Download Jupiter`s Moon Io: A World of Great Volcanoes

Geology of the Terrestrial
Planets: Moon, Mercury, Venus,
and Mars: An Introduction
Rosaly Lopes
JPL
Why do the terrestrial
planets and moons look so
different from each other?
The faces of the solid planets and
moons are a mix of the four major
processes in geology:
• Volcanism (volcanoes, lava flows)
• Impact cratering (craters)
• Erosion (by water, wind)
• Tectonism (mountains, faults)
The Moon:
Impact craters
and volcanoes
Earth’s Moon:
“seas” of lava
Lava flows in Mare Imbrium
Hadley Rille
Lava channel
Marius Hills:
cones and domes
Lava channels
and tubes: Kilauea,
Hawaii
Impact Craters
Meteor Crater, Arizona, USA
1.2 km wide, ~200 m deep
(0.75 mi wide)
Age: ~ 49,000 years
Euler Crater, Moon
28 km diameter, ~ 2.5 km
~18 mi, 1.5 mi)
Impact craters on Earth
Tenoumer
Serra da Cangalha
Araguainha Crater
The Araguainha Crater or Araguainha
Serra da Cangalha is an impact crater in Dome is an impact crater on the border of
the State of Tocantins, near the border of Mato Grosso and Goias. Diameter = 40 km,
it is the second largest known impact crater
Maranhão State, in northeastern Brazil.
in South America, and possibly the oldest.
The crater is between 12 and 13 km in
diameter, making it the second-largest
known crater in Brazil. Its age is estimated
to be about 220 million years (Triassic).
Vargeão Dome
The crater is an almost perfectly circular
depression with steep walls, 12 km in
diameter and up to 225 m deep relative to
its rim. Its age is estimated to be less than
70 million years
Landsat/ETM+ image showing the central
uplift of Araguainha (a). Digital elevation
models of some Brazilian impact craters,
based on the Shuttle Radar Topography
Mission: (b) Serra da Cangalha; (c)
Riachão; (d) Vargeão. (Romano and Crosta,
2004)
Other structures: Colônia, Vista Alegre
crater
Enhanced Color Map of Mercury
Raden Saleh Crater: ejecta rays
(crater ~23 km diameter)
Mickiewicz crater:
central peak
Oblique view of a 280 km long scarp. The color scale represents elevation in which
red is high and blue is low. This scarp is interpreted to be a surface-breaking thrust
fault. Thrust faults are surface manifestations of the shrinkage of the planet resulting
from the cooling of its interior. Notice that the terrain on the left side of the scarp
stands about 2 km higher than that of the right side of the scarp. The state of Delaware
has been superposed on the figure for scale.
Caloris basin, the
largest young impact
crater on Mercury,
dominates the scene.
With an east-west
diameter of 1,640
km, Caloris hosts a
wide variety of
tectonic features,
including graben,
ridges, and the
Pantheon Fossae.
Mercury: volcano
The role of volcanism in Mercury’s
history had been previously debated, but
MESSENGER’s discovery of the first
identified volcanoes on Mercury’s
surface shows that volcanism was active
in the distant past.
(~30 km diameter)
Venus: planet volcano!
Venus: recent volcanism
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100 km
Serova Patera (caldera)
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Sif Mons shield (2 km high)
Surface covered with volcanic plains and a
variety of volcanic features
Mostly effusive activity - 90 bar atmospheric
pressure and lack of water inhibits explosive
activity
Lavas most likely basalts
Thousands of caldera-like features (>1km
across)
Calderas on Venus described as “circular to
elongate depressions not associated with a
well-defined edifice and are characterized
mainly by concentric patterns of enveloping
fractures” (Head et al., 1992, JGR 97)
Typical dimensions ~40-80 km across, depths
500m-1.5 km. Sizes imply large magma
reservoirs. Calderas relatively shallow
(~500m, up to 1.5 km)
Venus: widespread volcanism
Sif Mons: shield volcano, long
lava flows (2 km high, 350 km
diameter
Flat-topped domes, up to
50 km diameter
Michael Carroll’s view of pancake domes on Venus
From: Lopes and Carroll, Alien Volcanoes, Johns Hopkins, 2008
Lassen Peak: lava dome
Last erupted in
1914-21.
Domes are formed
by high viscosity
lavas that are low in
gas content
Mars geology:
craters,
mountains,
canyons,
river valleys,
dunes….
and giant volcanoes!
Mars: giant volcanoes
• 6.1_MOLA_global_la
beled2.JPG
Topographic map of Mars, warm colors are high
elevations. Data from MOLA (Mars Global Surveyor)
Tectonism on Mars:
No plate tectonics,
but…
Valles Marineris,
a giant rift valley
Vallis Marineris, Mars:
Largest canyon known
in Solar System
Mars Odyssey
(Thermal Emission Imaging System multi-band camera
Tharsis volcanoes
Ascreus Mons
Pavonis Mons
Arsia Mons
Hawaiian eruptions and shield volcanoes:
effusive activity forms long lava flows
Basaltic lavas
Credit: S. Rowland
Mauna Loa from SIR-C
Arsia Mons
(Mars Global Surveyor)
A giant Tharsis shield
volcano
Caldera ~ 110 km across
Topography (MOLA,
MGS) over Viking
image
Possible skylights on Arsia Mons
The Solar System’s largest volcano
Olympus Mons:
600 km diameter,
26 km high
Lack of plate
tectonics allows
huge constructs!
Image from MOC,
Mars Global
Surveyor
Olympus Mons: scarp and caldera
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3D view from NASA Mars Observer
MOLA topographic data superimposed with
MOC wide-angle image mosaic.
Olympus Mons is ~600 km diameter, 24km high
Nested calderas ~60x90km across
caldera walls ~3km high
ESA Mars Express
HRSC image
At least 6 coalescing depressions
suggest a sequence of at least six
episodes of caldera collapse [Hauber
and Neukum, 2006]. Crater counts of
the caldera floors reveal an age of 100
to 200 Ma [Neukum et al., 2004].
Olympus Mons: Sequence of collapse and approximate ages
Unusual compared to calderas of other Martian volcanoes: ages of five caldera
floors cluster around 100-200 Myr ago (error ~50 Myr). Imply formation or
resurfacing within a narrow time span ~150 Myr ago.
From: Mouginis-Mark, Harris and Rowland (2004)
Olympus Mons: a giant shield volcano
Olympus Mons scarp and aureole: how did they form?
“The most persistent
explanation, however, has
been landslides. Large
masses of shield material
can be found in the
aureole area.”
HRSC (Mars Express)
HiRISE image ~ 1km wide (MRO) shows
N edge of scarp, nearly 7 km high at this
location. “Most scientists think the the
cliffs formed by landslides. This collapse
is driven by the weight of the huge
volcano exceeding the strength of the
rocks it is built of. ”
Michael Carroll’s
view of a volcanic
eruption on Mars
triggering flash
flooding
Erosion by water: river gulleys
Newton Basin, picture ~1.5 km (1.1 mi) across
Explosive eruptions
Mount St. Helens:
1980 eruption (Plinian)
Mars: evidence for explosive volcanism
MRO HiRISE
image of cone
on the flank of
Pavonis Mons
SP crater near
Flagstaff,
Arizona
On Mars, atmospheric pressure is sufficiently
low that explosive eruptions can form easily
if the magma has sufficient amount of
dissolved gases
Hecates Tholus (Elysium)
Caldera ~10 km diameter
tholus (tholeii) = small
dome-shaped hill
Mars: evidence for explosive volcanism
Tyrrhena Patera (THEMIS
mosaic, Mars Odyssey):
Colder nighttime
temperatures (blue hues)
indicate parts likely covered
with finer-grained materials
(pyroclastics). Warm (red)
area likely a rocky surface
Mars Exploration Rovers: Spirit and Opportunity
• Landed January 2004, designed to
operate for 3 months.
• Each has found evidence of long-ago
Martian environments where water
was active and conditions may have
been suitable for life.
• Spirit got stuck and batteries died,
Opportunity still sending back data
Meteorite found by
Opportunity, Sept 2010
Erosion and impact cratering:
Victoria Crater
Diameter 750 m
Depth 70 m
Path of rover Opportunity
Opportunity imaged by the Mars Reconnaissance Orbiter
Curiosity: sending the geologist to Mars
Curiosity on the parachute
Imaged by MRO
How to get the Data:
All spacecraft data are public and archived
Depending on purpose of search, specific websites
are useful
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Public outreach and education
Browsing data
Missions
Research
Planetary Photojournal
http://photojournal.jpl.nasa.gov
Excellent resource for general perusal of images and processed data,
teaching, illustrations
Click on a planet (for example, for Io or Europa, click on Jupiter)
Pages for individual missions: http://saturn.jpl.nasa.gov
Getting the Data: Planetary Data System http://pds.jpl.nasa.gov/