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Field CollectingAlpine Clefts -- Any in Colorado

15th Nov 2016 20:07 UTCScott Rider

I was perusing the alpine cleft locations of the Alps in Europe. I was wondering if there have been any recorded locations of Alpine-type fissures/clefts in Colorado? I have seen a myriad of geologic formations in my home-state, and I have seen the types of granite that appear much like the French and Swiss Alps. But I have never explored them before.

So I was wondering if there are any Alpine fissures in Colorado? I think there are some locations in eastern U.S., like North Carolina, but I was hoping there were some here in Colorado so I could check them out...

15th Nov 2016 22:18 UTCRudy Bolona Expert

Maybe not the right geological events in Colorado for them. If there were they would have been discovered by now.

15th Nov 2016 22:21 UTCAlfredo Petrov Manager

Alpine-type veins aren't likely in Colorado because they form in tightly folded rocks and the Rockies (at least the parts I've seen) aren't very folded. Same goes for the Andes Mts in South America.

Good mountains for yielding alpine-type veins are the Alps (of course), Himalayas, Urals, Appalachians (incl. N Carolina as you already mentioned), Pyrenees..... Any others I've forgotten?

15th Nov 2016 22:50 UTCRichard Gunter Expert

Alpine-type veins appear to require continent-continent collisions, which is why they occur in the Alps and the Himalayas but not in the Andes or the North American Cordillera which are active subduction zones. Small open veins occur in the northern Cascade Mountains of Washington-British Columbia where western North America collided with what is now Vancouver Island. I do not know whether these would qualify as Alpine-type. Alfredo the Rockies can be very folded, especially the Canadian portions, but I have not heard of any Alpine-type veins.

15th Nov 2016 23:16 UTCScott Rider

Very interesting! Well, I guess I'll have to visit the Alps in the near future then!!! I have become very comfortable digging in the numerous pegmatite fields in Colorado but wanted to try something new! Well, I guess I'll keep exploring the Rockies in the meantime! There is still plenty to discover here in the states!

As far as North Carolina, are those clefts very big? I haven't seen any Gwindels or unusual specimens that one would find in an alpine dike... Maybe that NC trip would be more viable for me now as I'm sure a visit to the Alps is quite expensive!!

But, thanks for your responses... I haven't studied Alpine deposits yet so I wasn't sure why there weren't any in Colorado, considering the diversity of geologic formations out here... Its interesting to hear that they are in continent to continent ranges and not in the Rocky Mountains...

15th Nov 2016 23:35 UTCDoug Daniels

Just a conjecture, hypothesis, whatever..... The Appalachians are fairly old, and deeply weathered, so possibly any Alpine-type clefts are long gone. The Alps are a bit younger, so the clefts are still there to be found. I could be wrong.

15th Nov 2016 23:53 UTCAmir C. Akhavan Expert

Alpine-type fissures are extensional fissures - these are not uncommon in many tectonically stressed environments.

The interesting thing about them in continental collision zones like the Alps, Urals, Himalayas etc. is that the opening happened deep within the crust, and that many of these cavities survived being uplifted by 10km or more.

An example that would count as extensional fissures are those that contain the skeleton quartz specimens in marls and sandstones

around Poretta Terme, Appenines, Italy. As far as I know, these rocks have not been deeply buried.

The Appalachians have undergone a very intense folding and thrusting. The age has little to do with it. The Urals are fairly old, too, as are the Caledonians in Norway or in Wales, and there are apparently similar parageneses and fissures in very old units in Namibia (where gwindels have been found). Erosion is actually a requirement to uplift the rock from depths where the fissures formed in the then somewhat malleable rock.

I have not heard of alpine-type fissure in the Pyrenees, the folding and thrusting there is much less intense than in the Alps (but next time I go there I will try to find some...)

The biggest problem is that alpine-type fissures are often very difficult to find in the field because they are isolated cavities in the rock and only rarely exposed by erosion. In the Appalachians working on them is relatively easy because the host rock has been deeply weathered.

16th Nov 2016 00:28 UTCRichard Gunter Expert

Hi Amir:

I agree with you on the difficulty in finding the Alpine-type clefts. An interesting case is the Daisy Lake occurrence near Squamish, British Columbia. Ray Hill and Uwe were collecting in 2008 and Uwe spotted a likely mixture of different rock types in a road-cut. In this case it was an experienced person in a good environment finding a series of clefts where none had been noticed before.

16th Nov 2016 09:15 UTCErik Vercammen Expert

In Maasacusetts: http://www.mindat.org/loc-6764.html

17th Nov 2016 22:47 UTCGuy Davis (2)

The North Carolina alpine clefts and fissures are not in the Appalachian mountains at all, but in the Piedmont where it is relatively flat. Many Raleigh/Wake County collectors do quite well scouring the ground at new construction sites looking for signs of quartz veins and multi-colored pocket clay, either in cut banks or on newly-graded surfaces. Although I have personally never seen a gwindel from NC they might exist. The most sought-after quartz habit found in the alpine fissures is the tessin habit, and some smoky tessins can get quite large. Some tessins also have interesting inclusions of hematite and can be found in association with other minerals as well.

18th Nov 2016 00:08 UTCAmir C. Akhavan Expert

As far as I understand it, the Piedmont zone is part of the Appalachians, but very much eroded.

18th Nov 2016 21:30 UTCRob Woodside 🌟 Manager

Further to what Richard said, Silica Bell http://www.mindat.org/loc-23414.html is an alpine cleft deposit in the Coast Mountains.

14th Jan 2017 19:57 UTCDustin Ryan Alexander

Yes there are alpine clefts in the gore range of summit county just most people around here are all about skiing/boarding and I've been snowboarding for 18 years learned to ski 27 years ago at Breckinridge when I was 3. Also the more I discover in this area the more I realize why the few that know what's available here don't talk to openly about it unless they know you have roots in the area ;) I've been hounding for the past 2 summers and have lot's to ask about that I'll be posting in the near future and would be happy to answer any questions about the area specifically the gore range

20th Jan 2017 21:47 UTCLászló Horváth Manager

In the north-eastern Appalachians (in southern Quebec) a number of Alpine clefts have been found and explored in the Windsor-Richmond, Ayer's Cliff and Saint-Pierre-de-Broughton areas. The problem is finding them in the heavily forested region. Just about the only way to find them is in exposures in quarries and road cuts.

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