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yes thank you Mike and all of the

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organizing committee so we are going to

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time to talk about a lot of some of the

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terms we've heard today sulfates

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alteration and specifically I'm going to

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talk about Nicaragua before i get into

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the science i just want to acknowledge

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my advisers and co-authors Kathy and

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Mickey or spectral experts and Caryn and

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Tom are in the field with us and of

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course funding from NASA and the

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department can use this so the

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motivation for this work is really

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surrounding the sulfates on Mars as many

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of you may know if you follow the

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rover's and/or the orbiters a number of

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sulfates have been observed on Mars

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including gypsum and keys right which

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are calcium and magnesium sulfate

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respectively poly hydrated sulfates are

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a little bit harder to identify

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specifically because of their spectral

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signature and jerra site is the big one

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that prompted ideas about this acidic

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informations so the general term that I

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study or the general formation mechanism

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is acid sulphate weathering but that can

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hurt happen in a number of ways

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including briny evaporating lakes and

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volcanoes and a number of other ways

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dirty-ice impacts so I'm going to focus

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on the volcanic hydrothermal alteration

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and see if we can identify on earth

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diagnostic features that if we then

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observed on Mars could inform us about

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the Paleo conditions so we do this using

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fieldwork models and experiments today

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I'm going to talk about the field work

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and for scale this little light dot is a

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person and specifically the August 2012

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field work which was the first time we

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focused on insta to studies previously

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there had been about five campaigns down

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to Nicaragua but it was all sample and

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return so we took down Terra which is an

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portable x-ray of xrd which is

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comparable to chemin on MSL and then we

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also took down Terra spec 4 which is a

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portable visible near-infrared

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spectrometer which is a

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rivlin but has a higher resolution to

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the orbiting spectrometers we also took

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biological samples and then in our

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makeshift hotel laboratory prepared them

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to go through customs so in Nicaragua

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just to give you some context you have

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the Coco's plates abducting under the

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Caribbean plate and we're focusing on

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the volcanoes right here in Nicaragua

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our main one is Sarah Negro but we also

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have visited Momo tumbo talika and then

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the mud pots that are on this flank of

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talika as Mike mentioned earlier Sarah

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Negro is our youngest volcano it has a

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well-documented history a farmer salt

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popping up in his field one year and

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ever since then people have been

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observing it it most recently erupted in

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1999 although it's overdue for an

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eruption it erupts a belt every 10 years

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moma tone bone talika are much older

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volcanoes and have varied or varied

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activity and generally because these

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volcanoes are close to each other they

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have similar basalt chemistry's in the

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basaltic basaltic andesite so the reason

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we like these as an analog is because of

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that real-time observation but also

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because the bed the basalt at Nicaragua

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closely matches that of Mars so in this

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plot the black line is the average

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Theron Edgar basalt the red lines are

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the Martian material some are the

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bedrocks and some are meteorites you'll

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notice that the two big differences are

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iron is a little bit lower and aluminum

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is a little bit higher so we do have to

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take those into account when we're

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interpreting our observations so now I'm

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going to look at each of those four

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sites i mentioned and just show you some

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of the spectra that we found so this is

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an overview of Cerro Negro you hike up

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the outside wall here and if you like to

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live dangerously you can climb to the

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top and cinder board down the outside

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but then you're picking glass out of

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your arm if you fall and you walk around

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here and these are people for scale and

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then you can see that this

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entire wall here is what very is

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extremely altered and this is the 1992

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eruption wall so you have extensive

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alteration and not that much time this

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area right here which you can kind of

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see in this picture we call monkey face

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because it looks like a monkey and

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there's a lot of the biological studies

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go on there Sara Negro has anywhere from

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negative 1 ph to more I'll say neutral

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but still acidic for pH and ranges from

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ambient temperatures up to 150 degrees

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in the steam or just below the surface

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so some of the spectra that we typically

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find there are gypsum and silica this

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top plot is gypsum and for reference all

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the black spectra are filled spectra and

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all of the colored are the library

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spectra so you can see in this top

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example that we basically found

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laboratory library quality spectra of

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gypsum and we found this at Monkeyface

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this is a close-up picture of monkey

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face and a lot basically all of this

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white stuff is either gypsum or silica

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unfortunately you can't distinguish

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between the two just by looking at them

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and then we also have an evaporating out

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wash basin which we found to be

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important because priam previous

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campaigns we were always missing the

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magnesium sulfate which is a very

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soluble sulfate and the rocks are

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magnesium rich but we weren't finding

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any magnesium alteration minerals we

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ended up finding them using the spectra

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in this out wash basin momo tambo is the

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hardest field site to access it's a four

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and a half hour climb up here our cars

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are out over here and you climb up this

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old lava outflow channel it's also the

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hottest and most acidic environment

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there were temperatures well over 500

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degrees c and ph is down at negative 1

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so this site is dominated by sulfur and

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silica really what was interesting was

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even what we picked up as a yellow

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crystal we all assumed to be pure sulfur

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actually had a lot of hydration despite

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the high temperature from just as a

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surface water and then

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we also started seeing clays here so

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clays all right sorry Clay's are

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identified generally by either 2.2 or

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2.3 depending on what metal is in there

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and of course a hematite so talika is a

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volcano that we can't access the most

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active part basically when you get up to

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this rim it's a 500 meter drop straight

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down and our studies were restricted to

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these rim alterations as well as some of

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the free boulders interestingly when we

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went there it sounded like you were

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standing next to a jet engine I thought

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that was totally normal when we got off

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the volcano my advisor said no it

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normally doesn't make that noise and he

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was actually quite nervous fortunate it

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did erupted actually like a couple

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months after we left but so so it's

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leaked it even though we don't have a

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lot of mineral diversity because we

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can't access the most hydrothermally

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active areas did have the most ala night

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and Jerris site and jerra site is one of

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those minerals that was found on Mars

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it's an iron three-plus mineral and

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allen night has the same structure but

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there's aluminum in place of the iron

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what's interesting is that in the

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chemical studies we did gerrae site is

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actually rather rare and what we see is

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an iron-rich ala night and specifically

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a natural innate and Tom Macomb who was

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one of the collaborators in the field

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just put out a paper that looked at the

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spectral comparison of the different end

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members of the jera site ala night

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mineral groups and found that as you add

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more iron to an ala night the aluminum

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mineral you actually transform it into a

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jar site signature so this might add

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some uncertainty and the observations

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that we see on Mars with the mossbauer

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okay so the last site we looked at is

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San Jacinto mud pots and this area is an

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old they're open sorry there's lots of

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basically subsurface water and local

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children will keep you

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from stepping into a boiling pot and

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there's a lot it's a much higher fluid

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Iraq ratio so you end up finding more of

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the clays so there's montmorillonite

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here which is an aluminum clay and i

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don't think i have an example if you're

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out here it is this one which is

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actually not marked is a two point three

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which is indicative of iron magnesium so

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just going to kind of show you this this

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is the xrd and this is the spectra we

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use them in conjunction I obviously only

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spoke about the spectra here today

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because they each have their own

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strengths and combining this story oh

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sorry i'll jump ahead combining the

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story we can kind of create a table of

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abundances and we determine that the

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primary controls are the actual

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composition of the gas in the rock and

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then secondary controls of alteration

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are the ph the fluid direct ratio and

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there are basically five categories that

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we classify here the hottest highest

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temperature environments you have

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elemental sulfur and amorphous silica at

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more moderate vents you have you start

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forming more more gypsum and other

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sulfates as well as the iron oxides and

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then all of your and then many of your

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hydrated sulfates start coming in in

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these washout areas and I just want to

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jump back to the biology because I

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skipped over it we find biology at Cerro

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Negro in particular or the best examples

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we find are at monkey cheek it's the

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characteristic red rock green

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photosynthetic layer and then the white

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center in this case the white center is

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actually silica and not gypsum and

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looking at that an SEM you have these

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fuels which are very carbon-rich and

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sometimes we find that they're encased

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in silica as a possible bio preservation

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and not in this example but in other

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ones you can actually see collapse

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murals and for those of you who know

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biology you can understand those names

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this is all work that Karen joe rogers

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does and so i don't know and then i'll

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just briefly make some connections to

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Mars if anyone works with Omega or prism

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data it can be much harder than field

253
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data most of our field site

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are dominated by silica so we would

255
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anticipate that they look more like this

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serious major identified by a broad hump

257
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here and then the interesting thing with

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detailed mineralogical spectra are the

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reverse of the global sequence which

260
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people have kind of said there are

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global or local differences and we say

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well we see all of these minerals in a

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volcanic environment so perhaps some of

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these areas can be explained that way

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and then jera site again maybe a

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localized vent especially due to its

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morphology the jarosite is this orange

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piece here and I'll leave these up and

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we can take questions before everyone

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rushes to coffee I think coffee is more

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of an attraction no oh he knows no no I

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mean I think waters I'm certainly

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there's strong strong evidence of water

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and I think that the fact that you have

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water and you have persistent water

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based on the valley networks and deltas

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and persistent vault volcanism which has

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a new paper with a kind of a co-worker I

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guess another student of my advisors

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showed that fault that volcanism ended

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as early as a few million years ago I

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think you combining those two you get a

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aqueous alteration in a volcanic

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environment but certainly you have lots