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41-445: The eastern Snake River Plain is a topographic depression that cuts across Basin and Range Mountain structures, more or less parallel to North American Plate motion. Beneath more recent basalts are rhyolite lavas and ignimbrites that erupted as the lithosphere passed over the hotspot . Younger volcanoes that erupted after passing over the hotspot covered the plain with young basalt lava flows in places, including Craters of

82-519: 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

123-522: A configuration which has given rise to increased shearing along the continental margin . The tectonic activity responsible for the extension in the Basin and Range is a complex and controversial issue among the geoscience community. The most accepted hypothesis suggests that crustal shearing associated with the San Andreas Fault caused spontaneous extensional faulting similar to that seen in

164-594: A group of related geologic features formed by crustal extension during the Cenozoic era (66.0 million years ago to present). The study of metamorphic core complexes has provided valuable insight into the extensional processes driving Basin and Range formation. Prior to the Eocene Epoch (55.8 ±0.2 to 33.9 ±0.1 Ma) the convergence rate of the Farallon and North American plates was fast, the angle of subduction

205-593: 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 fossilized rhinoceros and many other animals were preserved in two meters of volcanic ash. By its characteristic chemical fingerprint and

246-791: Is a depression, sinking under the weight of the volcanic rocks that formed it, through which the Snake River winds. Other observable volcanic features in the plain include: the Menan Buttes , the Big Southern Butte , Craters of the Moon , the Wapi Lava Field and Hell's Half Acre . These calderas are in an area called Island Park that is known for beautiful forests, large springs, clear streams, waterfalls, lakes, ponds, marshes, wildlife, and fishing. Harriman State Park

287-584: 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

328-417: Is mostly arid and sparsely populated, although there are several major metropolitan areas, such as Reno , Las Vegas , Salt Lake City , Phoenix , Tucson , El Paso — Ciudad Juárez , Mexicali , and Hermosillo . It is generally accepted that basin and range topography is the result of extension and thinning of the lithosphere , which is composed of crust and upper mantle . Extensional environments like

369-706: 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

410-745: 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 km (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

451-642: Is the source of the Mesa Falls Tuff. 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

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492-477: Is therefore thought to be unrelated to the kind of extension produced by mantle upwelling which may cause narrow rift zones, such as those of the Afar triple junction . Geologic processes that elevate heat flow are varied, however some researchers suggest that heat generated at a subduction zone is transferred to the overriding plate as subduction proceeds. Fluids along fault zones then transfer heat vertically through

533-466: The 1980 eruption of Mount St. Helens . Island Park Caldera has the smaller and younger Henry's Fork Caldera nested inside it. The caldera clearly visible today is the later Henry's Fork Caldera, which is the source of the Mesa Falls Tuff . It was formed 1.3 Ma in an eruption of more than 280 km (67 cu mi). The two nested calderas share the same rim on their western sides, but

574-884: The Wasatch Fault , the Colorado Plateau and the Rio Grande Rift . The province extends north to the Columbia Plateau and south as far as the Trans-Mexican Volcanic Belt in Mexico , though the southern boundaries of the Basin and Range are debated. In Mexico, the Basin and Range Province is dominated by and largely synonymous with the Mexican Plateau . Evidence suggests that the less-recognized southern portion of

615-427: The Basin and Range are characterized by listric normal faulting , or faults that level out with depth. Opposing normal faults link at depth producing a horst and graben geometry, where horst refers to the upthrown fault block and graben to the down dropped fault block. The average crustal thickness of the Basin and Range Province is approximately 30–35 km and is comparable to extended continental crust around

656-554: The Basin and Range province are controversial, and several competing hypotheses attempt to explain them. Key events preceding Basin and Range extension in the western United States include a long period of compression due to the subduction of the Farallon plate under the west coast of the North American continental plate which stimulated the thickening of the crust. Most of the pertinent tectonic plate movement associated with

697-568: The Early Miocene with the southern portion of the province representing a greater degree of displacement than the north. Evidence exists to suggest that extension initially began in the southern Basin and Range and propagated north over time. Clarence Dutton famously compared the many narrow parallel mountain ranges that distinguish the unique topography of the Basin and Range to an "army of caterpillars crawling northward." The tectonic mechanisms responsible for lithospheric extension in

738-487: The Great Basin. However, plate movement alone does not account for the high elevation of the Basin and Range region. The western United States is a region of high heat flow which lowers the density of the lithosphere and stimulates isostatic uplift as a consequence. Lithospheric regions characterized by elevated heat flow are weak and extensional deformation can occur over a broad region. Basin and Range extension

779-535: The Kilgore Tuff – which erupted 1800 km of ash, occurred 4.5 million years ago. The Yellowstone Plateau volcanic field is composed of four adjacent calderas. West Thumb Lake is itself formed by a smaller caldera 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 km (67 cu mi) 1.3 million years ago, and

820-716: The Moon National Monument and Preserve . 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 . 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

861-614: The Pacific-Farallon Ridge was subducted beneath North America ending subduction along this part of the Pacific margin; however, the Farallon plate continued to subduct into the mantle . The movement at this boundary divided the Pacific-Farallon Ridge and spawned the San Andreas transform fault , generating an oblique strike-slip component. Today, the Pacific plate moves north-westward relative to North America,

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902-430: The U.S. states of Idaho and Wyoming , is one of the world's largest calderas , with approximate dimensions of 80 by 65 km. Its ashfall is the source of the Huckleberry Ridge Tuff that is found from southern California to the Mississippi River near St. Louis . This super-eruption of approximately 2,500 km (600 cu mi) occurred 2.1 Ma (million years ago) and produced 2,500 times as much ash as

943-486: The area affected by this mid- Miocene volcanism is significantly larger than previously appreciated. Three silicic calderas have been newly identified in northwest Nevada, west of the McDermitt volcanic field as well as the Virgin Valley Caldera. 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

984-416: The crust. This model has led to increasing interest in geothermal systems in the Basin and Range, and requires consideration of the continued influence of the fully subducted Farallon plate in the extension responsible for the Basin and Range Province. In some localities in the Basin and Range, metamorphic basement is visible at the surface. Some of these are metamorphic core complexes (MCC), an idea that

1025-670: 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 . The Twin Falls and Picabo volcanic fields were active about 10 million years ago. The Picabo Caldera

1066-688: The greater Basin and Range physiographic region. Nor should it be confused with the Basin and Range National Monument , located in Southern Nevada, which is one small part of the much larger province. The Basin and Range Province includes much of western North America . In the United States, it is bordered on the west by the eastern fault scarp of the Sierra Nevada and spans over 500 miles (800 km) to its eastern border marked by

1107-618: The older Island Park Caldera is much larger and more oval and extends well into Yellowstone National Park . The Island Park Caldera is sometimes referred to as the First Phase Yellowstone Caldera or the Huckleberry Ridge Caldera. To the southwest of the caldera lies the Snake River Plain , which was formed by a succession of older calderas marking the path of the Yellowstone hotspot . The plain

1148-731: The province is White Mountain Peak in California , while the lowest point is the Badwater Basin in Death Valley at −282 feet (−86 m). The province's climate is arid, with numerous ecoregions . Most North American deserts are located within it. The Basin and Range Province should not be confused with the Great Basin , a region defined by its unique hydrological characteristics (internal drainage) that overlaps much of

1189-733: The province is bounded on the east by the Laramide Thrust Front of the Sierra Madre Oriental and on the west by the Gulf of California and Baja Peninsula with notably less faulting apparent in the Sierra Madre Occidental in the center of the southernmost Basin and Range Province. Common geographic features include numerous endorheic basins , ephemeral lakes, plateaus, and bolson valleys alternating with mountains (as described below). The area

1230-742: The province is the result of tectonic extension that began around 17 million years ago in the early Miocene epoch. The numerous ranges within the province in the United States are collectively referred to as the "Great Basin Ranges", although many are not actually in the Great Basin . Major ranges include the Snake Range , the Panamint Range , the White Mountains , and the Sandia Mountains . The highest point fully within

1271-595: The province occurred in the Neogene period (23.03-2.58 million years ago) and continues to the present. By the Early Miocene sub-epoch (23.03-15.97 million years ago), much of the Farallon plate had been consumed, and the seafloor spreading ridge that separated the Farallon plate from the Pacific plate ( Pacific-Farallon Ridge ) approached North America. In the Middle Miocene (15.97-11.63 million years ago),

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1312-569: The ranks of its deceased ancestors in the Snake River Plain. A 2020 study suggests that the hotspot may be waning. Basin and Range Province The Basin and Range Province is a vast physiographic region covering much of the inland Western United States and northwestern Mexico . It is defined by unique basin and range topography , characterized by abrupt changes in elevation, alternating between narrow faulted mountain chains and flat arid valleys or basins. The physiography of

1353-537: 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

1394-638: 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

1435-589: The waning stage of the Steens flood basalt volcanism. The northwest Nevada calderas have diameters ranging from 15 to 26 km and deposited high temperature rhyolite ignimbrites over approximately 5000 km. 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. The Bruneau-Jarbidge volcanic field erupted between ten and twelve million years ago, spreading

1476-424: The world. The crust in conjunction with the upper mantle comprises the lithosphere . The base of the lithosphere beneath the Basin and Range is estimated to be about 60–70 km. Opinions vary regarding the total extension of the region; however, the median estimate is about 100% total lateral extension. Total lateral displacement in the Basin and Range varies from 60 to 300 km since the onset of extension in

1517-412: Was completely consumed and volcanic activity ceased, in part. Olivine basalt from the oceanic ridge erupted around 17 Ma and extension began. In addition to small amounts of Nevada petroleum , the Basin and Range Province supplies nearly all the copper and most of the gold , silver , and barite mined in the United States. Island Park Caldera The Island Park Caldera , in

1558-455: Was first developed based on studies in this province. A metamorphic core complex occurs when lower crust is brought to the surface as a result of extension. MCCs in the Basin and Range were not interpreted as being related to crustal extension until after the 1960s. Since then, similar deformational patterns have been identified in MCCs in the Basin and Range and has led geologists to examine them as

1599-474: 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

1640-572: Was notable for producing the Arbon Valley Tuff 10.2 million years ago. 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 km of erupted magma. The final, extremely voluminous, caldera-forming eruption –

1681-566: Was shallow, and the slab width was huge. During the Eocene the Farallon plate subduction -associated compressive forces of the Laramide , Sevier and Nevada orogenies ended, plate interactions changed from orthogonal compression to oblique strike-slip , and volcanism in the Basin and Range Province flared up ( Mid-Tertiary ignimbrite flare-up ). It is suggested that this plate continued to be underthrust until about 19 Ma, at which time it

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