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1992LPSC...22...31Z Ascra.eus placing stand The is the named been surface. 750 general located mission volcanic preted summarized and rise, N40° an ing that but the 1974 The 350 The area the km all earliest bases rises a Tanaka ). E-trending portrayed (Scott 10 portion to general Tharsis (from of Hypotheses alternatives 1700 to datum them reports geologic apart An to materials. © 400 Mons were up ongoing of result 15 rise, Lunar and phases in even km the km to (1981). at km of From because Montes morphology the (Fig. discussed axis ( as similarities . histories. summit examination construction, terminate the catastrophic in the west 1 aligned elevations the Can-, in volcanos Can-, history O from high, epoch The larger investigation a Eruptions the The paleostratigraphic include for diameter northwestern km to of of large base single martian and 1). INTRODUCfiON of summit The three alignment 1973; north) consist of with 1978; the ( above Ascra.eus The They All along (Scott lobe-shaped to shield of at their Tharsis in are Planetary that volcanic Tharsis mass and higher origin 1barsis Center the the three flank summit, three 6 and Department the with began Can- regions, Scott erupted Arsia located are km. of the s location a (see have and volcanos ), and movement release volcano, along Tharsis N40°E Mons. volcanos slopes volcanos three are their and et for of more located Montes surrounding The than in Montes and southeastern Mons, unit Zimbelman Tanaka, complexity Proceedings features. been the al., the reconstruction enigmatic mostly l!artb the 9 8 from the on complex summits Montes, upon of large of Smithsonian are Institute most of than of Tanaka, Tharsis 1977), to trend in and Montes and followed exhibit display Tharsis shield the Olympus Tharsis recognized <5° crest Pavonis along large Geology, the shields geologic seen 10 and vents All Lunar 1986), lower 6000 the shield buried Vtking of of of ( km flanks Tharsis lobe-shaped Each volcanos, of morphology Lunar USGS, spaced and three different Montes Planetary et quantities the Modified to preserved the the Tharsis James 1986). rise by region region and the Mons, al., western km along above have are Kenneth Ari%ona following Mons, effusive volcanos Institution, each although that • by since maps and crest Mars: Planetary volcano beneath primary martian lobe-shaped Tharsis remain 1989). 1991), across ( shield about Provided inter- Scott Can-, Arsia each degrees significant Planetary were rise, dur- The was and R. the has the caldera StruHes, flanks features the of of of and of is Stale Institute, Zimbelman characteristics: Mons, the the s. perhaps Mariner Washington of subsequent due variation, while rials bury and counts degrees Hesperian Montes, which (Whitford-Stark, structs, ent at canos reflect within southwest shaped example, a caldera, . differing indicate 1986). "embayments" Crumpler 1973; Science, collapse features source University, Edgett Comparison National lobe circumferential differences The Crumpler single extending each Pavonis Houston, to trends by Saunders, on the pyroclastic mass and Ascra.eus Arsia have deposits Volume Carr 9 three the The shield are for deposit" but of and the and events, degrees differences start while large Differences reco~ce lower with the and Mons, Ascra.eus lavas Mr gentle structural flanks wasting 1992 to in timing particularly been DC several materials Tempe and over surrounding et around that Ascraeus and 1harsis 22, NASA at structural and Upper ( three secondary Aubele appear caldera, 20560 1979; Arsia extending terminology al., approximately pp. Ascraeus volcanism. elevations ( of and flanks Mons the 1982). ( are noted terminology along Aubele <5°) and of AZ Space 31-44 caldera studies in Mons 1977; Ascraeus the plains Montes due in evolution: Mons volcanos the (Scott 85287-1404 to the Mons Astrophysics the ( and of of previously flank shows Pavonis difficult caldera in 1978) the and summit-region Tharsis Museum, away plains involve Montes to cessation processes of the (1978) development, the suggest to Crumpler size trough 1972. being of Volcanic and individual slopes, N40°E a 10 temporal exhibit Mons, the from of youngest Carr, and shields complex the similar each noted, Arsia and are made are morphology to Mons some to Montes Carr (Mou~Mark, Tanaka, west Upon development in (McCauley the that each that 11 proposed have entrants of Hiller, interpret least 1973) depth trend, gross Mons age have and volcanic volcanic fonn et km large of oldest however, both funned characteristics to in there shield, closer (Blasius, broad with of are al., Data each development. up ( and depths 1981). age, on of 1981). Aubele, similarities, Scott similar is in of six and volcanic a are mapped 1977) Arsia is of on of et the the that large to also show al., System a that the interpreted volcanic and most All northeast 1976; These up 1981). eight Mons large the dimensions, 1978). to 1972; a flows three and the eruptions chambers there as temporal to probably different Tanaka, many its evolved Tharsis Plescia Upper nested Crater having appar- "lobe- 4 mate- west. small Carr, con- that vol- and For km are to of 31 1992LPSC...22...31Z

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= Fig. 1. Regional setting of the on Mars. Shaded relief rendition and I-km topographic contours are from USGS ( 1989 ), with names of selected features added for reference. The 7 2 area shown corresponds to 10 km , or about 1/14 of the surface area of Mars. 1992LPSC...22...31Z forms full volcanos purpose processes. insight modification scope synthesis for on Tharsis ~ed Data Detailed mis&ons. surfuces. frequency Crater exceeds of of 40 high-resolution lacking superposition craters canic of have units but Map similar ( (impact) 150 tigraphic basis simplified ships the counterparts 1973; 2) This This The A Pavonis all high-resolution m/pixel the establishing were history names m/pixel crater Unit visible synthesis of three on landforms that of on Blasius, deposits. areal units paper Counts using study into Montes morphologic complete positive the the However, © and here of in modeling from and difficult assessments The Designations from terrain Mons have Because information volcanos. are represented the chains density for Lunar terms 75 present ejecta on the of around the on over around presents makes METHODS relationships Viking is 1976). endogenic m/pixel of images latter different We used Arsia obtained volcanic orbital stratigraphic no with ( each relief following to differences to unit images set most of our it deposits. parallel of found of only paper. spatial apply highlight the is use characteristics For and to the stages Mons). the a images Blasius impact presented volcano maps of descriptions geomorphic of usually rims, resolution resolution results images, precludes volcanos. by of indicate three example, landforms from three of the PURPOSE ( Mariner AND styles Ascraeus and (22 to that volcanic characteristics: Planetary at the connections, the of to (Fig. Because the more craters Mariner and range relationships unit and ( latest m/pixel volcanos. volcanic new difficult Gault, ( both Blasius' 1976) Tharsis CONVENTIONS structural region, is e.g., of immense this here best terrain 2). down of contacts. presented ( no similarities 9 moderate-resolution volcanism quantitative Mons or 4) and by observations and in volcanic the processes caldera paper is the and of Units craters distinguished 1971, 9 available collapse) are commonly to for Montes criteria with erosional resolution activity rather craters superposition Most these obtained Mariner to best comparisons Institute characteristics as (Zimbelman, distinguish volcanic Viking trends, derived ( Ascraeus between are concentrates 45 1) The in floor 1979; isolated Viking on of present surfuces in difficulties, between m/pixel, elongate volcanos were is defined comparison lacking images correlation craters the limited Pavonis 9 and the that images. a nine unit beyond from ( Hartmann, solely constructs. and useful 3) endogenic images. Mons units useful planetary exogenic coverage than • tectonic form relation- of and provide can cf) on images craters images on of Viking visible which shape, 1984) rather based 90 crater Provided Mons these land- on from have stra- The tool vol- and the the the the but the be on to of of of a McBirney, features flanks flank younger floors The than flank regions: winding where units used ArsiaMons is shaped ( away are observations of consider of conduits deras ized ical Mons, troughs troughs, trend trend more trend times not upper upper western surfuce shallow ( (1978), along an are the ( 1989), 100 4) cf 1973) confined landforms Each Shield these 3° 1 asymmetric even ), a by entire absent subscript typically following km correlative here are lobe-shaped units is from here or being as greater of of to These an near contact sa 2 flanks, and the (Fig. feature" the physiographic of on designated and valleys have (1) and of which units. for be parallel each flank less for a nearby OMERVATIONS represents 5°, not flanks. irregular flank caldera 1979, to the have the within between for and the western similar simple, fluid nearly the sinuous entrants 4). NASA Pavonis common with shield circular relevant necessarily 2 "parasitic than to with volcano, sections allow rounded of distribution includes For volcanos. summit Tharsis the that around materials. are to west-northwest up This grabens. Zimbelman been concentric to topographic identify lavas p. a feature. 30- to twice in The 100 example, that scarp smooth few sa 10 it the to present flanks, entrants shield inward-facing trend 207). elevations rilles. subsequent were Mons, overall degraded be 1 in Astrophysics (Fig. regions ( to . to to designated describe the approximately e.g., the km shield oldest km Montes As caldera of terminations calderas" several form, concentric correlative, "a as all their Each SO-km-wide The at Both The each AND downslope Grabens with the any Finally, surf.tee caldera volcanos (2) and with large broad unit 2a). wide. Greeley, of three and to on appearance 10 on termed for flanks flank summit surfuce units source the associated of the Edgett: volcano western included the grabens INTERPRETA11ONS flank the respect rim. individual has the large km Grabens Arsia (sc of 3 volcanic other the sections 6 perpendicular Tharsis with Sinuous diameter by each is scarps. rim. for caldera are unit caldera the 1 and distinctive have grabens of 1971 include but northeast four ), elevation The three degraded vents, of Tbarsts aligned and "embayments" of and terraces Mons ( Cmmpler each interpreted Ascraeus of linear units, up shield, the flank has to and Data Below between and lava 11 volcano in vent" Arsia been ). on Montes term volcano: collapse the may to the volcanos. volcano. usually Elliptically this and km to rim rilles letters one shield sb of grabens, (3) Montes, flows the elliptical the and troughs (sb with the concentrate Mons summit aspects that given present and which ( each and construct. 10 System have relative (USGS, 15 ''flank case present physiographic (Fig. Williams to 1 or Mons. oldest eastern summit, volcanos. has are and ) are an shield have that depression, km km follow here the 1 the sc a, terminates southwest forms Mars more Common served of (sa they a for summar- elliptical irregular with by a 3). indicate vent" b, is narrow, troughs of caldera numer- Aubele shaped ( radiate N40°E N40°E 1989). wide), within to which slopes 1 "lobe- Shield shield USGS, to along many ) Arsia or flank flank each Carr and may The and cal- We the the the has fl.at on be as c, is 3 3 1992LPSC...22...31Z 34 flank), plains), plains), flank), Fig. northern s 3 (smooth). 2. Proceedings © d •· sc 118° r r +------'------'----'----'--'----'---+-~¾a• 3 Simplified 2 1 1 flank), (b) Lunar (caldera (ridged), (ridged), (smooth cf of 2 floor), sketch lower (caldera k1 and k Lunar 2 (knobby), (knobby), cw western maps Planetary and 3 floor), (caldera Planetary of 11 rk flank), terrain 2 (lobate), cw (ridged-knobby), wall), 2 (caldera Science, Institute cf units 1 p s (caldera 3 1 (flows on (smooth). wall), Volume and around floor), from 1 2 • df (lobate), 22 (b) (depresfilon Provided Ascraeus cw P, Pavonis 109° the 1 (caldera Sz Tharsis Mons), (smooth). Mons. 17•+--~-+--~-~-~-~-~-~-~-17• floor), 110° 110° by (c) wall), Montes. --+------p Units: the p (undivided 2 (c)Ascraeus p (flank 1 LEGEND contact scarp, trough, sa mare-type cone sinuous depression, NASA Astrophysics (a)Arsia (flank 2 or (shield), arrows vent graben small channel Tharsis wrinkle vent caldera shield downslope Mons. Mons. flows ndge flows sb nms plains), 2 from Units: Units: (degraded from Pavonis r sa 3 Arsia (ridged),~ 1 (shield), (shield), western _:_,_.1 Mons), __ , Mons), Data ./f,'.·, \-..- ,.,,,,. :_!J ,,,' __ 11 ~~(.'1'..__,,- 1.1?: 11]/ • f ) ;...... ~='""""' sb sb /i flank), ) ,:

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a a 35 35 1992LPSC...22...31Z 36 feature visible represent only as location is material PavonisMons smooth substantial an covered depressions downslope three {sa deposits they ( materials Fig. surrounding <2 The confined Shield two 2 irregular ) km materials meet 5. Proceedings © are terrain at s ( large wide), 1 unit within Portions is see Lunar much made some characterized flanks. lava unit the erosion. present to to plains, collapse as Fig. could units grabens present flows adjacent the the the is elliptical locations of up the of of 2a superposed Arsia and including the interior Lunar base {Fig. on of be The ), lobe-shaped source that depression suggesting at that individual the lobe Mons a plains by Planetary troughs, elevations of and 2b Pavonis emanated pyroclastic {Fig. western a cross of ). a the vent( lobe. surface predominance Planetary small {Fig. The on the Sb). feature shield and raises flows Subtle s). the that Mons all lobe southern 6). above crater from portion The but deposit An adjacent pits. lobe Science, Institute the The northwest in lineations with the (p shield close the isolated has and 10 unit Sinuous 2 unit {Fig. western ) possibility of of and km); basal arcuate with are its Volume since terrains, association the arcuate sa is may (arrows) ejecta 2a). eastern of 2 found outlier , divided the rilles the scarp lobe-shaped • and flank Arsia undergone have 22 lineations The Provided unit collapse that (Viking grabens as extend fanlike where at are flanks Mons. ( of once with well sb may unit into this the present 2 s ) 1 42B35, (a) fluted, wrinkle has has one other on obscure The is interpreted troughs western relief, collapse cating an onto cone. located identified the 1973). by Ridged at Summit. 85 center irregular, some the few scarps 45 several the northern the flanks. km rough-textured Four that northern km most The margin within ridges pits, locations near (Sbatp, rim older shield NASA at a in the at in to 6.1°S, additional small wide rough-textured upper troughs, The of the diameter likely diameter, the flank be on ridges of grabens 5 surface the (Viking 1973a). flank relatively km base the Arsia summit caldera circular 129.4°W). Astrophysics (5-10 (sc walls small due predate of floor. and features suggest of 2 elliptical Mons 42B39, {Fig. {Fig. and such ) the The to the has rilles wall, km) of caldera, of viscous cone One the mound small (b)Smooth mass lobe. 9b). 9; the the Pavonis western that only larger center superposed the {Fig. they arcuate other, McCauley of located to collapse smaller, Where volcanic caldera Ridges the presence these interpreted fa.int wasting circular bisected at caldera Data 8). are Mons flank offset 5.9°S, sc unit traces grabens. Subtle on ridges vertically 2 appear wrinkle event. rim simple on extrusions et unit System have (s following a has 124.6°W). toward has cones of by 1 al., fissure them; ) {Fig. of to extends lava linear a postdates superposed Wood six superposed two large, fissure grabens Three ridges be 1972; caldera offset, have flows the 9b). mare-type these near a calderas: {Fig. textures ( caldera raised- cinder 12 1979) north, cross ("m" Carr, large been Also, indi- that and the the km are are 7). on on 1992LPSC...22...31Z flows in imply stage standing, and of Montes than the the Arsia relative as are craters are along Mons of of in Ag. where small 1.6°N, Flank Lobe-shaped pyroclastic Pavonis 600 Fig. this the unconstrained recognized base convergence 6. Tanaka volcanic the summit (p) Mons extends a limited a 109.7°W). 9c) on lobe m case (Mouginis-Mark, ages N35°W Small sinuous © of fluted vents. surrounding in can these Mons may the lobe, Lunar the extends contains of vent ( features embayment activity 1986) be 250 strombolian on the walls rille western north flows be feature. to trend (b)Detailed (arrow) resolved it The of due the km the flows a is (arrows) numerous mapped from and volcanic at while four embay and at northern plains, enclosed lobe northwest to (Fig. 11-km Pavonis flank the on (Viking 1981 that the on on the units Planetary The activity deposits, the the 2b summits view on the infrequent occurrence the both emanated level ). the but ("v'' extrusion 6.5-km ). eastern 388805, lobe-shaped sinuous the southern by flank Mons, northern identified from surrounding No of surrounding it flank ( in occurred a shield USGS, flows now although definitive of marginal vent Fig. slope the elevation in center from the vent rilles Institute similar flank flank at portion contrast appears 7). base 1989 in (Fig. other of feature the these units during at plains the The craters plains. Pavoois (Fig. contacts ridge vent impact of ). 1.0°N, margin to up 8) The of two the Arsia to as that cones features vents at the (p of occurs unit has 2b (r the • younger the like as Mons. volcano 109.9°W). interior Pavonis Tharsis ). impact 2 the craters of ). plains ) Provided flanks Mons small high- P2· Srott (p late- may lack The the that the surrounding 2 at at (a) ) small Regional between features features km Ascraeus be better sequent symmetric other are at in lobe: lobe Mons to the the "ridged ( carr embayment Sbieldflanks. Fig. troughs the radial by absent flanks situation extension plains. terrains. ridged et lobe, Tharsis view 7). lower developed the and law al., must 0 the thrust Mons are around 2 within Box associated showing ), with knobby'' 1977), NASA flows flow flanks on units The terrain Montes. uniformly to and be shows faults Ztmbelman the the unit the about lobate the than quite around The appear a but smooth of unit eastern small smooth (r location Astrophysics (Pi), north, summit with due Olympus The Ascraeus 2 the the ), 100 flow variable distributed (rk the embayment to to and In knobby terraces small isolated terrain 2 flank where km be ). of unit features calderas, the loading flank Edgett: The Mons (b)(Vtking Mons of similar regimes constructional center among of supetpOSed the surface terrain have stratigraphic (Si), terraces Arsia into Tbarsts by 0 ( shidd with carr Data caldera 2 of to ) the been the that the plus appear the 210A38, Mons. (Fig. those the (k an Montes, et (~) shield, shidd present 2 Tharsis produced frame System on additional ), al., rim, interpreted shidd, a directed features 2c). relationships in Terraces lobate to all is transitional centered 1977) Mars originating similar construct there the relatively originate Grabens adjacent Montes on similar these Arsia flow 100- sub- ( is but the ''v'' on to to at a 37

1992LPSC...22...31Z

38 38

Viking Viking

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49B34-6, 49B34-6,

Proceedings Proceedings

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Institute Institute

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Volume Volume

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the the

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flows flows of of 1992LPSC...22...31Z Ascraeus of Mons km western primarily (Thomas surfaced shield sinuous similar cut emanate Fig. material troughs by produce sion a other also the summit (p). emanated the (Mouginis-Mam, cating central 1984, shorter Flank Summit. Arsia subtle flanks embayaportionofthe above 8. grabens, The and caldera has 1barsis p. materials it in caldera Northern of and channel along Mons. from the flanks the © flank Mons flank 75) north linear may vents. distance et is an from overall Ascraeus the Lunar grooves, lower large al., the irregular A floor and Montes. the distinct the represent vents erosion Near embayed basal are has features and nested many runs from flank 1990). (sb last flank Arsia appearance scarp 1981) The other into shield intensely the Mons. segments south, 3 on which the ), and break vent flooding closely collapse/flooding scarp The vents by complex Mons southern Ascraeus the base. interpreted PavonisMonslobe largest The interpreted the northern by (unit older to of back-wasting ~tting leaving Planetary numerous the flanks coalesce in early plains at Pavonis (p as lower channeled flank spaced to ( sb the slope event, 3 base and features. cf ) many of Mons 3 the stages and 3 but ) than vents portions base ) lacking 10 western calderas and Mons. only to to of into scarp indicate sources. (Fig. the troughs and km northeastern be as are the be the of would may of in by relationships events materials Institute complete The large last Flows flow vent eight elevation, this fluid smaller the took scarp an linear flank of 10). on flank have is flows, and the Prolonged obvious p manner. entrants. growth be that scarp, margins, the present occurred. that 3 lavas (Zimbelman, The place (arrow) vents over undermined and flows of required eastern and grooves floor, west evidenced emanate from flanks 20 Ascraeus between • scarp a that sinuous smooth as extend on source in subtle at croS&- Plains to Provided (mosaic went flank lavas indi- dfu- The and the the the six re- 30 on to of from is ofVlking the along deepest thermal the but (Luccbitta, of on indicate thirds resolution, slope fewer caldera of average The the has measurements rocks (Fig. from importantly, knobby the 90 embay Lobate Ridged Lobe-shaped a northern solid the km by entire still caldera three at talus distal 11 and troughs of that interior least some 49B41,78,80, the Tharsis from the ). terrain floor, an flows inertia caldera slope vertical terrain the slope lobe-shaped Shadow visible morphology portion order other form area wall except 1978). several NASA the a caldera upper which >26° (Zimbelman, volcanos, (1 parallel smooth values deposits indicate (r that are (Mouginis-Mam, Zimbelman 3 is base (~) feature. lobe relief of surface the 3 ), ) of measurements fluted center embayed The magnitude for centimeters has is displaying wall (Zimbelman, the caldera constrains portions terrains. of ( x 4 Astrophysics and features present of both to unit accumulated fuint that fluted than the (Zimbelman, indicative lobe at (Fig. is 2.9 the 10- and isolated 4.1°N, Ascraeus relatively by suggest shield is the 1984, rim, the km striations is The 3 lower Tharsis on Edgett: in 11 not caldera shield of segments cal the at of entire of ), 1981 111.6°W). from the other and the of lobate an along walls fine 1984, present cm- p. similar mountainous that the southern than beneath Mons featureless semicompetent flows Tharsis Tbarsts elevation base, distal 1984, ). yet 145). walls 2 the dust Data parallel caldera lobes southern The the sec- a flows values p. of of N85°W the (p to has rim at Montes, pp. margin, but wall 72). covering 112 have leveed ). Valles upper more region The the wall Ascraeus (Fig. System may thermal Toe the of to K- representative area at 147-148). to other is The caldera morphology 5.5 areas lower the 1 22 the trend, to competent smallest plains have Mars ) composed portion 2c). the (Fig. Marineris enclosing channels, materials probably obtained to virtually m/pixel have average highest central inertia plains- Mons. (m 7 come slope Most lavas two- with wall 12). km, 3 an of of ). 39

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Proceedings Proceedings

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Science, Science,

Institute Institute

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m m 9 9 1992LPSC...22...31Z likely Fig. is 892A09, shield channel and center, to Fig. materials the across accumulated into this 401818,20,22, nested terraced the ends 10. wall wall 11. the involved west surface calderas the the (arrow) centered caldera. © West at at is segment Southern and of smooth the a fluted, Lunar uppermost beneath the is in small center flank undulatory, at rim. re1ative1y the that shield(~) at Intermediate right has lower 12.4°N, indicating caldera resurfacing Foot of embayment at the emanates Ascraeus and and 2.9 10.8°N, floor of smooth eroded shield while a km wall wall 107.1 is pos.gble Planetary part wall the of of segment from Mons. 104.4°W). has in downslope of unit °W). rim. the and vertical of presence the Ascraeus material hummocky the lower the is Shadow on The shield crossed Ascraeus base a ( (arrow) reliet: digital upper uniform shield of is Institute Mons. of base. measurements probably of an deposits re1ative1y by Note portion the unit. irregular Mons that mosaic Upper a Fluid levtl irregular subtle stands the Rough that a lobe of lavas At talus competent portion • truncated, of saup the slumped sinuous the indicate (Viking in Provided terrain Viking saup were flank slope relief top the of Fig. knobby is interior the near 210AI0-12, Arsia rheologic order et ModificationofShiddFlanks portions subsequently on about western scarp, elevations of lower to to Mons that made Irregular Om- al., adjacent the by rise smooth 12. the produced Montes of represented than the western 1978) 300 the base knobby units, et near up base magnitude flanks. Lobe-shaped of al. properties to center (Fink flank of terrain the scarps the m NASA of with of ( the appear the been and 1977) terrain. ridged the below the the eastern eastern While Zimbelman and at surfaces, west leveed surface Olympus in the along 11.1 large shield flanks covered western higher to feature proposed inferred Zimbelman, terrain, Astrophysics Lobate the may °N, the detachment Pavonis be shield flanks channels lobe-shaped the possibly There of other and 108.2°W). have than the shield and west by Mons terrain flanks the similar western for were bases result initiate that plains. Edgett: values Mons been is Tharsis volcano of that flows due no 1986, surface. (Hulme, is are the Ascraeus surface to similarly ( of embayed sufficient unit deposit extend USGS, Tbarsis Montes, lacks obtained However, to other the consistently degraded Data lobes on mass 1990). very are present Arsia Perhaps degradation of a Mons. 1976), 1989). Tharsis upslope wasting degraded ( eroded northwest fluid on prominent a of mosaic System to for giant Mons the flanks the Ascraeus comparable allow Distal lava but 2 The lobes, Mars the ridged elevations to to and of to (Moore flows. of relative magma troughs are a of margin of Viking lower lower 3 flows Arsia basal level have with and and the the km an to 41 1992LPSC...22...31Z 42 volcano. that removed ported below for consist the A terminations. while on trend posed sion appear developed competent channel layers terrestrial uniform Origin A characteristics, lobes: Montes mon dastic landforms cbitta, this vation both and on and the within Tanaka, known terrains source shields. 6 content and , the California respectively, 1938) The Both successful uniform The The A and the not apparent the surface only glacial volcanos. that the possibility length landslide Proceedings origins. the defined the western © flank gravity-driven lower the (Macdonald, lobe-shaped that to lava of within only origin, glacial 1981). and ice 15° of Tharsis 10 the share floors areas However, restriction Two produced is depth found by Lunar a 1986) represent coalescing complex shield Lobe-shaped on where depth scarp origins. the (Crandell deposits limited low materials, km, (Figs. of vents the western the the flows an volume hypothesis from western Two It of the common by by Considerations of the the origin citing interpretation Sa.idmarreh Garr in which ancient lobes could and seems flank lobes hypothesized in where of and volcanos the consistent is the of on sufficient 13 fluid nearby light Tharsis primary Lunar and the relief their flanks volcanos volume a without features and of arrangements exist erosion at of of may western erosion et basal and channels the ice/debris landslides vents 1972, such largest the overall is flanks. lead et do lobe be suggests least the likely the lavas al. for the of awlanche morphologic sources. difficult and Planetary near southwestern Features 14 may prohibit ( al., not shields, apparent tend lobes, the Sharp, scarps the lobe slide origins as to the (1977) of equator, but formation west-northwest internal volume and/ present of pp. obvious Planetary along an In may could reached basal scarp that alignment documented must dense 1984), shield landslide. problems resemble have the of with Farmer result origin units to such also deposits. order that glaciers ( in or as Isolated 272-275). to the Garr 1973b). be and but effi.Jsion be ice of have in the martian Iran be experienced filling well dismissed blunt account lack the feeder reconcile and (nonvesicular) material on a they present atmospheric the built the various of volcanowide Science, and of the the extend to accumulation here Institute scenario, the of western et et due and been headwall ( The of the the for on (Wtllia,ms, the as fluid of at Harrison the al., simplest magnitude landslides headward al., associated All to surface Mt. all relative flank of of the dike terrestrial northeastern the elevations to we two polar of lobes related both layered "missing" for a Alternatively, 1977). western Volume adjacent three within could could numerous proposed landforms fluid 1977; a 20 Shasta common lava all a with three scarp will lack geometries. the volcanos. vent possible level the sporadic undermining three the must dose caps, and stratigraphic explanation and lavas lobes • resurfacing competent flank have pyroclastic basalt, from have 1978; (upslope) 22 reexamine and the of at Scott the landforms great less volcanos, indicates region channels slopes Provided subaerial landslide of between volcanic volume obvious 40 or address Falcon, Tharsis for to depth. super- where visible flanks obser- trans- pitted lobes. vents occur more vapor been pyro- steep com- than effu- Luc- near and but the size the km, the of of runout scarps lobes. deposits rials volcanos flanks, deposits aureole in 250 ( 1977; Montes at is those more other lobe the fluids volcanos 1988). Mons underlying smooth effi.Jsive lobate silicic) story. ficient deposit ing the unit Tanaka, smooth lithostatic resolution requires any Synthesis: fracturing embayment least ( emplacement. ( and cated lavas Scott by 2) 5) Most A We comparable most The Early scale submarine lobes shield lobe shield the near-surface km deposits. gravity-driven (7) the could The seven erupted comparable Luccbitta, slope within off Llneations to aureole; propose and flows and that general lengths lobe The activity have is of activity 2° remains that work unit (Tanaka, only ( to runout occur reduce and further 1985 effi.Jsive s) the emplacement morphologically NASA but slide data the load the of erosion, lobe (USGS, Geologic construction, the failure the submarine be stages: Tanaka, slopes size Valles emanate terrains could at proposed formation are Hawaiian the off ( from ), Lopes is subaerial adjacent to from lds have slides development postdated of origin that Can-, Ascraeus on the Tharsis resulting units lengths controversial. Tharsis 1978, and friction an magma might to investigation, the superposed (and to some up 1985; martian features catastrophic Marineris Astrophysics 1989). generally slopes have ( the additional ( pyroclastic unroof upcoming result 1) lobate the 6) 1974; shield et must proposed Development from 1986) to (rand 1979), landslides pyroclastic?) martian islands western fissures provide possibly m., activity lobes. Lopes proposed formation terrestrial volcanos terrestrial west emanated slopes and Mons 100 ( the from very e.g., ( >20° The distinctive crust. 3) of troughs Plescia involve that margins a flanks. 1982; of <5°, and emplacement and k), on km magma volcanic of still associated et missions emplacement as distinct However, great might for the (Moore, caldera especially (probably landslide around slide, a along are that plains (Siebert, a around but was al., the adjacent particularly The originate advocated (Sharp, the slide were Francis well the for Pyroclastic viable and submarine from of landslides Tharsis additional in in lacking volcanism of Data size preceded 1982) volcano. the result chamber detachment triggered perhaps the the the shields Olympus portions origin the from component have the to the Saunders, short event. formation, Olympus 1964; preceded large features lobate of the mechanism 1984). with basaltic units, Mars. crest 1973a; lava large lower of and Montes Arsia on Tharsis Tharsis make upslope System from the slopes the for along the as associated of Olympus of activity This coalesced processes. slides, grabens Lipman shallow involving The following shield or of the Wadge, Mons of flows emplacement, by lobe Tharsis Tharsis implying the a the lobes. flanks and the The either comparable Mons these Garr the rather 1982) the scarps to the involved pyroclastic by their hypothesis of lobes, release ( lack Montes improved from Olympus 350 4) the features, such postdat- Pavonis aureole aureole for 0.5° growth, smooth (l) Tharsis intense lack Tharsis within slopes et of et attain mate- Mons lobes 1983; lobes insuf- basal with pore from flank than lobe of indi- lobe and The that and and but al., the the the m., to as of of at a 1992LPSC...22...31Z Blasius Carr Carr Carr provided Crumpler Crandell Fink Farmer port ics support. a cript, Crumpler, Texas. Fink Branstrator, Francis to National by Space Greeley Greeley Geologic tion youngest wasting by rise The to mits Montes. the VISi.ting Acknowledgments. volcanic 4062. Icarus, Orbiters. Mars. Newhall (1977) ancestral P. Mons, ters. Hawaii. 87-96. Gardens logical 8344. nology Formation 479. crater ~ed the volcanic Program. the lobate smooth 774. }. J. E. for M. M. (Scott M. western of as The Research J H. H. (1977) K C. Pavonis P. J R west H. R this H. H., well Aeronautics S. and D. all counts Pavonis Mapping 34, much Geopbys. 2 properties © L Scientist and and Geopbys. and In of R and W B., shields Lunar Some (1974) basalt Mount J Selkirk lava J. 0- ( C. (1973) Greeley R, and S. three work structures, 1971) 496-511. Portions {pyroclastic?) Lunar eruption by Lava the resurfacing (1976) Geopbys. as M of and H. D. Zimbelman Zimbelman Gault and G. Mars: flanks as&stance Miller Mons on flows Moore, Association gravitational helpful and Fink, Mons, martian flows, each Crown of plains program Tanaka, Shasta Res., (1984) from provided Wadge Flows at Aubele Res., volcanos. Volcanism the Observations the D. of R, and D. Water Planetary of The the ed.), study, C. Res., of 82, within Hawaii. and from E. lavas: The inner shield Tharsis and NASA and Kilauea W, Blasius input 79, Volcano, this flows. for Space and D., REFEREN~ ( volcanic with by J. Lunar }. within J. the 4225-4248. record Catastrophic G. pp. 1971) 82, vapor 3943-3949. 1981). Holland R Ascraeus valuable unit thorough under R work (1990) authors C. fluid and and spreading. flank Glicken Planetary wall Puu grant from Institute All ( Domes, on Mod A 157-173. region 3985-4015. are all the shields 1983) Administration. ( K ( Lobe volcano, and 1986) California 1978) of the in volcanism Craddock Endogenic observations Mars. P. of Oo three of were lavas. three R, features photographs. vents grant superposed M. NAGW-1390 Calderas the Geol, actively A Longitudinal R Planetary wish impact Copernicus. drafting Planetary of Mons: H. reviews emplacement Guest basalt IAVCEI The is Robinson. L, Rheology J J Structural were Ouistensen Mars. Springer-Verlag, debris lobes carried Hawaii. The operated volcanos X, lobes no. along 2, Laporte Geopbys. Geopbys. to Geology, for Olympus of as forming craters Tharsis 207-223. Institute J. Ouistiansen flows, cratering Icarus, as.sistance lobe-shaped formed of NASW-4574 Proceedings Geology thank from at the Institute This modified comments viewed E., and out and }.RZ. BuJl. the the as upon Arsia Science, of variations KS.E. by evolution and D. Tharsis were part interpreted Kilauea the while Res., Res., is avalanche region the 12, for original 29, S. the lava N40° deposition was Mons D., Volcano/., LPI received on and at and Murray from Viking New Rowland, all thanks 143-146. in and of 343-361. 1983 Universities advice 88, and 78, R pertaining tubes 171, by J.RZ. the modified followed the • Contribu- region Geophys- in with E Houston, the features but of volcano, in Pavonis aureole: of York. L, D. manus- Viking Provided 4049- trend 8333- Doms Volca- mass- Royal Mars. sum- Orbi- rheo- great J. Arsia from 477- J. from Mars sup- was and Ball and and the 48, the W. of B. of L Greeley Harrison Hulme Hartmann Neukum Lipman Lucchitta Lopes Lucchitta Lucchitta McCauley Macdonald Moore Plescia Moore Mouginis-Mark Scott Scott Sharp Scott Plescia Siebert Sharp Thomas Tanaka USGS J 9th,pp. volcanoes. Res., features. flows: volcanoes. In 89, Hawaii. Saidmarreh evidence effusion of of Geol C. 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