblage: (1) crater counting places the age of Gale Crater at the Late Noachian (4.1 to 3.5 Ga) with deposits in the crater being Late Noachian into the Hesperian (3.5 to 2.9 Ga) [Anderson and Bell, 2010; Schwenzeretal., 2012; Grantetal., 2014, and references therein] and (2) in situ K-Ar age dating of the Sheepbed mudstone gives an age of 4.21 ± 0.35 Ga [Farley et al., 2014].

2.2. NWA 7034 Martian meteorite NWA 7034, and paired stones, is a polymict basaltic regolith breccia with a bulk composition similar to the average Martian crust [Agee et al., 2013] and noble gas signatures similar to the modern Martian atmosphere [Cartwright et al., 2014]. It is thought to be Noachian in age (4.428 ± 25 Ma [Humayun et al.,2013;Cartwright et al.,2014;Yin et al., 2014]), although younger ages (4.35 Ga, 2.1 Ga, 1.7 Ga, 1.6 Ga, 1.44 Ga, 1.35 Ga, and 170 Ma) have also been reported [Agee et al., 2013; Humayun et al., 2013; Cartwright et al., 2014; Yin et al., 2014]. These younger dates may reﬂect ages of disturbance (alteration or metamorphism) and are not thought to represent the initial age of formation [e.g., Humayun et al., 2013; Cartwright et al., 2014]. Since the bulk composition represents diverse clastic material, it does not represent a magma composition and is not relevant to this study; however, individual clasts within the

meteorite are appropriate for comparison with rocks on the surface. Udry et al. [2014b] recently investigated a vitrophyric clast within NWA 7034 that contains skeletal olivine and pyroxene with mesostasis which has a similar bulk composition to the surface basalt Humphrey at Gusev Crater. The bulk composition may have been contaminated by a chondritic impactor, which affected the Ni concentration, but the overall similarity of the major element composition with Humphrey suggests that the contamination did not signiﬁcantly alter the major elements. Therefore, we will use the bulk composition in our calculations. The vitrophyric clast has not been age dated; we will cautiously use the 4.4 Ga age, thought to be the age of the rock [Humayun et al., 2013; Cartwright et al., 2014], with the caveat that the clast could be younger (2.1 or 1.4 Ga) in age [Agee et al., 2013; Yin et al., 2014].

2.3. Gusev Crater: Age and Rock Discussion Mars Exploration Rover Spirit analyzed the largest number of basalts of any of the landers on Mars [e.g., McSween et al., 2006; McSween et al., 2008]. Therefore, we have the best constraints on the source region of these basalts [e.g., Schmidt and McCoy, 2010; Filiberto and Dasgupta, 2011]. We have previously discussed the mantle source conditions needed to form different classes of basalts analyzed in Gusev Crater [Filiberto and Dasgupta, 2011]. Therefore, we will only brieﬂy summarize our previous results in order to make a direct comparison with the rocks of Gale Crater, Meridiani Planum, and Martian meteorites. Basalts in Gusev Crater can be broadly classiﬁed into three main groups based on the P-T of formation: Barnhill-class basalts at Home Plate, Wishstone-class basalts in the Columbia Hills, and the Adirondack-class basalts on the Gusev plains. These basalts are thought to be 3.65 Ga old based on crater counting of the Gusev Lava Plains [Greeley et al., 2005]; however, we do not have an exact age for any of these rocks.

Barnhill-class basalts: Our estimates show very consistent P-T conditions needed to produce most of the Home Plate basalts and suggest that the entire sequence may be related to a single batch of magma equilibrated in the mantle at ~1.1 GPa and 1410°C. Adirondack-class (and Irvine-class basalts): The temperatures needed to produce both the Adirondack-class and Irvine-class basalts are signiﬁcantly higher than any of the other basalts in Gusev Crater. They yield an average condition of melt-mantle equilibration of ~2 GPa and 1490°C. Wishstone-class basalts:The Wishstone-class basalts, unlike the Adirondack-class basalts and Home Plate basalts, are fractionated alkalic basalts [e.g., Usui et al., 2008a; Udry et al., 2014a]. The pressures and temperatures of formation calculated needed to produce the parental magma to these basalts are just above the mantle solidus, suggesting that their parental magmas may represent low-degree partial melts (≪ 5 wt %) from deep Martian mantle.

2.4. Meridiani Planum: Age and Rock Discussion The only basaltic sample analyzed in Meridiani Planum that has not undergone extensive weathering is Bounce Rock [Rieder et al., 2004]. Its bulk chemistry is similar to some of the basaltic shergottites [Zipfel et al., 2011] but not the basalts in Gusev Crater analyzed by Spirit rover [e.g., McSween et al., 2004]. Modeling results show that it has a similar temperature of formation but a signiﬁcantly shallower depth of formation than the basalts analyzed in Gusev Crater [Filiberto and Dasgupta, 2011]. Again, we do not have an exact age of formation for Bounce Rock, but based on the geology of the area, Meridiani plains materials are thought to be Middle to Late Noachian [Arvidson et al., 2003]. However, Bounce Rock may have derived from beneath the plains unit and then have been thrown to the surface by impact, making Bounce Rock potentially older than the plains units [Zipfel et al., 2011].

2.5. Shergottites: Age and Rock Discussion Olivine-phyric shergottites are a signiﬁcant and important subgroup of Martian shergottites [Goodrich, 2002]. They contain large olivine crystals with lesser orthopyroxene and chromite grains set in a ﬁne-grained matrix mainly pigeonite and plagioclase [e.g., Goodrich, 2002, 2003; Usui et al., 2008b; Basu Sarbadhikari et al., 2009; Gross et al.,2011;Filiberto et al., 2012]. The high-MgO contents of Ol-phyric shergottites have led previous researchers to suggest that they could represent primitive mantle melts [Goodrich,2002; Musselwhite et al., 2006; Usui et al., 2008b; Gross et al.,2011];however,manydonotrepresentmagma compositions but contain excess olivine, complicating their use to understand mantle melting conditions [Goodrich, 2002; Sheareretal., 2008; Filiberto et al., 2010b; Filiberto and Dasgupta, 2011]. We have

Table 1. As Is Rock Compositions and Calculated (in Equilibrium With a Martian Mantle Containing Fo77 Olivine) Primitive Magma Compositions in Gale Crater and a Clast in NWA 7034 a SiO2 TiO2 Al2O3 Cr2O3 FeOT MnO MgO CaO Na2OK2O Jake_Mb 52.84 0.52 16.83 0.03 9.80 0.15 3.78 6.35 7.39 2.31 Jake_M_2 51.82 0.68 15.34 0.09 11.15 0.18 4.79 6.87 6.95 2.11 Jake_M_2_night 51.29 0.77 15.36 0.04 11.48 0.22 4.83 7.11 6.92 1.98 BI for real 45.93 1.17 8.31 0.43 23.03 0.82 9.04 6.62 2.35 2.29

21.Aeia epyia no.AlRgt Reserved. Rights All Union. Geophysical American ©2014. BiI top 46.30 1.10 8.47 0.37 21.96 0.45 9.26 6.78 2.26 3.04 Et_Then 47.58 0.77 8.88 0.84 27.80 0.41 4.42 4.51 3.12 1.66 Rocknest_3 49.02 1.02 11.20 0.27 19.59 0.48 5.68 6.46 4.29 1.98 NWA 7034_vitrophyre clastc 47.5 1.14 9.4 0.22 20.1 0.36 10.8 7.25 2.31 0.33 Calculated Primitive Magma Composition SiO2 TiO2 Al2O3 FeO MnO MgO CaO Na2OK2OFe2O3 Jake_M 52.24 0.50 16.16 9.85 0.14 5.14 6.10 7.10 2.22 0.52 Jake_M_2 51.39 0.66 14.86 10.95 0.17 5.83 6.66 6.73 2.05 0.60 Jake_M_2_night 50.80 0.74 14.81 11.32 0.21 6.03 6.86 6.67 1.91 0.61 BI for real 44.79 1.00 7.12 22.15 0.70 13.12 5.68 2.02 1.96 1.10 BiI top 45.36 0.97 7.51 21.13 0.40 12.50 6.02 2.00 2.69 1.08 Et_Then 43.62 0.48 5.52 27.48 0.26 15.41 2.80 1.93 1.03 0.96 Rocknest_3 47.05 0.85 9.26 19.81 0.40 11.01 5.34 3.54 1.64 0.90 NWA 7034_vitrophyre clast 47.49 1.11 9.19 19.26 0.35 11.62 7.09 2.26 0.32 1.09 d e f g h Ol (wt.%) F (wt. %) T (°C) P (GPa) T P (°C) Jake_M 4 20–24 1115 0.9 1200–1230 Jake_M_2 3 12–17 1152 0.9 1200–1230 Jake_M_2_night 4 10–15 1162 1.0 1200–1225 BI for real 17 4–9 1476 2.3 1465–1490 BiI top 13 5–10 1452 2.2 1445–1470

Et_Then 61 21–25 1560 2.8 1630–1650 10.1002/2014JE004745 Rocknest_3 21 7–12 1390 1.6 1400–1430 NWA 7034_vitrophyre clast 8 3–8 1419 1.2 1415–1445 a FeOT = total FeO (FeO + Fe2O3). bOriginal surface compositions from Schmidt et al. [2014] and Stolper et al. [2013]. cOriginal composition from Udry et al. [2014b]. dOl (wt. %) = amount of olivine addition. eCalculated melt fraction (wt. %) based on Ti partitioning. fTemperature calculated based on Putirka [2005]. gPressure calculated based on Lee et al. [2009]. hMantle potential temperature. 4 Journal of Geophysical Research: Planets 10.1002/2014JE004745

pressure-temperature estimates of formation for meteorites Yamato 980459, NWA 5789, and NWA 1068 based on high-pressure laboratory experiments on the putative melt compositions and/or pMELTS modeling [Musselwhite et al., 2006; Filiberto et al., 2010b; Gross et al., 2011]. We will brieﬂydiscuss these results.

2.6. Yamato 980459 (Y98) Y98 is a basaltic Martian meteorite with abundant magnesium olivine phenocrysts [Greshake et al., 2004; Mikouchi et al., 2004]. The most magnesium olivine is in equilibrium with the bulk composition, suggesting that the bulk composition represents a magma composition with no excess olivine [McKay et al., 2004; Filiberto and Dasgupta, 2011]. Using the inverse experimental approach, Y98 is found to be saturated with olivine and orthopyroxene on the liquidus at 1.2 GPa and 1540°C, suggesting that it represents a primitive mantle-derived melt [Musselwhite et al., 2006]. It is 472 ± 47 Ma based on Sm-Nd isochron [Shih et al., 2005].

2.7. NWA 5789 NWA 5789 has a bulk chemistry similar to Y98, suggesting that they may be possibly related [Gross et al., 2011]. We currently do not have a crystallization age for NWA 5789, but its similar bulk chemistry to Y98 suggests that they may have a similar age [Irving et al., 2010]; therefore, we will assume the same age. Similar to Y98, the magnesium olivine cores are in equilibrium with the bulk composition of NWA 5789, suggesting that it too represents a magma composition [Filiberto and Dasgupta, 2011; Gross et al., 2011]. However, unlike Y98, experiments have not been conducted on NWA 5789; instead, pMELTS modeling has been done to calculate the pressure and temperature of formation [Gross et al., 2011]. The calculated conditions of formation for NWA 5789 are 1.1 GPa and 1525°C.

2.8. NWA 1068 Similar to NWA 5789 and Y98, NWA 1068 is an olivine-phyric shergottite that has primitive characteristics [Barrat et al., 2002; Goodrich et al., 2003]. Unlike NWA 5789 and Y98, NWA 1068 is enriched in trace elements, while Y98 and NWA 5789 are depleted in trace elements [Barrat et al., 2002]. This may suggest a difference in formation conditions between these source regions. Furthermore, NWA 1068 is younger than the other stones at 185 ± 11 Ma based on Sm-Nd and Sr-Rb isochrons [Shih et al., 2003]. Inverse experimental petrology has suggested that NWA 1068 contains cumulate olivine [Filiberto et al., 2010b]; therefore, caution must be used when using the pressure and temperature of formation from these experiments to understand the Martian interior. However, recent work reinvestigating the bulk and mineral chemistry of NWA 1068 has suggested that olivine accumulation may not be as large as previously calculated [Collinet et al., 2012]. Therefore, we will cautiously use the experimental results. The Ol-Opx-L multiple saturation point and therefore last condition of melt-mantle equilibration for NWA 1068 occurs at 1.7 GPa and 1520°C.

3. Methods for Modeling the Pressures and Temperatures of Formation The rocks analyzed in Gale Crater and the clast in NWA 7034 are evolved rocks that are not in equilibrium with the Martian mantle. In order to calculate the conditions of formation (pressure and temperature) for these basalts within the Martian mantle, we ﬁrst calculate the primary magma compositions following the approach used for basalts in both Gusev Crater and Meridiani Planum [Filiberto and Dasgupta, 2011]. We add

back olivine in 0.01 wt % increments using the appropriate KD (0.35 ± 0.01) until the calculated basalt composition (Table 1) is in equilibrium with the Martian mantle (Fo77). While we do not know the exact composition of the Martian mantle, a Martian mantle olivine composition of Fo77 is the average of the estimated Martian mantle compositions (see Filiberto and Dasgupta [2011] for the full range of mantle compositions. The average composition was calculated from McGetchin and Smith [1978], Morgan and Anders [1979], Goettel [1981], Dreibus and Wänke [1985], Ohtani and Kamaya [1992], Bertka and Fei [1996], Lodders and Fegley [1997], Sanloup et al. [1999], Agee and Draper [2004], and Taylor [2013]). To estimate the pressures and temperatures of formation for these calculated primary magma compositions, we use olivine-melt Mg-exchange thermometry [Putirka, 2005] and silica activity in the melt barometry [Lee et al., 2009] that have been shown to be appropriate for Martian surface basalt compositions [Filiberto and Dasgupta, 2011]. A shift in the mantle olivine composition of 1 Fo unit causes a shift of ~0.1 GPa and <20°C in estimated pressure and temperature, respectively.

Figure 1. (a) SiO2, (b) FeOT, (c) Al2O3, and (d) CaO versus MgO for rocks from Gale Crater as analyzed (gray squares) and the clast in NWA 7034 as analyzed (gray diamond) and their calculated composition in equilibrium with the Martian mantle (black squares and black diamond, respectively). Olivine (Ol) addition vectors are shown (solid black lines), connecting rock compositions as analyzed and the calculated primary compositions, with the amount of olivine added for each datum given in Table 1. Shown for comparison are the rocks of Gusev Crater (as analyzed: gray circles and calculated primary compositions: white circles), Bounce Rock in Meridiani Planum (as analyzed: gray star and calculated primary composition: white star), and Ol-phyric shergottites (as analyzed: gray triangles). Data for Gusev Crater and Meridiani Planum (as analyzed basalts and calculated primary magma compositions) are from Filiberto and Dasgupta [2011, and references therein]. Data for Ol-phyric shergottites are from Filiberto et al. [2012, supplemental data set] and Meyer [2012]. Corrected Gale Crater compositions compare well with the corrected compositions of characterized basalts from Gusev Crater and Meridiani Planum as well as Martian meteorites, lending conﬁdence that the Gale Crater compositions also represent basalts on the Martian surface.

4. Calculated Results 4.1. Primary Magma Compositions Figure 1 shows the as analyzed and calculated primary magma compositions for Gale Crater rocks and a clast in NWA 7034 compared with rocks (as analyzed and the calculated primary magma compositions) from Gusev Crater and Meridiani and the bulk composition of olivine-phyric shergottites [Filiberto and Dasgupta, 2011; Filiberto et al., 2012]. Primary magmas were calculated by adding olivine until the calculated basalt composition is in equilibrium with the Martian mantle. For rocks of Gusev Crater, we previously showed that this was acceptable because rocks of Home Plate were related by olivine-only fractionation [Filiberto and Dasgupta, 2011]; however, rocks analyzed in Gale Crater may not be related by simple fractionation processes [Schmidtetal., 2014]. Comparing the rocks (as is and calculated parent compositions), with the previous work on rocks from Gusev Crater and Meridiani, we can constrain if Ol-only fractionation is acceptable for Gale Crater rocks as well. Rocks from Gale Crater have similar chemistry to other rocks analyzed on the surface but extend the known compositions to lower silica contents. The amount of olivine addition

(Table 1) is similar to our previous calculations [Filiberto and Dasgupta, 2011] and are reasonably low (<20% addition), suggesting that olivine-only fractionating assemblage may be acceptable. The similarity in bulk chemistry for the compositions in this study to rocks of Gusev Crater and Meridiani Planum (withtheexceptionofEt_Then)is consistent with previous work, Figure 2. Temperatures and pressures calculated for primitive magma compositions suggesting that they represent estimated for Gale Crater rocks (gray squares) and the clast in NWA 7034 (gray near-igneous compositions with diamond) compared with basalts from Gusev Crater (white circles), Bounce Rock only isochemical alteration in Meridiani Planum (white star), and Ol-phyric shergottites (white triangles) (Figure 1) [Schmidt et al., 2014]. (Table 2). Experimental estimates for the Gusev Crater rocks Humphrey and Fastball (white hexagons) are shown as an internal calibration between experimental and Et_Then does not fit with the modeling results [Monders et al., 2007; Filiberto et al., 2008, 2010a]. Also shown for other known compositions by reference, by the dashed line, is the solidus of nominally volatile-free Martian mantle having much higher Fe [Filiberto and Dasgupta, 2011]. contents and having a high amount of olivine addition (>20%). This is presumably due to the weathered nature of Et_Then increasing the Fe content [Schmidt et al., 2014] or due to orthopyroxene fractionation at depth increasing the Fe content and decreasing the Si content of Et_Then [Balta and McSween, 2013a]. Therefore, our calculated results below for Et_Then are not indicative of the primary magma composition nor of its formation conditions, and we will exclude them from the final evaluation. The vitrophyre clast in NWA 7034 contains olivine and pyroxene in a mesostasis. It requires only 8 wt % olivine addition to be in equilibrium with the mantle and compositionally is similar to Gusev Crater basalts [Udry et al., 2014b]; therefore, we feel confident that olivine-only fractionation occurred.

4.2. Petrogenesis of Gale Crater Basalts BecauseJake_Mistheonlydefinitively igneous rock [Stolper et al., 2013], we will discuss its formation condition first. The calculated P-T of formation for Jake_M is at 0.9–1.0 GPa and 1115–1160°C (range of calculated pressures and temperatures from the different analyses of Jake_M). This is significantly below the experimentally determined solidus curve for nominally anhydrous Martian mantle [Bertka and Holloway, 1994a, 1994b; Agee and Draper, 2004; Filiberto and Dasgupta, 2011]. This should not be surprising as Jake_M is a mugearite and not a typical basalt composition. On Earth, evolved silica-undersaturated basalts can be produced by fractionation of a more primitive basalt, dominated by pyroxene, and not olivine, fractionation [Green, 1970; Filiberto and Nekvasil, 2003; Filiberto, 2006]; therefore, adding olivine back in, such as what we have done here, may not be appropriate for

such a basalt composition. Further, silica-understaturated basalts on Earth may require CO2 in the mantle source regions [e.g., Hirose, 1997; Dasgupta et al., 2007]. CO2 in the form of carbonates lowers the mantle solidus and produces both carbonatitic melt and carbonated silicate melt well below the

CO2-free peridotite solidus [e.g., Eggler, 1978; Falloon and Green, 1989; Dasgupta and Hirschmann, 2006; Dasgupta et al., 2007, 2013]. Although melting of Martian mantle compositions in the presence of carbonates has not been explored experimentally, it is expected that the melting of the carbonated Martian mantle compositions will also commence below the volatile-free solidus as shown in Figure 2 [Bertka and Holloway, 1994a, 1994b; Agee and Draper, 2004; Filiberto and Dasgupta, 2011]. Alternatively, Stolperetal.[2013] hypothesized that in order to produce Jake_M by fractional crystallization, the parental magma would have had to be hydrous in order to suppress plagioclase crystallization. This could also explain the calculated P-T of formation being below the dry solidus, as water is known to depress the peridotite solidus, melting the mantle at lower temperatures [e.g., Mysen, 1975; Gaetani and Grove, 1998; Médard and Grove, 2006; Till et al., 2012; Green et al., 2014]. Therefore, for the rest of this discussion, we will

Table 2. Calculated Mantle Potential Temperature (TP in °C) and Age of Martian Rocks b b Tp (°C) ± Age (Ga) ± References (TP) References (Age) Gale Crater 1450 30 4.21 0.35 1 7 Gusev Crater 1445 85 3.65 n.r.a 2, 6 8 Merdiani Planum 1475 15 3.8 0.5 2 9 Hesperian surface 1400 30 3.7–3.0 3 3 Amazonian surface 1370 40 3.0–0.0 3 3 Y98/NWA5789 1550 10 0.472 0.042 4, 5 10 NWA 1068 1480 10 0.18 0.011 12 11 NWA 7034 Clast 1430 15 4.428 0.025 1 13 an.r. = not reported bData From: (1)This study, (2) Filiberto and Dasgupta [2011], (3) Baratoux et al. [2011], (4) Musselwhite et al. [2006], (5) Gross et al. [2011], (6) Filiberto et al. [2010a], (7) Farley et al. [2014], (8) Greeley et al. [2005], (9) Arvidson et al. [2003], (10) Shih et al. [2005], (11) Shih et al. [2003], (12) Filiberto et al. [2010b], (13) Humayum et al. [2013].

ignore the Jake_M composition as its parental magma was likely to be carbonated and/or hydrous, even though it is important to understand for Martian mantle evolution.

4.3. Bradbury Assemblage (Without Jake_M) The rest of the Bradbury Assemblage (Bathurst Inlet, Et_Then, and Rocknest) yield P-T ranging from 1.6 to 2.8 GPa and 1390 to 1560°C. Et_Then has the highest P and T of formation, consistent with it representing an altered basalt. The other rocks at Gale Crater (without Et_Then) are similar to the formation conditions calculated, and experimentally determined, for the basalts in Gusev Crater [Filiberto et al., 2010a; Filiberto and Dasgupta, 2011]. Both the formation conditions for the Gusev rocks and Gale rocks are signiﬁcantly of higher pressure than those for the Meridiani Planum Bounce Rock [Filiberto and Dasgupta, 2011]. In particular, the rocks at Gale Crater have similar formation conditions to Humboldt Peak in Gusev Crater.

4.4. NWA 7034 The vitrophyre clast in NWA 7034 yields P-T of 1.2 GPa and 1419°C. This is in the center of the range of formation conditions calculated for basalts of Gusev Crater [Filiberto and Dasgupta, 2011] and consistent with the clast having similar bulk chemistry to the Gusev Basalt Humphrey [Udry et al., 2014b].

5. Methods for Mantle Potential Temperature Calculation Our estimates of pressures and temperatures of formation for basalts in Gale Crater and a clast in NWA 7034 allow us to place further constraints on the mantle potential temperature for Mars and its plausible evolution following our previous approach [Filiberto et al., 2010a; Filiberto and Dasgupta, 2011]. To calculate the mantle potential temperature, we ﬁrst evaluate the percent of melt fraction needed to produce the

calculated primary magma compositions (Table 1); for this, we rely on TiO2 partitioning [Prytulak and Elliott, 2007; Filiberto et al., 2010a; Filiberto and Dasgupta, 2011]. We assume that each primary magma is derived

from a mantle composition (0.14 ± 0.01 wt % TiO2)ofDreibus and Wänke [1985]andreviewedbyTaylor mantle/melt [2013] and a bulk partition coefﬁcient, DTi of 0.05–0.10 [Bertka and Holloway, 1994a, 1994b; Prytulak and Elliott, 2007]. A change in mantle composition of 0.01 wt % TiO2 (corresponding to the uncertainty reported by Taylor [2013]) results in <10°C change in calculated mantle potential temperature.

To calculate the potential temperature, TP of the Martian mantle, we correct the average pressure and temperature of putative primary basalt compositions to zero pressure using a mantle adiabatic gradient of 0.18°C/km [Kiefer, 2003]. We correct for the effect of latent heat of fusion on the temperature using 5 À1 À1 the expression ΔTfus = F(Hfus/CP), where F is the melt fraction, Hfus (6.4 × 10 JK kg [Kiefer,2003])isthe À1 À1 heat of fusion, and CP (1200 J K kg [Kiefer, 2003]) is the heat capacity at a constant pressure.

6. Mantle Potential Temperature Results The calculated results (Table 2) imply an average mantle potential temperature for the rocks in Gale Crater of 1500 ± 100°C and for the clast in NWA 7034 of 1430 ± 10°C. Et_Then gives the highest mantle potential temperature at ~1600°C. This is consistent with Et_Then, having the largest amount of olivine added back to the bulk composition in order to be in equilibrium with the mantle and with Et_Then representing the most

altered (or least igneous) composition in the Bradbury Assemblage [Schmidt et al., 2014]. If we remove this analysis from the calculation, we end up with a mantle potential temperature of 1450 ± 30°C for Gale Crater, i.e., within error of the mantle potential temperature of 1430 ± 10°C for the clast in NWA 7034.

7. Mantle Potential Temperature Result Comparisons

Estimates for the mantle potential temperature, TP based on rock analyses in Gusev Crater and Bounce Rock in Meridiani Planum, are 1445 ± 85°C and 1475 ± 15°C, respectively [Filiberto and Dasgupta, 2011], i.e., within error similar to the average obtained for Gale Crater and the clast in NWA 7034. The rocks in Gale Crater, Gusev Crater, Bounce Rock, and the clast in NWA 7034 are all thought to be Noachian in age based on geomorphology, crater counting, the single age date for Gale Crater, and age dating of NWA 7533, which is paired with NWA 7034 [Arvidson et al., 2003; Greeley et al., 2005; Anderson and Bell, 2010; Schwenzer et al.,

2012; Humayun et al., 2013; Farley et al., 2014], and give us the same range in TP [Filiberto et al., 2010a; Filiberto and Dasgupta, 2011]. This suggests that the calculated average TP (1450 ± 70°C) may represent an average global mantle temperature during the Noachian.

Further, we have TP estimates for the Hesperian and Amazonian from the analyses of surﬁcial material [Baratoux et al., 2011] and Amazonian (~472 and 180 Ma) from the SNC meteorites [Musselwhite et al., 2006; Filiberto et al., 2010b; Gross et al., 2011]; these estimates are 1400 ± 40°C and 1370 ± 30°C for surface ﬂows and 1550 ± 10°C and 1480 ± 10°C for SNC meteorites (Table 2). Therefore, we can investigate how the mantle temperature may have changed through time and if there were changes in the style of melting during these Martian eons. The results from NWA 7034, Gale Crater, Gusev Crater, and Meridiani Planum are consistent

with an average Noachian TP of 1450 ± 70°C. The TP estimates for the Hesperian and Amazonian are based on orbital analyses of the crust and are lower in temperature than the estimates for the Noachian [Baratoux et al., 2011]. This is consistent with the simple convective cooling of the interior of Mars and may reflect the fact that the conditions of mantle melting capture secular cooling of the whole mantle [e.g., Breuer and Spohn, 2006; Baratoux et al.,2011;Filiberto and Dasgupta, 2011]. However, estimates for the SNC meteorites [Musselwhite et al., 2006; Filiberto et al., 2010b; Gross et al., 2011], which are for the youngest rocks [e.g., Jones, 1986; Nyquist et al., 2001; Walton et al., 2008; Moser et al., 2013], are significantly higher than those for equally young rocks viewed from orbit [Baratoux et al., 2011] and are similar to our estimates for rocks from the Noachian. This discrepancy can be explained by one of two hypotheses: (1) the shergottites are actually ancient (~4.0 Ga) rocks [Bouvieretal., 2005; 2008] or (2) the parental melt of meteorites do not derive from average global mantle melting and thus does not capture the thermal state of background mantle. The Martian meteorites are thought to be relatively young rocks based on Sm-Nd, Rb-Sr, and K-Ar systematics [e.g., Jones, 1986; Nyquist et al., 2001; Walton et al., 2008]; conversely, the Pb-Pb age dating gives an ancient crystallization age [Bouvier et al., 2005; 2008; 2009], giving the possibility that they represent Noachian crustal material consistent with the rocks analyzed by the Mars Exploration Rover and Mars Science Laboratory. However, recent work on age dating of microbaddeleyite and launch-generated zircon has also confirmed the young ages of the Martian meteorites [Moser et al., 2013]. Therefore, we consider the possibility that the Martian meteorites do not represent basalts produced by average global-scale mantle melting, which is represented by the rocks in Gusev and Gale Crater, Meridiani Planum, and surface lava flows. Instead, the Martian meteorites represent localized melting similar to hot spots or plume melting in the Earth, which is consistent with Martian meteorites representing only a small of ejection events (≤10) and therefore a small number of locations in the crust [e.g., Eugsteretal., 1997; Nyquist et al., 2001; Head et al., 2002].

Estimates for the TP of intraplate ocean island basalts on Earth are often as much as 100–200°C hotter than those for mid-ocean ridge basalts [Putirka, 2005; Courtier et al., 2007; Herzberg et al.,2007;Putirka et al., 2007; Lee et al.,2009;Herzberg et al., 2010], although strongly silica-undersaturated basalts from intraplate ocean

islands that are affected by CO2 and/or eclogite in their mantle source regions may not require any substantial thermal anomaly and could be generated by small-scale convections at the base of matured lithosphere [Mallik and Dasgupta, 2012; 2014]. Alternatively, the Ol-phyric shergottite source region may have been enriched in

H2O or Cl [e.g., Filiberto and Treiman, 2009a; McCubbin et al., 2012; Balta and McSween, 2013b; Gross et al., 2013], although this would require >3 wt % more magmatic H2O or Cl in the shergottites compared with the surface basalts to lower the temperature by 100–200°C [Médard and Grove, 2008; Filiberto and Treiman, 2009b; Filiberto et al.,2014;Green et al., 2014]. While arguments have been made for ~1 À 1.5 wt % volatiles in Martian

magmas, >3 wt % is signiﬁcantly higher than any estimate of the preeruptive volatile contents of Martian magmas [e.g., Dann et al., 2001; McSween et al., 2001; Filiberto and Treiman, 2009a; McCubbin et al., 2012; Balta and McSween, 2013b; Gross et al., 2013], and the melt inclusions in Yamato

980459 contain <250 ppm H2Oandare consistent with a relatively dry mantle

(15–47 ppm H2O) source region [Usui et al., 2012]. Assuming that 100–200°C temperature difference between intraplate volcanic settings such as Hawaii and mid-ocean ridge basalt on Figure 3. Mantle potential temperature (TP) versus age for surface rocks from Gale Crater (black squares) (this work), the clast in NWA 7034 (white Earth is appropriate for background diamond) (this work), Gusev Crater (black circle) [Filiberto et al., 2010a; mantle melting conditions versus Filiberto and Dasgupta, 2011], and Bounce Rock in Meridiani Planum (black star) thermal-boundary layer-driven active [Filiberto and Dasgupta, 2011] compared with similar estimates for surface upwelling and melting scenarios, the volcanics (gray circles) [Baratoux et al., 2011] and Ol-phyric shergottites (white circles) [Musselwhite et al., 2006; Filiberto et al., 2010b; Gross et al., 2011]. temperature estimates for the Martian Uncertainty in the age for the lava ﬂows in Gusev Crater was not originally meteorites compared with surface reported [Greeley et al., 2005]; we have assumed an error of 0.5 Ga. Data for rocks are consistent with the former potential temperature, age, uncertainties, and references are from Table 2. being representative of localized melting product (Figure 3). Estimates of mantle temperature and convective style have also been made from analyses of the surface chemistry, as well as geophysical modeling [Zuber et al., 2000; McGovern et al.,2002;Kiefer and Li, 2009; Baratoux et al., 2011; Ruiz et al., 2011; Baratoux et al., 2013; Ruedas et al., 2013; Ruiz, 2014]. The results of these models have been used to debate the cooling history of the interior of Mars and the process by which it loses heat [McGovern et al., 2002; Kiefer, 2003; Kiefer and Li, 2009; Baratoux et al., 2011; Ruiz et al., 2011; Baratoux et al., 2013; Ruiz, 2014]. Some models have suggested that the interior of Mars has actually heated up through time [Ruiz et al., 2011; Ruiz, 2014]; others have suggested simple heat loss from the interior as a function of whole mantle convection [McGovern et al., 2002; Kiefer, 2003; Kiefer and Li, 2009; Baratoux et al., 2011]. Our results, combined with the analyses of surface materials [Baratoux et al., 2011], place constraints on this debate. Mantle potential temperatures derived for ancient rocks in Gusev Crater, Gale Crater, Merdiani Planum, and NWA 7034 are all similar within error, suggesting that they represent an average mantle potential temperature for the

Noachian. Estimates for the Hesperian and Amazonian mantle TP that come from GRS surface analyses suggest a progressive cooling of the interior, as would be expected for a simple cooling of the interior [Baratoux et al.,

2011]. The TP estimates of the meteorites are signiﬁcantly higher than the estimates based on surface chemistry. This could imply a heating up of the interior of Mars over the last 1–2 Ga (Figure 3), as has been suggested based on paleo-heat-ﬂow estimates [Ruiz et al., 2011; Ruiz, 2014]. However, the SNC meteorites have been suggested to not represent the average composition or mineralogy of the Martian crust because there are very limited areas in the Martian crust with similar mineralogy and chemistry to the shergottites [e.g., Hamilton et al., 2003; Taylor et al.,2006;Lang et al., 2009; McSween et al., 2009; Filiberto, 2011; Ody et al., 2014; Werner et al., 2014], and they represent only a small number of ejection events (≤10) from an equally small number of locations in the crust [e.g., Eugsteretal., 1997; Nyquistetal., 2001; Head et al., 2002]. This suggests a unique localized source region for the shergottites, which may not represent the average crust (and therefore mantle). Therefore, instead of heating up of the mantle [Ruiz, 2014], localized hot spot melting likely produced the shergottite parental magmas.

8. Concluding Remarks

Estimates for the mantle potential temperature, TP based on Noachian age rock analyses in Gale Crater, Gusev Crater, Bounce Rock in Meridiani Planum, and a clast in NWA 7034 are within error, which suggests

that the calculated average TP of 1450 ± 70°C may represent an average global mantle temperature during the Noachian. The TP estimates for the Hesperian and Amazonian, based on orbital analyses of the crust [Baratoux et al., 2011], are lower in temperature than the estimates for the Noachian, although hotter temperatures derived from young shergottites suggest the presence of localized thermal anomalies. The calculated potential temperatures do not require the mantle to be heating up for the most part of the history of Mars, as has recently been suggested based on paleo-heat-ﬂow estimates [Ruiz, 2014]. Instead, our analyses are consistent with simple convective cooling of the interior of Mars.

Acknowledgments References Data supporting the entire paper are available in Tables 1 and 2. We thank Agee, C. B., and D. S. Draper (2004), Experimental constraints on the origin of Martian meteorites and the composition of the Martian mantle, – Brian Balta and three anonymous Earth Planet. Sci. Lett., 224, 415 429, doi:10.1016/j.epsl.2004.05.022. reviewers, as well as Editor David Agee,C.B.,N.V.Wilson,F.M.McCubbin,K.Ziegler,V.J.Polyak,Z.D.Sharp,Y.Asmerom,M.H.Nunn,R.Shaheen,andM.H.Thiemens – Baratoux, for their helpful comments, (2013), Unique meteorite from early Amazonian Mars: Water-rich basaltic breccia Northwest Africa 7034, Science, 339, 780 785, which greatly improved the manuscript. doi:10.1126/science.1228858. J.F. received support from NASA grant Anderson, R. B., and J. F. Bell (2010), Geologic mapping and characterization of Gale Crater and implications for its potential as a Mars Science – NNX13AG35G. R.D. received support Laboratory landing site, Mars, 5,76 128, doi:10.1555/mars.2010.0004. from a Packard Fellowship for Science Arvidson, R. E., F. P. I. Seelos, K. S. Deal, W. C. Koeppen, N. O. Snider, J. M. Kieniewicz, B. M. Hynek, M. T. Mellon, and J. B. Garvin (2003), Mantled and Engineering and a NASA grant and exhumed terrains in Terra Meridiani, Mars, J. Geophys. Res., 108(E12), 8073, doi:10.1029/2002JE001982. NNX13AM51G. Balta, J. B., and H. Y. McSween (2013a), Application of the MELTS algorithm to Martian compositions and implications for magma crystallization, J. Geophys. Res. Planets, 118, doi:10.1002/2013JE004461. Balta, J. B., and H. Y. McSween (2013b), Water and the composition of Martian magmas, Geology, 41, 1115–1118, doi:10.1130/G34714.1. Baratoux, D., M. J. Toplis, M. Monnereau, and O. Gasnault (2011), Thermal history of Mars inferred from orbital geochemistry of volcanic provinces, Nature, 472, 338–341, doi:10.1038/nature09903. Baratoux, D., M. J. Toplis, M. Monnereau, and V. Sautter (2013), The petrological expression of early Mars volcanism, J. Geophys. Res. Planets, 118,59–64, doi:10.1029/2012JE004234. Barrat, J. A., A. Jambon, M. Bohn, P. Gillet, V. Sautter, C. Göpel, M. Lesourd, and F. Keller (2002), Petrology and chemistry of the picritic shergottite Northwest Africa 1068 (NWA 1068), Geochim. Cosmochim. Acta, 66(19), 3505–3518. Basu Sarbadhikari, A., J. M. D. Day, Y. Liu, D. Rumble III, and L. A. Taylor (2009), Petrogenesis of olivine-phyric shergottite Larkman Nunatak 06319: Implications for enriched components in Martian basalts, Geochim. Cosmochim. Acta, 73, 2190–2214. Bertka, C. M., and J. R. Holloway (1994a), Anhydrous partial melting of an iron-rich mantle.1. Subsolidus phase assemblages and partial melting phase relations at 10 to 30 kbar, Contrib. Mineral. Petrol., 115(3), 313–322. Bertka, C. M., and J. R. Holloway (1994b), Anhydrous partial melting of an iron-rich mantle. 2. Primary melt compositions at 15 kbar, Contrib. Mineral. Petrol., 115(3), 323–338. Bertka, C. M., and Y. W. Fei (1996), Constraints on the mineralogy of an iron-rich Martian mantle from high-pressure experiments, Planet. Space Sci., 44(11), 1269–1276. Blaney, D. L., et al. (2014), Chemistry and texture of the rocks at Rocknest, Gale Crater: Evidence for sedimentary origin and diagenetic alteration, J. Geophys. Res. Planets, 2109–2131, doi:10.1002/2013JE004590. Bouvier, A., J. Blichert-Toft, J. D. Vervoort, and F. Albarède (2005), The age of SNC meteorites and the antiquity of the Martian surface, Earth Planet. Sci. Lett., 240, 221–233, doi:10.1016/j.epsl.2005.09.007. Bouvier, A., J. Blichert-Toft, J. D. Vervoort, P. Gillet, and F. Albarède (2008), The case for old basaltic shergottites, Earth Planet. Sci. Lett., 266, 105–124, doi:10.1016/j.epsl.2007.11.006. Bouvier, A., J. Blichert-Toft, and F. Albarède (2009), Martian meteorite chronology and the evolution of the interior of Mars, Earth Planet. Sci. Lett., 280, 285–295, doi:10.1016/j.epsl.2009.01.042. Breuer, D., and T. Spohn (2006), Viscosity of the Martian mantle and its initial temperature: Constraints from crust formation history and the evolution of the magnetic ﬁeld, Planet. Space Sci., 54, 153–169, doi:10.1016/j.pss.2005.08.008. Bridges, J., S. Schwenzer, F. Westall, and M. Dyar (2013), Gale Crater’s Bathurst Inlet and Rocknest_3 compositions, Lunar and Planetary Institute Science Conference Abstracts, 44, Abstract# 1973. Cartwright, J. A., U. Ott, S. Herrmann, and C. B. Agee (2014), Modern atmospheric signatures in 4.4 Ga Martian meteorite NWA 7034, Earth Planet. Sci. Lett., 400,77–87, doi:10.1016/j.epsl.2014.05.008. Collinet, M., E. Medard, B. Devouard, and A. Peslier (2012), Constraints on the parental melts of enriched shergottites from image analysis and high pressure experiments, paper presented at Lunar and Planetary Institute Science Conference Abstracts. Courtier, A. M., et al. (2007), Correlation of seismic and petrologic thermometers suggests deep thermal anomalies beneath hot spots, Earth Planet. Sci. Lett., 264, 308–316. Dann, J. C., A. H. Holzheid, T. L. Grove, and H. Y. McSween (2001), Phase equilibria of the Shergotty meteorite: Constraints on pre-eruptive water contents of Martian magmas and fractional crystallization under hydrous conditions, Meteorit. Planet. Sci., 36(6), 793–806. Dasgupta, R., and M. M. Hirschmann (2006), Melting in the Earth’s deep upper mantle caused by carbon dioxide, Nature, 440, 659–662. Dasgupta, R., M. Hirschmann, and N. Smith (2007), Partial melting experiments of peridotite + CO2 at 3 GPa and genesis of alkalic ocean island basalts, J. Petrol., 48, 2093–2124. Dasgupta, R., A. Mallik, K. Tsuno, A. C. Withers, G. Hirth, and M. M. Hirschmann (2013), Carbon-dioxide-rich silicate melt in the Earth’s upper mantle, Nature, 493, 211–215. Dreibus, G., and H. Wänke (1985), Mars, a volatile-rich planet, Meteoritics, 20(2), 367–381. Edgett, K. S., R. A. Yingst, M. E. Minitti, E. Heydari, S. K. Rowland, K. E. Herkenhoff, L. C. Kah, M. R. Kennedy, G. M. Krezoski, and M. J. McBride (2014), Curiosity’s Mars Hand Lens Imager (Mahli)–Primary mission (ﬁrst Mars year) results, paper presented at 2014 GSA Annual Meeting in Vancouver, British Columbia. Eggler, D. H. (1978), The effect of CO2 upon partial melting of peridotite in the system Na2O-CaO-Al2O3-MgO-SiO2-CO2 to 35 kbar, with an analysis of melting in a peridotite-H2O-CO2 system, Am. J. Sci., 278(3), 305–343. Eugster, O., A. Weigel, and E. Polnau (1997), Ejection times of Martian meteorites, Geochim. Cosmochim. Acta, 61(13), 2749–2757. Falloon, T. J., and D. H. Green (1989), The solidus of carbonated, fertile peridotite, Earth Planet. Sci. Lett., 94(3), 364–370.

Farley, K. A., et al. (2014), In situ radiometric and exposure age dating of the Martian surface, Science, 343, doi:10.1126/science.1247166. Filiberto, J. (2006), Constraints on the chemistry of Martian magmas, PhD Dissertation thesis, 163 pp., SUNY Stony Brook, Stony Brook. Filiberto, J. (2011), Geochemical differences between surface basalts and Martian meteorites: The need for Martian sample return, Workshop, Solar System Sample Return Mission, Abstract #5004. Filiberto, J., and A. H. Treiman (2009a), Martian magmas contained abundant chlorine, but little water, Geology, 37, 1087–1090. Filiberto, J., and A. H. Treiman (2009b), The effect of chlorine on the liquidus of basalt: First results and implications for basalt genesis on Mars and Earth, Chem. Geol., 263,60–68. Filiberto, J., and H. Nekvasil (2003), Linking tholeiites and silica-undersaturated alkalic rocks: An experimental study, GSA Abstracts With Programs, 35(6), 632. 2+ Filiberto, J., and R. Dasgupta (2011), Fe -Mg partitioning between olivine and basaltic melts: Applications to genesis of olivine-phyric shergottites and conditions of melting in the Martian interior, Earth Planet. Sci. Lett., 304, 527–537. Filiberto, J., A. H. Treiman, and L. Le (2008), Crystallization experiments on a Gusev Adirondack basalt composition, Meteorit. Planet. Sci., 43, 1137–1146. Filiberto, J., R. Dasgupta, W. S. Kiefer, and A. H. Treiman (2010a), High pressure, near-liquidus phase equilibria of the home plate basalt fastball and melting in the Martian mantle, Geophys. Res. Lett., 37, L13201, doi:10.1029/2010GL043999. Filiberto, J., D. S. Musselwhite, J. Gross, K. Burgess, L. Le, and A. H. Treiman (2010b), Experimental petrology, crystallization history, and parental magma characteristics of olivine-phyric shergottite NWA 1068: Implications for the petrogenesis of “enriched” olivine-phyric shergottites, Meteorit. Planet. Sci., 45, 1258–1270. Filiberto, J., E. Chin, J. M. D. Day, I. A. Franchi, R. C. Greenwood, J. Gross, S. C. Penniston-Dorland, S. P. Schwenzer, and A. H. Treiman (2012), Geochemistry of intermediate olivine-phyric shergottite Northwest Africa 6234, with similarities to basaltic shergottite Northwest Africa 480 and olivine-phyric shergottite Northwest Africa 2990, Meteorit. Planet. Sci., 47, 1256–1273. Filiberto, J., R. Dasgupta, J. Gross, and A. Treiman (2014), Effect of chlorine on near-liquidus phase equilibria of an Fe–Mg-rich tholeiitic basalt, Contrib. Mineral. Petrol., 168,1–13. Gaetani, G. A., and T. L. Grove (1998), The influence of water on melting of mantle peridotite, Contrib. Mineral. Petrol., 131(4), 323–346. Goettel, K. A. (1981), Density of the mantle of Mars, Geophys. Res. Lett., 8(5), 497–500, doi:10.1029/GL008i005p00497. Goodrich, C. A. (2002), Olivine-phyric Martian basalts: A new type of shergottite, Meteorit. Planet. Sci., 37,31–34. Goodrich, C. A. (2003), Petrogenesis of olivine-phyric shergottites Sayh al Uhaymir 005 and Elephant Moraine A79001 lithology A, Geochim. Cosmochim. Acta, 67(19), 3735–3772. Goodrich, C., D. van Niekerk, and M. Morgan (2003), Northwest Africa 1110: A new olivine-phyric shergottite possibly paired with Northwest Africa 1068, Lunar and Planetary Science, 34, Abstract #1266. Grant, J. A., S. A. Wilson, N. Mangold, F. Calef, and J. P. Grotzinger (2014), The timing of alluvial activity in Gale Crater, Mars, Geophys. Res. Lett., 41, 1142–1149, doi:10.1002/2013GL058909. Greeley, R., B. H. Foing, H. Y. McSween, G. Neukum, P. Pinet, M. van Kan, S. C. Werner, D. W. Williams, and T. E. Zegers (2005), Fluid lava flows in Gusev Crater, Mars, J. Geophys. Res., 110, E05008,, doi:10.1029/2005JE002401. Green, D. H. (1970), A review of experimental evidence on the origin of basaltic and nephelinitic magmas, Phys. Earth Planet. Inter., 3, 221–235. Green, D. H., W. O. Hibberson, A. Rosenthal, I. Kovács, G. M. Yaxley, T. J. Falloon, and F. Brink (2014), Experimental study of the influence of water on melting and phase assemblages in the upper Mantle, J. Petrol., 55, 2067–2096. Greshake, A., J. Fritz, and D. Stöffler (2004), Petrology and shock metamorphism of the olivine-phyric shergottite Yamato 980459: Evidence for a two-stage cooling and a single-stage ejection history, Geochim. Cosmochim. Acta, 68, 2359–2377. Gross, J., A. H. Treiman, J. Filiberto, and C. D. K. Herd (2011), Primitive olivine-phyric shergottite NWA 5789: Petrography, mineral chemistry, and cooling history imply a magma similar to Yamato-980459, Meteorit. Planet. Sci., 46, 116–133. Gross, J., J. Filiberto, and A. S. Bell (2013), Water in the Martian interior: Evidence for terrestrial MORB mantle-like volatile contents from hydroxyl-rich apatite in olivine-phyric shergottite NWA 6234, Earth Planet. Sci. Lett., 369–370, 120–128, doi:10.1016/j.epsl.2013.03.016. Grotzinger, J. P. (2013), Analysis of surface materials by the Curiosity Mars rover, Science, 341, 1475, doi:10.1126/science.1244258 . Hamilton, V. E., P. R. Christensen, H. Y. McSween, and J. L. Bandfield (2003), Searching for the source regions of Martian meteorites using MGS TES: Integrating Martian meteorites into the global distribution of igneous materials on Mars, Meteorit. Planet. Sci., 38, 871–885. Head, J. N., H. J. Melosh, and B. A. Ivanov (2002), Martian meteorite launch: High-speed ejecta from small craters, Science, 298(5599), 1752–1756. Herzberg, C., P. D. Asimow, N. Arndt, Y. Niu, C. M. Lesher, J. G. Fitton, M. J. Cheadle, and A. D. Saunders (2007), Temperatures in ambient mantle and plumes: Constraints from basalts, picrites, and komatiites, Geochem. Geophys. Geosyst., 8, Q02006, doi:10.1029/2006GC001390. Herzberg, C., K. Condie, and J. Korenaga (2010), Thermal history of the Earth and its petrological expression, Earth Planet. Sci. Lett., 292,79–88. Hirose, K. (1997), Partial melt compositions of carbonated peridotite at 3 GPa and role of CO2 in alkali-basalt magma generation, Geophys. Res. Lett., 24(22), 2837–2840, doi:10.1029/97GL02956. Humayun, M., et al. (2013), Origin and age of the earliest Martian crust from meteorite NWA 7533, Nature, 503, 513–516. Irving, A., S. Kuehner, C. Herd, M. Gellissen, R. Korotev, I. Puchtel, R. Walker, T. Lapen, and D. Rumble (2010), Petrologic, elemental, and multi-isotopic characterization of permafic olivine-phyric shergottite Northwest Africa 5789: A primitive magma derived from depleted Martian mantle, Lunar and Planetary Science, 41, Abstract# 1547. Jones, J. H. (1986), A discussion of isotopic systematics and mineral zoning in the shergottites: Evidence for a 180 Myr igneous crystallization age, Geochim. Cosmochim. Acta, 50(6), 969–977. Kiefer, W. S. (2003), Melting in the Martian mantle: Shergottite formation and implications for present-day mantle convection on Mars, Meteorit. Planet. Sci., 38(12), 1815–1832. Kiefer, W. S., and Q. Li (2009), Mantle convection controls the observed lateral variations in lithospheric thickness on present-day Mars, Geophys. Res. Lett., 36, L18203, doi:10.1029/2009GL039827. Lang, N. P., L. L. Tornabene, H. Y. McSween Jr., and P. R. Christensen (2009), Tharsis-sourced relatively dust-free lavas and their possible relationship to Martian meteorites, J. Volcanol. Geotherm. Res., 185, 103–115. Lee, C.-T. A., P. Luffi, T. Plank, H. Dalton, and W. P. Leeman (2009), Constraints on the depths and temperatures of basaltic magma generation on Earth and other terrestrial planets using new thermobarometers for mafic magmas, Earth Planet. Sci. Lett., 279,20–33. Lodders, K., and B. Fegley (1997), An oxygen isotope model for the composition of Mars, Icarus, 126(2), 373–394. Mallik, A., and R. Dasgupta (2012), Reaction between MORB-eclogite derived melts and fertile peridotite and generation of ocean island basalts, Earth Planet. Sci. Lett., 329–330,97–108. Mallik, A., and R. Dasgupta (2014), Effect of variable CO2 on eclogite-derived andesite and lherzolite reaction at 3 GPa: Implications for mantle source characteristics of alkalic ocean island basalts, Geochem. Geophys. Geosyst.,15, 1533–1557, doi:10.1002/2014GC005251.

McCubbin, F. M., E. H. Hauri, S. M. Elardo, K. E. Vander Kaaden, J. Wang, and C. K. Shearer (2012), Hydrous melting of the Martian mantle produced both depleted and enriched shergottites, Geology, 40, 683–686. McGetchin, T. R., and J. R. Smith (1978), The mantle of Mars: Some possible geological implications of its high density, Icarus, 34(3), 512–536. McGovern, P. J., S. C. Solomon, D. E. Smith, M. T. Zuber, M. Simons, M. A. Wieczorek, R. J. Phillips, G. A. Neumann, O. Aharonson, and J. W. Head (2002), Localized gravity/topography admittance and correlation spectra on Mars: Implications for regional and global evolution, J. Geophys. Res., 107, doi:10.1029/2002JE001854. McKay, G., C. Schwandt, T. Mikouchi, E. Koizumi, and J. Jones (2004), Yamato 980459: The most primitive shergottite?, LPS, XXXV. McSween, H. Y., T. L. Grove, R. C. Lentz, J. C. Dann, A. H. Holzheid, L. R. Riciputi, and J. G. Ryan (2001), Geochemical evidence for magmatic water within Mars from pyroxenes in the Shergotty meteorite, Nature, 409(6819), 487–490. McSween, H. Y., et al. (2004), Basaltic rocks analyzed by the Spirit rover in Gusev Crater, Science, 305, 842–845. McSween, H. Y., et al. (2006), Alkaline volcanic rocks from the Columbia Hills, Gusev Crater, Mars, J. Geophys. Res., 111, E09S91, doi:10.1029/ 2006JE002698. McSween, H. Y., et al. (2008), Mineralogy of volcanic rocks in Gusev Crater Mars: Reconciling Mössbauer, APXS, and Mini-TES spectra, J. Geophys. Res., 113, E06S04, doi:10.1029/2007JE002970. McSween, H. Y., G. J. Taylor, and M. B. Wyatt (2009), Elemental composition of the Martian Crust, Science, 324, 736–739. Médard, E., and T. Grove (2008), The effect of H2O on the olivine liquidus of basaltic melts: Experiments and thermodynamic models, Contrib. Mineral. Petrol., 155, 417–432. Médard, E., and T. L. Grove (2006), Early hydrous melting and degassing of the Martian interior, J. Geophys. Res., 111, E11003, doi:10.1029/ 2006JE002742. Meyer, C. (2012), Mars meteorite compendium; JSC #27672 Revision CRep, Astromaterials Research and Exploration Science (ARES) Johnson Space Center Mikouchi, T., E. Koizumi, G. McKay, A. Monkawa, Y. Ueda, J. Chokai, and M. Miyamoto (2004), Yamato 980459: Mineralogy and petrology of a new shergottite-related rock from Antarctica, Antarct. Meteorite Res., 17,13–34. Minitti, M. E., et al. (2013), MAHLI at the Rocknest sand shadow: Science and science-enabling activities, J. Geophys. Res. Planets, 118, 2338–1360, doi:10.1002/2013JE004426. Monders, A. G., E. Médard, and T. L. Grove (2007), Phase equilibrium investigations of the Adirondack class basalts from the Gusev plains, Gusev Crater, Mars, Meteorit. Planet. Sci., 42, 131–148. Morgan, J. W., and E. Anders (1979), Chemical composition of Mars, Geochim. Cosmochim. Acta, 43(10), 1601–1610. Moser, D., K. Chamberlain, K. Tait, A. Schmitt, J. Darling, I. Barker, and B. Hyde (2013), Solving the Martian meteorite age conundrum using micro-baddeleyite and launch-generated zircon, Nature, 499, 454–457. Musselwhite, D. S., H. A. Dalton, W. S. Kiefer, and A. H. Treiman (2006), Experimental petrology of the basaltic shergottite Yamato-980459: Implications for the thermal structure of the Martian mantle, Meteorit. Planet. Sci., 41, 1271–1290. Mysen, B. (1975), Melting of hydrous mantle: I Phase relations of natural peridotite at high pressures and temperatures with controlled activities of water, carbon dioxide, and hydrogen, J. Petrol., 16(3), 520–548. Nyquist, L. E., D. D. Bogard, C. Y. Shih, A. Greshake, D. Stöffler, and O. Eugster (2001), Ages and geologic histories of Martian meteorites, Space Sci. Rev., 96(1), 105–164. Ody, A., K. Cannon, F. Poulet, J. Mustard, C. Quantin, and J. Filiberto (2014), Search for analogue sites of new Martian shergottite spectra using NIR data, Lunar and Planetary Institute Science Conference Abstracts, 45, Abstract #2207. Ohtani, E., and N. Kamaya (1992), The geochemical model of Mars: An estimation from the high pressure experiments, Geophys. Res. Lett., 19(22), 2239–2242, doi:10.1029/92GL02369. Prytulak, J., and T. Elliott (2007), TiO2 enrichment in ocean island basalts, Earth Planet. Sci. Lett., 263, 388–403. Putirka, K. D. (2005), Mantle potential temperatures at Hawaii, Iceland, and the mid-ocean ridge system, as inferred from olivine phenocrysts: Evidence for thermally driven mantle plumes, Geochem. Geophys. Geosyst., 6, Q05L08, doi:10.1029/2005GC000915. Putirka, K. D., M. Perfit, F. J. Ryerson, and M. G. Jackson (2007), Ambient and excess mantle temperatures, olivine thermometry, and active versus passive upwelling, Chem. Geol., 241, 177–206. Rieder, R., et al. (2004), Chemistry of rocks and soils at Meridiani Planum from the alpha particle X-ray spectrometer, Science, 306, 1746–1749. Ruedas, T., P. J. Tackley, and S. C. Solomon (2013), Thermal and compositional evolution of the Martian mantle: Effects of phase transitions and melting, Phys. Earth Planet. Inter., 216,32–58. Ruiz, J. (2014), The early heat loss evolution of Mars and their implications for internal and environmental history, Sci. Rep., 4, 4338, doi:10.1038/srep04338. Ruiz, J., P. J. McGovern, A. Jiménez-Díaz, V. López, J.-P. Williams, B. C. Hahn, and R. Tejero (2011), The thermal evolution of Mars as constrained by paleo-heat flows, Icarus, 215, 508–517. Sanloup, C., A. Jambon, and P. Gillet (1999), A simple chondritic model of Mars, Phys. Earth Planet. Inter., 112(1–2), 43–54. Santos, A., C. Agee, F. McCubbin, C. Shearer, and P. Burger (2013), Martian Breccia NWA 7034: Basalt mugearite and trachyandesite clasts, Meteorit. Planet Sci. Suppl., 76, 5284. Sautter, V., A. Cousin, G. Dromard, C. Fabre, O. Forni, O. Gasnault, S. Le Mouélic, N. Mangold, S. Maurice, and M. Minitti (2013), Is Bathurst Inlet Rock an evidence of explosive volcanism in the Rocknest area of Gale Crater?, paper presented at Lunar and Planetary Institute Science Conference Abstracts. Sautter, V., et al. (2014), Igneous mineralogy at Bradbury Rise: The first ChemCam campaign at Gale Crater, J. Geophys. Res. Planets, 119,30–46, doi:10.1002/2013JE004472. Schmidt, M. E., and T. J. McCoy (2010), The evolution of a heterogeneous Martian mantle: Clues from K, P, Ti, Cr, and Ni variations in Gusev basalts and shergottite meteorites, Earth Planet. Sci. Lett., 296,67–77. Schmidt, M. E., et al. (2014), Geochemical diversity in first rocks examined by the Curiosity rover in Gale Crater: Evidence for and significance of an alkali and volatile-rich igneous source, J. Geophys. Res. Planets, 119,64–81, doi:10.1002/2013JE004481. Schwenzer, S. P., et al. (2012), Gale Crater: Formation and post-impact hydrous environments, Planet. Space Sci., 70,84–95. Shearer, C. K., P. V. Burger, J. J. Papike, L. E. Borg, A. J. Irving, and C. D. K. Herd (2008), Petrogenetic linkages among Martian basalts: Implications based on trace element chemistry of olivine, Meteorit. Planet. Sci., 43, 1241–1258. Shih, C. Y., L. E. Nyquist, H. Wiesmann, Y. Reese, and K. Misawa (2005), Rb-Sr and Sm-Nd dating of olivine-phyric shergottite Yamato 980459: Petrogenesis of depleted shergottites, Antarct. Meteorite Res., 18, 46. Shih, C.-Y., L. Nyquist, H. Wiesmann, and J. Barrat (2003), Age and petrogenesis of picritic shergottite NWA1068: Sm-Nd and Rb-Sr isotopic studies, paper presented at Lunar and Planetary Institute Science Conference Abstracts. Stolper, E. M., et al. (2013), The petrochemistry of Jake_M: A Martian mugearite, Science, 341, doi:10.1126/science.1239463. Taylor, G. J. (2013), The bulk composition of Mars, Chem. Erde, 73, 401–420, doi:10.1016/j.chemer.2013.09.

Taylor, G. J., et al. (2006), Bulk composition and early differentiation of Mars, J. Geophys. Res., 111, E03S10, doi:10.1029/2005JE002645. Till, C., T. Grove, and A. Withers (2012), The beginnings of hydrous mantle wedge melting, Contrib. Mineral. Petrol., 163, 669–688. Treiman, A. H., and J. Filiberto (2014), Geochemical diversity of shergottite basalts: Mixing and fractionation and their relation to Mars surface basalts, Meteorit. Planet. Sci., doi:10.1111/maps.12363, in press. Udry, A., J. B. Balta, and H. Y. McSween (2014a), Exploring fractionation models for Martian magmas, J. Geophys. Res. Planets, 119,1–18, doi:10.1002/2013JE004445. Udry, A., N. G. Lunning, H. Y. McSween Jr., and R. J. Bodnar (2014b), Petrogenesis of a vitrophyre in the Martian meteorite breccia NWA 7034, Geochim. Cosmochim. Acta, 141, 281–293. Usui, T., H. Y. McSween Jr., and B. C. Clark III (2008a), Petrogenesis of high-phosphorous Wishstone Class rocks in Gusev Crater, Mars, J. Geophys. Res., 113, E12S44, doi:10.1029/2008JE003225. Usui, T., H. Y. McSween Jr., and C. Floss (2008b), Petrogenesis of olivine-phyric shergottite Yamato 980459, revisited, Geochim. Cosmochim. Acta, 72, 1711–1730. Usui, T., C. M. O. D. Alexander, J. Wang, J. I. Simon, and J. H. Jones (2012), Origin of water and mantle–crust interactions on Mars inferred from hydrogen isotopes and volatile element abundances of olivine-hosted melt inclusions of primitive shergottites, Earth Planet. Sci. Lett., 357–358, 119–129. Walton, E. L., S. P. Kelley, and C. D. K. Herd (2008), Isotopic and petrographic evidence for young Martian basalts, Geochim. Cosmochim. Acta, 72, 5819–5837. Werner, S. C., A. Ody, and F. Poulet (2014), The source crater of Martian shergottite meteorites, Science, 343, 1343–1346. Yin, Q.-Z., F. McCubbin, Q. Zhou, A. Santos, R. Targese, X. Li, Q. Li, Y. Liu, G. Tang, and J. Boyce (2014), An Earth-like beginning for ancient Mars indicated by alkali-rich volcanism at 4.4 Ga, paper presented at Lunar and Planetary Institute Science Conference Abstracts. Zipfel, J., et al. (2011), Bounce Rock: A shergottite-like basalt encountered at Meridiani Planum, Mars, Meteorit. Planet. Sci., 46,1–20. Zuber, M. T., et al. (2000), Internal structure and early thermal evolution of mars from mars global surveyor topography and gravity, Science, 287(5459), 1788–1793.