Mars: The Basics and Geology

How many planets is Mars away from the Sun?

- fourth planet from the Sun

What has been suggested to have been accomplished by early basaltic material being weathered, eroded, and redistributed by winds?

It has blanketed Mars with red soil/dust that gives geochemical signature that matches these Martian basaltic breccias

How is the crustal thickness of Mars determined?

Mars Global Surveyor data to range from as little as 3 km to as much as 90 km, with an average of 50 km

What are Pateras?

large structures of low relief, often with central volcanoes and flows of vast extent, but also what appear to by pyroclastics

When was the Tharsis uplift believed to have originated and terminated?

originated before 3.7 Ga, terminating perhaps in 2.3 Ga, as hot mantle material rose by convection

Why is it not surprising that Mars has a lower density that mercury?

Mars probably formed much farther from the Sun in a region of lower temperature (thus, lighter) condensates

What does Mars have its own of?

Milakovitch cycles

why is Olympus Mons so big?

the lack of plate tectonics on mars, such that single "mantle plume" operating over a long span of time would generate a singe enormous volcano

Which terrestrial planet is Mars?

the last of the inner/terrestrial planets.

what is the argument for glacial activity on Mars? (3 points)

the polar ice caps are largely H2O ice,so it should be possible; there is a peculiar spiral form to the polar ice caps, suggestive of some kind of dynamic; deposits who overlap

What do the highlands represent?

the preserved ancient crustal surface, almost certainly older than 4.0 Ga

what is another consequence of the restoration after mass imbalance cause by the Tharsis uplift?

the stream-dissected terrain south of the escarpment, currently irregularly distributed, now take on a latitudinal pattern

characterize Mars atmoshpere.

thin; with a pressure of only 6 mb (compared to Earth at 1000 mb), dominated by CO (at 95%, with lesser N, H20 at 0.03%, O2, and Ar)

what is included on Tharsis Uplift?

Olympus Mons, the largest single volcano in the Solar system at 27 km height and 600 km diameter

What are the names of the two major crustal upwarps?

Tharsis and Elysium

What is a possibility that the eruption of material that formed the Tharsis Uplift created?

a mass imbalance that was stabilized by the shifting/rotation of the crust-mantle system independent of the core, to place the near-surface excess mass on the rotational equator

what would have controlled the precipitation that cause the network of valleys south of the Tharsis Uprift?

adiabatic cooling of air masses rising as they crossed to the southern highlands; growth of ice masses would have resulted as well

what shows that Mars has a warming climate?

after two Martian years, the Mars Global Surveyor noticed that the CO2 that had been lossed had not been redeposited

Discuss Mars' magentic field.

almost nonexistent; less than 0.01%; it is a weak remnant field in the Martian crust from a warmer period in Mars' history when it would have had an active field

Explain how Martian basalts differ from terrestrial basalts.

appear to be enriched in K ad Na (volatiles) and Fe, and depleted in Al compared to terrestrial basalts

2 meteorites are believed to be representative of an 'average' martian crust consisting of what?

basaltic breccias, with fragments of basaltic volcanic rocks in a matrix of basaltic material that may represent melt sheet materials

How much does Mars obliquity vary? Why?

between 15 and 35; its small satellites do not stabilize Mars obliquity the way the larger Moon stabilized Earth's

What is the fundamental division on Mars?

between the North and South hemispheres, with a diametric but non-equatorial separation, plus other features of note

How do others argue that these features once though to be formed by liquid water came to be?

blocks of dry ice, detaching from a blanket of CO2 frost, would ride down a cushion of vaporizing CO2 as 'hover ice' to create these gullies plowing up ridges of sediment at their sides

What is Mar's density?

3.93 g/cm3 (5.52 g/cm3 for Earth)

what percentage is Mars further from the Sun than Earth?

50%

What is Mars diameter?

6,790 km, just slight more than 1/2 of Earth's

What are the 5 geological provinces of Mars?

1. Densely cratered highlands 2. Northern Plains 3. Global Escarpment 4. Crustal Upwarps 5. Polar Regions

What are the two tectonic features on Mars?

1. Mare Ridges/Wrinkle ridges 2. Canyons

What are the three volcanic features on Mars?

1. Shield Volcanoes 2. Volcanic Plains 3. Patera

describe Mars mantle.

1300-1800 km thick, and is understood to be convecting

What is the surface temperature of Mars?

150-300 K (-123-27 degrees C)

This mass imbalance moved the equitorial position by how much?

20-25 degrees latitude

when were the last eruptions on Olympus Mons?

200 my to even as little as 10 My since the last eruptions

How often does Mars rotate on its axis? How often does it rotate around the sun?

24 1/2 hours, in 1.88 years

What is the incline of Mars axis of rotation?

24 degrees

Name a significant canyon on mars. Describe it. (3 points)

Valles Marineris on Tharis dome; it is 4000 km long by 700 km wide by 7 km deep, comparable in scale and configuration to the East African Rift

Incision of valley networks before the mass imbalance caused by the Tharsis uplift would have been primarily driven by what?

a belt of precipitation approx. 14 degrees latitude wide, centered on 24 degrees south latitude

What does suspended dust in the Martian atmosphere do?

causes the atmosphere to heat up very rapidly, temperature rising by 7 degrees C just after sunrise; this captured heat triggers growth of vortices that may grow rapidly, and cover vast areas

Describe the Martian polar caps.

consist of water ice and also some dry ice in winter, when polar temperatures reach 130K v. freezing point of carbon dioxide of 148 k

what effect does the freezing of CO2 have on atmospheric circulation?

consists of a single Hadley cell where surface movement is from the summer (H) to winter (L) hemisphere

What is the global escarpment?

contact between the older southern and younger northern hemisphere that effectively encircles Mars, with a few interruptions

what are fault structures/grabens related to on Mars?

crustal extension as upwarps occurred

Describe the Northern plains (2.points)

dominate the northern hemisphere and are separated from the southern highlands by an escarpment that is 2-3 km high

what are the tectonic features associated with patera?

extensional tectonic features

What did the Mars Global Surveyor mission notice about the south polar icecap? Describe in some detail.

features on teh south polar ice cap had changed; was rapid retreat of the faces of scarps and pits in the layered CO2 ice at rates averaging 3m per Mars year, and int eh extreme reaching 8 m per mars year

What may the fluctuation in CO2 ice cover be responsible for?

features once attributed to flow of liquid water; dunes are cut by gullies, which are noteworthy for having raised edges, and pits rather than sediment deposits at their down-slope end, and also their remarkable straight path

How is the composition of Mars crust known?

from SNC meteorites, recent orbiters, and landers

Why are the differences between Martian basalts and terrestrial basalts expected?

given the Mars is supposed to have formed farther from the Sun and should be more volatile-rich

describe the upwarps.

have shield volcanoes, lava flows, calderas, and radial fracture systems; basaltic composition seems likely

What are the arguments against glacial movement on Mars? (3 points)

if it is CO2 ice it would be too brittle to flow/be plastic; even if H2O, the caps are too thin at the Martian gravitational field to weak for them to flow under their own weight; the spiral troughs would seal or open

How may have these ejecta deposits be described to have happened?

impact melts ice, adn the liqiud mixes with ejecta to form a slurry

Is the structure of Mars comparabel to Earth?

in gross terms

Where are the two major crustal upwarps located?

in the Northern plains

What does removal of CO2 by freezing do to the Martian atmosphere?

it causes a drop in atmospheric pressure over the winter pole

What are the modifications to the global escarpment? (2 points)

it is dissected by stream erosion and mass movement/slumping, and there are isolated blocks/mesa just north of it in what is called fretted terrain

What can be concluded from the fact that its surface rocks are less dense than the planet's average?

it likely has an iron core (perhaps, with S, O) of 1500-2000 km radius, that is now solid

What is an argument to how the global escarpment was produced?

it was produced by a large scale impact

What are the features that make up the northern plains?

mare-type basalts, other volcanic features, some stream-borne sediments, and evidence of Aeolian activity

Explain Patera's explosive activity

may constitute a form of phreatic eruption as ice goes to steam due to the approach of magma/lava

What are there several of in the densely cratered highlands

multiring impact basins; including Hellas at 2000 km

Explain how the Valles Marineris was produced. Which two processes have substantially modified it?

produced by extensional tectonics, but has been substantially modified by two processes: mass movements and fluvial erosion

What comprises the densely cratered highlands?

southern hemisphere, of Mars; similar to the ancient cratered terrains of the moon and Mercury

How are mare ridges produced?

the buckling of cooling lavas in volcanic plains

What is unusual about martian cratering?

the character of the ejecta; although some craters show classic rays and secondary cratering, many show evidence of the flow of ejecta, suggesting the involvement of water; ejecta radius of 1.5 to 2x the crater radius (typical values of 0.7 for the Moon, and 0.5 for Mercury)

what are some intrigueing ideas about what rampart craters might allow or reveal

the distribution of such craters might allow mapping of groundice/groundwater variation, and that the smallest size of ramapart crater might reveal the minimum depth to H2O

describe Rampart or splash craters.

wherein the ejecta moved as heavy mudflows, with lobate flow fronts having steep or rampart faces, rather than airborne rays

What did the Mars Global Surveyor note?

wind storms with wind speeds as high as 580 km/h, almost 5x the minimum for a hurricane on Earth