MARS TECTONICS & VOLCANOLOGYZachary Gallegos

University of New Mexico / Mars One

Mars Orbiter Laser Altimeter Map

Plate Tectonics• Lithospheric plates sliding

on the asthenosphere, above the mantle

• Exists on Earth

• Theory proposed in the early 1900’s

• Does it exist on other bodies in the solar system?

Plate Tectonics• Recycles material

• Regulates the atmosphere• CO2 sequestration and output

• Linked with mantle convection• Push new material to surface

at divergent boundaries• Pulls old material into the

Earth at convergent boundaries

Tectonics of Earth• Picture of plates

Plate boundaries

• Divergent• Spreading apart

• Convergent • Moving together

• Strike-slip• Sliding past

Divergent

• Mid-Atlantic ridge• Oceanic

• East African Rift• Continental

• Rio Grand Rift• Continental

Convergent

• Mariana Islands/Trench • oceanic-oceanic

• Pacific Northwest • oceanic-continental

• Himalayas • continental-continental

Strike-slip

• San Andres fault • right lateral

Plate Tectonics of Mars

Tectonics of Mars

• Mars seems to lack global, Earth-like tectonics• Too small?• Not enough water?

• Large scale faulting

• HUGE scale rifting

Topography

• Mars’ planetary dichotomy• Not tectonic in origin

• Bolide impact , water resurfacing

• Slow sloping at the dichotomy• not pronounced

• Earth’s dynamic lithosphere• Tectonic in origin• Steeply sloping at the margins

• Continental and oceanic crust

Magnetics • Mars lacks a current magnetic field

• Magnetic reversals recorded on Earth

Magnetics• Possible magnetic reversals recorded in early Martian crust

Interior of Mars• Smaller/colder

• Less water

Faulting• Tectonic movement

• Normal (extension)

• Reverse (compression)

• Strike-slip (lateral)

Faulting on Mars• Thrust faulting

• Amenthes Rupes

• Normal faulting• Circum-Tharsis

• Strike-slip faulting??• Within Valles Marineris

Faulting on Mars• Circum-Tharsis

• Extensional faulting

Valles Marineris• Giant tectonic fissure in

the crust• Not the result of plates• Result of Tharsis uplift

• Length: > 4,000km

• Width: > 200km

• Depth: > 7km

• Largest known valley in the solar system

Valles Marineris• Nearly ¼ or the planets circumference

• Nine times longer than the grand canyon

Vallis Marineris

Volcanology• Study of volcanoes

• Volcanoes bring new material to the surface from below• Lava, ash, gas

Volcanology of Earth• Most of Earth’s volcanism is related to plate tectonics

• Divergent and convergent boundaries

Volcanology of Mars• No planetary tectonics

• Shield forming• Hot spot volcanism (e.g. Hawaii)

• Mostly basaltic in compositions• From ultramafic komattiatic to dacitic

Rocks and Minerals• Mars has a different volcanic signature than Earth

Why Basalt?• Hot spot volcanism produces basalt

Volcanism and Tectonics• With no tectonics, volcanoes grow to enormous size

Montes• Mons are large shield volcanoes

• Earth analogue: Hawaii

• Gentle slopes < 6°

Ascraeus Mons Pavonis Mons Arsia Mons

Tholi• Tholus is a term for

smaller, dome shaped volcanoes• Older than Mons

• Buried by later flows

• Steeper flanks

• Different material than Montes?

• Less material than Montes?

Patera• Term given to small volcanoes with large calderas

• Latin translation: shallow drinking bowl

• Larger calderas than the tholi

• Probably represent larger volcanoes

• Buried beneath flows and sediment

Rootless Volcanoes & Pseudocraters• Show no sign of magma conduit

• Analogues on Earth erupt due to a magma body flowing over a surface or subterranean water source

Martian Volcanic Provinces

Tharsis• Largest volcanic province on Mars

• 25% of the planets surface

• Avg. 7-10km above datum

• Youngest flows on Mars

Tharsis

Arsia Mons

Olympus Mons• Largest mountain in the solar system

• Height: > 22km

• Diameter: > 500km

• Slope: ~ 4°

• 6 nested calderas• 3.5km deep

Alba Mons• North of Tharsis buldge

• Very low slopes ~ .5°

• 1600km across

• Rises 3km above plains

Elysium• Second largest volcanic

province• 1,700x2,400 km

• Elysium Mons• 13km high

• Hecates Tholus• North

• Albor Tholus• South

Syrtis Major

• 1200km across

• 2km high

• 2 calderas• Nili Patera, Meroe Patera

• Silica rich rocks• Dacite & Granite

Isidis Basin

Highland Patera• Near the Hellas impact basin

• Impact induced volcanism along fractures?

Arabia Terra• Low relief Patera

• Structures that look like Earth’s supervolcanoes• e.g. Eden Patera

Questions?

Geography of Mars

Volcanic Provinces

Exploration Sites