Presentation is loading. Please wait.

Presentation is loading. Please wait.

Aqueous Alteration on Mars

Published byLuke Parker Modified over 8 years ago

Similar presentations

Presentation on theme: "Aqueous Alteration on Mars"— Presentation transcript:

1 Aqueous Alteration on Mars
Importance Some background Alteration products in Martian meteorites Martian origin for products Nature of products Experimental data Ages of weathering products Evidence from Viking, Pathfinder, and MER analyses Rates of weathering Jeff Taylor Aqueous Alteration on Mars

2 Importance of Understanding Aqueous Alteration on Mars
Understand geologic environments at surface, including habitability Estimate duration of surface-water events Estimate conditions of groundwater-cryosphere system Date times of aqueous alterations Understand history of climate on Mars Jeff Taylor Aqueous Alteration on Mars

3 Aqueous Alteration on Mars
Definition: Change in chemical and/or mineralogical composition of rock in response to interactions with H2O-bearing ices, liquids, and vapors at ambient or hydrothermal (above ambient) temperatures. Chemical alteration takes place by hydrolysis, hydration, oxidation, carbonation, ion exchange (between crystals and solutions) Alteration without removal of elements is isochemical (closed system). Opposite is open system alteration Excellent general discussion can be found in Chapter 23 of The Martian Surface: Composition, Mineralogy, and Physical Properties (Jim Bell, editor). The chapter is by Doug Ming, Dick Morris, and Ben Clark. A good review about alteration products in Martian meteorites is: Bridges, J. C. et al. (2001) Alteration assemblages in Martian meteorites: Implications for Near-Surface Processes. Space Sci. Rev. 96, Jeff Taylor Aqueous Alteration on Mars

4 Aqueous Alteration on Mars
Variables Initial rock mineralogy Anhydrous igneous minerals not stable at surface with water Temperature Water chemistry (e.g., no SO4-2, no sulfate forms) pH (H+ activity) Pressure Jeff Taylor Aqueous Alteration on Mars

5 Aqueous Alteration on Mars
Settings Weathering—Surfaces of Earth and Mars Hydrothermal alteration (> ~25C, ≥ 1 bar) Late-stage magmatic fluids Fumeroles (magmatic fluids and rain or groundwater) Burial Subduction Internal heating of rock/ice mixtures Jeff Taylor Aqueous Alteration on Mars

6 Aqueous Alteration on Mars
pH, in case you forgot H2O H+ + OH- Kwater = mH+ + mOH- = (dissociation constant of water) m = moles of solute/kg of water (Always some of both H+ and OH-) Can give acidity by conc of H+ alone: pH = -log(mH+), hence log of the activity of H+ Acidic, < 7 mH+ Neutral, 7 mH+ Alkaline (Basic), >7 Jeff Taylor Aqueous Alteration on Mars

7 Hydrolysis Definition: The breakup of a chemical bond using
water. For example: Cl-(aq) NaCl Na+(aq) +Cl-(aq) Na+(aq) Jeff Taylor

8 Hydrolysis of Silicates
Mg2SiO4 + 4H2O Mg2+ + 4OH- +H4SiO4 Mg2SiO4 + 4H Mg2+ +H4SiO4 Fe2SiO4 + 4H Fe2+ + H4SiO4 The Fe2+, Mg2+ and other ions may not stay in solution: (Fe,Mg)2SiO4 +4H+ = Fe2+ + Mg2+ +H4SiO4 Fe3O4, Fe2O3 MgSO SiO2 (amorphous) FeO(OH) MgCl Silicious clays FeSO Mg3Si2O5(OH)4 Jeff Taylor Aqueous Alteration on Mars

9 Aqueous Alteration on Mars
Jeff Taylor Aqueous Alteration on Mars

10 Aqueous Alteration on Mars
Giant’s Causeway 30-meter thick soil layer 1-2 My time gap between lower and upper flows Jeff Taylor Aqueous Alteration on Mars

11 Giant’s Causeway Corestone
Jeff Taylor Aqueous Alteration on Mars

12 Aqueous Alteration on Mars
Critical Zone According to a National Research Council report, the Earth's Critical Zone is the “heterogeneous, near surface environment in which complex interactions involving rock, soil, water, air, and living organisms regulate the natural habitat and determine the availability of life-sustaining resources” (from Critical zone: Heterogeneous, near surface environment that features complex interactions among rock, soil, water, air, and organisms. Jeff Taylor Aqueous Alteration on Mars

13 Aqueous Alteration on Mars
Weathering on Earth Jeff Taylor Aqueous Alteration on Mars

14 Terrestrial Mineral Evolution
Increasing number of water-bearing minerals Hazen, R.M. and Ferry, J.M. (2010) Mineral evolution: Mineralogy in the fourth dimension. Elements 6, DOI: /gselements.6.1.9 Jeff Taylor Aqueous Alteration on Mars Hazen and Ferry (2010)

15 Mars Mineral Evolution
Igneous rocks Olivine Pyroxenes Plagioclase Ilmenite Magnetite Apatite Jeff Taylor Aqueous Alteration on Mars

16 Common Alteration Minerals: Phyllosilicates (Clay Minerals)
Three-layer structure: Smectite: montmorillonite, (Na,Ca)(Al,Mg)2(Si4O10)•nH2O vermiculite, (Mg,Ca)(Mg,Fe3+,Al)3((Al,Si)4O10•H2O Two-layer structure Kaolinite, Al2Si2O5(OH)4 Jeff Taylor Aqueous Alteration on Mars

17 Common Alteration Minerals: Carbonates
Note miscibility gaps, based on experiments Compositions in shaded areas not common and if present represent nonequilibrium conditions Jeff Taylor Aqueous Alteration on Mars

18 Common Alteration Minerals: Sulfates and Halides
There are > 100 sulfate minerals Common in Mars Meteorites and inferred on surface: Anhydrite, CaSO4 Gypsum, CaSO4•2H2O Epsomite, MgSO4 •7H2O Kieserite, MgSO4·H2O Halides Halite, NaCl (rock salt) Sylvite, KCl Jeff Taylor Aqueous Alteration on Mars

19 Common Alteration Minerals: Zeolites
At least 40 different minerals in zeolite group Framework silicates Tetrahedra of SiO4 and AlO4 linked to form channels, cages, rings, loops Form cage-like openings in structure Channels and cages permit cations and H2O to pass in and out Result: can be used as molecular sieves in water softeners, or as kitty litter Typically form as secondary minerals in cracks or cavities in mafic igneous rocks Examples: Natrolite,Na2Al2Si3O10 •2H2O Chabazite, CaAl2Si4O12 •6H2O Heulandite, CaAl2Si7O18 •7H2O Stilbite, CaAl2Si7O18 •7H2O Jeff Taylor Aqueous Alteration on Mars

20 Common Alteration Minerals: Iron Oxides and Hydroxides
Hematite, Fe2O3 Magnetite, Fe3O4 Goethite, FeO(OH) Lepidocrocite is a polymorph Limonite is fine-grained geothite Ferrihydrite, Fe2O3 •0.5 H2O Nanophase iron oxide Jeff Taylor Aqueous Alteration on Mars

21 Common Alteration Minerals: Iddingsite
Rusty red stuff that forms veinlets Common alteration product Mixture of Fe-bearing smectite and iron oxides (ferrihydrite and magnetite) Smectite usually poorly crystalline Jeff Taylor Aqueous Alteration on Mars

22 Aqueous Alteration in SNC Meteorites
Fusion crust cuts across alteration Best evidence for extraterrestrial origin Jeff Taylor Aqueous Alteration on Mars

23 Evidence for Martian Origin
Pre-terrestrial fracturing D/H in some phases too high to be terrrestrial, but consistent with high D/H in Martian atmosphere Phases with C, O, and S isotopes inconsistent with terrestrial alteration Ages far older (> 600 My) than terrestrial residence times However, except for ALH84001 and the nakhlites, others have not been as well documented Jeff Taylor Aqueous Alteration on Mars

24 Summary of Alteration Phases in Nakhlites
Lafayette: Ca-rich siderite, smectite, gypsum Governador Valadares: Smectite, siderite, gypsum Nakhla: Smectite, siderite, gypsum, anhydrite, halite, epsomite, goethite These form an evaporation sequence from a brine (Bridges and Grady, 2000): Lafayette, 25% brine remaining Governador Valadares, 20% brine remaining Nakhla, 10% brine remaining Bridges, J. C. and Grady, M. M.(2000) Evaporite mineral assemblages in the Nakhlite (Martian) meteorites. Earth Planet. Sci. Lett. 176, Jeff Taylor Aqueous Alteration on Mars

25 Alteration in Nakhlites
50 microns Halite (h), anhydrite (a), and siderite (sd) in Nakhla Iddingsite in Lafayette; sd is Siderite, sm is smectite Jeff Taylor Aqueous Alteration on Mars

26 Alteration in Chassigny
Occurs in veins in olivine; probably deposited from brines Calcite Magnesite Gypsum Not an alteration product: Amphibole (kaersutite) in melt inclusions Shows there was water in magma Jeff Taylor Aqueous Alteration on Mars

27 Alteration in Shergottites
Have to worry about effects of shock on alteration phases—can convert low-T products to higher-T products No systematic study of alterations and shock has been done Alterations described only from Shergotty and EET 79001: Calcite Gypsum Sulfates Phyllosilicates (Shergotty) Jeff Taylor Aqueous Alteration on Mars

28 Aqueous Alteration on Mars
Alteration in ALH 84001 Carbonates in ALH84001 form disks with compositions varying continuously among carbonate endmembers (gray field) On the diagram, Lafayette points are crosses, GV are triangles, Nakhla is circles Important point: some carbonate on Mars Jeff Taylor Aqueous Alteration on Mars

Download ppt "Aqueous Alteration on Mars"

Similar presentations

Unit 5: Minerals.

Unit 5: Minerals.
Sub-solidus evolution. Mineral transformations Secondary minerals Fluids expulsion and movement –Pegmatite/aplite veins –Mineralized veins Hydrothermal.

Sub-solidus evolution. Mineral transformations Secondary minerals Fluids expulsion and movement –Pegmatite/aplite veins –Mineralized veins Hydrothermal.
Dissolution and Precipitation

Dissolution and Precipitation
 Rocks are continually recycled on the Earth’s surface and in Earth’s interior, on a geological time scale.  Rock is often exposed to an environment.

 Rocks are continually recycled on the Earth’s surface and in Earth’s interior, on a geological time scale.  Rock is often exposed to an environment.
Some Basic Terminology

Some Basic Terminology
Minerals A. Changing scales to looking at the elements of the earth and its crust (8 most common) B. Introduction to minerals that comprise rocks (11 most.

Minerals A. Changing scales to looking at the elements of the earth and its crust (8 most common) B. Introduction to minerals that comprise rocks (11 most.
Six-sided, pyramidal Quartz Crystals.

Six-sided, pyramidal Quartz Crystals.
Sedimentary Materials

Sedimentary Materials
Ch. 3 Earth Materials Minerals and Rocks Grotzinger, Jordan Press and Siever, 5th Ed. 2007 Adapted by Juan Lorenzo from Lecture Slides prepared by Peter.

Ch. 3 Earth Materials Minerals and Rocks Grotzinger, Jordan Press and Siever, 5th Ed Adapted by Juan Lorenzo from Lecture Slides prepared by Peter.
Sedimentary Minerals We will focus on some minerals which form from precipitation of dissolved ions  other minerals in sedimentary rocks are derived from.

Sedimentary Minerals We will focus on some minerals which form from precipitation of dissolved ions  other minerals in sedimentary rocks are derived from.
Early martian surface conditions from thermodynamics of phyllosilicates Vincent F. Chevrier Workshop on Martian Phyllosilicates: Recorders of Aqueous Processes?

Early martian surface conditions from thermodynamics of phyllosilicates Vincent F. Chevrier Workshop on Martian Phyllosilicates: Recorders of Aqueous Processes?
Martian Mineralogy: Important Minerals for Understanding Geological Processes on Mars Liz Rampe (NASA-JSC/ORAU) 9 July 2012

Martian Mineralogy: Important Minerals for Understanding Geological Processes on Mars Liz Rampe (NASA-JSC/ORAU) 9 July 2012
Ch 4. Minerals.

Ch 4. Minerals.
Workshop on Martian PhyllosilicatesWednesday, October 22, 2008 Smectites on Early Mars Gain a more quantitative description of conditions bracketing smectite.

Workshop on Martian PhyllosilicatesWednesday, October 22, 2008 Smectites on Early Mars Gain a more quantitative description of conditions bracketing smectite.
UNIT 2 MINERALS PART 2 full lecture Structure of minerals Composition of magma or fluids from which the minerals form. Conditions like temperature and.

UNIT 2 MINERALS PART 2 full lecture Structure of minerals Composition of magma or fluids from which the minerals form. Conditions like temperature and.
Atoms, Compounds, Minerals and Rocks. Atoms Atoms - the smallest unit of an element that retains the physical and chemical properties of that element.

Atoms, Compounds, Minerals and Rocks. Atoms Atoms - the smallest unit of an element that retains the physical and chemical properties of that element.
Mineral Weathering and Secondary Mineral Formation weathering: chemical alteration of minerals (in soils, involves water, gases, acids, etc). Parent material.

Mineral Weathering and Secondary Mineral Formation weathering: chemical alteration of minerals (in soils, involves water, gases, acids, etc). Parent material.
MINERALS TYPES OF BONDING INTERMOLECULAR BONDING HYDROGEN BONDING Occurs primarily between water molecules due to polarity. VAN DER WAALS BONDING Occurs.

MINERALS TYPES OF BONDING INTERMOLECULAR BONDING HYDROGEN BONDING Occurs primarily between water molecules due to polarity. VAN DER WAALS BONDING Occurs.
Minerals and Rocks. Lecture Outline What are minerals? What are minerals? Common rock-forming minerals Common rock-forming minerals Physical properties.

Minerals and Rocks. Lecture Outline What are minerals? What are minerals? Common rock-forming minerals Common rock-forming minerals Physical properties.
Minerals Review.

Minerals Review.

Similar presentations

Ads by Google