1981mrbf.conf..227C flanks collapse classification Abstract-The morphometry, become peaks sequence for and Graben diameters rings with utilizing boundary peak-, scaling, strength constrained The thermal terrestrial engendered deniable. craters. influence aspects graphy pretation ference and and or oscillating nested waves rim problems 1974). The plastic the the © (Dence, the slumping impact and ongm of and peak Lunar high-pressure Quantitative megablock (Van next more cratering and crater, difficulty observed models, possible the and with of Peak However, history, conditions at of of of The new planetary of by planets central which central uplift), Lunar Main basin scheme inner ring-, The of craters physical complete gravity a basin morphology basin 1%8; and Dorn, no large transitional sequence rings the and experimentally of rings importance commensurate and concentric exception apparent particle in zone, structure Planetary initial they Outer transient and and of Outer and formation form peak of Head, of multiringed modification constitutes and structural layered correspondences 1969; aspects apparently and interiors anomaly Multi-ring properly Planetary ring basin and first multiring-basins possibly mechanisms Main Conditions boundary excavation of rims rings within basin flow (Murray, discontinuities. Intermediate and structures of structure. prominent become 1974), Baldwin, (ring crater ring crater Institute and ring Outer Outer planetary Basins, obey have may in analyses models types, (Melosh the generating signatures or Institute, begin structural number impact the scaling Schultz basins chemical constrained sheer conditions fracturing Steven and structures be visually collapsed rims peak) stages. Proc. plus rings, strength focused 1980). INTRODUCTION Gordion characteristic with associated with 1974), producing • in to basin P. of have between LIUlar form Printed and are Provided crusts complexity New volcanic in H. and initially basins stage form form 3303 laboratory terrestrial of types. Events increasing of Secondary detectable. and fault shaping composition have explosion full-scale scaling. set "megaterrace" central Planet. Kent morphologies on and rings in McKinnon, hypotheses been a Merrill associated NASA by ring 227 within (Hodges Knot at U.S.A. by single Rings scarps mechanisms on as and by specific slumping the basin studies also Sci. modification of characteristically geophysical the incomplete R. impacts. uplift based A other the rim the Croft the of Intermediate (1981), the energy Road of B., Of craters impact were formation nature continuous basin ring scenario forming multiring been diameters strength the eds. NASA diameter. and the strength planetary morphology, (the of of 12A, 1978; has with which structures planets primarily 1, classified of Simple six sources structure problem slumping and terrestrial of Wilhelms, ancient Houston, employed latter p. that signatures, experiments and been at transient Astrophysics classifiable of W-257. the (Hartmann formation: crater large McKinnon, a crater. numerical rings basins Incipient include: morphological significantly inconspicuous basin constant from could appear and are transient geology. in on re-examined on planetary of in boundary. the originate Texas impact of indirectly. the geophysical complex disputed. Peak explosion competent formation 1978), (e.g., crater theoretical basin photogeologic terrestrial necessitates reproduce modification between the ring basis structures simulations radial "frozen" and crater Data and 77058 rings 1980), The smaller transient structures, Howard in and basins formation rims of craters, All structures and Wood, crusts to position the the System Basin the obey morphology, and rocks is dominating and Qualitative basin scaling a establish fracturing explosion structure, Horst observed of into presented structural fluidized main stage than tsunami obvious as the on the impact gravity central central is on crater et 1971), Ridge inter- in topo- rings, bases fluid final that and and has rim the un- the the are al., the in- a 1981mrbf.conf..227C 228 basin theoretical provide been basin Curran cratering observed initial longer It high high-pressure which transient by simulation formation as geological, assumed formation, and order of continuum crater transient transient basins, brief based be stage structure culations, formation diameter. empirical induced impact Mars, morphological have sequence explosions cratered Attention 1971; 1973; 1980). has Paper expected lack morphological Head, pressure © recognized been description formation as Pike, contact Hodges ring been of on material Such on and modification Lunar angle, peak et a of void), planetary that constrained crater crater crater One). of process increasing starting form. S. of structural Recently crater with dynamical of al., has incremental of scenario of documented sufficient of spacing, and 1976). as recognized its 1977) observed K. irregularities basin to ring the and and the impact pre-impact and 15% between 1977). energies, and recently sequences well emphasis is surroundings, Croft produce have as The into were dimensional Theoretical transient requires restoration (Gault point (PR) Planetary various both excavation may It of and excavation structures classes crust. have well Wilhelms, reviewed observations phase BASIN to the as purpose the can diameter Based understanding been cratering observations discussed an by THE craters for changes between basins be for ejected the observed observational. been between it been structure et as large, on one be interpretation Differences the topography, may morphological use between crater discussed divided some should physical during al., that projectile Institute on the the calculations argued model. FINAL analysis for of by stages, MORPHOLOGICAL initial and observed data drawn and stages and of 1978), are: discontinuous result and such 1968; and in in modifications energy this complex show time (defined Hodges other simple as of basin the of basins. be Paper multiring which into the of the set fracture simple modeling. of displaced that • Then boundary terrestrial calculations many but paper in the CP to of from in Kreyenhagen and that possible of initial Provided or APPARENT impact the increasingly current Significant a separate sufficiently (Davis final three of dimensions sources crater the morphology classes modelling and final have craters One. in the and as basins companion the craters Particle target, impact a properties craters, discontinuous is indirect basin any conditions, the (MR) mechanics irregularities scenario mechanical complex changes boundary Wilhelms necessary to basin. transient Construction stages: to and In been to and formation condition by models impact maximum of large being consider and classifications. form available 2) this and and structures construct ring the basins positions explosion of effort Carnes, impact accurate and complex a sources of successfully complex Lastly, paper basins NASA and of CRATER: longer report the 1) some of PR in scale the craters and considered craters of structure such (e.g., crater CLASSES (1978), to condition Schuster, a shock-processed the and/or basin (nomenclature which modification differences culminating has basin the of radial basins implications transient transform short structures o drive to (Croft, explosion of 1972). Astrophysics and observational continuous could the phenomenon, on of as attention cratering final and craters, Knowles basin craters nature a structure (e.g., is resulting been the impact formation information comprehensive formation the Indeed, relationship thermal velocities expansion comprises high used modified based (Hartmann The craters. ubiquitous be 1977) the which 1981a; recognized structure moon, crater, Smith modification put of the placed and in are craters, central pressure in is flow limited stage energy, to transitional and of from dimensional the following impact on Data such first with that structure structure a into generated investigate hereafter comprises numerical materials. is studies, Hence, are such at into the and of model Mercury and phase Brode, the geophysical, modification is in as of constructed the and turned System the "identical" (Wilhelms, enough peak the transitions number and increasing discussed. would numerical hampered classes a proposed the model phase Sanchez, possible, transient the 3) velocity, as number time impact impact Wood, of during of if of Wood of on it a form. basin basin 1977; cited (CP) by final The it to still cal- and and has not the the the the the the an of of of to of in is a a 1981mrbf.conf..227C basins construction In the mechanism basin basin between placed pretation. (e.g., few determined details a 4. How morphologies. view bounding 1. system: structures structures? equivalent 2. 3. What phologically again cases) lunar basins, lunar What narrow The air What 1. assignments lunar Wood preted manageable On this Morphology Transitional Ridge Geophysical Relative gravity © same scattered touchstones ring of scaled center in the and is is basins, is Lunar report and Bouguer at and (Croft, in negative comparison the the basin this the basis the large Rings structures Much six structure rings of Head where discussion signature of short Transitional dominant relation position outward): based recognizable and range, relative "structurally basin's of the limitation, length. only lunar distinct formation 1979a). massifs. morphological This of diameters gravity between measurements forms (1976), annulus, of Planetary a (RR): primary of for these do on the scenario this shock basins, extensive with do of section central (e.g., is position of morphology morphology new comparison classifications anomalies. Crisium the a exist, In Wilhelms criteria, section are forms individual the (e.g., different the "bulls-eye": bounded rings tends geophysical equivalent Institute pressures a fault, ring rings the delineated depression. following few of outlines prototype classes, and (inside, on-site slump, are and/or in to and is best Croft basin Ring first cases, anticline), et the For largely basins of question by abstracted basins are emphasize • indispensable al. Humorum experienced). Provided rings" briefly the as studied establishment measurements a uplift, large signatures a (1979a, a outside) characteristic primarily appear (1977), the formation correlative classification basins. broad, discussed strong ridge proposed ring and follow are prototype lunar to means characterized deposition), composition largely different in and from by 1980b) Head (1977), the characteristic rings very relative of positive Basins question those Conditions by the available basins in differences. below. that the preserved two criteria Many correlative Croft concentric of weak NASA establishing are deleted presently stratigraphic suggested basins of a ring basin rings have to can (e.g., center, correlation inward and Wilhelms (scarps, positive of (1979a, (e.g., are Astrophysics as recognized were and in of to in geophysical give types these been Orientale) set relation illustrated follows impossible question the ring However, mare different keep McCauley that sequence surrounded facing ejecta, structural chosen of chapter isolated facies? rise annulus. free is and substantially properties formation between basin the ridge basins fundamental to (proceeding rings McCauley to Data air slopes the relative basins present melt, point in signatures? to This systematics to rings and 5); (1977). massifs, systems the and primary equivalences by Fig. in System analyze perform. structurally of supporting cannot of or criteria bedrock), that its the a observed (in could paper re-inter- to simpler 2. weaker Among impact scarps (1971), to a and inter- etc.)? from have solar mor- free- Ring few For 229 the the be be of In to is a 1981mrbf.conf..227C 230 ally the usually mercurian PR's to within whose blanket facing 4. 2. 6. 5. 3. low Table to basins, Peak according Fig. abbreviations is PR SIR= Hu= Ap The a 800 200 allow consist Peak Intermediate Main Outer Secondary = data least-squares peak swell similar 1. 0 Apollo, and © Humorum, Secondary Ring 5-1). ring the steepest Relation scarp well Lunar with for and assignment Rings generally to ring locally S. Outer Rings peak negative of Peak This diameters basins to the within structural K. Hz= are: peak generally and massif O • the are between faces Intermediate Sm fit 200 Croft ring RR inner Intermediate SIR Ring figure IR MOR (PR): Co bounded Rims (OR): Rings Hertzsprung, Planetary to ring = central the continuous plot within gravity = in MOR basins basins Smythii, are blocks of Compton, class. edge builds the central usually diameter Peak marking as (MOR): all (IR): are oriented and the ring by peaks 400 on of annulus. lunar (Wood single MOR= Institute Ring. ring Or= very on similar PR the a the negative Rings positive Hb consist classifications consist Po= and basin-facing the along the diameter data moon, basins The Orientale, of = positive toward consist points subdued Main and Humboldtianum, format Poincare, ridge-like, complex • inner in for (SIR): line 600 of of Provided gravity the Mercury gravity Head, morphology Outer whose RING lunar a labeled and isolated in the of outer Cr= abcissa edge more used structures scarp Fig. Mo= are are weak basins basin all DIAMETER craters. 1976). Rim, anomaly. annulus. a and ring Crisium, by gravity Head by other of 800 continuous ill-developed plotted morphology 1, peaks Moscoviense, and/or the and Mars. IR= FS center, of Head to structures the whereas to (1978) ring all NASA The = delineated dominant all and Intermediate those In annulus. Freundlich-Sharonov, strongly or in The morphological (1977, a diameters other a and peaks 1000 groups Fig. Im few is few Astrophysics curved ring basins a = are in more in Ko= are least-squares 1 Imbrium. rugged 1978) rings lunar of radially segments (data IR's. lunar where are sufficiently of located line of Ring, rugged Korolev, commonly with peaks classes. unoriented in 1200 along Lunar basins, from labeled SIR's basins massifs. his identifiable Data RR= textured three exterior massif of fit morphologic- studies Croft, the Ne= Gr= Basins The undegraded are Croft portions System to but Ridge an found ordinate. MOR or 1400 two Grimaldi, and Nectaris, located inward appear blocks ejecta 1979a, (1979a) to plotted of more by Ring. letter are the PR and of in a 1981mrbf.conf..227C classifiable absolute parent dimensional PR to relation from smoothly larger identical MOR tend the ratio data, between Rims slightly all diameter The Fig. Eq. MOR three were seen in A crater characteristic dimensional Paper may with (Dr= few complete of ring, represent responds the more basin. CP smallest Figure brief Schrodinger Imbrium, part dimensions Copernicus PR basins rims basins. © (1) relative 1 to a be segments data in CP is not (Croft, planets 162 data MR massive data Lunar was is terraced In One). from fall diameters is non-linear given re-interpretation Fig. the the -150 basin of to basins still dimensional than made km), to 2a Peak a ring of basins with an and of for below not rings fit other the Head's result decrease the genesis the interrelationships. relationships. Head 1 the and is 1979a), Copernicus the lunar small (Croft, incipient by: inner PR to of to basins and and shown complex in noted. (Dr= a of because in rimwall, Ring 1977 and the are upper most definitely figure Planetary smallest Lunar be rayed, plot small Head's which predicted relatively Basins relation kilometers. of (1977), mare -350 prominent (Head, Re-interpretation enough morphologically rim (1978) which crater slightly other and 1979a) lunar basins, 328 on horizontal in in relationships complex The as end Ridge that peaks and craters. PR PR variations flat a Fig. the km simple of km), ridges (1978) on (Dr= horizontal CP development but Ridge fall might is Institute 1977) natures In relation) of fresh linear to by rim diameter the fresh floor is Basins smooth the in earth, Mercury a displaced the Dpr 2d, basin the below ring. than the surrounding particular, be least-squares virtually shown Relations extrapolation diameter. 93 lunar morphologic linear crater However, between in rings be strength and is = ring central and affected continuous PR complex PR km), relation in 1.20 Mercury the of in more only, If (equivalent areal • between is the walls similar combined rows Dpr, MR has the basins, central Provided vs. CP or in fit the this in shown prototype relative -680 ± identical shown extrapolation of peak for Mars. Fig. of Similar 0.08D~·s appropriate. The with each data which been and MOR the discontinuities basins. extent the basin. departures by of the interpretation the for of the craters fit morphologic Dr to and of m sequence peak is simple nature the 2e, target concurrent PR in has central to suggest connected absolute similar by classification massive found. large :S the A in lunar, in terraced to the in data ring have Mars Head to least-squares Fig. the 7 central 150 is The (Dvorak fit Conditions structural the ± vs. diameter Fig. Head's complex. disappeared, diameter 0 linear Head's combined - in the 011 strength of craters. entire of complex for classifications km NASA from slightly 1. of martian MOR main no peak (Croft, exponents - a calculated of 2b, the the width central prototype The the in PR 32.4 (D, peak intersected increase similar is relation simple basins points. (1978) solid spectrum form a ring is (1978) and to the rim linear Astrophysics sequence correct, The data near and = basins, ring The manner smaller xii relatively exhibit (Quaide of larger a of craters. the 1979a, and basin fits PR Diameter linear peak. line ratio prototype of but Phillips, ring of individual is Bo'uguer analytic relation. rough the size classifications. for Gambart largest Figure relation were linear was combined in to mercurian two-ring, Schrodinger, basin given Eq. in the and forming MOR's with of D,/Dpr formation by the then variations CP 1980b). similar Except peak MR relation and Fig. Compton reflected range Lunar (1) floor found peak the fits of other Data basins, to complex to data a fitting 1 1977). for gravity Compton This Oberbeck basins complex 1 to rimwall MOR), distinct, with T ring illustrates both crater, at illustrate to denoted fit to or Equation a of (Head, roughly Dr~ basins PR for ring showing System suggested ring continuous for set a the for the systematic implied is Peak in this functions. also respect as however, given that Compton vs. It illustrate the anomaly connect because craters) the 500 appears and (nearly PR MOR's rims PR classes well terrace as nearly is crater crater is on MOR 1978) Main has 1968; peak Ring may ring cor- km. ring this the 231 ap- 1 the PR vs. the the vs. (1) by all as of to is a a 1981mrbf.conf..227C 232 blocks (data visual the the rimwall slowly (B) crater downward complex a quadrant onset inside Fig. relative has modification. between Schrodinger Orientate. Main Unfortunately, fairly Copernicus absolute diminished 2. SW Outer characteristic © -135 derived the (A) impression prominent width is than Lunar quadrant), peak central width have (G) peak approximately Unnamed extrapolation S. Rim km (LO of The the rimwall ring K. Orientale a to in much and from ring (LO the and peak. (lower IV-SM), scarp-like peak diameter Croft the absolute central and of terraced that Planetary the fresh, are more V-151M), point detail new Croft, Dotted ring and multi-ring width Peak (LO of thought curve the a ring regions simple 328 with scarp-like Eq. independent that only appearance. rimwall of rim rim ,+ IV-194M), Ring -,.<1-_,., circle (distance 1978). structures. km Institute the a (1) central -1/4 in -r;:~ to ,,' 93 --, basins. of crater diameter, peak to of is rim Fig. , be is km represents Schrodinger indicated the a of Consequently this significantly ; than peak. rim elements _> region ring the a -700 diameter 3) (F) The from outermost • (D) Compton peak of ,_'; floor-fractured diameter Provided 928 decrease basin the /~- Two Hertzsprung rim as inconspicuous min has by ring crater predicted km rim may of (A). arcs the with complex diameter smaller diameter been is in prototype scarp an of of arrow. less by the of both be a rim relative (LO 93 incipient prominent either destroyed mare the NE position km. and than (LO crater seen extensive, crater to V-181M), near The incipient the (Melosh NASA quadrant, multi-ring (C) a ridges crater for V-24Hl), Compton few ridge from Gambart to terraced are size Chaplygin Copernicus, with of peak by '' the Astrophysics traces on covered a incipient floor) Intermediate ring rugged, secondary of and 160 the terraced illustrating either ring basin rim a rimwall T terrace or km of brought 556 (Lunar upper McKinnon, and increases (LO diameter, Copernicus. slump side central with with and peak km and no walls, I-l region crater of portions Data Orbiter the curve Ring basin blocks the central out basalt ring 15M), in terraces the peak inconspicuous places flat primary by much System between central chains of obtained giving transitional 1979) a II-171Hl). flows. in basin peak. of magmatic this floor and Despite complex remain. the Fig. more (e.g., basin from rings peak with and The the and the SW (E) the by 3 1981mrbf.conf..227C form appearance the typical Schrodinger structural Schrodinger indicated IV-122M), Peak Rook, (arrow the separated around Space Secondary marginally © and between Science and Al) Lunar the (though Intermediate by by and at basin, equivalence the arrows. of a 1469 is is near and zone Intermediate Data Peak the a not inferred the different floor-fractured) km peak Planetary the of complex a Center. outer The ring in rings collapsed crater smaller diameter, ring of Main is not ring are ring. the appearance the Archimedes in Institute massifs. to of crater flooded rim Inner Compton Photographs two which rim, be is is the complex a the and Montes rims but by The new largest is • (arrow Cordillera mare considered Provided of is doubled PR between is structure an the Fig. in Rook. relatively basalts. supported crater basin, Ar) independent Figs. 2(B). rims is Intermediate Scarp, by to The seen the 2B-2H The Conditions strongly namely be the exterior fresh of central the Ridge to the Intermediate by NASA consist Copernicus incipient were basin Intermediate consideration structure. the ring ring to implies peak Astrophysics supplied on of of the CP can is two beginnings the ring ring unnamed. and crater basin. be Conversely, moon. that tiers and ring courtesy in traced formation rim the of of rim, the is Schrodinger, In Data Much of fairly vicinity of (H) the the nearly particular, yet peak of an but Outer Imbrium System transitional of large another the the otherwise all of is the National ring the in the Montes massifs rim Ridge, fact Alps ring, 233 (LO way the the of of 1981mrbf.conf..227C 234 © Lunar S. K. and Croft Planetary Institute • Provided Fig. Fig. 2(C). 2(D). by the NASA Astrophysics Data System 1981mrbf.conf..227C by phological first floor. Chaplygin CP as equivalent completely differing peak somewhat conspicuously diameter diameter gradually incomplete, between pearance suddenly suggested diameter and of between 1974) The Orientale suitably others a basins © Main precursors model This rings. with Lunar utility the range indicated only between complex at of (Hartmann more to (Dr= Outer- comparisons to separated partial the as photographed encloses basin a inconspicuous peak Extrapolation for and of PR the be diameter intermediate large in Ridge-, as the complete 130 application Planetary the of basin rim (Dr ring that (Cordillera) ring Chaplygin these craters by concept km), blocks an and reasons from the of = the structures, of Peak- it of Schrodinger 928 are smaller incipient two a Wood, central fresh is peaks circle -0.7Dr and Institute typical slumped and ring km), and of not between of less revealed in structures. why (Inner rings transitional Eq. peak-like as craters PR hillocks of comparisons craters. is of shown 1971; peak complete. the (Hartmann peak complex clear. morphologically peak blocks dots • (1) ais revealed basins rimwall and indicated. Montes complex Provided natural several Wood complex in downward in This imbedded on Examination ring. rings the Fig. with the Fig. on forms crater the Examination material and 2(E). Rook), MR argument and variability between the examples 140-180 It were by increasing 2g, craters The floor and Conditions Head, is the appears basin Wood, floors with is in to not similar extensive previously Intermediate- the NASA of transitional corresponds the and of km Copernicus and an PR exhausted has Orientale Copernicus 1976), of of of prototype craters floor 1971). rim are transitional -90° of that incomplete to crater Astrophysics complex been PR and of other the but suggested diameter. differences material. ring arc thought basins. peak intermediate MR made forms. reflect is peak structures with roughly (Outer multiring predicts of in formation stated craters craters basins rings diameter peaks and Fig. in the ring Figure These Data to The to the Examination different Montes in explicitly inconspicuous recognition to 2b. appear represent of begin in basin that and a on where large System morphology gradual in a blocks The peak Compton, 2c the range its circle diameter the become (Head, Rook), gap shows words rather crater as circle same mor- here lack ring 235 the ap- are are an of of of in 1981mrbf.conf..227C 236 massifs and incipient the increasing transitional basins the the well-defined dominant in Intermediate 20 MOR's basins, Schrodinger's shown Fig. km). Outer PR grow © PR Lunar intermediate 2f) in between and that Grimaldi, Moscoviense and PR in Montes rings S. are Fig. basin forms. MOR, a MR and have K. MOR, ring. of asymmetric, way PR 2f. are Croft Chaplygin. diameter, Planetary the basin, Rook. Particularly traces Korolev, (though analogous and Both in found Two and PR and size are no and The increasing of basins basins Institute inconspicuous Grimaldi between with and elements Humboldtianum Hertzsprung's These terrace and MOR next to in (2) their the have Hertzsprung, just Moscoviense, smaller that observations that • recognized PR; are in blocks, of steep Provided smaller prominent are completeness a Intermediate heavily beginning Fig. massif possible basin, PR faces suggestive (D, but 2(F). than by the PR is = are cratered, imply Apollo are towards blocks the 645 ridge-like Peak massifs IR and as Nectaris nearly NASA primarily rings km) subdued, and are of that: MR (D, Rings forming an the and visible. of but topographic in Astrophysics = basins identical incipient in (1) the basin (D, 490 multiring Hertzsprung both scarp-like. similar incomplete sections), Intermediate Intermediate = a km), The also broken 857 center, exhibit IR in is next in km), yields basins prominence Data analogous flooded size morphology and Between reminiscent third (D, rings short three the System evidence (D, rings ring (the = prominent ring, between 556 between smallest = smaller arcs (arrow to Outer 430 begin these km), with the the of of of to ± 1981mrbf.conf..227C
scarp-like existence Montes and and
Archimedes
and this
few of which
relief
Secondary Ridge
the
©
the
a
McCauley,
class,
isolated
similar
Lunar
few
consists
RR
Rook
rims
rings
is
MOR's
massifs.
but
of
suggested
"Island"
and
of
to massifs
Crisium
Intermediate
appear
at
not
of
the
complex
1971;
Orientale)
Planetary
of
an
marked
Radar
RR
MR
in
inward
protruding
section
Croft, primarily
to
of
Fig.
craters basins
consist
Orientale
Institute
sounding
are
by
Rings
1
facing
1979a)
of
to
the
mare
by
are
Imbrium
develop
despite
through
of
(SIR's)
new
the
•
the
scarp
a
(Peeples (-1
and
ridges,
Provided
flooded
extra
structural structural
km,
the
the
parallel
Fig.
the
(Fig.
with
are
differences
ring
is
Howard
"extra"
2(G).
et
maria.
inward
by
the poorly
2h).
a
al.,
Conditions
to
of
smooth
the
elements.
equivalents
innermost
IR's.
isolated
1978)
These
NASA
tier
er
facing
developed
al.,
in
One
rounded
of
shows
morphology.
Astrophysics
observations
1974)
of
This
massifs
scarp
massifs
ring
of
ring
ring
the
the
in
that
falling
crest
in
(fault?)
of
formation
turn
at
MOR's
subsurface
in
lunar
Orientale
is
Crisium
(McCauley,
Data
the
also
suggests
dimensionally
suggest
with
basins.
Alps
of
marked
System
(Wilhelms
PR
a
(Fig.
structure
that
that
and
vertical
basins
Their
1977)
by
237
2g),
the
the
the
in
a 1981mrbf.conf..227C
238
other
RR Poincare
become incipient
and venation Peak
multiring diameter: ties change
tures
This
2)
1)
of
©
Schultz
New
to
There
Ring
RR's
that
Lunar
Orientale.
re-interpretation
in
be
apparent
mechanism
scarp
(?)
basins.
ring
S.
morphology
and
may
increase
appear
characteristic
K.
(1980), and
and
structures
Ridge
structures
be
Croft
Planetary
The
Compton
when
the
to
for
in
suggested
Ring
possible
be
surface
and
topographic
of
lunar
activated
appear
no
may
have Institute
of
the
among
morphometry
discontinuities
the presence expressions
and
sequence
by
be
been
gradually,
Schultz
commonly
by
morphologic
martian basins
•
prominence
identified,
Provided
magmatic
of
Fig.
of
(1976), smaller
beginning
from
of incipient
craters.
basin
2(H).
in
flooded
present
by
ring
the
complex
changes
modification
the
Schultz
and
morphologies
than
Ridge
RR's
Finally,
structure;
as
NASA
scarps
in
completeness
inconspicuous,
400
small
in
and
Ring
craters
observed
Astrophysics
km
only
structurally
in
Glicken
forces
basins,
i.e., is
every
in
suggests
the
inside
to
diameter
there
with
Peak
mare-flooded
with
similar
case
(1979),
but
fragmentary
of
Data
equivalent
several
is
increasing
the Ring
increasing that
where
suggests
a
to
System
and
Peak
continuous
they
basins
the
regulari-
Schultz
both
basins
to
struc-
Ring.
reju-
only
that
rim
the
rim
to
a 1981mrbf.conf..227C derived Rims magmatic under Some crater able. occur of diameter. indicating Rim. the inside craters Flat equivalent 3) floor next © (Roddy, plains Gagarin diameter, crater Fig. New Both the This have inferences the in ...... collapse Lunar 0 i c( C ...... c( I- ai: ll.I II.I the in fractured from interior craters 3. 0.5 0.6 0.4 0.8 0.1 0.2 Main The the the modification rings, material "incipient rim floors STRUCTURAL to the Absolute (the and 10 1976). .__ the series extent D,. gradual and Peak appearance calculations, 1) Outer __ with of ring; of point Planetary slumped of The the analysis (Stuart-Alexander, craters ring significantly that Ring/Main and of otherwise exception ...__ growth" Rim edge e.g., labeled appearance straight subsurface of structure may relative included suggest (Schultz, of Institute rims ...... otherwise the of of and the G) ___._.._.__._ fault lines INTERPRETATION concept Intermediate Rim terrestrial of typical of rimwall which flat smaller basin so the that the complex of fracturing, or • are 1978). crater dimensional RIM 1976) central Provided unobservable rings Ridge slump is the be ring width, least-squares is simple ...... a diameters DIAMETER The drawn floor Main 100 supported degraded and ring implies morphometry. craters Ring ring, scarps. uplift __ rimwall Wi, and (if by also explosion Outer structures, from relation Conditions any). of appear the between 3) ___. explosion peak that than and structures lunar fits by However, width comparison NASA by _ Rims morphology the ___._..._ Peak the to ring the where OF between and craters craters is the 23 of Astrophysics beginnings incipient 2) basin the enhancement of craters RING the Ring multiring data --- Peak such 500 further mass they ring ...... distance as appearance of the partially that ..._ alone; points, a Basins. scaling formation Ring as first Snowball function ..... TYPES central Main deficiency inferences were of basins 1000 the between Data e.g., became and filled such excluding by Outer s 10 so 1 theory, circular of of the uplift System Main Main structurally subsequent and with structures rim new the Rim smallest analysis observ- may Prairie model found Outer Outer rings rings 239 and be 1981mrbf.conf..227C central The 240 Figure terrestrial the circumferential and of and increasingly gradually be between structure). central disturbed circumferential megablock the rebound and crater morphological terrestrial Innes, schematically It relatively horst Ries uppermost Manicouagan primary very large © is (see 4 1961; Lunar depression uplift suggested (Pohl is or uplifted and merge near Multiring zone blocks complex The S. from fractured Fig. tectonic uplift proximate excavation. weakly zone Fig. uplift unfractured structural ordered Dence, K. and graben, is et at 4. sequence t-ou~ ~------Dd------~ ~---Dr I I the layers central fault fault, 1, into with Croft implies Croft (with al., bounded A material structure the Planetary of (Currie, defined Paper rim inflection covered that schematic bedrock basin. craters 1977), a position bedrock (Dct). 1965; A (Dct), and bottom much of diameter (1979a, slump as uplift (D,), features schematic that a rock One, of the circumferential at Major and Popigai 1972; Dct stratigraphically by that (hatched Dct Institute Milton "bridge" is and lunar ____ by Terrestrial less of structural the the is original zone, ie in line originating chapter a of that is and an downdropped is Du), surrounded has the are the melt negative Floran rim features typically Wells typically Fig. Bouguer rock basins "inflection (Masaytis Croft, still et are zone) transient the formed lightly a • Fig. of ground (which connecting central cross-section al., 5) Provided 4, _..,_ covered oriented fracturing slumped the Creek and fault and and 4. at is the of zone 1980a) gravity 1972; fractured impact equal equal by excavation just the depth Thus upright crater the peak Dence, shows material et uplift in is (Dd)- Bouguer line" a structure that by al., with cross-section megablock Bouguer inside possibly stratigraphically Masaytis megablock to chaotically was profile to ring terrestrial the of the (hatched wall extends The craters 1976; disturbed whose -2Dr. an marking -2Dr, vanishes a with 1976; ejecta on significantly NASA peak on terrestrial the cavity, idealized inferred Inflection parallels gravity the Polyakov (Wilson the gravity underlain et increasing Dence, transient The zone shoulder The shoulder and zone to ring zone Astrophysics zone near al., crater outside. the near are and an from basin exterior the exterior anomaly extending melt, in radial Line upright in 1976; derived signature. filled approximate extending and inside the 1977; outer, hence the cross-section. and terrestrial of Fig. is by crater structures the showing that range. the is The crowned central Stearns, cross tectonic with Pohl Trukhalev, an boundary 4) boundary limit Sweeney, the Data the positions central associated from of to poorly terminates rim. occurrence surrounding incipient to As the melt, the the ap- tectonic section et The of System basins a uplift, studies boundary by al., indicated rim with transient 1968). defined ejecta, blocks of of in a 1978). 1974), 1977; (e.g., of with ring ring in is rim but the the the the of of A a a a a 1981mrbf.conf..227C brecciated for craters center complex more Sweeney, surface crater correspond craters mascon). and that: negative similar equivalent fault-scarp negative rims terrestrial with structures corresponds difference, and in the the mascon "bridge" structure similar ejecta Grimaldi crustal Consequently, correspondence, patterns basins such Grimaldi's outer For the Outer of Outer damage The discussed strength different extensive one central terrestrial outer rock © each negative peak the 1) of as edge dense rim. rims Lunar rims of and like impact thickness are origin, show the lunar rocks. of extends craters terrestrial Bouguer over crater outer between Grimaldi, failure has The the Bouguer of 1978). edge of are in rocks disturbed free-air to Grimaldi's positive tectonic ring, Grimaldi Orientate of fractured of indicative 2) association of roughly lunar and to than lunar these Paper sub-surface the negative the Bouguer peak central a the multiring negative processes the the structurally Peak differences Bouguer Fig. negative of in Phillips pronounced between Some during Planetary with and a the same Main lunar ~2 negative signatures near the basins) multiring depth size. anomaly, basins, Main ring anomaly conclusion rims anomalies 4 complex except One, to Ring is and zone 3) low material uplift may densities Bouguer of times negative zone large gravity bulls-eye primarily Outer of portion the the and subsequent basins. surface basin: The and limits gravity and of subsurface Outer of Nectaris ~40 the fracture density basins both Institute may equivalent, between the be (Dd annulus the excavation (Du that Main terrestrial which terrestrial then of basins uplift farther Dvorak's porosity approximate associated negative craters extent Rims Mass considered and of zones of Grimaldi central signature implies terrestrial Manicouagan similar complex gravity of of in be suggested Rims analyses rocks pattern the due are the the their Outer material zones Fig. Bouguer (Scott, may Fig. ~ (presumably expected • isostatic is of are lunar porosity 140 deficiency out, of of structurally Provided association to uplifted and megablock structures. near basins is and basins lunar positive (1981) Bouguer to and (e.g., 4) respective annulus be 4) terrestrial the due that an (Phillips with km as crater Rim consists also that craters. have the corresponds but and the 1974; areal basins 2) also due the with between uplifted that modification fracture anomalies compensation in craters to is may Sweeney, depending also terrestrial lunar intrinsic that preferred extend structure consistent and cross-section by mantle the terrestrial Main correct, diameter rims mascon been to the is correspondence observed Sjogren by anomaly related the Conditions in Therefore, the analysis equivalent zone. and of The be with have the and uplift an Bouguer a fracture each craters plug same and and morphological negative NASA the zone Outer strong due lunar carried to additional Dvorak, similar suggestion is density lunar to associated then relatively The induced the overlaps model 1978), the to basins. of phases on: (Dvorak case et the PR tectonic of with to mascons not the for structural roughly is and/or Astrophysics al., are rim. Outer rock crater anomalies mantle very it of borders density positive basin of to positional craters Main free-air and out 1) directly lunar annulus of near-side association explicitly is of their 1981). for or a 1974; ring the presumably the If of If indication the by suggested from of dense the for typical more by positive MOR n Phillips, and magmatic with Rings. uplift Outer rims tectonic size) this the coextensive crater (or Grimaldi central Cordillera-class material. formation the shock crust/mantle arguments, denote correlation Main elements Sweeney is of Frontispiece, gravity central inner several The proportional whose depth concentric implies correlations between implied terrestrial heavily rocks multiring Data much rims consists relative are their shown. rim peak of formation. of The Outer "bump" lunar fragmentation peak (Croft, that rings rim. the modification. produced less wherein System the intrinsically Assuming of outer anomaly anomaly of structurally fresh from (1978) generating lower. respective that ring scarp-like 1977) structural fractured existence the with Grimaldi complex with mascons complex Fracture complex rim and tectonic to By and of mascon heavily density gravity impact 1979a) to at 1977). imply limits depth these lunar basin Main Main local both with The that and this 241 the the the the the the the As by of (a a 1981mrbf.conf..227C form craters 242 than the where between supported falls collapse in D rather modified significant scale of D,/Do, transition the tectonic the slumping diameters crushed until manifestations physical speculation and linearly collapse Ch. craters. The Both transient craters chosen collapse Outer model volumes multiring and ~ 8 330 The strength :S f total ratio 4; ratio the floor can fD., fD fD. below diameters © at with km, a than rims f for 1979b) to first with Lunar •. (Dete) with to corroboration is structural some zone begins The mechanism. interpretation is rim ~40 D,/Dg be amount comparable craters Dr/D. the associated This rim model multiring basins well diameter, diameters S. lunar a the of by wall reached be a properties of equation that a the the obtained constant. D transient K. diameter and collapse the and discussed and critical diameter which the Comparison strength constant the 3 relation, both into • of at whenever remains 4 strength negative slumping of basins Croft rim whose consistent or predicts of the Planetary crushed the finding ~140km equivalence the diameter the craters where basin D complex Dg with subsurface diameters obtains of The is 4 with rim value therefore, simple-complex When crater with dependence, diameter strength model of of =Dex= are crater, to coupled dimensions fraction obtained equals crater, in fresh constant, Bouguer the dimensions diameter in the relation the of the the the geometrical zone Paper those both used Institute with increasing in and of terraces the rim the craters Dvorak transition of effective peak effective is then: lunar diameter strength disturbed of If of D,, fD., the fracturing, crater. with range of Dete usually and continues from of collapse diameter collapses observed estimated observed the purely from One. in ring complex anomaly the between by so of ring are implies the Main = rim and the • complex and the spall characteristic using and assumption. Main f = f the crater Provided the 1.41 range strength an strength morphometry from extrapolated properties This strength is scaling near the diameters D, geometrical PR derivation zone Peak suggestion becomes Dex/D. final Outer obtained of Phillips empirical ratio outward craters values models, zone ± ejecta suggests radially = is the that for Outer Eq. mass basins. 0.2D,°' simple transition in the from fD. 1/2 proportional craters modified Ring diameter rim the by of the rises of turn (3) D,/D. = discussed rims crater gravity-scaled imply volumes, assuming deficiency, rims may the the of The 1/2 (1977) of the 87 the basin Orientale diameter by during rim yields outward, that of to In of from basins. in "' crater scaling complex above is and 0 NASA of material by to · at complex complex comparison Eq. 02 Paper complex point in is that be observations final diameters diameter, Eq. similar complex the • for 1/3. these the 2(a MOR's all that those radially independent rim associated the (3), to in collapse rim the the proportional Extrapolation diameters (3) Astrophysics of morphological rim terrestrial of and onset slumpblock = One For ~M, theory craters D/. Paper modification heights, D, for in critical Outer multiring transient the 3.4) craters. observed to heights, impact, ranged craters craters, crater diameter. corresponds the of Imbrium and D craters The concentric that which complex the of extrapolated •. diameter, to complex model that and One, with transient This three rings and of 3(a an value. depths, there ratio cubic of craters (D,) From from is implies apparent Data transient crater basins complex Peak for is larger basins; the by extension the of = initiated any leading basins supposition stage (Croft, may classes. equations. a Equivalently, lunar is: between 3.56). is craters simple slumpblock, dependence the An ratio measure collapse Dex, Paper edge System to ~ crater and a is Ring particular do and than that 14 be transient the until estimate gradient collapse i.e., smaller depths, if craters craters craters indeed of km At to of of 1979a, ejecta direct when lunar scale One, D, Main ratio to wall wall Dex, and rim the the the the the the the (2) (3) of of to is is a 1981mrbf.conf..227C f and of derived and completely The The diameters identical. variable, the theory where value between between 3.45 to consistent in transient plication uplift, diameter (Roddy, data inferred 1977). the by dots into terrestrial side division and dependent Intermediate moves suggested central = The The Elimination Equations the Eq. Fig. Dr- 1/2.3 bracketed mean a ± basins. ratio rim the two © the from are for 0.08 apparent Equation is The third (3). Dq Lunar second and the approximately uplift 4 in transient of 1976) Dpr scaling diameters the the at Dg spatial and parts of that a crater absolute Equations of inferred and is craters Fig. Paper with Thus division curve as dashed on the experiment different the is equation and the + Further, gravity peak the the (3) and then rings and consistent term 32.4, the of and the should the by equation ring 1 diameter simple-complex the peak (6) and Eq. Dr coefficient observed association are apparent transition Dr One somewhat, Planetary the crater becomes ring the gravity rewritten in peak peak simple-complex line which from implies in relation consistent and in structure of from scaling plotted data (4), (5) (3) hypervelocity is ring megablock be De,c for transient all Eq. and fills origin marked (cf. Eq. the ring are and ring, as derived is of equivalent. with the three sets, impacts Eqs. originate = (plus scaling (4) diameter in the that (Dpr Institute diameter Eq. Paper part the the associated between a. compared the (1) coefficient. Dg, as again ratios. (4) but of into geological yields of the which the with Varying are position (3) ratios Dpr transient megablock rewritten equations + the crater a (3) both of transition. the by transient from it basin zone 32.4) constant) (Dpr two range One). coefficient complex in substituting remarkably and remains is the transition The peak impact in that of definition. to • 1.43, Equating transient the rock between is the of relate + groups Provided the rim: implies scaling with curve Paper = central the (5) rings of Dex the ring 32.4) of derived the Assuming structure crater, region ring 1.20 right-hand in a correspond collapsing yields: on the crater zone. craters rim values the Substituting between the value obeys explosion a transient outermost by Main structure marked = for ± implied plus originating, the diameter One form considerations, the transient exponents strength-scaled uplift, crater similar, Dr diameter Ridge 0.08Dr°' Equations by 0.85Detc• diameters several of an from The a moon Conditions consistent for Outer existence during for a the gravitational in central a= of implication rewritten parallel reasonable side small the crater water and Restored Restored crater Ds ring NASA and by a terrestrial an of to craters the 878 3.45 (Dex/Dr= surface kilometers crater yields from these Rim PR's of of lunar using the ±o.oi empirical the of respectively, the Intermediate the the constant of uplift and (3) exponents central (Gault Eq. rim to simple and of Dr Astrophysics and with the 1 of as Main with collapse • 3.4 and implies and values Eqs. wall modification (from and basins consistent at Peak Snowball TC Eq. TC implies range scaling. (1) expression that functions ring the and other final impact least 1, to the and the Rims Ds uplift Rims divided (5), craters gravity and is (2): Outer collapse near (3) Dex= value 3.6 in the Ring formation Fig. approximately is empirical of of a of IR's, apparent as Greeley, two model. rings in and the a derived numerical suggested seen a Dr the hinge is a, curve craters. Data and = parameters. implies the the with 2 Rims 14 which of of from is by and mechanisms terminology Eq. scaled 3/0.87 being (4): of confirming of Dq, model. inflection stage in km to Dr. Dq region -0.85 independent Prairie Dr, System Paper This zone the the Fig. (3) in Secondary be coefficient 1978). and crater of from = 3.4 The in occur virtually The that ± showing Fig. by relation 0.06 relation craters, divided divided is craters central Fig. 0.02 5. model of (Pike, of to f equal One) solid both also into Flat The The The two line 5 rim im- km 243 the the the the 3.6 (6) (5) (4) in- of of 5) = is 1981mrbf.conf..227C 244 frequently Rings terrestrial rings ring several Consideration craters appearance Intermediate relative multiring suggested hinge. peak formation. ring © in .... a:: a:: z w w a gravity Fig. rim the Restored those two represented rims. only. Hence, 2000 and Lunar 1000 consistent Prairie to 100 basins and 5. rim classes: obtained S. planets by: 10.._ cited originating their between basins Lunar K. vs. rings and a) diameter. multiring of at TC __ Flat strength Croft as Cb It the with best, by the respective 1) with Planetary Rims structural by lunar as results. in also those ..._ continuous the all the various in all the a lcti the __ the rings is The crater basins; formed crater the points dashed basin analogs / peak originating morphological the LEGEND "new" Main • 0 rings First, ring / Institute ....., megablock solid in peak ratio SECONDARY PEAK INTERMEDIATE INTERMEDIATE RIDGE scaling. indirect / ___ collapse rings c) certain data out line, morphometrical Outer ~'l~ inside RING in RINGS ring dots the of RINGS the I rings on Prairie \ plotted I '· a and the The but • \ 0.5 I Implications \ I approximate I structural I .._ in the sources DIAMETER/MAIN zone (e.g., limitation Provided are model. rims large the RINGS RINGS transient classes __ are transient multiring Main expressed central as not Flat transient between Roddy, of the explosion ratios ...._ A of the Outer Peak 0 by are with __ uplift quantity nearly equivalence crater relation crater in information basins the of coincidence actual the analogs 1976; by comparing 0 crater Oo Ring the ___. the rims within NASA rim rim craters identical transient ___ RIM Eq. main