Just watching a volcano blow up and I was wondering if anyone is aware of a Limestone Cave that has been lost to a volcanic eruption?  Measured and mapped by cavers. 

Interesting question.  From my limited knowledge I suspect volcanoes are rare in limestone regions. Interestingly many caves have formed as an indirect effect of volcanic activity eg caves formed in coralline limestones that have formed round old voclanoes eg the Mendips. I am sure experts in the field will be able to expand further.

The Carboniferous period in the Peak District was slightly more exciting than it was here in the Dales, as there were occasional volcanic eruptions (resulting in the Cavedale & Millersdale lavas, for example). I believe there are examples pf palaeokarst thought to date back to around then. So just maybe there might be the odd passage that got eliminated by the Speedwell Vent, or whatever?

Pitlamp said:

The Carboniferous period in the Peak District was slightly more exciting than it was here in the Dales, as there were occasional volcanic eruptions (resulting in the Cavedale & Millersdale lavas, for example). I believe there are examples pf palaeokarst thought to date back to around then. So just maybe there might be the odd passage that got eliminated by the Speedwell Vent, or whatever?

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Yes but I think the question is specifically in reference to caves which were known about by cavers, mapped and then infilled by lava ie an observed volcano infill. I don't know of any examples of this, but it's very unlikely. Volcanoes tend to 'build up' over time as more material is erupted (with the initial rising of magma being due to either a thinning of the crust due to rifting as we see in Iceland or the East African Rift, a rising 'mantle plume' eg Hawaii, or subduction-induced melting as in the Andes). Therefore, cave systems immediately proximal to volcanoes are likely to have been buried by their deposits early on in the life of the volcano.

A possible mechanism for volcanic infill of a cave would be by pyroclastic density currents. These are not 'lava' as you might see in Hawaii or at Etna, but mixtures of very hot gases and sediments, from very fine (ash) to big blocks. A well known occurrence of these is the 1980 eruption of Mount St Helens, where lava dome collapse initiated many such flows. These flows are remarkable in that they have the energy to surmount topography and travel many tens of kilometres from the vent. So a cave in limestone outcropping some distance from the volcano could be infilled by these given the right topographic conditions and flowpath.

Good candidates for the locations of such caves would be young volcanoes in subduction margins, which tend to be more explosive, and where topography building is more variable. The Andean volcanic arc in Ecuador and Peru are possibilities: Ecuador has quite a bit of outcropping limestone which is karstified (but underinvestigated). These volcanoes are also thought to be quite young mostly (Pleistocene or younger, though some are much older).

Other potential sites would be the southeast asian islands of the Philippines and Indonesia which house abundant karst and volcanoes, though I know little of the karst here so can't really comment.

mrodoc said:

Interesting question.  From my limited knowledge I suspect volcanoes are rare in limestone regions. Interestingly many caves have formed as an indirect effect of volcanic activity eg caves formed in coralline limestones that have formed round old voclanoes eg the Mendips. I am sure experts in the field will be able to expand further.

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I once saw someone drill a volcano in the Carboniferous that someone thought was a faulted anticline (a triangle thing :blink. Who?d be a geologist? Personally I thought it looked like a volcano, but it wasn?t my area.

If you potter around places in the western Pacific (Tonga for instance) there is a great deal of activity around the carbonate reefs and islands. On the islands there is a fair amount of karst. There is a volcano building up just to the west of central Tonga that covers the sea in pumice and is depositing subsurface. It is strange to suddenly find yourself in foot thick layer of pumice in the middle of the sea.

My mind wandered to Japan and Mexico.  In Mexico volcanos are close to some caving areas. I suspect they have buried limestone before humanity came along.

Some passages in Clearwater cave in Mulu have been infilled with volcanic ash (which has weathered to a clay). The best example is a side passage just before Sump 1 in the Clearwater streamway which was completely choked with ash. Subsequent partial washing out of the clay has created a passage within the ash deposit..

Pindale End Mine in Castleton has thick beds of volcanic ash (the Pindale Tuff) that also filled vertical fissures, seemingly before mineralisation took place, so it possibly filled nearby caves too. The first shot shows the bottom end of Dirtlow Rake looking 'uphill', with light blue ash on either side of the vein - there is also vertical displacement on the fault, with ash on the right wall and limestone on the left. The ash really is that colour. The top entrance shaft has a vertical 'trough' of ash running all the way down it, and the bottom shaft base area has a roof of shale and a floor of ash, with no limestone at all between them. There's a pipe working above Pindale Quarry that has a higher (unnamed) bed of ash running semi-vertically through the wall.

The second shot shows a passage cut through lava (or very compacted ash) at the base of an internal shaft at about 75m depth in a mine on Moss Rake - this went from a crosscut in limestone into rough lava and back into limestone within a few metres, and it definitely looked a bit 'cavey' behind the lava. Slickensides are also visible contacting the lava, so this possibly happened before mineralisation too, though the lava had small and thin calcite veins within it.

There are large dark green blocks of basalt at the base of George Cooper Aven, before dropping further down into Echo Chamber in Peak Cavern, and also more in the top choke in Victoria Chamber - these are from the Cave Dale Lava. A few of us at the TSG helped Mark Harwood of TerraDat do some subsurface scanning of the Speedwell Vent in 2017, and there are possibly some natural voids around the base of Cowlow that might contain lava rather than sediment, especially at the toe below the shale contact.

That's really interesting, I'd be very keen to have a look at these Peak caves. Would be very cool to date the ash deposits.

I'm not sure how much analysis has been done on the Pindale Tuff, other than geo-advice for the cement works, which has been done. But given the troughing seen in the mines, which also happens with shale, there must have been some natural voids that were open when the eruptions were taking place. If a pipe is a cave that fills with minerals, and that mineralisation happened after the ash deposition, it suggests that some of the old caves may have filled with ash or lava before they had chance to fill with mineral. I'm only guessing, being a non-expert, but I've got plenty of photos if anyone is.

Elias Pedley's Level, a mine further around the hill at Nunlow End (now within the cement works), had a vein of lead ore running through a bed of this lava, and a famous French geologist came over to inspect it in about 1789, as it was unheard of. He concluded instead, after seeing it himself, that it couldn't be lava as it contradicted his own theory and wrote a paper (wrongly) about it. Elias Pedley was right.

If I remember rightly from the Speedwell Vent scanning, the toe of the lava (an agglomerate really, as far as can be seen on surface), which is on top of the reef limestone, then slips under a thin skin of the Eyam limestone just before the shale contact - this is seen in that tiny old quarry near the ruined barn. So there could well be infilled caves just below the surface there. Peakshole Sough has a phreatic tube at the west end, not that far away, just below surface, with a shale roof and much shale and sediment infill.

Just did a quick search, the derbyshire orefield was surveyed and dated using K-Ar dating by Ineson and Mitchell in 1973 (other earlier studies provided some dates), pretty standard for dating volcanic deposits. From these dates they deduced at least two mineralisation periods, one at 270 ma and one at 235 ma, with mineralisation likely continuing until 180 ma. Also found  a study on the speedwell vent (Cheshire and Bell, 1976) which proposes that the flow tongue entered the sea.

If anyone wants these papers then drop me an email/message. You won't find them on SciHub as they're before the time of doi's.

Would be an interesting study to try and work out what was going on here. I'm no mineral geologist but I know a few...

I am not aware of any limestone cave explored / surveyed and then lost to volcanc action.  I do know of several lava tube caves that have been lost in Iceland and in Hawaii, in the latter case even having heard the account of being in the cave when it was happening(!).  I have also seen first hand evidence of newer lavas having blocked lava tube entrances.

I have asked around a few friends in the UIS Commission on Volcanic Caves, and the nearest I can get is in New Mexico where there are apparently gypsum caves that were partially filled with lava in prehistoric times.  Apparently there are places where the floor is gypsum and the roof lava.  It was also pointed out to me that the Etna massif "pops up" through massive limestone.

nobrotson said:

If anyone wants these papers then drop me an email/message. You won't find them on SciHub as they're before the time of doi's.

Would be an interesting study to try and work out what was going on here. I'm no mineral geologist but I know a few...

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I'd like to see those papers, definitely - it's an area I haven't had chance to follow up much yet, due to other projects, but it's all interrelated with the work we were doing up at Longcliffe. The Speedwell Vent also sits in the path of much of the downstream flow to the resurgences, and whilst it may be too high to affect them, if it is a true vent then it should go much deeper. Mark's project was summarised in TSG 19, and was then developed further by Nathalia Da Costa Vieira as part of her MSc, and we helped her on that one too.

There's more discussion on this topic here:

https://ukcaving.com/board/index.php?topic=26027.0

Here's the full list of references from Mark's article:

Aitkenhead, N., Chisholm, J.I. & Stevenson, I.P.  1985.  Geology of the Country around Buxton, Leek and Bakewell.  Memoir of the British Geological Survey, Sheet 111.

Arnold-Bemrose, H.H.  1907.  The toadstones of Derbyshire: their field relations and petrography.  Quarterly Journal of the Geological Society of London, 63, 241-281.

Cheshire, S. G.; Bell, J.D.  1976.  ?The Speedwell Vent, Castleton, Derbyshire: A Carboniferous littoral cone?.  Proceedings of the Yorkshire Geological Society. 41 (2)

Eden, R.A., Orme, G.R., Mitchell, M. & Shirley, J.  1964.  A study of part of the margin of the Carboniferous Limestone ?massif? in the Pindale Area of Derbyshire.  Bulletin of the Geological Survey, London. 21.  73-118.

Fearnsides, M.A. & Templeman, H.M.  1932.  A boring through Edale Shales to Carboniferous Limestone and pillow lavas, at Hope Cement Works, near Castleton, Derbyshire.  Proceedings of the Yorkshire Geological Society, 22, 100-121

Ford, T.D.  2010.  The Geological Setting of the Lead Mines in the Northern Part of the White peak, Derbyshire.  Mining History - The Bulletin of the Peak District Historical Society Ltd. 17,  5.  1-48.

Heathcote, C., 2010.  A history and gazetteer of the lead mines within Bradwell Liberty, Derbyshire:1216-1890.  Mining History - The Bulletin of the Peak District Historical Society Ltd. 17, 5.  55-85.

MacDonald, R., Gass, K.N., Thorpe, R.S. & Gass, I.G.  1984.  Geochemistry and petrogenesis of the Derbyshire Carboniferous basalts.  Journal of the Geological Society of London, 141, 147-159.

Parkinson, D.  1947.  The Lower Carboniferous of the Castleton district, Derbyshire.  Proceedings of the Yorkshire Geological Society. 27, 99-124.

Sadler, H.E.  1964.  The origin of the ?beach beds? in the Lower Carboniferous of Castleton, Derbyshire.  Geological Magazine, 101, 360-72.

Shirley, J. & Horsfield, E.L.  1940.  Carboniferous Limestone of the Castleton - Bradwell area, north Derbyshire.  Quarterly Journal of the Geological Society, London. 96, 271-99.

Stevenson, I.P. & Gaunt, G.D.  1971.  Geology of the country around Chapel-en-le-Frith. Memoir of the British Geological Survey.  Sheet 99.

Stevenson, I.P., Gaunt, G.D., Edwards, W.N., Woodland, A.W. and Ponsford, D.R.A.  1975.  1:25000 geological map, Castleton (Sheet SK 18).  British Geological Survey, Keyworth, Nottingham.

Walters, S.G. and Ineson, P.R.  1981.  A review of the distribution and correlation of igneous rocks of Derbyshire, England.  Mercian Geologist, 8, 81-132.
Waters, C N, Waters, R A, Barclay, W J, and Davies, J R. 2009.  A lithostratigraphical framework for the Carboniferous successions of southern Great Britain (Onshore). British Geological Survey Research Report, RR/09/01. ISBN 978 0 85272 626 6