Forum Index > Trail Talk > Edaphic Specialization: Helena Lake, Helena Mines
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Sculpin
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PostSat Feb 04, 2017 9:55 pm 
NWHikers has reached critical mass in terms of being a resource. Kudos to the contributors! One hobby I enjoy is exploring edaphic specialization. The term refers to unusual plant communities that appear on specific types of rock. The most famous examples of edaphic specialization are ultramafic outcrops, where rocks from the mantle have pushed through the crust and are exposed on the surface. The mountains surrounding the Teanaway - Paddy Go Easy Pass all the way to Tronsen Ridge - are ultramafic rocks and they feature a flora that is both unique and yet also typical of temperate ultramafic exposures on the west coast of the US. Other ultrafamic exposures, often called "serpentine," are found in just a few places in western Washington, for example the Twin Sisters near Mt. Baker and in the San Juans. The rocks of the mantle are primarily peridotite but in the crust peridotite is hydrothermally altered to serpentine, a greasy greenish rock. Another series of exposures of ultramafic rock occur between Three Fingers and Darrington. On the USGS map, the exposures are in slices. One slice drops across a subalpine slope and intersects Helena Lake. A larger slice makes up the ridge between Independence Lake and Helena Lake. So I want to go to these places and see if there are edaphic specialists, especially ones with showy flowers. Can I find information on NWHikers? You bet I can. Daffish did the trip from Independence Lake to Helena Lake: https://www.nwhikers.net/forums/viewtopic.php?t=7993088&highlight=helena+lk+lake I won't cross the ridge where he did because I will follow the ultramafic outcrop, but the beta is useful. I'm also suspicious that there might be an ultramafic outcrop at Helena Mines, even though it doesn't show on the USGS map. Valuable mineral deposits are often found at the interface between ultramafics and the surrounding rock. I appreciate the descriptions from Whitebark and Jimbo. Whitebark has a tremendous body of work on all sorts of places, including a nice description of the trail to Helena Mines, and Jimbo has shared a lot about mines in Washington. So I am wondering if there is more knowledge in this community: Is the Coal Creek Road closed...indefinitely? Does anyone have images of unusual plants from the Helena Lake or Helena Mines area? Has anyone noticed outcrops of ultramafic rocks in that area?

Between every two pines is a doorway to the new world. - John Muir
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whitebark
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PostSun Feb 05, 2017 11:45 am 
It's been a few years since I was at Helena Mines. I recall that the area features some nice red rock (can you tell I'm not a geologist smile.gif ).

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Sculpin
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PostMon Feb 06, 2017 12:05 pm 
whitebark wrote:
I recall that the area features some nice red rock
Which may very well be peridotite, but unfortunately I cannot identify peridotite in images, I need to actually see it. In sleuthing around at the Burke Herbarium, I see that three serpentine indicator ferns are found north of Silverton, Polystichum lemmonii, Polystichum kruckebergii, and Aspidotis densa. The location information for one specimen of P. lemmonii is very specific: "East side of Devil's Thumb, in rocky bowl below southern point on ridge, above Windom Lake." Gimpilator posted an image that shows lots of red rock on this ridge, with Devil's Peak in the background...I am closing in on it.

Between every two pines is a doorway to the new world. - John Muir
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Ringangleclaw
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PostMon Feb 06, 2017 1:26 pm 
There is a bunch of ultra-mafic rocks in the Cascades. I assume you have looked at this:https://pubs.usgs.gov/sim/2940/ The issue you may have is that many mapped units may in fact be altered to serpenite. Does this affect your interest? But there's bodies of altered and un-altered ultra-mafic rocks all over the place, primarily in the Eastern Melange Belt, the Ingalls, the Helena-Haysack melange, various units inside the Welker Peak Nappe, smaller units in the Easton Nappe and the Fidelgo Ophiolite.

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PostMon Feb 06, 2017 2:01 pm 
So are you looking for ultra-mafic rocks or serpentine?

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Sculpin
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PostMon Feb 06, 2017 4:10 pm 
Ringangleclaw wrote:
So are you looking for ultra-mafic rocks or serpentine?
Both. Serpentine is an ultramafic rock by chemistry. Both peridotite and mantle-derived rock altered to serpentine show the "serpentine syndrome," which is a type of edaphic specialization. There are lots of exposures in the Cascades, as you attest. However, most are very small and are part of a mélange, and do not have specialized plants except maybe the indicator ferns. Botanist Alex Wright pointed me to the Helena region exposures as having a specialized flora so I am currently researching that (been to the Teanaway exposures more times than I can remember). But any observations about ultramafics or associated plants along trails are of interest to me.

Between every two pines is a doorway to the new world. - John Muir
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whitebark
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PostMon Feb 06, 2017 5:42 pm 
Here are some pictures of the rock around Helena Mines that I took in 2009. Hope this helps:

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Ringangleclaw
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PostMon Feb 06, 2017 9:33 pm 
Sculpin wrote:
Both. Serpentine is an ultramafic rock by chemistry. Both peridotite and mantle-derived rock altered to serpentine show the "serpentine syndrome," which is a type of edaphic specialization.
What I was trying to get to was whether you need ultra mafic rock exposures, or their hydrated products. It seems like both give the same results that you seek. Helena Ridge shows in Tabor and Haugerud as being in the Eastern Melange Belt, with the creek lying in the Haystack melange. Some of the serpentinite exposures in both of these melanges are extensive. Photo TKhm in Tabor and Haugerud's SIM 2940 show how aerially large these serpentinite exposures are. And of coarse there is the Twin Sisters

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Chief Joseph
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PostMon Feb 06, 2017 9:45 pm 
I saw some cool greenish looking rock (slimy? probably) the one time I went to Helena mine, but the water was a bout a foot deep and I wasn't in the mood to wade, but I would say definitely worth exploring. Some say there is a cache of mining items hidden somewhere around there below Helena peak. I don't know about Coal creek road's status, but I do recall Hulk saying there were a couple of culverts plugged and a washout was just a matter of time. I have always wanted to go to Helena lake and doubt I ever will unless I go with someone who knows a good route. I did make it to Windom lake, lol. Btw, you know that access to Helena peak-mines is via the Deer creek road, not coal creek road? Although I imagine a cross country route exists as well.

Go placidly amid the noise and waste, and remember what comfort there may be in owning a piece thereof.
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puzzlr
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PostTue Feb 07, 2017 3:42 am 
What about serpentine rock on Serpentine?
Serpentine.
Serpentine.

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Yana
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PostTue Feb 07, 2017 8:08 pm 
I have no useful information to contribute to this thread right now, Sculpin, sorry. But I did want to say that this is absolutely the best thread of all time on nwhikers. wub.gif wub.gif wub.gif wub.gif wub.gif wub.gif wub.gif wub.gif wub.gif wub.gif

PLAY SAFE! SKI ONLY IN CLOCKWISE DIRECTION! LET'S ALL HAVE FUN TOGETHER!
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Sculpin
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PostWed Feb 08, 2017 4:47 pm 
Thanks for posting the images of Helena Mines, Whitebark. This one is useful:
whitebark wrote:
It sure looks like the mine is cut into peridotite. The ferns on either side of the entrance look suspiciously like Shasta Fern, Polystichum lemmonii. And it is a hilarious picture of your dog! The rock in Puzzlr's hand is indeed serpentine, part of the large set of exposures between Tronsen Ridge and Paddy Go Easy Pass. Mines are common in there. I am no geologist but here is what I learned: A large body of magma that cools below the surface (a pluton) becomes granitic rock. While it is cooling, heavy metals like gold and copper settle out by gravity. If the bottom of that pluton rests against the mantle, metal-rich veins will form at the mantle/pluton boundary. Later the pluton can be thrust upward and turn on its side, exposing the mantle rock underneath. So the boundary between the Mt. Stuart Batholith, formerly a large pluton, and the ultramafic mantle rocks of the Wenatchee Mountains that ring the Teanaway, are that type of boundary, and that is why mines are sprinkled all along there. The boundary pretty much follows Ingalls Creek most of the way. Yana...I think you are being sincere...so thanks!

Between every two pines is a doorway to the new world. - John Muir
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Ringangleclaw
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PostWed Feb 08, 2017 10:07 pm 
Sculpin wrote:
A large body of magma that cools below the surface (a pluton) becomes granitic rock. While it is cooling, heavy metals like gold and copper settle out by gravity. If the bottom of that pluton rests against the mantle, metal-rich veins will form at the mantle/pluton boundary. Later the pluton can be thrust upward and turn on its side, exposing the mantle rock underneath. So the boundary between the Mt. Stuart Batholith, formerly a large pluton, and the ultramafic mantle rocks of the Wenatchee Mountains that ring the Teanaway, are that type of boundary, and that is why mines are sprinkled all along there. The boundary pretty much follows Ingalls Creek most of the way.
Well, that's not really correct, even in the broadest sense.
Sculpin wrote:
It sure looks like the mine is cut into peridotite.
Many other rocks would appear the same in a photo, namely meta-argillite which is common in the melanges and NWCS

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Yana
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PostWed Feb 08, 2017 11:42 pm 
Ringangleclaw wrote:
Well, that's not really correct, even in the broadest sense.
In that case, can you please clarify? Sculpin - yes, most definitely sincere. You're welcome! :-)

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PostThu Feb 09, 2017 9:07 am 
Yana wrote:
In that case, can you please clarify?
Really? Basically we're talking about the entire geotectonic cycle, half a text book on economic geology and another half of both igneous and metamorphic petrology. In it's simplest terms the ultra mafic rocks and their oceanic basalt cover were stripped from the their location on a sea floor and thrust onto an island chain. The Mount Stewart batholith does not sit on the mantle rocks, but intruded thru the previously obducted terranes as a molten mass. Some economic minerals segregate themselves gravitationally in some ultra mafic bodies. That doesn't seem common here. Most of the economic minerals of concern in Washington stay in solution in more acidic magmatic waters and are then found in faults, veins and the such. Many types of enrichment can then occur.

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