Monday, March 31, 2008

Geology on the Road: Highway 50 #2

Austin Summit, Nevada, Revisited:
Austin







These photos were taken on Highway 50 near Austin Summit (elev 7484'), just uphill from last week's Austin Summit roadcut photos (also between Milepost 27 and Milepost 28). This reddish to reddish orange ash-flow tuff may underlie the tuffs seen earlier. This tuff shows columnar jointing, and the flattened pumice are more difficult to see than the reddish tuff in the previous post. This ash-flow tuff - unlike my "guess" of last week - is 30.8 Ma, according to Stewart and McKee (1977). The granitic rock the tuff is lying on (the light gray rock on the left of the photo) is a Jurassic quartz monzonite, 157 Ma, which hosts the silver veins of the Austin or Reese River mining district. Here's a more detailed geologic map of the Austin Summit area, from the Lander County Report, showing the ash-flow tuff as "Twt."
Judging by scattered references I could find or access on the web, this ash-flow tuff may correlate with the 31.4 Ma Windous Butte Formation, which erupted from the Williams Ridge Caldera near Hot Creek Canyon and Morey Peak, Nevada. Some of the calderas erupting the large-volume ash-flow tuffs of Nevada are truly huge, as can be seen in the last link and in this one, where the debatable subject is whether the ignimbrite flare-up had anything to do with regional extreme extension in Nevada.

References:

NBMG Report 40 - Sediment-Hosted Precious-Metal Deposits of Northern Nevada - Road log/trip guide for SEG precious metals field trip, fall 1984, by J. V. Tingley, H. F. Bonham, Jr.

Geology & Ore Deposits of the Great Basin Symposium, Field Trip #2 Guidebook, Skarn Deposits in Nevada - Geology, Geochemistry, Mineralogy, and Petrology of Au, Cu, W, and An Skarns, leader L. D. Meniert, G. L. Myers, and J. W. Brooks, 1990.

NBNG Bulletin 88 - Geology and mineral deposits of Lander County, Nevada; Part I, Geology, by John H. Stewart and Edwin H. McKee, Part II, Mineral deposits, by Harold K. Stager, 1977.

UPDATED 10July 2010

Darn It!

The Blog-O-Cuss Meter - Do you cuss a lot in your blog or website?

I'm just not up to snuff on the cuss-o-meter. Darn!
Seen today at The Ethical Paleontologist.

Saturday, March 29, 2008

Drilling on The Carlin Trend

I have once again been out in the field getting drill sites ready for drilling. Sometimes this will involve a rather quick trip out to a drill site, sometimes it can involve a few days or several half days spent locating sites on the ground using a GPS, staking the sites, and then getting a cat operator in for pad building. Sometimes sites have to be relocated due to inaccessibility. The weather has overall been good: not too hot, not too cold.



The place I work has had mining going on for a long time, as have many mines and districts along the Carlin Trend and Battle Mountain-Eureka Trend of mineral deposits. Although most mining at Carlin, itself, didn't begin until 1961, minor discoveries were made there in the 1870's and early 1900's, including discoveries of some small placer deposits. In general, gold was too fine-grained at Carlin for the oldtimers to find it or do much with the minor amount they found.

Sometimes called "invisible gold" because it can usually only be seen with an SEM, the gold on the Carlin Trend is nothing like Geotripper's gold from The Mother Lode of California.

John Livermore, discoverer of the Carlin Mine and "invisible gold."
Invisible gold
Gold nanoparticles
Carlin Trend history
Nevada mining history

Friday, March 28, 2008

Friday Fossil Day

It's Friday Fossil Day, and although all my fossils are boxed up or at my other home - I'm here at my little house in the "Nevada outback" - you can see fossils on several other geoblogoshperic sites:

Nova Geoblog has some neat Silurian fossils, including trilobites, my favorite (next to dinosaurs).

Geotripper has a Mesozoic fossil from the Sierra Nevada.

Clastic Detritus has a very nice, and possibly popular (see comments) crinoid fossil from New Mexico. Crinoids are some of my favorite friends. UPDATE: Mel has a photo of the same crinoid at Ripples in Sand.

Geology.com has a link to a new plesiosaur fossil from a mine in Canada.

And Dinochick often has some good dinosaur fossils and other paleontological information, including a recent post about the Gray Fossil Museum. UPDATE: Dinochick has some wonderful stromatolites for Fossil Friday - 1.1 billion years old!

UPDATE: The Lost Geologist has a mysterious fossil for his Weekend Fun series.

Search around, and you will probably find some more good fossil pictures and sites!

Thursday, March 27, 2008

Thoughts from Today: Mine Dumps


Coeur Rochester Mine, Nevada
USGS photo by Alan R. Wallace, 2005.





I work in a place that has a lot of mine dumps, and that's because I work at a mine.


Mine dumps come in all kinds of shapes, sizes, and colors.


Often, younger material is dumped on older material, creating patterns of multiple unconformities: different ages of dumped material dipping in different directions, and all of it sitting on bedrock.


When the bedrock below dumped material is broken, faulted, sheared, shattered--as is often the case in mining districts because structural preparation of the rocks often plays a significant role in the location of the ore deposit in question--sometimes a quick glance will not distinguish overlying dump material from underlying broken and shattered rock.







Springtime in Nevada: Rye Patch Reservoir

Rye Patch Reservoir, as seen from Interstate 80, looking to the northwest. A typical spring snow shower. Rye Patch, between Winnemucca and Lovelock, is a wide spot in the Humboldt River (above Rye Patch Dam), just before the Humboldt ends in the Humboldt Sink. On a few rare occasions, the Humboldt will fill the Humboldt Sink, flooding the two lane road between Lovelock and Fallon, and will then dump into the Carson Sink, joining the Carson River. Those years have been rare ones. The entire scenery, here along the west side of the Humboldt Range, was once mostly under water during ancient Lake Lahontan times, and the steps of ancient shorelines are everywhere.

Wednesday, March 26, 2008

Geology on the Road: Highway 50 #1

Austin Summit, Nevada:
Austin




These photos are from just east of Austin Summit, Nevada, just barely on the eastern, downhill side of the summit, between Milepost 27 and Milepost 28. Two exposures, this being the second on the way downhill, show welded ash-flow tuff. In this exposure, the red-gray to reddish gray ash-flow tuff is lying on a whitish unit of poorly welded tuff, air-fall tuff, or base surge tuff. The white unit lies on a gray, blocky-weathering ash-flow tuff, which can be seen to the left in the stitched photo. The compaction foliation and jointing in the red-gray and reddish ash-flow tuff to the right is roughly parallel to jointing or foliation in the tuff on the left, and roughly parallel to the contact.

The tuff and tuff-tuff contact is dipping roughly northeastward to eastward, away from the summit. I tried to find a reference giving the name or origination of these particular tuff formations, but so far haven't found one. It would fall into the 17 to 34 m.y. old category of central Nevada ash-flow tuffs (part of the Mid-Tertiary ignimbrite flare-up), and is probably in the 22 to 25 m.y. old range (that's my guess based on work in the region quite a while ago - the rocks haven't aged too much since then).

I thought while looking at this outcrop the last time I stopped, that there might be some faulting or shearing between the whitish layer and the upper, densest part of the welded tuff (the reddish gray, bouldery, hard-looking stuff) with possible shearing taken up in part in the brighter reddish zone, in which you can still see some compaction foliation.

Andrew has quite a lot of links about Nevada Geology, inlcuding one to this map, which shows a pinkish blob of Tv just a bit to the left of the label, next to some reddish "TMzi" - the granite of Jurassic or Cretaceous age. The map is from the Nevada Bureau of Mines and Geology (NBMG).

Also see:

Stewart, J.H. and Carlson, J.E., 1976, Distribution and Lithologic Character of 34- to 17-Million-Year-Old Sedimentary and Igneous Rocks of Nevada, Showing Centers of Volcanism, Nevada Bureau of Mines and Geology Map 52, Sheet 2, Cenozoic Rocks of Nevada.

UPDATED 10July2010

Tuesday, March 25, 2008

Survivor is a Meme?

It seems that the email I posted about yesterday, which came from the Uncyclopedia, has been cited in several blogs, sometimes as thought it's reality (or a silent spoof?). Here are a few:

Isaac at Think Deviant, March 8, 2008.
John Wilkins at Evolving Thoughts, March 7, 2008.
Chris Keating at Tales from the Travels, February 28, 2008.
This post at jetxt.de, February 27, 2008.
Steph Stockman at Geosteph, September 4, 2007.

So, this is nothing new - been going around awhile like a bad winter bug.

RE: More on Geologists

Subject: Fw: Geologist Monkeys
(Another ridiculous/funny/haha/you-choose-the-word email.)

A tourist walked into a pet shop and was looking at the animals on display. While he was there, another customer walked in and said to the shopkeeper, "I'll have a Geologist monkey please."

The shopkeeper nodded, went over to a cage at the side of the shop and took out a monkey. He fitted a collar and leash, handed it to the customer, saying, "That'll be $5000."

The customer paid and walked out with his monkey.

Startled, the tourist went over to the shopkeeper and said, "That was a very expensive monkey. Most of them are only few hundred dollars. Why did that one cost so much?"

The Shopkeeper answered, "Ah, that monkey is a GIT - Geologist In Training - it can lick rocks and tell you the exact mineralogy, well worth the money."

The tourist looked at a monkey in another cage. "That one's even more expensive! $10,000! What does it do?"

"Oh, that one's a P.Geo - a Professional Geologist - is can log drill holes, update and construct geological models, they are experts in igneous and metamorphic petrology and petrography, hydrogeology, sedimentology and structural geology. SOME can even do basic calculations. All the really useful stuff," said the shopkeeper.

The tourist looked around for a little longer and saw a third monkey in a cage of its own. The price tag around its neck read $50,000. He gasped to the shopkeeper, "That one costs more than all the others put together! What on earth does it do?"

The shopkeeper replied, "Well, I haven't actually seen it do anything, but it says it's an Engineer."

UPDATE: Dinochick has much better graphics on this one over at her site!

Monday, March 24, 2008

A New Geologist Survivor TV Show

Well, not really.... There is, once again, an email going around to various geological types (this is the second time I've seen it) which refers to Uncyclopedia's take on Geologists. The email circulating now, describes a 'geologist survivor-type' show, supposedly being considered by CBS in 2008 (reality TV?).

They were successful in finding nine geologists, 6 males and three females, between 25 and 50 years of age, and they quickly set up the first challenge; researching an active volcano in the Phillipines. The geologists and camera crew set up camp near the bottom of the volcano. The camera crew filmed the nine geologists bonding. The geologists were supplied with alchohol (a common strategy to loosen up the cast in reality TV), but the camera crew was surprised to notice that even after drinking gallons of the liquid, the geologists did not change their behavior, and continued talking in an obscure jargonized language about 'bombs', 'breccia,' and 'lahars,' none of which made for good reality TV.

Does the above sound at all familiar? I'm reminded of certain Death-Defying Geologists and their lava photos! The reality-TV-type testing goes on, with the geologists just not being able to leave or be voted off the show.
Finally, few of the scientists [geologists] seemed to understand the concept of 'voting off' another member. After consulting a nearby university, the crew finally explained that the geologists were 'competing for a GSA research grant.' This didn't go well either, as the geologists pointed out that they didn't have the time to write a research paper. Finally, they were simply told to get rid of someone on some sort of criteria. After a council, the geologists decided that whoever had the worst aim with a rock hammer would be told to leave.

Congratulations to certain geoblogosherians who have recently completed such research-type papers (and sorry if I've left some of us out!). As you can see above, geologists are simply not well suited to reality TV, since they (we) have their own way of doing things. The second event that is designed to get rid of some geologists takes place in Alaska.
The second event, landing in a bush plane in upper Alaska, was a complete failure. None of the geologists were nervous at the idea, which destroyed the drama the crew was hoping for, and worse yet, no-one in the production crew was willing to accompany the geologists to the site, out of sheer terror. The result was that small cameras were given to two of the geologists to film themselves. When the footage and geologists returned, the editors found tapes filled with footage and commentary about mountains and 'glacial erratics'. Only ten percent of the footage featured humans, and most of that footage was simply the petrologist standing by outcrops for scale.

By the time the production reached Hawaii, most of the camera-crew had quit (because of the steady diet of chili and the dangerous situations), and only five of the geologists were left; not because they had been voted off, but because they had been over-excited by rock formations at various locations and had refused to leave. Moreover, paying for an almost-constant supply of beer and transportation of the geologists' luggage (which mainly consisted of rock samples and unmentionably dilapidated field clothing), had almost exhausted the budget. CBS finally pulled the plug on the project in January of 2008, despite their fear that they might be sued for withdrawing the promise of a prize; however, none of the geologists sued, as they were still under the impression that they needed to publish a research paper to receive the money.

As you can see, geologists are simply not suited for reality shows, living as they (we) do in their (our) own reality. The rest of the article entitled "Geologist" is also interesting (although some parts are more humorous than other parts), and it includes a section about "Geologists in the Movies." Sound familiar? And more:

How to spot a Geologist
To spot a geologist in the wild, look for:
  • Hand-lens, compass, pen-knife, handcuffs etc. tied round neck with string. ...
  • When helping someone move and you ask "is this box full of rocks?" They answer "yes, be careful."

If you remain unsure, ask the subject to draw an annotated diagram of a trilobite. A true geologist will immediately reach for their waterproof notebook - this is your opportunity for escape.

And so it goes...

UPDATE: This part of the Unclyclopedia article on geologists has apparently now made it into hard print - see Highly Allochthonous for links.

Saturday, March 22, 2008

Star Trek TOS: The Devil in the Dark

Accretionary Wedge #7; Geology/Geologists in the Movies
Hosted by Tuff Cookie at Magma Cum Laude.

I enjoy the occasional disaster flick, most of which have geological backgrounds or orientations, even if they don’t have any geologists in them. I wanted to go back a little farther, though, than the fairly recent Dante’s Peak, Armageddon, or Deep Impact (all of which, especially the first two, have geological problems in them but were, nevertheless, enjoyable in my opinion). So I’ve chosen the somewhat geological Star Trek TOS (The Original Series), Season 1, Episode 26: The Devil in the Dark.

The episode is about mining and a mining colony, and it refers to the classic though trite antagonism between geologists and engineers. Devil in the Dark introduces a new, silicon-based life form, a life form somewhat rock-like in appearance and composition, and therefore to be admired, in this geologist's opinion.

The Starship Enterprise goes to the pergium mining colony on planet Janus VI because an unknown monster or creature has been destroying equipment and killing the underground miners. Janus VI, BTW, also contains abundant reserves of uranium, cerium, and platinum, elements which I am somewhat more familiar with. I don’t really know where pergium fits on the Periodic Table of Elements . For more details about the episode, an Excruciatingly Detailed Plot Summary, by Eric W. Weisstein, is available.

The reason I remember this episode so well (besides seeing it numerous times) is that it introduces a non-carbon-based life form, the Horta, which turns out to be sentient and intelligent. The Horta is a silicon-based, rock-like entity made of a material similar to asbestos. It can tunnel through rocks using heat and acid (possibly that’s why an asbestos-like substance was thought by the writers to be necessary), which it somehow generates by consuming rocks as its source of “food.” At the time—the episode first aired on March 9, 1967 when I was 14 years old—I found it “fascinating” to imagine a silicon-based lifeform. Since that time, I have incorrectly remembered the Horta as a silica-based, quartz-like lifeform, rather than an asbestos-like lifeform, perhaps the result of bad memory. The Horta reproduces by laying roundish, silicon-based eggs (possibly made of raw silicon or silica, but looking a lot like brown balloons). It has killed, trying to protect its eggs from a bunch of obnoxious (to it) offworld, Federation miners.

The geology (or mineralogy?) is probably far-fetched—as is space travel with our given physics and engineering limitations, but interesting nonetheless. Mineralogically speaking, I’m not sure what form of “asbestos” would be more likely to be a good base or substance for life. Perhaps some mineralogists could comment on this issue.

In the episode, Spock behaves somewhat like a geologist (after all, he is usually the one with the all-element-reading tricorder). He is therefore (like any real geologist) the first one that can actually relate to this rock-like being. Like a stereo-typical geologist, Spock relates better to rocks than he does to people, and in this episode he relates better to the Horta than he does to most, well – humans (they are so illogical). In fact, he relates so well to the rock entity, that he is able to mind meld with it, an experience similar to what some geologists undertake when out in the field trying to figure out the geology of a particular field area.

As usual, there is tension between the logical Spock and the emotional Doctor McCoy. In addition, there is the stereotypical tension (and even animosity) between the mining engineers or mine managers of Janus VI and the explorationists of the Starship Enterprise. In this case, the explorationists aren’t really geologists, but they serve that purpose as far as the mining v. exploration tension goes. In the photo , Captain Kirk points a phaser at the Horta.

A few good quotes come from the episode, some of which might only be of interesting to other Star Trekkians (Trekkers, not Trekkies, as far as I’m concerned). The first relates directly to the rift between an engineer v. geologist perspective:

Chief Engineer Vanderberg: Look, we didn't call you here so you could collect rocks!
The second brings out Doctor McCoy’s bedside manner while trying to heal wounded rock-like beings:
McCoy: I'm a doctor, not a bricklayer!
And a few other quotes are of interest:
Spock: The odds against both of us being killed are 2,228.7 to 1.
Kirk: 2,228.7 to 1? Those are pretty good odds, Mr. Spock.
Spock: And they are of course accurate.
Kirk: Of course. Well, I hate to use the word, but, logically with those kinds of odds you might as well stay. But please stay out of trouble, Mr. Spock.
Spock: That is always my intention, Captain.
Kirk: Think she'll go for it? [A proposed truce between Horta and miners.]
Spock: It seems logical, Captain. The Horta has a very logical mind. And after close association with humans, I find that curiously refreshing.

Spock: Curious. What Chief Vanderberg said about the Horta is exactly what the Mother Horta said to me. She found humanoid appearance revolting, but she thought she could get used to it.
McCoy: Oh, she did, did she? Now tell me--did she happen to
make any comment about those ears?
Spock: Not specifically. But I did get the distinct impression she found them the most attractive human characteristic of all. I didn't have the heart to tell her that only I have...
Kirk: She really liked those ears?
Spock: Captain, the Horta is a remarkably intelligent and sensitive creature with impeccable taste.
Kirk: Because she approved of you.
Spock: Really, Captain, my modesty...
Kirk: Does not bear close examination, Mr. Spock. I suspect you're becoming more and more human all the time.
Spock: Captain, I see no reason to stand here and be insulted.

Friday, March 21, 2008

Friday Fault Photos


Just a quick post of some fault outcrops. The first, above, is nearly dip-slip in relative movement, and you can see a close-up of the footwall breccia. The second fault, below, shows oblique-slip slickensides, and beneath the slickensides, in the footwall, are some calcite masses and a footwall breccia.


Thursday, March 20, 2008

Questions in The Night


Ah, the smell of coffee in the morning...

Well, I'm up early, and it's still dark outside, because we have been under the domain of Daily Time for a couple weeks, now. The sunrise above, is what it might look like here in an hour or more.

Getting up early sometimes leads me to wondering perennially stupid questions, at least if I'm not woken up by work worries or other things, which is fortunately not usually the case, unless I'm overly concerned about drill rigs or things like that. Questions:

  • How large will the Basin and Range and Intermountain West become in the next 10 to 50 million years?

  • Is the entire Basin and Range underplated by core complexes that we simply haven't seen yet (because they are presently too deep to see)?

  • Will the ocean move into the rifted Intermountain West before Las Vegas or Los Angeles can steal northern Nevada's groundwater?

  • Will we discover a "Walker Lane of the East" somewhere, somehow bounding the eastern part of the Great Basin the way the Walker Lane more or less bounds the western part?

  • Will the mantle (or "Serpentosphere"??) ever be proven to be a source of methane? And will we tap it for energy by drilling deep into the San Andreas fault?
  • Will we survive the next 300 years of natural and user-enhanced global warming (according to Milankovitch cycles, much pooh-poohed by many geologists, we will reach a temperature peak naturally in about 300 years, and in fact are already over the main temperature hump toward a long cooling trend)?

  • And what will our slide into the next ice age bring in the years following that upcoming peak be like (provided, of course that we don't change all that)?
  • Will Yellowstone erupt sometime within the next 500,000 to 1,000,000 years (or Any Day Now), thereby putting an immediate halt to any current man-made and natural global warming?

  • Will geologists discover a gold deposit in the present locality of the Mendocino Triple Junction in 1 to 3 million years, which would be similar to the McLaughlin gold deposit near Clear Lake, CA , which formed within a couple million years of the triple junction passing through that area?

These are the things that wake geologists up in the middle of the night! Stay tuned to find out the answers, if any are forthcoming.

Monday, March 17, 2008

St. Patrick's Day Green

Above: A copper-bearing rock with Malachite, Azurite, and Chrysocolla.


Above and below: Malachite, credit to The Lost Geologist.

Following on from Ron's Green Guessing Game (GGG) at http://ron.outcrop.org/blog/?p=144, I'm posting these photos via email. Feel free to name the main mineral, or any others you see. I hope these will turn out, as I have only tested email posting once.

Well, the email thing didn't quite work, so here they are, late on St. Pat's Day. Oh, and the orange is for my dad.

Update: Tuff Cookie has some green rocks and an explanation about what they are.

And: Andrew has another green rock, a bit of a mystery.

More green rocks/minerals: Julian has a green mystery mineral, The Lost Geologist finally found a green mineral, and Brian has a green outcrop!

Sunday, March 16, 2008

Out Walking

Shoe

I've been lucky enough recently to do some walking about town, and wanted to share some photos. First thing I noticed was, the sun is out (most of the time) and the snow is melting.

Sun Circle
There are a few signs of early spring - the juncos have been hanging around all winter, but they are out more often now, instead of just immediately after it starts snowing.

Juncos
In the plant world, I saw a few early buds, like on this tree, which is possibly an elm (non-native).

Buds
Also, up in the hills, it's not so muddy and maybe the prickly pear is looking a little greener.

Prickly Pear

Above, that's a shiny quarter for scale.

Actually, until our most recent walk/hike, MOH and I together, I hadn't really noticed the prickly pear. They are small and low to the ground. One usually thinks of cactus as belonging in the true desert, not in pinon-juniper country, but I've found that some species of prickly pear can be found at relatively high elevation, growing in amongst the pinon-juniper (don't try to get me to narrow them down by species - my cactus book is at my other house, not out here in the field).

I've seen prickly pear at Pete's Summit in the Monitor Range of central Nevada (a place of pictographs and graptolites - take Highway 50 east from Austin to old 8A, turn south, and then immediately east toward Spencer's Hot Springs), and they grow here and there through the state. You won't, however, find any variety of cholla in with the pinon-juniper -at least not to my knowledge - cholla in Nevada grow to just a little bit north of Tonopah, which is a little farther north than the Joshua trees make it - the Joshua trees fade away somewhere between Goldfield and Tonopah, near the turnoff to Silver Peak.

Update: Other geoblogospheroids have been out walking: see Geology Happens and All of My Faults are Stress-Related.

Saturday, March 15, 2008

At it Again

Well, Stan Keith is at it again, at least in making up new words that can be applied to either plate tectonics or mineral deposit formation. Unfortunately for all, the new word "Serpentosphere" can only be investigated, as far as I can find, by attending an upcoming meeting of the Geological Society of Nevada on Friday, March 21st in Reno, NV. Free beer is at 6:00 pm, dinner at 7:00, and the talk at 8:00. (Contact Kelly Parsons for reservations or more info, 775/323-3500, gsn@gsnv.org.) The talk is being authored also by Monte M. Swan, Martin Hovland, Hakon Rueslatten, and Hans Konrad Johnsen. Because the abstract has been published in a newsletter by the Geological Society of Nevada (GSN), I'll quote it below:

The Serpentosphere consists of an earth-wide nearly continuous layer (or spherical shell) of rock dominated by serpentine group minerals (serpentinite). The Serpentosphere is typically about two kilometers thick beneath ocean basins where it is mainly composed of lizardite. Beneath continents, the Serpentosphere is mainly composed of antigorite (alpine peridotite/serpentinite) and may be several kilometers thick. The base of the Serpentosphere coincides with the gravity and high-velocity seismically defined transition beneath both continents and ocean basins commonly referred to as the Moho. Beneath ocean basins and adjacent to spreading centers, oceanic Serpentosphere is continuously generated by the interactions of deep circulating marine composition water – partly in super-critical state –with harzburgitic peridotite in a process referred to as serpentinization. Conversion of the harzburgite to lizarditic serpentine under supercritical condition is texturally preservative and probably induces about 40% volume expansion. The volume expansion provides an excellent mechanism to expel and propel fluid products – including hydrocarbons – from the area of serpentinization to seep sites at the crust hydrosphere/atmosphere interface. A downward diffusing, super-critical serpentinization front is present beneath every ocean basin and is more active where it originally formed near oceanic ridge thermal anomalies. When ocean Serpentosphere is subducted beneath continental or oceanic crust areas, it converts to antigorite-dominated serpentinite rock (generally coincident with greenschist facies metamorphism). During flat subduction, the relatively lowdensity antigorite ‘floats’ and is underplated to the base of the continental crust at the Moho geophysical interface.

In effect, both oceanic and continental Serpentospheres reflect a deep ‘weathering’ process that consists of the interaction of deep crustal and oceanic, water-dominated fluids with the upper portion of a mainly harzburgitic peridotite at the top of the earth’s lithospheric mantle. The process is analogous to the formation of the pedosphere through interactions of the earth’s hydrosphere-atmosphere layer with the top of the earth’s lithospheric crustal layer. In this context, the Serpentosphere may be viewed as a thin membrane that separates water-absent, life-free abiogenetic processes in the mantle from water-present, life-related processes above the Serpentosphere in the oceanic crust.

The Serpentosphere has enormous and novel implications for four major geologic problems that are of current interest to the geologic and social community: the driving mechanism for plate tectonics, the origin of life, the origin of hydrocarbons, and contributions to global climate. A close relationship between trace elements in crude oils and serpentinite has been found. Migration of the serpentine-associated hydrocarbons to seep sites on the ocean floor and in subaqueous continental environments is essentially the base of the food chain for the biosphere and provides a nutrient and energy source for life in these environments. Heat, methane and carbon dioxide generated during the serpentinization reaction provide a major thermal and greenhouse effect to the earth’s hydrosphere-atmosphere system that is overlooked and underappreciated by the current global climate science. The ductility of the serpentine group minerals provides the tectonic “grease” that allows crustal plates to be able to slide and glide around on the earth’s crust at the Serpentosphere/Moho interface. Because Serpentosphere has been continuously generated since the beginning of geologic time it must be considered as one of the fundamental entities of our water-surfaced planet – the only water-planet we know of ...

Online references to this idea are scant, consisting of these two, and this interesting cartoon:

I won't analyze this Serpentosphere concept, and will just say that I find it interesting because it is related to flat subduction and the concept of hydrothermal hydrocarbons, evidence for which has been seen in the mercury deposits of the California Coast Ranges. Also, he is trying to promote a new model for oil exploration, which can't be knocked these days (unless it doesn't pan out). I won't be at the meeting, so will not be able to hear about this first hand.

Today: A Day Off

Well, I'm going to try a little blog post about a typical day off out here in the outback of Nevada. I'm not working today, but am out in the field; that is, I am not at home, my primary place of residence, but am at "our little house," where MOH and I reside a good portion of the time, working or otherwise.

Today was supposedly a day of getting ready for work, but it actually has been a day of relaxing and reading and enjoying. I managed to run a few errands around town, without actually overdoing it - I mean, I didn't get everything done that I'd planned to do, and goofed off some, instead. While out, I washed and waxed my truck at one of those self-service places, and nearly froze my fingers off. My truck now weighs about 2 tons less than before because of all the mud that's gone.

We are experiencing a return of cold weather, with tomorrow's forecast low being below 10 F and forecast high being barely above freezing. A warming trend is supposed to set in again in a couple days, going for lows in the 20's to highs in the 50's (Fahrenheit).

I suspect that we could still get some snow...

Friday, March 14, 2008

Ruby Mountains




We took a mini road trip the other day, and drove by the east side of the Ruby Mountains (first photo above) and the east side of the East Humboldt Range (second two photos above), which are both south of Wells. Nevada. The East Humboldt Range appears to be partly a topographic or structural continuation of the Ruby Mountains (MSRMaps), possibly with some complications from Basin-and-Range faulting. The Ruby Mountains (and East Humboldt Range?) are part of a metamorphic core complex, like the core complex in the northern Snake Range, part of which can be seen in the header photo at the top of this blog. Both core complexes are the result of more or less east-west extreme extension, which took place during the early to middle Tertiary, prior to classic Basin-and-Range extension.

A core complex is a doubly plunging antiform, with one axis parallel to the extension direction. A core complex exposes rocks that were ductilely deformed at depth against rocks that were brittlely deformed closer to the surface. These rocks come into contact along a detachment fault or decollement. The core complex belt in the North American Cordillera runs from British Columbia south into Mexico. [That last link also shows a cartoon of a core complex with upper plate rocks dipping in opposite directions, which is either inaccurate or misleading). There are several models for their formation, and they may form differently in places outside the belt, like in the Walker Lane.

If you look at a core complex perpendicular to the extension direction, you can usually see that the antiform is not perfectly symmetrical. For example, if you stand on Highway 50 east of Sacramento Pass, where it passes between the northern Snake Range to the north and Wheeler Peak to the south (part of Great Basin National Monument), you will see the core complex and detachment fault looking somewhat like the banner photo above. That photo was taken from the road to Wheeler Peak, looking north. What you'll notice, either from Highway 50 or from Wheeler Peak, is that the northern Snake Range core complex has a fairly steep western side (not seen in the banner photo) and a more subdued eastern side. The detachment fault associated with a particular core complex will also follow this pattern of dipping more steeply on one side and more gently on the other side.

In the Snake Range, the blocks of brittlely deformed upper-plate strata (Paleozoic in general) dip to the west on listric-normal faults that dip eastward and merge downward into the detachment fault. Because down-to-the-east motion on these normal faults can be inferred (and demonstrated), one can then tell that the upper plate moved eastward relative to the lower plate.

Above, we have some photos of the steep east sides of the Ruby Mountains and East Humboldt Range. The steepness of this eastern side may have been influenced by Basin-and-Range faults that formed after the original geometry of the Ruby Mountains core complex (Basin-and-Range faults that are presumably active today, judging by some of the recent earthquake damage in Wells - albeit on a fault farther to the east).

Now, if you drive west from Wells toward Elko on Interstate I-80 and look south, you'll see the Ruby Mountains western aspect, below. This western side confirms the typical core-complex asymmetry, with the overall appearance of the mountains being steep on the east side and gently westward dipping on the west side.

Because of what we've already seen with the northern Snake Range core complex, we can figure out just by looking at the shape of this western side (above) that the brittlely deformed rocks in the upper plate of the Ruby Mountains core complex dip to the east on westward dipping listric-normal faults, and that the relative motion on the detachment fault is upper plate moving to the west with respect to the lower plate - and that's all opposite to dip directions and relative motion in the Snake Range. You can confirm the relative sense of motion in the Ruby Mountains core complex here.

Overall Reference for Core Complexes:

Coney, P.J., 1980, Cordilleran metamorphic core complexes—An overview, in Crittenden, M.D., Jr., Coney, P.J., and Davis, G.H., eds., Cordilleran metamorphic corecomplexes: Geological Society of America Memoir 153, p. 7–34.

Updated 30Jul2010: Wherein I added mentions of the East Humboldt Range and linked to a map location.

Thursday, March 13, 2008

Mining - A Bit of News

Things are looking fairly good in the mining industry - for companies, for new geologists, and for older, experienced geologists who aren't ready to retire yet (like me). Not only are the prices of metals up, but so are the prices of oil and coal. Consequently, geologists in the mining industry are finally making as much money in constant dollars as we were in the 1980's (no data on that last assertion, just some experience). There was a period of time after the price of gold went down in 1997 (and after the Bre-X scandal of 1997), that salaries stayed the same (in current dollars) and maybe even dropped a little. The AGI report compares geoscientist's 2005 salaries with 2004 salaries, and you can see a summary here. As was mentioned in Arizona Geology, the AGI data is really pretty old - out here in the mining fields of Nevada, salaries have increased considerably since 2004, and any geologist - good, bad, or ugly (or indifferent?) - is hard to find. In fact, maybe the name of the game should be exploring for geologists.

And it's also a good time to buy a gold mine in Arizona, I hear.


Update: A good summary of starting salaries for college graduates at Reporting on a Revolution, along with some information geology salaries in India and speculation about the future.

Tuesday, March 11, 2008

Logging: A Song

I said I'd talk about logging drill chips, so here goes:

Logging (Chip Trays!) Lyrics
(To the tune of Rawhide)

Logging Logging Logging
Loggin’, Loggin’, Loggin’
Loggin’, Loggin’, Loggin’
Loggin’, Loggin’, Loggin’
Chip Trays!

Keep loggin’, loggin’, loggin’,
Don’t be disapprovin',
Keep them chip trays movin'
Small Chips!
Keep tryin’ to understand 'em,
Make sure you’ve logged and scanned 'em,
They’re all right there at your fingertips.
Your eyes are calculatin'
Percentages and veining,
Watch out while your acid bottle drips.

Load 'em up, bring 'em out,
Bring 'em out, move 'em in,
Move 'em in, stack 'em up
Chip Trays!
Set 'em out, haul 'em in
haul 'em in, lay 'em out,
Stack 'em up, pile 'em in
Chip Trays.

Loggin’, Loggin’, Loggin’
You’ve got to go on toilin’
To keep them chip trays rollin'
Chip Trays!
We’re all in this together
Missing the outdoor weather
Wishing that we won’t see another chip.
Yes, lots of things you’re missin',
Good vittles, love, and kissin',
They’re waiting at the end of your trip

Load 'em up, bring 'em out,
Bring 'em out, move 'em in,
Move 'em in, stack 'em up
Chip Trays
Set 'em out, haul 'em in
haul 'em in, lay 'em out,
Stack 'em up, pile 'em in
Chip Trays!

Keep loggin’, loggin’, loggin’
Don’t be disapprovin'
Keep them chip trays movin'
Chip Trays!
You’ll never understand 'em
Just count, and code at random
Perhaps someday we’ll run out of trays!
When you’re done with estimating,
Over or understating,
Your mind and eyes will be in a haze.

Chip Trays!
Chip Trays!
© Looking for Detachement
by Silver Fox


Also see Lyrics Freak for Rawhide.

Monday, March 10, 2008

Fairview Peak, Nevada


The winner of Where in The West - March is Geotripper, with the correct answer: Fairview Peak, Nevada, which is located on Highway 50, about 40 miles SSE of Fallon by road. Nevada, being in the Basin and Range, has a history of earthquakes, some more recent than others.

Fairview Peak was the site of the well-known Nevada earthquakes of 1954, which caused ground ruptures along the east side of Fairview Peak and northward into Dixie Valley. The images from Google Earth show a few good viewing places, although the scarps have deteriorated with time. I haven’t been to location #1 to the left in the upper image, which must be the easiest one to get to, but can recommend site #2 to the right in the upper image, although walking or very good 4WD is required. The #3 site in the middle image can be a little hard to identify in some lighting, and you can feel a bit like you are wandering around in the badlands, especially if it’s summer (because you are).

The location of Frenchman, formerly known as Frenchman’s Station, is shown on these images, and is especially visible in the lower image. There hasn’t been anything at Frenchman since the Navy took over the area, burned or dismantled Frenchman (a store – gas station – motel that was open in the 1980’s and earlier) and also took over Dixie Valley in general. The location of Frenchman, as shown, is from Google Earth and may not be precise.

A story about the area, related to the earthquakes and possibly apocryphal, goes as follows. A resident of Austin, Nevada had driven into Fallon, presumably to stock up on food, but maybe just to attend a different watering hole than the usual Austin offerings. The day was December 16, 1954. He’d stayed in the bar late, and it was dark as he drove Highway 50 from Fallon toward Austin. As he came over Drumm Summit, a small hill between Dixie Valley and Labou Flat, and was about to drop down into Stingaree Valley, he was shocked out of his semi-drunken state when he drove off the newly formed fault scarp, which had cut the pavement of Highway 50 and dropped it down to the east by several feet.


A few references:

Bunny Corkill, Water Holes, In Focus, Vol. 17, 2003-2004 (includes an old photo of Frenchman's Station).

William Least Heat-Moon, Blue Highways, 1982 (includes a photo of Frenchman's Station from 1978).

Saturday, March 8, 2008

Detachment News: Arizona

Due to the name of this blog (not to mention the interest of the blogger), I need to report some recent detachment news from Arizona Geology, as quoted in part below:

Dave Maher says we can find new porphyry copper systems in southeast Arizona by exploring for the roots of Laramide igneous systems (island arcs) and working our way up the geologic section. Dave presented the results of his recent PhD dissertation (UA, Dec 2007) at the Arizona Geological Society monthly dinner meeting last night.

And from his meeting abstract:

In east-central Arizona, overlapping sets of Tertiary normal faults [have] dismembered, variably extended, and exposed up to 15 km of the upper crust, including portions of several Late Cretaceous to Paleocene (Laramide) igneous centers and their associated porphyry copper systems.... The field evidence and the reconstructions demonstrate ... extension of about 100% across the study area, but the amount of extension locally varies from less than 20% to well over 400%....

Now, the fact that many porphyry copper deposits in Arizona (and elsewhere) have been affected by mid-Tertiary extreme extension is not really news. What is news here, is that he has suggested a new way to explore for porphyry copper deposits - exploring by going in the opposite direction than the direction taken in the past. In the past, deposits have been found by looking for and very successfully finding the tops of deposits (hence, the low price of copper for such a long time interval until fairly recently). He suggests that explorationists wanting to find more copper - a good commodity to look for with the price up so high - should look for the roots of systems and work their way back up-section to probably fault-offset, mineralized portions of porphyry systems.

Friday, March 7, 2008

On Mud and Getting Stuck

Mud can create a sticky situation. It helps to be paying attention to the condition of the road when driving through Nevada during any month of the year, even in the summer when mud is not prevalent and the springs are often dry—but they are not always dry.

While I was working for Northern Exploration Company back in the late 1970's, we had a large claim staking crew out in central Nevada. A couple of the claim stakers—in their zeal to drive as close to the claim-post site as possible, a thing that all good claim stakers excel at—failed the spring test by not getting out to see if they could walk through the green, grassy area ahead of them. “Don’t walk when you can drive,” is a good policy when doing exploration—but please don’t drive through things that look like springs without checking them out. The claim posters drove full speed ahead into the grassy area around the Northumberland spring and sank their truck up to the sideboards in mud. The truck stayed stuck in the mud for several days before a bulldozer arrived to pull them out.

I prefer to be in four-wheel drive rather than two-wheel drive when driving over any questionable terrain—especially mud, sand, and snow. It's true, however, that if you get stuck when already in four-wheel drive, you are really stuck. In four-wheel drive you might drive farther into a muddy area before getting stuck than you would in two-wheel drive, and you will have a longer distance to dry or passable land. You will also have to work harder to get unstuck. If, however, you were in two-wheel drive when you drove into the muddy area, you might get stuck in a relatively small mud hole that wouldn't have caused any problem had you already been in 4WD. And now that you are stuck in 2WD, switching to 4WD might not help out at all.

Once upon a time, I got stuck in mud near a now-former gold mine in northern Nevada. But hey, what am I saying, that I got stuck—I wasn't driving. We were up there taking soil samples along claim lines in the early spring, when the ground was still muddy. There was one especially bad mud hole, and R. decided we could make it through. He drove the truck into the mud hole fast, thinking that the speed would carry the truck to the other side. It didn’t. We were stuck, right in the middle. Because his truck didn't have a handyman jack (always be prepared?), we walked back to my truck (fortunate to have two trucks, eh?) and got my handyman jack. BTW, the little jack that comes with your truck, which is often located somewhere under the hood, is usually of little help in getting unstuck.

Being stuck in mud requires either building a road underneath the truck, being pulled out with a bulldozer, or waiting until the mud dries out. We didn't have a dozer, and weren't about to sit around waiting until mid-summer. So, we looked around until we found a flat rock to set the jack on, and then we jacked up the truck — all four tires, one at a time — to place sagebrush under and in back of each tire. We would have to build a road behind the truck to get out — if we went forward, we would simply have a truck on the wrong side of an impassable mud hole.

It was a long, tedious procedure: after we got all four tires of the truck set back down onto semi-solid muddy sagebrush, R. got in, put the truck in gear, and spun out all the brush we had collected, putting the truck right back down in the mud. So we again jacked the truck up, four times, once for each tire, and put even more sagebrush under the tires. [Rocks or boards work better for building road, but sagebrush was what we had on hand.] R. got in again, put the truck in gear, and spun it back into the mud. On the third try, we got enough sagebrush underneath and in back of each tire that we had enough traction to back out of the mud hole. By that time we were thoroughly tired of both mud and sagebrush—and, we were left with a much longer distance to carry our soil samples.

Another Day

This is what it’s looking like these days where I’m working, at least on the north-facing slopes. As Kim pointed out, the aspect effect is important to consider this time of year, as is elevation. Some of the south-facing slopes here are currently clear of snow, some are not. Where they are snow-free, they are muddy. Consequently, I'm sticking mostly to frozen and muddy roads these days and not doing much hiking around (where would I find an outcrop - maybe in a roadcut). I hear that real spring - with no mud being the definition of real spring - often doesn’t come to this part of the woods (desert? upland steppe?) until May or June. Until then, my boots and truck will be full of mud.

Thursday, March 6, 2008

Exploration on Mars

There’s been some talk recently about Mars - although strangely enough I can't find the all the links right now - maybe Mars is being talked about because it’s in a very close position to the earth, or maybe because of the landslides.

Here's an opinion: I think it’s about time that we sent real geologists to Mars, the Moon, and anywhere else we can get to, and see what is really going on. I suppose our unmanned probes are getting better, but as far as I’m concerned, there’s nothing like a real person for making observations and testing hypotheses. As geologists, we are trained observers, as my dad likes to say, and so I’d say we should get into the field Out There.

Once upon a time, I thought I might be one of the ones to go into space to explore, because when I was young, I really though we would be colonizing other planets or going on long space treks to other solar systems, soon, Any Day Now. That’s what I thought—maybe it was a Star Trek thing, maybe it was an Isaac Asimov thing. By the time I was 18 or 20, however, I could see that we would probably not take to space in any meaningful way in my lifetime, or least not until I was probably too old to be considered for colonization or exploration. So, I’ve stuck to exploration here, on this planet.

And that’s worked out well for me, overall.

More Work Today

Sfx Field Book I'm continuing to add old posts I had created elsewhere before starting here on Blogger. In the meantime, I'm still at work, keeping track of drill rigs and drill sites while logging a seemingly endless array of RC chips. So, just a quick note, and I'm off to work.

Tuesday, March 4, 2008

Defying Death?


Well, I've just sat down to relax after a long day of work, and find out there's a kind of geological meme going around about death-defying geological experiences. Geotripper, what have you started?!

As a rule, I personally try to avoid death-defying experiences, and consider things like downhill skiing and white-water rafting to be extreme enough, and I haven't done either of those things in a good number of years. Many of the stories I could tell, would really be of other people, or would be about getting stuck in 4WD a long way from anywhere.

So here goes: Flying around in a helicopter 50 feet off the ground while contouring around the hills and mountains of the Great Basin -- rather than flying a grid so that the U-Th-K spectrometer wouldn’t need any elevation correction -- was death defying enough for me. And then when our end-of-field-season replacement pilot forgot to pick me up one night, and then when he simultaneously forgot where he was supposed to pick me up, well, that isn’t really death-defying, I don't think. It's merely very inconvenient. I stayed out overnight with water-proof matches, one wool sweater, a small snack, less than a cup of water, and one so-called helicopter blanket (kind of like those thin, reflective “space blankets” but bright orange on one side, so you might be able to flag down a wayward or lost helicopter). It was early October in central Nevada, in the high country, in a not particularly warm year.

Northumberland Caldera
I learned that it takes about a half hour to collect enough sagebrush to keep a fire going for about a half an hour, and that sleeping wrapped in a space blanket, in amongst the low branches of a juniper tree, with a few bushes stuffed around for “insulation” is downright ridiculous. I walked out the next day, and met the only other geologist in camp -- he knew right where I was and brought a candy bar for my breakfast -- while the rest of our crew and the pilot searched diligently for me three miles to the south in a different drainage area.

But, like many geologists, I too have stood on barely cooled basaltic lava (non-explosive, definitely not pyroclastic).

Update: Check out Highly Allochthonous for a lot of stories, many in the comments.
Update-Update: Geotripper is keeping a list of all posts for this impromptu carnival.