The central Snake River plain is similar to the eastern plain, but differs by having thick sections of interbedded lacustrine (lake) and fluvial (stream) sediments, including the Hagerman Fossil Beds.
Nevada–Oregon calderas
Although the McDermitt volcanic field on the Nevada–Oregon border is frequently shown as the site of the initial impingement of the Yellowstone Hotspot, new geochronology and mapping demonstrates that the area affected by this mid-Miocene volcanism is significantly larger than previously appreciated.[2] Three silicic calderas have been newly identified in northwest Nevada, west of the McDermitt volcanic field as well as the Virgin Valley Caldera.[3] These calderas, along with the Virgin Valley Caldera and McDermitt Caldera, are interpreted to have formed during a short interval 16.5–15.5 million years ago, in the waning stage of the Steens flood basalt volcanism.[4] The northwest Nevada calderas have diameters ranging from 15 to 26 km and deposited high temperature rhyolite ignimbrites over approximately 5000 km2.
As the hotspot drifted beneath what is now Nevada and Oregon, it increased ecological beta diversity locally by fragmenting previously connected habitats and increasing topographic diversity in western North America.[5]
The Bruneau-Jarbidge volcanic field erupted between ten and twelve million years ago, spreading a thick blanket of ash in the Bruneau-Jarbidge event and forming a wide caldera. Animals were suffocated and burned in pyroclastic flows within a hundred miles of the event, and died of slow suffocation and starvation much farther away, notably at Ashfall Fossil Beds, located 1000 miles downwind in northeastern Nebraska, where a foot of ash was deposited. There, two hundred fossilizedrhinoceros and many other animals were preserved in two meters of volcanic ash. By its characteristic chemical fingerprint and the distinctive size and shape of its crystals and glass shards, the volcano stands out among dozens of prominent ashfall horizons laid down in the Cretaceous, Paleogene, and Neogene periods of central North America. The event responsible for this fall of volcanic ash was identified as Bruneau-Jarbidge. Prevailing westerlies deposited distal ashfall over a vast area of the Great Plains.
Volcanic fields
Twin Falls and Picabo volcanic fields
The Twin Falls and Picabo volcanic fields were active about 10 million years ago. The Picabo Caldera was notable for producing the Arbon Valley Tuff 10.2 million years ago.
Heise volcanic field
The Heise volcanic field of eastern Idaho produced explosive caldera-forming eruptions which began 6.6 million years ago and lasted for more than 2 million years, sequentially producing four large-volume rhyolitic eruptions. The first three caldera-forming rhyolites – Blacktail Tuff, Walcott Tuff and Conant Creek Tuff – totaled at least 2250 km3 of erupted magma. The final, extremely voluminous, caldera-forming eruption – the Kilgore Tuff – which erupted 1800 km3 of ash, occurred 4.5 million years ago.[6][7][8][9][10]
The Yellowstone Plateau volcanic field is composed of four adjacent calderas. West Thumb Lake is itself formed by a smaller caldera[a] which erupted 174,000 years ago. (See Yellowstone Caldera map.) The Henry's Fork Caldera in Idaho was formed in an eruption of more than 280 km3 (67 cu mi) 1.3 million years ago, and is the source of the Mesa Falls Tuff.[11] The Henry's Fork Caldera is nested inside of the Island Park Caldera and the calderas share a rim on the western side. The earlier Island Park Caldera is much larger and more oval and extends well into Yellowstone Park. Although much smaller than the Island Park Caldera, the Henry's Fork Caldera is still sizeable at 18 miles (29 km) long and 23 miles (37 km) wide and its curved rim is plainly visible from many locations in the Island Park area.
Of the many calderas formed by the Yellowstone Hotspot, including the later Yellowstone Caldera, the Henry's Fork Caldera is the only one that is currently clearly visible. The Henry's Fork of the Snake River flows through the Henry's Fork Caldera and drops out at Upper and Lower Mesa Falls. The caldera is bounded by the Ashton Hill on the south, Big Bend Ridge and Bishop Mountain on the west, by Thurburn Ridge on the North and by Black Mountain and the Madison Plateau on the east. The Henry's Fork caldera is in an area called Island Park. Harriman State Park is situated in the caldera.
The Island Park Caldera is older and much larger than the Henry's Fork Caldera with approximate dimensions of 58 miles (93 km) by 40 miles (64 km). It is the source of the Huckleberry Ridge Tuff that is found from southern California to the Mississippi River near St. Louis. This supereruption occurred 2.1 million years BP and produced 2500 km3 (700 mi³) of ash. The Island Park Caldera is sometimes referred to as the First Phase Yellowstone Caldera or the Huckleberry Ridge Caldera. The youngest of the hotspot calderas, the Yellowstone Caldera, formed 640,000 years ago and is about 34 miles (55 km) by 45 miles (72 km) wide. Non-explosive eruptions of lava and less-violent explosive eruptions have occurred in and near the Yellowstone Caldera since the last super eruption. The most recent lava flow occurred about 70,000 years ago, while the largest violent eruption excavated the West Thumb of Lake Yellowstone around 150,000 years ago. Smaller steam explosions occur as well – an explosion 13,800 years ago left a 5 kilometer diameter crater at Mary Bay on the edge of Yellowstone Lake.
Both the Heise and Yellowstone volcanic fields produced a series of caldera-forming eruptions characterised by magmas with so-called "normal" oxygen isotope signatures (with heavy oxygen-18 isotopes) and a series of predominantly post-caldera magmas with so-called "light" oxygen isotope signatures (characterised as low in heavy oxygen-18 isotopes). The final stage of volcanism at Heise was marked by "light" magma eruptions. If Heise is any indication, this could mean that the Yellowstone Caldera has entered its final stage, but the volcano might still exit with a climactic fourth caldera event analogous to the fourth and final caldera-forming eruption of Heise (the Kilgore Tuff) – which was also made up of so-called "light" magmas. The appearance of "light" magmas would seem to indicate that the uppermost portion of the continental crust has largely been consumed by the earlier caldera- forming events, exhausting the melting potential of the crust above the mantle plume. In this case Yellowstone could be expiring. It could be another 1–2 million years (as the North American Plate moves across the Yellowstone hotspot) before a new supervolcano is born to the northeast, and the Yellowstone Plateau volcanic field joins the ranks of its deceased ancestors in the Snake River Plain.[12]
A 2020 study suggests that the hotspot may be waning.[13]
Owyhee-Humboldt volcanic field, Owyhee County, Idaho, Nevada, and Oregon; around 12.8 to 13.9 Ma.[21]
McDermitt volcanic field, Orevada rift, McDermitt, Nevada/ Oregon (five overlapping and nested calderas; satellitic to these are two additional calderas), 20,000 km2 (7,700 sq mi):[23]
Calavera Caldera, (size: 17 km wide); 15.7 Ma; 300 cubic kilometers (72 cu mi) of Double H Tuff.[20][21][24][25]
Trout Creek Mountains, Pueblo Caldera (size: 20 x 10 km), Oregon; 15.8 Ma; 40 cubic kilometers (10 cu mi) of Trout Creek Mountains Tuff.[20][24][23]
Hoppin Peaks Caldera, 16 Ma; Hoppin Peaks Tuff.[23]
Washburn Caldera, (size: 30 x 25 km wide), Oregon; 16.548 Ma; 250 cubic kilometers (60 cu mi) of Oregon Canyon Tuff.[20][24][25]
Yellowstone hotspot (?), Lake Owyhee volcanic field; 15.0 to 15.5 Ma.[26]
Yellowstone hotspot (?), Northwest Nevada volcanic field, Virgin Valley, High Rock, Hog Ranch, and unnamed calderas; West of the Pine Forest Range, Nevada; 15.5 to 16.5 Ma; Tuffs: Idaho Canyon, Ashdown, Summit Lake, and Soldier Meadow.[3][27][28][29][30]
Columbia River Basalt Province: Yellowstone hotspot sets off a huge pulse of volcanic activity, the first eruptions were near the Oregon-Idaho-Washington border. Columbia River and Steens flood basalts, Pueblo, and Malheur Gorge-region, Pueblo Mountains, Steens Mountain, Washington, Oregon, and Idaho; most vigorous eruptions were from 14 to 17 Ma; 180,000 cubic kilometers (43,184 cu mi) of lava.[20][31][32][4][33][34][35][36]
Harney Basin (Devine Canyon Tuff), McDermitt volcanic field, Owyhee-Humboldt volcanic field, Lake Owyhee volcanic field (or Jordan Valley volcanic field, Lake Owyhee), Jordan Craters, Santa Rosa – Calico volcanic field, Hawkes Valley – Lone Mountain volcanic field, Northwest Nevada volcanic field, Juniper Mountain caldera complex, and Silver City – Delamar caldera complex (Silver City, Idaho) are nested in one area. Geologic landmarks of the area: Steens Mountain, Northern Nevada Rift, Midas Trough, Santa Rosa Mountains, Bull Run – Tuscarora Mountains, Owyhee Mountains, Oregon-Idaho Graben, and western Snake River Plain.[37]
Other manifestations of the Yellowstone hotspot: Rexburg Volcanic Field (4.3 Ma), West of Rexburg, Idaho; Henry's Lake Volcanism (1.3 Ma), Henry's Lake; Blackfoot Volcanic Field (3 Ma), Northwest of Soda Springs, Idaho; Gem Valley Volcanic Field (600 to 50 ka), near Grace, Idaho.[46]
^West Thumb Lake is not to be confused with West Thumb Geyser Basin. The caldera created West Thumb Lake and the underlying Yellowstone hotspot keeps West Thumb Geyser Basin active. See Fig. 22.
^ abMatthew A. Coble & Gail A. Mahood (2008). New geologic evidence for additional 16.5–15.5 Ma silicic calderas in northwest Nevada related to initial impingement of the Yellowstone hot spot. Earth and Environmental Science. Vol. 3. p. 012002. Bibcode:2008E&ES....3a2002C. doi:10.1088/1755-1307/3/1/012002.
^ abcdefLisa A. Morgan & William C. McIntosh (March 2005). "Timing and development of the Heise volcanic field, Snake River Plain, Idaho, western USA". Geological Society of America Bulletin. 117 (3–4): 288–306. Bibcode:2005GSAB..117..288M. doi:10.1130/B25519.1.
^Christiansen, R.L. (2001). "The Quaternary and Pliocene Yellowstone Plateau volcanic field of Wyoming, Idaho and Montana". U.S. Geol. Surv. Prof. Paper. 729: 146.
^Lanphere, M.A.; Champion, D.E.; Christiansen, R.L.; Izett, G.A.; Obradovich, J.D. (2002). "Revised ages for tuffs of the Yellowstone Plateau volcanic field: Assignment of the Huckleberry Ridge Tuff to a new geomagnetic polarity event". Geol. Soc. Am. Bull. 114 (5): 559–568. Bibcode:2002GSAB..114..559L. doi:10.1130/0016-7606(2002)114<0559:RAFTOT>2.0.CO;2.
^Pierce, K.L. & Morgan, L.A. (1992). Link, P.K.; Kuntz, M.A. & Platt, L.B. (eds.). "The track of the Yellowstone hot spot: Volcanism, faulting, and uplift". Regional Geology of Eastern Idaho and Western Wyoming. Memoir 179: 1–52.
^ abcdSteve Ludington; Dennis P. Cox; Kenneth W. Leonard & Barry C. Moring (1996). Donald A. Singer (ed.). "Chapter 5, Cenozoic Volcanic Geology in Nevada". An Analysis of Nevada's Metal-Bearing Mineral Resources. Archived from the original on 2010-06-21. Retrieved 2010-03-23.
^Noble, D.C. (1988). "Cenozoic volcanic rocks of the northwestern Great Basin: an overview". Spring Field Trip Guidebook, Special Publication No. 7: 31–42.
^Castor, S.B. & Henry, C.D. (2000). "Geology, geochemistry, and origin of volcanic rock-hosted uranium deposits in northwest Nevada and southeastern Oregon, USA". Ore Geology Review. 16 (1–2): 1–40. Bibcode:2000OGRv...16....1C. doi:10.1016/S0169-1368(99)00021-9.
^Carson, Robert J.; Pogue, Kevin R. (1996). Flood Basalts and Glacier Floods:Roadside Geology of Parts of Walla Walla, Franklin, and Columbia Counties, Washington. Washington State Department of Natural Resources (Washington Division of Geology and Earth Resources Information Circular 90).
^
Tolan, T.L.; Reidel, S.P.; Beeson, M.H.; Anderson, J.L.; Fecht, K.R. & Swanson, D.A. (1989). Reidel, S.P. & Hooper, P.R. (eds.). Revisions to the estimates of the areal extent and volume of the Columbia River Basalt Group. Geological Society of America Special Papers. Vol. 239. Geol. Soc. Amer. Spec. Paper. pp. 1–20. doi:10.1130/SPE239-p1. ISBN978-0-8137-2239-9. {{cite book}}: |journal= ignored (help)
^Hart, W.K. & Carlson, R.W. (1985). "Distribution and geochronology of Steens Mountain-type basalts from the northwestern Great Basin". Isochron/West. 43: 5–10.
Mark H. Anders. "Yellowstone hotspot track". Columbia University, Lamont–Doherty Earth Observatory (LDEO). Retrieved 2010-03-16.
"Map of Nevada"(PDF). Nevada Bureau of Mines and Geology, University of Nevada (NBMG). Archived from the original(PDF) on 2004-10-21. Retrieved 2010-03-25.
DeNosaquo, Katrina R.; Smith, Robert B.; Lowry, Anthony R. (20 November 2009). "Density and lithospheric strength models of the Yellowstone-Snake River Plain volcanic system from gravity and heat flow data". Journal of Volcanology and Geothermal Research. 188 (1–3): 108–127. Bibcode:2009JVGR..188..108D. doi:10.1016/j.jvolgeores.2009.08.006.
Farrell, Jamie; Husen, Stephan; Smith, Robert B. (20 November 2009). "Earthquake swarm and b-value characterization of the Yellowstone volcano-tectonic system". Journal of Volcanology and Geothermal Research. 188 (1–3): 260–276. Bibcode:2009JVGR..188..260F. doi:10.1016/j.jvolgeores.2009.08.008.