MARS TECTONICS VOLCANOLOGY Zachary Gallegos University of New

MARS TECTONICS & VOLCANOLOGY Zachary 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 • CO 2 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, 000 km • Width: > 200 km • Depth: > 7 km • 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 -10 km above datum • Youngest flows on Mars

Tharsis Arsia Mons

Olympus Mons • Largest mountain in the solar system • Height: > 22 km • Diameter: > 500 km • Slope: ~ 4° • 6 nested calderas • 3. 5 km deep

Alba Mons • North of Tharsis buldge • Very low slopes ~. 5° • 1600 km across • Rises 3 km above plains

Elysium • Second largest volcanic province • 1, 700 x 2, 400 km • Elysium Mons • 13 km high • Hecates Tholus • North • Albor Tholus • South

Syrtis Major • 1200 km across • 2 km 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