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Tyee Wildfire 1994-035
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strap_hanger
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| Kilbourne Hole, Maar Volcano |
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Kilbourne Hole: Located at Lat N31.97198° Long W106.96463°
Kilbourne Hole is the result of a volcanic explosion crater in southern Dona Ana County, about 30 miles from Las Cruces New Mexico. This crater is situated in a desert basin between the Portrillo Mountains to the west and the Rio Grande to the east. Kilbourne Hole is roughly elliptical in shape and is about 1.7 miles long, over a mile across and hundreds of feet deep. The edge of the crater contains older basaltic lava which was intruded by the volcanic explosion with pyroclastic ash deposits more than 100 feet high covering the basalt.
Kilbourne Hole has none of the classic volcanic features such as a cinder cone or lava dome. It is technically know as a maar; which is a pit or depression caused by volcanic explosion with little volcanic material emitted except for gas. Maars, especially large ones such as Kilbourne Hole, are not a common geologic feature, making Kilbourne hole a unique specimen.
The age of this crater is between 100,000 years (post Afton Basalt), and possibly as recent as 24,000 years old. Molten rock came in contact with subsurface water and vaporized a vast quantity of the water, turning it into super-heated steam. The extreme pressure could not be contained by the surface.
Probably over a few weeks, it erupted in a series of explosions, with so much energy that it blew more than 500 million cubic yards of ash, rock and alluvium over a 20 to 30 square mile area. A comparable volume fell back into the crater. Eventually, portions of the crater collapsed inward to the present size.
The oldest geologic strata is exposed on the south end of the crater and is composed, not of volcanic materials, but of sand, clay and silt known as the Camp Rice Formation and was deposited prior to the emerging volcanic event. The overlying lava flow capping the Camp Rice is a basalt flow 2 to 12 feet thick. Where the contact between the lava and the underlying beds are exposed, sand and silt occasionally still show discoloration caused by the intense heat of molten rock at nearly 2000 degrees F.
The volcanic ejecta lying on the basalt lava flow rimming the crater is composed of tuffaceous ash, cinders, and objects referred to as "volcanic bombs." These bombs rage from a few inches up to a foot in diameter and were blown from the vent in a near plastic state.
The crusts of the Kilbourne Hole volcanic bombs are dull black or brown, but when broken open, the often reveal a brilliant, sparkling yellow and green interior of olivine glass granules. The northern rim area has yielded jewel-quality olivine crystals, called peridot. The peridot originated more than 50 miles deep in the earth and measures to a maximum of 2 inches. The same area also yields high quality augite, a mineral which occurs as prismatic crystals of deep green or black, and also measures up to 2 inches in diameter.
Kilbourne hole is such a remote area an so geologically unique that Apollo Astronauts trained here in the 1970's.
Olivine Crystals: Peridot
Peridot is a green gem variety of Forsterite Olivine and it's chemical composition is Mg2SiO4...
Kilbourne Hole peridot has a greater color range than the San Carlos, Arizona peridot but is optically similar and has similar physical characteristics. Although the deposit is not being mined commercially, thousands of carats of gem-quality peridot have been found at Kilbourne Hole. Finding peridot from the xenolith bombs in sizes of two to three carats is not uncommon. (Hits: 2551)
Found: 26 image(s) on 2 page(s). Displayed: image 1 to 15.
kilbournehole 01 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 02 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 04 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 05 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 06 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 07 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 08 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 09 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 10 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 11 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 12 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 14 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 15 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 16 (strap_hanger)
Kilbourne Hole, Maar Volcano
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kilbournehole 17 (strap_hanger)
Kilbourne Hole, Maar Volcano
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