Volcanism on the Marius Hills plateau: Observational analyses using Clementine multispectral data

Volcanism on the Marius Hills plateau: Observational analyses using

Clementine multispectral data

David J. HeatherResearch and Scientific Support Department, ESA-ESTEC, Noordwijk, Netherlands

Sarah K. Dunkin1

Department of Earth Sciences, University College London, UK

Lionel WilsonEnvironmental Science Department, Lancaster University, Lancaster, UK

Received 17 May 2002; revised 2 October 2002; accepted 19 December 2002; published 18 March 2003.

[1] We have studied the Marius Hills region and mapped the spectrally distinct flowspresent for the first time, using photographic and Clementine multispectral data. Thebasalts on the plateau are varied in age and composition but are dominated by a high-titanium Eratosthenian basalt, most likely from the same source as the Flamsteed Basalt,further south. The thickness of the basalts across the plateau is consistently greater than120 m and is considerably thicker in some areas. A lower limit of 5320 km3 of basalts hasbeen erupted onto the plateau. The domes and cones in the region do not appear to berelated to any specific basalt or volcanic episode but occur at all levels in the stratigraphythat can be derived in the region. The eruption conditions required to form these constructsindicate that they must represent a series of separate volcanic episodes occurringthroughout the history of the plateau. Cones on the Marius plateau are dominated by astrong glassy signature and often have an associated microlitic structure. Examples areshown of localized microlitic or glassy materials in regions where no cone is evident in thephotographic data. These features are proposed to represent short-lived pyroclasticepisodes that have deposited glassy and microlitic units on the plateau but have not beenmaintained for long enough to develop a cone. The volcanic history of the Marius Hillsregion is extremely complex, and most likely involved several separate episodes ofvolcanism with a large contrast in eruption styles and characteristics. INDEX TERMS: 6250

Planetology: Solar System Objects: Moon (1221); 5464 Planetology: Solid Surface Planets: Remote sensing;

5480 Planetology: Solid Surface Planets: Volcanism (8450); 5470 Planetology: Solid Surface Planets:

Surface materials and properties; 5410 Planetology: Solid Surface Planets: Composition; KEYWORDS: Moon,

volcanism, spectral reflectance, mineralogy, Clementine

Citation: Heather, D. J., S. K. Dunkin, and L. Wilson, Volcanism on the Marius Hills plateau: Observational analyses using

Clementine multispectral data, J. Geophys. Res., 108(E3), 5017, doi:10.1029/2002JE001938, 2003.

1. Introduction

[2] The Marius Hills region comprises a plateau with anarea of approximately 35,000 km2 [Greeley, 1971;Whitford-Stark and Head, 1977] (Figure 1), rising several hundredmeters from the surrounding plains of Oceanus Procellarum[McCauley, 1967]. The mare flows in the region are pre-dominantly Eratosthenian in age, although volcanic activityon the plateau is thought to have extended from the Imbrianthrough to the Eratosthenian period [McCauley, 1967; Whit-ford-Stark and Head, 1980]. The plateau contains the highest

concentration of volcanic structures in Oceanus Procellarum,including low domes, steep sided domes, cones, and rilles[e.g., McCauley, 1967; Greeley, 1971; Guest, 1971; Whit-ford-Stark and Head, 1977]. The wide variation in domemorphology ledMcCauley [1969] to suggest that the MariusHills region could show evidence for igneous differentiation.However, it is also possible that variations in effusion ratehave caused the diversity now seen in the volcanic structures[e.g., Whitford-Stark and Head, 1977; Gillis and Spudis,1995; Weitz and Head, 1999].[3] In this study, we use the Clementine UVVIS camera

data to complete the first detailed spectral mapping of thebasalts at Marius Hills (section 3). The Clementine data arethen used in combination with Lunar Orbiter photographyto investigate the compositions and morphologies of thedomes, cones, and rilles in the region (section 4). The

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. E3, 5017, doi:10.1029/2002JE001938, 2003

1Also at Rutherford Appleton Laboratory, Didcot, UK.

Copyright 2003 by the American Geophysical Union.0148-0227/03/2002JE001938

3 - 1

interpretations of these results are then used to infer thenature of the volcanism that has shaped the Marius Hillsplateau (section 5). This forms the first part of a two-phasestudy. The second phase, to be published separately, will useresults from these analyses such as the basalt thicknessvariations, dome and conemorphologies andmorphometries,and volcanic eruption history to develop theoretical modelsfor the rise and eruption characteristics of the basalts atMarius Hills, using methods described by Heather et al.[2000].

2. Data Reduction

[4] The five-band UVVIS data from the Clementinemultispectral data set were used in this study, coveringwavelengths from 415 nm to 1000 nm. Data reduction was

completed using the ISIS software distributed by the U.S.Geological Survey (USGS), following their recommendedprocedures (available at the USGS ISIS Homepage, athttp://wwwflag.wr.usgs.gov/isis-bin/isis.cgi) (T. Becker,personal communication, 1996). As Marius Hills is closeto the lunar equator, the initial data reduction suffered fromproblems with the photometric calibration in the form ofphase angle corrections. The Clementine data were col-lected over 2 months, with the second month data filling inthe gaps of the first. The data were taken at significantlydifferent phase angles from one month to the next and thisleads to orbital stripes appearing in mosaics, particularly inareas close to the lunar equator where the standard photo-metric correction employed by the USGS does not performparticularly well. To correct for this, we applied the proce-dure of J. Gillis (personal communication, 1996), adjusting

Figure 1. Map of Oceanus Procellarum on the lunar nearside showing the location of the Marius Hillsvolcanic complex. Adapted from Whitford-Stark and Head [1980].

3 - 2 HEATHER ET AL.: MARIUS HILLS VOLCANISM

the data with a lower phase angle to match that of the higherphase angle data prior to the application of the standardphotometric corrections. A simple code to complete thisprocedure was written in IDL, and the resulting imagesshow almost no sign of the original striping from the phaseangle problem. The photometric coefficients used duringdata reduction, as defined by the USGS AstrogeologyTeam (data available at the USGS ISIS Homepage athttp://wwwflag.wr.usgs.gov/isis-bin/isis.cgi), are given inTable 1.[5] For mapping of the flows on the plateau (section 3),

Clementine mosaics of 157 m/pixel resolution were pro-duced to cover the region from 9.15�N to 17.43�N and300.53�E to 313.02�E. The entire Marius Hills plateaustretches a little further south than this, to approximately

6.00�N. This part of the plateau had already been incorpo-rated into another region as part of a separate study [Heather,2000; Heather and Dunkin, 2002] and mosaicked at aresolution of 200 m/pixel. For all studies a series of Clem-entine images were produced, including multispectral ratio,FeO, and TiO2 maps. The multispectral ratio image producedfor this study is provided in Figure 2, and the correspondingTiO2 and FeO maps are provided in Figures 3 and 4,respectively. The single filter ‘‘albedo’’ image usually rep-resented by the Clementine 750 nm mosaic is not provided,as this region shows very little contrast.[6] The multispectral ratio images identify compositional

and maturity variations across the region using the standardratios to control the spectral channels (red = 750 nm/415 nm,green = 750 nm/950 nm, blue = 415 nm/750 nm). In theseimages, a red color indicates a mature low-Ti basalt, blueregions are mature high-Ti basalts, and green and yellowareas represent freshly exposed basalt. Cyan colors mayindicate either a fresh highland soil or fresh mare basalt andthe FeO map, and five-point spectra (spectral reflectanceplots constructed using the reflectance value in each UVVIScamera band) must be used to distinguish between the twoscenarios. The FeO and TiO2 maps were produced using thealgorithms of Lucey et al. [2000]. These remove the effectsof maturity from the Clementine images, isolating those

Table 1. Photometric Coefficients Used in the Reduction of the

Clementine Data for This Researcha

BSH3 H D E F G3

A filter 2.31 0.062 0.0 �0.222 0.5 0.39B filter 1.6 0.054 0.0 �0.218 0.5 0.4Other filters 1.35 0.052 0.0 �0.226 0.5 0.36

aSee the USGS ISIS Homepage http://wwwflag.wr.usgs.gov/isis-bin/isis.cgi) for a definition of the coefficients.

Figure 2. Clementine multispectral ratio image of the Marius Hills plateau produced using the standardratios of 750/415 nm = red, 750/950 nm = green, and 415/750 nm = blue. The boundaries shown arethose of the final unit map, identifying the basalt flows mapped using the UV/VIS and 1 mm data. Solidlines are definite spectral boundaries; dashed lines are uncertain borders. The Reiner Gamma swirl featureis labeled ‘‘R.’’

HEATHER ET AL.: MARIUS HILLS VOLCANISM 3 - 3

differences that are due to compositional variations. Thequoted accuracy of these algorithms is ±1 wt% for both FeOand TiO2. The FeO and TiO2 maps are particularly useful fordistinguishing between highland and mare units and aretherefore used to search for evidence of an impact craterhaving excavated highland materials from beneath the marebasalts [e.g., Heather et al., 1999] (section 3.3). Cautionmust be exercised when taking FeO and TiO2 measurementsfrom steep slopes, as this can have a significant effect on theperformance of the algorithms. Therefore throughout theseanalyses, care was taken to avoid measuring points on steepslopes wherever they occur in the region.

3. Spectral Mapping of the Mare Basaltsin Marius Hills

[7] There have been no previous attempts to categoricallymap the basalts that cover the Marius Hills plateau, althougha number of studies have been made to investigate their basicproperties using spacecraft data. Using Galileo data, Sun-

shine et al. [1992] identified two high-titanium units in theMarius Hills region. One unit had a strong 1 mm absorptionband similar to that of the basalts of the surrounding plains ofOceanus Procellarum, and the second showed a weaker 1 mmband than the surrounding basalts. A more diverse range ofbasalts was since recognized by Weitz and Head [1999] onthe basis of the UV/VIS ratio and 1 mm data from Clem-entine. They used the global TiO2 and FeO maps of Lucey etal. [2000] and found a wide range of values on the plateau,consistent with the surrounding Oceanus Procellarum. How-ever, they could only clearly identify two main units: a high-titanium basalt and a lower-titanium unit, leaving severalintermediate areas that could not be placed into either of thetwo main categories. No boundaries were drawn for any ofthe observed units. The FeO and TiO2 maps produced for thecurrent mapping exercise indicate values of 15–19 wt% FeOand 5–9 wt% TiO2 for the bulk of the plateau.

3.1. Mapping Technique

[8] In order to map the compositional boundaries acrossthe plateau from these data, a system was used that is based

Figure 3. TiO2 map of the Marius Hills plateau produced using the algorithms of Lucey et al. [2000].Brighter regions are higher in TiO2, which ranges from approximately 5 to 9 wt% across the bulk of theplateau. The dotted line on the map represents the boundary of the raised plateau, while the solid linesand black dots show the location of the domes and cones respectively.


upon ground-based telescopic techniques originally devel-oped in a series of papers by Pieters and McCord [1976]and Pieters [1977, 1978]. These papers classified the basaltson the lunar nearside using a series of spectral reflectancecriteria, including the strength of the 1 mm and 2 mmabsorption bands, the albedo, and the steepness of thereflectance slope between the UV and VIS spectral regions.The Clementine UVVIS data do not extend to 2 mm but canbe used to quantitatively investigate the strength of the 1 mmband (950/750 nm value), the steepness of the UV/VISslope (415/750 nm value), the albedo (750 nm value), andthe FeO and TiO2 abundance of a soil. Furthermore, theClementine data are of a significantly higher spatial reso-lution than ground-based data.[9] The mapping technique used in this research began

with the tracing of boundaries from the multispectral ratioimage (Figure 2). The spectral character of the basalts in thismosaic is primarily dictated by their UV/VIS ratios, whichin turn are empirically related to the abundance of titaniumin the soils [Charette et al., 1974]. Therefore variations inthe multispectral ratio mosaic will generally correlate withchanges in composition, provided soil maturity is similar.This allows for the tracing of first-order boundaries on themosaic, which must then be validated and confirmed usingquantitative methods.[10] After initial boundaries were traced, a search was

completed for variations in any or all of the measuredproperties (950/750 nm value, 415/750 nm value, and 750nm value) along all of the potential compositional boun-daries seen in the Clementine data. A difference in one ofthe spectral properties above an empirically derived valuewas taken as a true compositional boundary, while boun-daries showing differences below an empirically selected

lower limit were removed. A difference between these twovalues was left as an uncertain boundary. Differences inresolution and measurement techniques preclude the use ofthe previously identified boundary values from Pieters[1978], so it was necessary to derive new limits fromthe Clementine data. The boundary values used in thisstudy were derived from analyses of five known basaltspreviously identified in the Oceanus Procellarum region byPieters et al. [1980] and Whitford-Stark and Head [1980].Clementine 1 mm and UV/VIS measurements were madefor these basalts to derive the boundary values that couldbe used to successfully identify each of the units. Thesevalues were then tested successfully via independentmapping of the Flamsteed region of Oceanus Procellarum,previously mapped telescopically by Pieters et al. [1980].Full details of this validation and the mapping techniqueemployed in this study is given by Heather [2000], and ithas been applied to Oceanus Procellarum on a moreregional scale by Heather and Dunkin [2002].[11] When characterizing the basalts on the plateau, the

steepness of the UV/VIS slope and the strength of the 1 mmbandwere measured as high, medium, or low relative to otherunits in Marius Hills and are not quoted as absolute values.[12] Throughout the mapping, the domes and cones

across the plateau were not considered unless there was aclear compositional boundary corresponding to the locationof such a construct. Typically, however, the domes are noteasily distinguishable from the background mare (see alsosection 4.1).

3.2. Mapping Results

[13] The boundary map of the Marius Hills region con-structed from this study is shown in Figure 2, overlain on

Figure 4. FeO map of the Marius Hills region produced using the algorithms of Lucey et al. [2000],highlighting the two most prominent rilles on the Marius Hills plateau. The rilles are labeled A and Bafter Greeley [1971]. Brighter regions are higher in FeO abundance, and no impact craters appear to haveexcavated low-FeO materials.


the multispectral ratio image. The application of the UV/VIS ratio and 1 mm band strength mapping criteria allow atotal of 27 units to be spectrally distinguished from theirneighbors. A solid line in Figure 2 represents a definitespectral boundary and a dashed line shows uncertainty dueto spectral differences located between our selected upperand lower limits for mapping.[14] To place the mapped units into their stratigraphic

sequence, the Lunar Orbiter V photographic data set wasused, along with the existing stratigraphic column derivedfor the surrounding Oceanus Procellarum by Whitford-Starkand Head [1980] (Table 2). This stratigraphy, comprising aseries of basalts in four formations, provides the frameworkwithin which the Marius Hills complex developed. As partof their mapping process, Whitford-Stark and Head [1980]also included some spectral properties of the basalts derivedfrom ground-based telescopic studies (e.g., those of Pieterset al. [1980]). These properties were used as an additionaltool in this mapping effort to help recognize and mapknown basalts within the Marius Hills complex and placethem stratigraphically.[15] The oldest units on the plateau belong to the Her-

mann Formation (3.3 ± 0.3 Ga; Imbrian), and the memberpresent on the plateau was mapped by Whitford-Stark andHead [1980] as the Marius Basalt. This basalt is interpretedas having been emplaced through a series of eruptionsspread over a considerable period of time. Marius Basaltunits can be seen to overlie some Eratosthenian impactdeposits from the crater Reiner (south of Marius Hills) butare themselves overlain by units of a similar age in other

areas. A similar picture is seen in the ejecta of Cardanusimpact crater (west of Marius Hills) [Whitford-Stark andHead, 1980; Heather, 2000; Heather and Dunkin, 2002].Different Marius Basalt flows are seen to predate andpostdate the formation of the crater. In addition, severalpartially buried rilles in the Marius Basalt were recognizedby Whitford-Stark and Head [1980] to have been embayedby later phases of Marius Basalt eruptions.[16] The addition of the Clementine UVVIS data shows

significant changes to the composition of the Marius Basaltto have occurred throughout this sequence of eruptions andallows its separation into two compositionally distinctgroups. Mottled medium titanium units with 3–6 wt%TiO2, high UV/VIS value, and a strong 1 mm band (e.g.,m15 and m19, here termed as ‘‘Marius Basalt 2’’), underliethe more prominent younger phases. The younger flows,termed ‘‘Marius Basalt 1’’ in this work, are mottled and ofintermediate tending toward low UV/VIS values, with 2–4wt% TiO2 and intermediate 1 mm band strengths (e.g., m3to m7). Marius Basalt 1 represents the member that wasspectrally characterized in the Flamsteed region by Pieterset al. [1980] and was largely fed by the 210 km long rilleon the southwestern edge of the Marius Hills plateau[Whitford-Stark and Head, 1980], visible in the m5 unitin Figure 2. This unit extends from the plateau to cover alarge portion of Oceanus Procellarum to the south andsouthwest [Whitford-Stark and Head, 1980; Heather andDunkin, 2002].[17] Unit m22, while appearing of similar spectral char-

acter to the Marius Basalt 2, in fact correlates to the locationof a dome and is therefore mapped separately as a volcanicconstruct.[18] Sharp Formation Basalts (2.7 ± 0.7 Ga; Imbrian to

Eratosthenian) are dominant across the plateau and are theyoungest Basalts present in the Marius Hills region. Unitsm20, m21, m23, m25, and m27 are all high-titanium (5–9wt% TiO2), with a high UV/VIS ratio and strong 1 mmabsorption. These properties are identical to those of theFlamsteed Basalt, studied as part of the ground-based tele-scopic mapping of the Flamsteed region by Pieters et al.[1980] and more recently shown to extend throughoutmuch of the region to the southeast of Marius Hills[Heather, 2000; Heather and Dunkin, 2002]. The m20 unitin Figure 2, which dominates the majority of the MariusHills plateau, is contiguous with this unit and is thereforealso mapped as the Flamsteed Basalt.[19] The more localized units m23 and m25 show similar

spectral properties to the Flamsteed Basalt but in factcorrelate with the location of older dome materials (section4.1). The m21 and m27 units also have similar spectralcharacteristics to the Flamsteed Basalt but are more likely tohave been sourced from the north and form part of theSchiaparelli Basalt Member as mapped by Whitford-Starkand Head [1980].[20] Units m14, m17, and m18 are mottled (2–5.5 wt%

TiO2) and display an intermediate tending towards high 1mm band strength and UV/VIS value. These are spectrallysimilar to the ‘‘undifferentiated high UV/VIS’’ flows rec-ognized by Pieters et al. [1980] in the Flamsteed region andhad not been previously identified in the Marius Hills area.In this study, they are termed ‘‘undifferentiated medium-titanium basalts.’’

Table 2. Stratigraphic Column of the Oceanus Procellarum

Region as Mapped by Whitford-Stark and Head [1980]a

Member Defined Spectrab Age, Gab

Sharp Formation (2.7 ± 0.7 )Roris Basalt hDSA 3.2 ± 0.2Damoiseau Basalt mottled 3.2 ± 0.2Hansteen Basalt mottled 3.2 ± 0.2Zupus Basalt 2.7 ± 0.7Flamsteed Basalt HDSA, hDSA 2.5 ± 0.5Humorum Basalt hDSP 3.2 ± 0.2Kunowsky Basalt hDSP 2.5 ± 0.5Schiaparelli Basalt hDSA, HD_ 2.5 ± 0.5Ulugh Beigh basalts 3.2 ± 0.2East Nubium basalts HD_ and mottled 2.7 ± 0.7

Hermann Formation (3.3 ± 0.3)Delisle Basalt LBS 3.2 ± 0.2Marius Basalt mISP 3.3 ± 0.3Cognitum Basalt mIG 3.3 ± 0.3Lavoisier basalts mISP 3.5 ± 0.1Nubium basalts mIG 3.5 ± 0.1

Telemann Formation (3.6 ± 0.2)Dechen Basalt LBG 3.6 ± 0.2Aristarchus Basalt LBG 3.65 ± 0.05Dark mantle materialsSouth Procellarum Basalts LBSP, LI_

Repsold Formation (3.75 ± 0.05)Gerard Basalt hDW 3.75 ± 0.05Dark mantle materials

aThe basalts and formations present on the Marius Hills plateau areshown in bold italic.

bSee Pieters et al. [1980] for a description of the defined spectra. Ageestimates are from Whitford-Stark and Head [1980].


[21] One group of Sharp Formation flows remains thatcannot be easily classified into the existing members of thestratigraphic column. These are medium-low titanium units(2–3.5 wt% TiO2) bordering the Marius plateau (e.g., m1,m2, and m8–m12), displaying low UV/VIS ratios and weak1 mm bands. These basalts do not fit with the characteristicsof the Sharp Formation members noted by Whitford-Starkand Head [1980] and Pieters et al. [1980] and are placed inthe stratigraphic column noting their characteristics only.Unit m13 shows similar spectral character, but is related to adome and mapped as such.[22] The final geological map produced from this work is

provided in Figure 5, and all of the Basalts present in

Marius Hills are fully characterized in Table 3. The units arethen placed in the refined stratigraphic column (Table 4).[23] The units identified from this work are tied in to the

updated regional stratigraphy of southern Oceanus Procel-larum by Heather [2000] and Heather and Dunkin [2002].

3.3. Basalt Thickness

[24] The thickness of the basalt flows across a maria is ofcritical importance to understanding the way in whichvolcanic flux has changed through time, as well as the totalvolume of erupted materials in a region. These are param-eters that will be required for the second phase of this studyin which we aim to model the rise and eruption character-

Figure 5. Final geological map of spectrally distinguishable units in the Marius Hills region, related tothe stratigraphy of the Oceanus Procellarum Group defined by Whitford-Stark and Head [1980].


istics of the basalts at Marius Hills. The Clementine data canbe used to approximate the thickness limits of mare basaltson the Marius Hills plateau by looking for craters that haveexcavated highland material from beneath the basalts. High-land materials on the surface will have spectra that contrastsharply with those of fresh basaltic lavas and will have asignificantly lower FeO abundance.[25] For simple craters (<15 km diameter on the Moon)

that have excavated highland material the excavation depthcan be calculated using the following relationship derivedby Croft [1980]:

Hexc ¼ 0:1Dt; ð1Þ

where Hexc is the depth of excavation and Dt is the diameterof the transient crater (approximated to the observeddiameter). This technique provides upper limits to basaltthickness in the cases where highland materials have beenexcavated and lower limits in the cases where the crater hasnot penetrated to the highland materials below.[26] A total of 183 craters were measured in Marius Hills,

none of which show any evidence of having excavatedhighland materials in the FeO map (Figure 4), with con-sistently high iron abundances across the plateau. As for allmeasurements from the FeO and TiO2 map, steep slopesthat could deliver erroneous results were avoided, and allmeasurements were taken from points on flat crater floors orejecta blankets in the FeO map (Figure 4). Therefore despitethe fact that several of the craters appear to show a pale bluecolor in the multispectral ratio mosaic, the FeO results showthat all excavation depths provide lower limits for basaltthickness. This gives an average lower limit value of 152 m,with typical values ranging from 75 m to 400 m. Largerimpacts on the plateau show minimum basalt depths of up

to 1100 m, suggesting the actual thickness across theplateau to be far larger than the 152 m lower limit average.[27] The 152 m average gives a lower limit to the volume

of lava erupted of 5320 km3. The actual volume erupted willbe much greater since extensive flows sourced from MariusHills can be found outside the region mapped here. Detailsof how the values on the Marius Hills plateau combine withthose for the rest of Oceanus Procellarum are provided byHeather [2000] and Heather and Dunkin [2002].

4. Spectral Analyses of Volcanic Featureson the Marius Hills Plateau

[28] The Marius Hills plateau contains the highest con-centration of volcanic structures in Oceanus Procellarum[e.g., Whitford-Stark and Head, 1977]. Domes, cones, andrilles are all present in a variety of morphologies suggestingan extremely broad range of volcanic styles to have beenactive on the plateau throughout its history. A positivegravity anomaly (+65 mgal) over the Marius Hills plateauindicates that almost no isostatic adjustment occurred duringbasaltic flooding and that the volcanic features in the regionare supported by the lunar crust [Taylor, 1982]. The gravityanomaly could either be due to the presence of surfaceeruptives or to the presence of something more deep-seated,possibly at the crust-mantle interface. The anomaly isstrongly related to the origin of the volcanics on the plateauand perhaps the origin of the rise itself.[29] This section will investigate the three main morpho-

logical volcanic structures present across the plateau.

4.1. Domes

[30] A survey of more than 200 lunar domes by Head andGifford [1980] recognized a unique class of dome in the

Table 3. Characteristics of the Basalts Identified in the Marius Hills Region Using the Clementine Data and Their Relation to the Units

Mapped in Oceanus Procellarum by Pieters et al. [1980] and Whitford-Stark and Head [1980]a

Marius Unit(Figure 2)

ClementineCharacteristics

Corresponding UnitFrom Telescopic Data

Stratigraphic Placementand Comments

m1, m2, m8–m13 Medium to low titaniumbasalts (2 to 3.5 wt% TiO2),displaying low UV/VISratios and weak 1 mm bands.

None These units are seen to border theMarius plateau, and do not fitwith the characteristics of theSharp Formation members notedby Whitford-Stark and Head [1980]and Pieters et al. [1980].

m3–m7 Mottled and of intermediatetending toward low UV/VISvalue, 2 to 4 wt% TiO2

and intermediate 1 mmband strengths.

The mISP Marius Basalt, asseen by Pieters et al. [1980]in the Flamsteed area.

Hermann Formation Marius BasaltMember.

m14, m17, and m18 Mottled (2 to 5.5 wt% TiO2)and display an intermediatetending towards high UV/VISvalue and 1 mm band strength.

Undifferentiated high UV/VIS basalt,as seen by Pieters et al. [1980]in the Flamsteed area. Not identifiedpreviously in the Marius Hills region.

These medium-titanium SharpFormation units are spectrallysimilar to the undifferentiated highUV/VIS basalts mapped in theFlamsteed region by Pieters et al.[1980].

m15, m16, m19, m22,and m24

Mottled basalt with high UV/VISvalues and strong 1 mm bands,containing 3 to 6 wt% TiO2.

Early Marius Basalt, not classifiedspectrally.

This is considered to represent an earlyphase of the Marius Basalt HermannFormation Member.

m20, m21, m23, m25–m27 High UV/VIS values, 5 to 9 wt%TiO2, and strong 1 mm bands.

HDSA and hDSA Flamsteed Basaltand Schiaparelli Basalt.

Sharp Formation basalts of or similarto the Flamsteed Basalt. Flows m21and m27 on the northwest edge ofthe plateau are most likely a sectionof the Schiaparelli Basalt extendingnorth from the mapped area.

aSee Table 2 for the characteristics of the Oceanus Procellarum Group basalts in the regional stratigraphic column.


Marius Hills, with complex surface features, irregular bor-ders with the surrounding mare, and few summit craters.This unique morphology suggests correspondingly uniqueaspects in the nature of their formation or physical make-up.[31] Marius Hills contains 262 domes [Whitford-Stark and

Head, 1977], which themselves can be subdivided into twomain classes: low domes and steep-sided domes [McCauley,1967]. The plateau contains 135 low domes, which are amaximum of 25 km in diameter and between 50 and 200 mhigh; the 127 steep-sided domes are between 2 and 15 km indiameter and rise 200 to 500 m from their surroundings

[Whitford-Stark and Head, 1977]. All domes therefore haveslopes of less than 15 degrees, allowing for use of theClementine FeO and TiO2 maps without the significantadverse effects that would appear on more severe slopes.[32] A closer view of the morphology of the domes is

provided in Figure 6. It can be seen in this image that steep-sided domes are often located on the low domes and thatlow domes are commonly truncated by adjacent mare plains(arrows in Figure 6), implying that they represent an olderstage of volcanism and have been embayed by youngerflows.

Table 4. Updated Stratigraphic Column Including the Information From the Clementine Observations of Marius

Hills in This Studya

Member Defined Spectrab Age, Gab Clementine Results Unitc

Sharp Formation (2.7 ± 0.7)Roris Basalt hDSA 3.2 ± 0.2Damoiseau Basalt mottled 3.2 ± 0.2 Mottled 6 to 11 wt% TiO2 basalt with

a high UV/VIS ratio and a weak1 mm absorption

Hansteen Basalt mottled 3.2 ± 0.2 Mottled basalt with intermediate,tending to high UV/VIS valueand medium to strong 1 mm band.2 to 4.5 wt% TiO2.

Zupus Basalt 2.7 ± 0.7 Extremely low UV/VIS value andwt% TiO2, weak 1 mm band.

Flamsteed Basalt HDSA,hDSA

2.5 ± 0.5 High UV/VIS ratio, 5 to 9 wt%TiO2, and strong 1 Mm bands.

(F)

Humorum Basalt hDSP 3.2 ± 0.2Kunowsky Basalt hDSP 2.5 ± 0.5 High UV/VIS value, 5 to 9 wt% TiO2,

and strong 1 mm band.Schiaparelli basalts hDSA, HD_ 2.5 ± 0.5 High UV/VIS value, 5 to 9 wt% TiO2,

and strong 1 Mm band.(S)

Ulugh Beigh basalts 3.2 ± 0.2East Nubium basalts HD_ and

mottled2.7 ± 0.7

Undifferentiated MediumTitanium Basalt

mottled Mottled basalt with 2 to 5.5 wt%TiO2 and medium to strong 1 Mmband

(UnH)

Medium - LowTitanium Basalt

Low titanium basalt (2 to 3.5 wt% TiO2)with low UV/VIS ratio and weak1 Mm band.

(L)

Hermann Formation (3.3 ± 0.3)Delisle Basalt LBS 3.2 ± 0.2Marius Basalt 1 mISP 3.3 ± 0.3 Mottled with medium tending toward

low UV/VIS value, 2 to 4 wt% TiO2

and medium 1 Mm band strength.

(M)

Marius Basalt 2 Mottled with high UV/VIS values, astrong 1 Mm band and 3 to 6 wt%TiO2.

(M)

Cognitum Basalt mIG 3.3 ± 0.3 Mottled with medium tending towardlow UV/VIS value, 1 to 4 wt% TiO2

and medium 1 mm band strength.Lavoisier basalts mISP 3.5 ± 0.1Nubium basalts mIG 3.5 ± 0.1

Telemann Formation (3.6 ± 0.2)Dechen Basalt LBG 3.6 ± 0.2Aristarchus Basalt LBG 3.65 ± 0.05Dark mantle materialsSouth Procellarum Basalts LBSP, LIG Low UV/VIS ratio, extremely low wt%

TiO2, medium to strong 1 mm band.

Repsold Formation (3.75 ± 0.05)Gerard Basalt hDW 3.75 ± 0.05Dark mantle materials

aMembers present on the Marius Hills plateau are shown in bold italics.bWhitford-Stark and Head [1980]; Pieters et al. [1980].cDesignated unit in geological map (Figure 5).


[33] Domes on the Moon are thought to develop throughthe slow eruption of low gas content or low-temperaturelavas [Wilson and Head, 1981]. Each of these factors willencourage the build-up of extruded lavas around a vent. Theunique steep-sloped morphology of the domes at MariusHills [Head and Gifford, 1980] therefore suggests lunarvolcanism with an unusually low effusion rate and low gascontent, erupting high-viscosity, low-temperature lavas toform short flows. A lava’s high viscosity could result from alow temperature and higher crystal content or from anincreased silica content [e.g., Head et al., 1978]. The lastof these factors led to the suggestion by McCauley [1969]that the steep-sided domes in Marius Hills represent theeruption of more evolved felsic magmas. However, Ruth-erford et al. [1974] showed it to be unlikely that igneousdifferentiation occurred in the lunar basalts to form moreevolved lavas. The slow effusion of a low-temperature, highcrystal content lava is therefore the preferred hypothesis forthe materials that formed the domes in Marius Hills [Weitzand Head, 1999]. The short flow length suggested by this isdifficult to verify using the Clementine or Lunar Orbiterdata. The multispectral studies show what could be local-ized flows associated with a few of the domes (e.g., unitsm25, m23, m22, and m13 in Figure 2). However, embay-ment and truncation by younger units, uniformity of com-position between the domes and background mare, and thelack of flow fronts in the Orbiter photography preclude thedirect measurement of flow lengths.[34] The domes cannot be differentiated from their

surroundings, even when using the detailed mapping

criteria outlined in section 3 (Figures 2–5), confirmingthe observations of Gillis and Spudis [1995] and Weitz andHead [1998, 1999] that the domes do not correlate withdistinct compositional boundaries. The locations of thedomes mapped by Whitford-Stark and Head [1977] areshown in Figure 3, superimposed on the Clementine TiO2

map. The compositional uniformity between the domesand surrounding mare plains is supported by the five-pointspectra averaged from measurements of a 5 � 5 pixel boxon 40 typical domes (Figure 7). The spectra display asubtle 950 nm absorption and a match between thesteepness of the continuum slope for mare flows anddomes of similar colors. The features are therefore con-firmed as being basaltic and do not represent the morefelsic eruptions suggested by McCauley [1969]. Figure 3also shows some examples of domes which display asharp truncated boundary with the surrounding plains(labeled ‘X’), as was also seen in the photographic data(Figure 6), supporting their relatively old age comparedwith the youngest Eratosthenian flows in the region. Thedomes themselves are not of a uniform composition anddisplay a variety of titanium contents in the Clementinedata (Figure 3), similar to the variation of the surroundingmare plains. This suggests that either the domes developedfrom a number of localized sources of various composi-tions or that they formed from a single large source regionover a period of time long enough for the titanium contentof the magma to evolve. The low effusion rate, lowtemperature, and high crystal content of the lavas requiredto form the domes are most likely to result from the

Figure 6. Examples of domes in the Marius Hills region, from a section of Lunar Orbiter V image215M. An outline map on the right illustrates the boundary between the steep (S) and low (L) sideddomes. The arrows on the image show examples of younger mare flows having truncated or embayed thedomes.


terminal stages of volcanic activity [Weitz and Head,1999]. This would support dome formation from a numberof localized sources such as dykes, which have transportedmagma to shallow depths.

4.2. Cones

[35] There are 59 cones, interpreted to be composed ofpyroclastic materials, on the raised plateau of Marius Hillsand these are up to 3 km in diameter and 300 m high

[Whitford-Stark and Head, 1977]. Lunar cones are broaderand lower than their terrestrial counterparts as a result of thelower gravity and lack of atmosphere on the Moon, whichcauses a wider dispersal of pyroclasts than is seen on Earth[Wilson and Head, 1981]. Apart from this, the cones inMarius are morphologically similar to the cinder cones ofHawai’i and the Snake River Plain [e.g., Weitz and Head,1998] and commonly display a horseshoe appearanceresulting from the breaching of one side of the cone by a

Figure 7. Five-point spectra of 40 domes averaged, in comparison to the surrounding mare plains inMarius Hills, normalized to 415 nm to accentuate differences in the UV/VIS slope. The signature of thedomes cannot be clearly distinguished from that of the mare flows.


lava flow. Examples of cones in the Marius Hills are shownin Figure 8, with breaches identified by the arrows. Conesoccur on the domes, close to the head of at least one rille[Greeley, 1971] (section 4.3) and on the plains betweendomes. They show no linear alignment that would otherwisesuggest them to have formed from degassing of near-surfacedykes, such as those offset from the Rima Parry V rille[Head and Wilson, 1993]. The locations of the cones asmapped by Whitford-Stark and Head [1977] are shown inFigure 3. As with the domes (section 4.1), the cones ofMarius that occur on the plains are truncated by theEratosthenian lavas of the mare (arrows in Figure 8) andmust therefore represent an older phase of volcanic activityin the area. The superposition of several cones on top of thedomes implies that the cones are younger and may have

exploited essentially the same channels to the surface as themagmas that formed the domes.[36] The formation of lunar cones demands a fast rate of

cooling of pyroclasts while they are in flight and theformation of coarse (at least millimeter-sized) clasts duringmagma fragmentation [Wilson and Head, 1981]. Smallerclasts will typically be widely distributed to form mantlingdeposits, and slower cooling of coarse clasts in an opticallydense lava fountain over a high effusion-rate vent mayallow for the formation of a lava flow if the dispersed clastsare able to accumulate rapidly enough [Head and Wilson,1989]. Cones will therefore develop from strombolianactivity in the form of intermittent explosive bursts andthe eruption of coarse clasts [Weitz and Head, 1999]. OnEarth, conical structures and domes commonly form from

Figure 8. Section for Lunar Orbiter V image 215M showing examples of cones in Marius Hills. Manycones are breached on one side by lava flows, shown by black arrows. As with the domes, the cones arealso commonly truncated by the more recent Eratosthenian flows, as shown by the white arrows.


the eruption of an evolved magma from a shallow magmareservoir; this is unlikely to be common on the Moonhowever, as the low density crust inhibits the developmentof a shallow neutral buoyancy zone [e.g., Head and Wilson,1991, 1992]. This has resulted in the majority of lunareruptions being fed from deep-seated sources to produceeffusive activity, precluding the formation of pyroclasticconstructs such as those seen at Marius Hills. It is thereforesuggested that the shallow reservoirs that are inferred hereto have fed the domes in Marius Hills were refilled by themagmas that formed the cones. This would replenish thevolatile content of the materials and allow for the disruptionof the magma into coarse clasts and would support thedevelopment of strombolian volcanism. This also helps toexplain the preponderance of cones on top of the domes, ifsimilar channels to the surface were exploited by themagmas that formed both constructs. Several of the conesdisplay lava flows, and Weitz and Head [1998, 1999]suggest that these may have resulted from the rapid coa-lescence of dispersed clasts that landed hot. However, suchprocesses are more typical of highly effusive fire fountaineruptions from which cones would be unlikely to form. Amore reasonable suggestion is that the flows are simply theresult of late-stage, low-effusion eruptions from the strom-bolian activity that formed the cones themselves.[37] As with the low and steep-sided domes (section 4.1),

the cones are indistinguishable from their surroundings inthe Clementine multispectral ratio image and TiO2 map(Figures 2 and 3). Recent analyses of Marius Hills by Weitzand Head [1999] using the Clementine data have identifieda correlation between the cones and dark spots (often partly

surrounded by bright red units) in an adapted multispectralimage. This new image stack comprises the 750/415 nmratio in the red, 750/950 nm in the green, and the 750 nmimage in the blue. This multispectral stack is shown inFigure 9, with selected cones located by the arrows.[38] While there is a correlation between the majority of

cones and dark spots in the image, there are cases where thedark spots are not clearly visible although a cone is present(e.g., points labeled X in Figure 9). In some but not allcases, this is most likely to be the result of the presence ofan associated red flow from the cone covering the spots.Conversely, points labeled ‘Y’ in Figure 9 show a numberof clear dark spots in regions where no cone can beidentified. Weitz and Head [1999] put this down to asignificant fraction of the cone being destroyed to precludeits identification from photogeological observations. How-ever, it is difficult to envisage a process that would destroythe morphology of a cone enough to render it unidentifiablefrom high-resolution photographic materials while main-taining its spectral character. The abundance of dark spots inFigure 9 not associated with domes and the few examples ofcones with no associated dark spots argue for (1) a morediverse spectral signature for the cones than is recognizedby Weitz and Head [1999] and (2) the localized presence ofdark materials (with similar spectral characteristics to thedark spots in the multispectral stack) in regions with noassociated pyroclastic construct.[39] The spectral signatures of a representative sample of

20 cones both with and without distinct dark spots areshown in a plot of their 415/750 nm and 750/900 nm values(Figure 10), designed to show variations in color and the

Figure 9. Clementine image of the Marius Hills region (red = 750/415 nm, green = 750/950 nm, andblue = 750 nm) after Weitz and Head [1999]. Cones generally appear as black spots and are often flankedby bright red lava flows. Examples of cones displaying these spectral characteristics are indicated by theunlabeled arrows. Exceptions are labeled X (cones with no identifiable dark spot) and Y (representingdark spots in areas where no corresponding cone is seen in the photographic data).


1 mm absorption band strength. The 750/950 nm ratio ismore typically used to indicate the 1 mm band strength, butthe 750/900 nm value is used here to allow comparisonsbetween these results and those of Weitz and Head [1999].As the spectral signatures are often localized in Figure 9,measurements were taken as an average of a 3 � 3 pixel boxfor each cone. Values are compared with those for variousunits within the mare flows but cannot be compared directlywith those obtained by Weitz and Head [1999] (theirFigure 5) due to differences between the photometric cali-bration used in the production of their data and that usedthroughout this project. However, similar patterns are seen inthe distribution of the most extreme dark spot/red cone datapoints in Figure 10 with the spectral points of Weitz andHead [1999]. As noted by Weitz and Head [1999], the darkspots are by far the bluest features in the region, considerablybluer than the most titanium-rich flows, and with a weakerabsorption in the 1 mm region. Also noted byWeitz and Head[1999], the red flanks of the cones are typically of compa-rable color to the mare units and display a stronger 1 mmabsorption than the dark spots. The points in Figure 10 havesimilar extremes in both color (415/750 nm) and absorption(750/900 nm) to the more limited sample studied by Weitzand Head [1999], but the majority of cones in Figure 10 areintermediate to these and were not characterized by theiranalyses. This supports the inference that the cones display amore diverse spectral character than implied by the results ofWeitz and Head [1999] and in several cases are difficult todistinguish from the surrounding mare basalts, particularlyin terms of the red signatures.

[40] The origin of the dark spots is suggested by Weitzand Head [1999] to be an abundance of spatter and cinderwith a microlitic structure. These microlites would bepulverized to a fine grained component of the soil duringregolith formation and then act to darken the soils andreduce the strength of the 1 mm absorption feature in asimilar fashion to the agglutinitic glasses produced viaspace weathering. The microlites do not redden the soilsas agglutinitic glass does, however, allowing for the differ-entiation between the two. The wider variation in spectralcharacter of the cones in this study indicates that not all ofthe cones have produced this microlite structure and thatsome have a higher microlite abundance than others. Theadditional presence of dark spots in Figure 9 outside regionsin which cones have been recognized from the photographicdata suggests localized spattering to have occurred in shorteruptive episodes to produce materials with a similar micro-litic structure to that on the cones. The lack of a recogniz-able cone implies the activity in these areas to have beenshort-lived. Alternatively, the materials (often accompaniedby red flanks or flows in Figure 9) may represent thelocalized dispersal of submillimeter clasts to form mantlingdeposits in short-lived fire fountain eruptions or mantlingdeposits such as those at the Apollo 17 landing site. Thelatter suggestion is unlikely however, as spectral studies ofthe Apollo 17 and other similar deposits [e.g., Weitz et al.,1998] show them to be more glassy in nature than the unitsat Marius Hills. Their dark appearance would make themdifficult to differentiate from the background mare inphotographic data, and the mantle may cover the vents.

Figure 10. Plot of UV/VIS (415/750 nm) and 1 mm band strength (750/900 nm) for the dark spots andred flanks of 20 cones in the Marius Hills region in comparison to averaged values for the mare flows inthe area. Dark spots show the bluest signatures and weakest absorptions. Red flanks have strongerabsorption bands and are typically of comparable color to the mare flows. These are generalizations, andthere is considerable scatter in the results, as discussed in the text.


Weitz and Head [1999] suggest that the annular red depositscommon to the cones represent a combination of basalticlava and submillimeter glasses produced during eruptionsand deposited on the cone flanks. The variation in absorp-tion strength in the 1 mm region indicated for the red flanksin Figure 10 may be the result of the mixing of varyingamounts of microlitic materials with these glassy lavas. Thisinterpretation is supported by the results from this study.

4.3. Rilles

[41] The Marius Hills plateau contains 20 sinuous rilles[Whitford-Stark and Head, 1977], some of which appear tohave fed many of the basalts in the central and southeasternsections of Oceanus Procellarum [Whitford-Stark and Head,1980; Heather, 2000; Heather and Dunkin, 2002].[42] The two most prominent rilles in the Marius Hills

area are shown in the FeO map (Figure 4), labeled Rille Aand Rille B after Greeley [1971]. Both rilles appear a paleblue color in the multispectral ratio image (Figure 2),suggesting they may have excavated through to exposehighland bedrock beneath the basalts [Gillis and Spudis,1995; Bussey and Spudis, 1996]. However, the FeO map inFigure 4 shows the floors of both rilles to contain abundantiron, up to 20 wt% FeO, which is similar to the freshexposures of basalt seen on the floors of many of the impactcraters across the area. Therefore contrary to the suggestionsof Gillis and Spudis [1995] and Bussey and Spudis [1996],neither rille has eroded deep enough to expose highlandbedrock. Hence the depths of the rilles provide lower limitsfor the thickness of the basalt layers in these regions, 56 maverage for Rille A and 29 m average for Rille B [Greeley,1971]. These are consistent with values measured using theimpact craters in this area (section 3.3).[43] If an erosional origin for the rilles is accepted [e.g.,

Hulme, 1973; Ciesla and Keszthelyi, 2000; Fagents et al.,2000], then the mare basalts in this region will have beenproduced in high effusion rate eruptions. Traces of rilles areseen at many levels in the stratigraphy, cutting into flowsfrom both the Hermann and Sharp Formations. The basaltsproduced from these eruptions are now seen on the surfaceof the plateau and clearly embay or truncate many of thedomes and cones (sections 4.1 and 4.2). The rille eruptionstherefore represent later phases of activity than the domeand cone forming events, and the highly effusive nature ofthese eruptions suggests that they originated from deepreservoirs, as opposed to the shallow sources required toform the domes and cones [e.g., Head and Wilson, 1991,1992].

5. Summary of the Nature of the Volcanismon Marius Hills

[44] The diversity and density of volcanic features seen inthe Marius Hills region support a similar diversity in thenature of the volcanic activity that structured the region.Evidence of this diverse range of volcanism is present at alllevels of the stratigraphic column visible on the plateau.[45] Surface flows are seen to age from the Imbrian

through to the Eratosthenian epochs and include membersof the Hermann and Sharp Formations as defined in thestratigraphic column of Whitford-Stark and Head [1980].These basalts are typically seen to embay the domes and

cones in the region and therefore represent later phases ofhighly effusive activity, sourced by many of the rilles nowseen on the plateau.[46] The domes and cones in the area are truncated by

these younger mare flows and represent the oldest visiblevolcanic features in the area. The formation of the domes inMarius Hills is most likely to have been through loweffusion rate eruptions of low-temperature crystalline lavas.The wide variation in titanium content of the domessuggests that either they developed from a number oflocalized sources of various compositions or they formedfrom a single large source region over a period of time longenough for the titanium content of the magma to evolve.The cones in Marius Hills also suggest a low effusion rateeruption, and require the production of large (larger thanmillimeter) clasts [Wilson and Head, 1981]. The coneserupted quenched materials in the form of microlites andglasses, and these are now seen in varying concentrations ontheir flanks and summits (Figures 9 and 10). Localizedmantles of glassy and microlitic materials are also seen inthe multispectral data, with no corresponding pyroclasticconstruct in the photographic data, suggesting either (1)eruptions that were too short-lived to allow for the develop-ment of a cone or (2) extremely low effusion rate eruptionsof submillimeter clasts. The similar characteristics requiredto form both the domes and cones in the area and thelocation of many cones on top of the domes suggest refillingof shallow magma chambers may have occurred after thedome-forming eruptions. This would allow for the replen-ishment of volatiles in the magma chamber, required todisrupt the magmas during the strombolian activity thatformed the younger cones, and would explain the commonlocation of cones on top of the domes (if similar reservoir-surface channels were exploited).[47] Overall, the domes and cones at Marius Hills are

most likely to be the result of low effusion rate eruptionsfed by numerous dykes and shallow magma reservoirs.The later highly effusive eruptions more typical of theMoon [Head and Wilson, 1991] occurred primarily in theEratosthenian epoch (3.2 to 1.2 Ga) and resulted in theformation of the sinuous rilles and many of the basaltsnow seen on the plateau. The lower limit for the basaltthickness in the Marius Hills region is an average of 152 mand in places is seen to exceed 1 km. A lower limit for thevolume of basalts erupted onto the plateau is calculated at5320 km3.

[48] Acknowledgments. DJH is a European Space Agency Post-doctoral Research Fellow. This work made use of the ISIS software,distributed by the US Geological Survey. SKD was funded as a PPARCResearch Fellow and subsequently as a Royal Society Dorothy HodgkinEliz Challenor Research Fellow for the duration of this work. Thanks areextended to an anonymous reviewer for a constructive and helpful appraisalof the original manuscript.

ReferencesBussey, D. B. J., and P. D. Spudis, A compositional study of lunar sinuousrilles, Lunar Planet. Sci., XXVII, 183–184, 1996.

Charette, M. P., T. B. McCord, and C. M. Pieters, Application of remotespectral reflectance measurements to lunar geology classification anddetermination of titanium content of lunar soils, J. Geophys. Res., 79,1605–1613, 1974.

Ciesla, F. J., and L. Keszthelyi, A simple model for lava flow quarrying:Mechanical erosion of the substrate, Lunar Planet. Sci., [CDROM],XXXI, abstract 1647, 2000.


Croft, S. K., Cratering flow fields: Implications for the excavation andtransient expansion stages of crater formation, Proc. Lunar Planet. Sci.Conf. 11th, 2347–2378, 1980.

Fagents, S. A., D. A. Williams, and R. Greeley, Thermal erosion by laminarlava flows: New inferences, Lunar Planet. Sci., [CDROM], XXXI, ab-stract 1038, 2000.

Gillis, J. J., and P. D. Spudis, Clementine color mosaics of procellarumvolcanic complexes: Evidence for dome morphology linked to volatilecontent and eruption rate, Lunar Planet. Sci., XXVI, 459–460, 1995.

Greeley, R., Lava tubes and channels in the lunar Marius Hills, Moon, 3,289–314, 1971.

Guest, J. E., Centres of igneous activity in the maria, in Geology andPhysics of the Moon, edited by G. Fielder, pp. 41–53, Elsevier Sci.,New York, 1971.

Head, J. W., and A. Gifford, Lunar mare domes: Classification and mode,Moon Planets, 22, 235–258, 1980.

Head, J. W., and L. Wilson, Basaltic pyroclastic eruptions: Influence of gas-release patterns and volume fluxes on fountain structure, and the forma-tion of cinder cones, spatter cones, rootless flows, lava ponds and lavaflows, J. Volcanol. Geotherm. Res., 37, 261–271, 1989.

Head, J. W., and L. Wilson, Absence of large shield volcanoes and calderason the Moon: Consequence of magma transport phenomena?, Geophys.Res. Lett., 18, 2121–2124, 1991.

Head, J. W., and L. Wilson, Lunar mare volcanism: Stratigraphy, eruptionconditions, and the evolution of secondary crusts, Geochim. Cosmochim.Acta, 56, 2155–2175, 1992.

Head, J. W., and L. Wilson, Lunar graben formation due to near-surfacedeformation accompanying dike emplacement, Planet. Space Sci., 41,719–727, 1993.

Head, J. W., P. C. Hess, and T. B. McCord, Geologic characteristics of lunarhighland volcanism (Gruithuisen and Mairan region) and possible erup-tion conditions, Proc. Lunar Planet. Sci. Conf. 9th, 488–489, 1978.

Heather, D. J., Geological investigations of the lunar surface using Clem-entine multispectral data, Ph.D. thesis, University of London, London,2000.

Heather, D. J., and S. K. Dunkin, A stratigraphic study of southern OceanusProcellarum using Clementine multispectral data, Planet. Space Sci., 50,1299–1309, 2002.

Heather, D. J., S. K. Dunkin, P. D. Spudis, and D. B. J. Bussey, A multi-spectral analysis of the Flamsteed region of Oceanus Procellarum, inWorkshop on News Views of the Moon II: Understanding the MoonThrough the Integration of Diverse Datasets, LPI Contrib. 980, pp.24–26, Lunar and Planet. Inst., Houston, 1999.

Heather, D. J., L. Wilson, and S. K. Dunkin, Theoretical modeling of thethermal and physical evolution of the Moon, Lunar Planet. Sci., [CD-ROM], XXXI, abstract 1354, 2000.

Hulme, G., Turbulent lava flows and the formation of lunar sinuous rilles,Mod. Geol., 4, 107–117, 1973.

Lucey, P. G., D. T. Blewett, and B. L. Jolliff, Lunar iron and titaniumabundance algorithms based on final processing of Clementine ultravio-let-visible images, J. Geophys. Res., 105, 20,297–20,305, 2000.

McCauley, J. F., Geologic map of the Hevelius region of the Moon, U.S.Geol. Surv. Misc. Invest. Ser., Map, I-491, scale 1:1,000,000, 1967.

McCauley, J. F., The domes and cones in the Marius Hills region—Evidence for lunar differentiation?, Eos Trans. AGU, 50, 229, 1969.

Pieters, C. M., Characterization of lunar mare basalt types, II, Spectralclassification of fresh mare craters, Proc. Lunar Planet. Sci. Conf. 8th,1037–1048, 1977.

Pieters, C. M., Mare basalt types on the front side of the Moon, Proc. LunarPlanet. Sci. Conf. 9th, 2825–2849, 1978.

Pieters, C. M., and T. B. McCord, Characterization of lunar mare basalttypes, I, A remote sensing study using reflection spectroscopy of surfacesoils, Proc. Lunar Planet. Sci. Conf. 7th, 2677–2690, 1976.

Pieters, C. M., J. W. Head, J. B. Adams, T. B. McCord, S. H. Zisk, and J. L.Whitford-Stark, Late high-titanium basalts of the Western Maria: Geol-ogy of the Flamsteed region of Oceanus Procellarum, J. Geophys. Res.,85, 3913–3938, 1980.

Rutherford, M. J., P. C. Hess, and G. H. Daniel, Experimental liquid line ofdescent and liquid immiscibility for basalt, Proc. Lunar Planet. Sci. Conf.5th, 569–583, 1974.

Sunshine, J. M., C. M. Pieters, and J. W. Head, Oceanus Procellarum asviewed by Galileo: Evidence for compositional diversity in the maredeposits and at the Marius Hills Plateau, Lunar Planet. Sci. XXIII, 3,1387–1388, 1992.

Taylor, S. R., Planetary Science: A Lunar Perspective, Lunar and Planet.Inst., Houston, 1982.

Weitz, C. M., and J. W. Head, Diversity of lunar volcanic eruptions at theMarius Hills complex, Lunar Planet. Sci., [CDROM], XXIX, abstract1229, 1998.

Weitz, C. M., and J. W. Head, Spectral properties of the Marius Hillsvolcanic complex and implications for the formation of lunar domesand cones, J. Geophys. Res., 104, 18,933–18,956, 1999.

Weitz, C. M., J. W. Head, and C. M. Pieters, Lunar regional dar mantledeposits: Geologic, multispectral, and modeling studies, J. Geophys. Res.,103, 22,725–22,759, 1998.

Whitford-Stark, J. L., and J. W. Head, The procellarum volcanic complexes:Contrasting styles of volcanism, Proc. Lunar Planet. Sci. Conf. 8th,2705–2724, 1977.

Whitford-Stark, J. L., and J. W. Head, Stratigraphy of Oceanus Procellarumbasalts: Sources and styles of emplacement, J. Geophys. Res., 85, 6579–6609, 1980.

Wilson, L., and J. W. Head, Ascent and eruption of basaltic magma on theEarth and Moon, J. Geophys. Res., 86, 2971–3001, 1981.

��S. K. Dunkin, Department of Earth Sciences, University College London,

Gower Street, London, WC1E 6BT, UK. ([email protected])D. J. Heather, Research and Scientific Support Department, ESTEC (SCI-

SR), Keplerlaan 1, Postbus 299, 2200 AG Noordwijk, Netherlands.([email protected])L. Wilson, Environmental Science Department, Institute of Environ-

mental and Natural Sciences, Lancaster University, Lancaster, LA1 4YQ,UK. ([email protected])


Documents

Volcanism on the Marius Hills plateau: Observational analyses using Clementine multispectral data