Geochronologic and paleomagnetic evidence defining the relationship between the Miocene Hiko and Racer Canyon tuffs, eccentric outflow lobes from the Caliente caldera complex, southeastern Great Basin, USA

Grommé, Sherman; Deino, A.; Best, Myron G.; Hudson, Mark R.

doi:10.1007/s004450050172

Cited by 6 publications

(7 citation statements)

References 26 publications

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“…The Fraction Tuff of Ekren et al (1971) is similar in age and composition, including trace amounts of titanite (Fig. 70), to the 18.51 ± 0.05 Ma Hiko and the 18.57 ± 0.03 Ma upper Racer Canyon Tuffs, which are the youngest ignimbrites in the Indian Peak-Caliente fi eld to the east (Best et al, 2013b;Gromme et al,1997). This is yet another example of near-simultaneous eruptions, in this case of similar magmas, from independent and well-documented sources in the southern Great Basin ignimbrite province; they are as little as 100 km from one another, after correction for extension.…”

Section: Fraction Tuffmentioning

confidence: 82%

The 36–18 Ma Central Nevada ignimbrite field and calderas, Great Basin, USA: Multicyclic super-eruptions

Best

Grommé²,

Deino

et al. 2013

Geosphere

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One of the greatest global manifestations of explosive silicic volcanism in the terrestrial rock record occurred during the middle Cenozoic over a large part of southwestern North America, from the Great Basin of Nevada and western Utah into Colorado, Arizona, New Mexico, and Mexico. This subduction-related ignimbrite fl areup is the only one known in the world of its magnitude and of Mesozoic or Cenozoic age that is not related to continental breakup. The southern Great Basin ignimbrite province was a major product of the fl areup . Its central and eastern sectors developed on the Great Basin altiplano, a high orogenic plateau of limited relief dating from pulses of late Paleozoic through Mesozoic orogenic contractile deformation. Caldera-forming activity migrated southwestward through time in response to rollback of a once-fl at slab of subducting lithosphere.In the central sector of the southern Great Basin ignimbrite province, 11 partly exposed, mostly overlapping source calderas and one concealed source comprise the 36-18 Ma Central Nevada caldera complex. Calderas have diameters as much as 50 km, to possibly 80 km. Intracaldera tuff and intercalated wall-collapse breccia are at least 2000 m thick.Surrounding outfl ow ignimbrites consist of 17 regional cooling units (>200 km 3 ) that have been correlated over two or more mountain ranges on the basis of stratigraphic position, paleomagnetic direction, chemical and modal composition, and 40 Ar/ 39 Ar age. Many additional smaller cooling units have been recognized. Possibly as many as eight of the ignimbrites resulted from super-eruptions of 1000 km 3 to as much as 4800 km 3 . This Central Nevada ignimbrite fi eld is presently exposed over an area of ~65,000 km 2 in south-central Nevada and had a volume of 25,000 km 3 corrected for post-volcanic crustal extension. Six of the largest eruptions broadcast ash fl ows over an extension-corrected area of greater than 16,000 km 2 and as much as 160 km from their caldera sources. Individual sections of outfl ow tuff include as many as 14 ignimbrite cooling units; aggregate thicknesses locally reach a kilometer, and stacks a few hundred meters thick are common. Sequences are almost everywhere conformable and lack substantial intervening erosional debris and angular discordances that would testify to synvolcanic crustal extension. Beds of fallout ash a few meters thick associated with the largest eruption have been recognized in the mid-continent of the U.S.Six caldera-forming eruptive episodes are separated by fi ve lulls in activity, each lasting from 1.7 to 4.4 m.y., during which time little (<200 km 3 ) or no ignimbrite was deposited. Some of the longer lulls that preceded the most voluminous eruptions likely refl ected the time for accumulation of magma in huge shallow chambers before eruption was triggered. Other long lulls preceded the last two, single eruptions as the arc magma-generating system was waning prior to the transition to non-arc magma production to the south in the Southwestern Nevada volcanic fi eld....

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Section: Fraction Tuffmentioning

confidence: 82%

The 36–18 Ma Central Nevada ignimbrite field and calderas, Great Basin, USA: Multicyclic super-eruptions

Best

Grommé²,

Deino

et al. 2013

Geosphere

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“…At sites within a few tens of kilometers on either side of the Utah-Nevada state line the two units overlap. The unusually thick section of cooling units of rhyolite ignimbrites near Panaca Summit, originally mapped as all Racer Canyon Tuff (Williams et al, 1997), has now been divided into 390 m of the Hiko Tuff above a prominent layer of vitrophyre (paleomagnetic sample 0P284 in Gromme et al, 1997) and 485 m of the underlying Racer Canyon Tuff.…”

Section: Stratigraphymentioning

confidence: 99%

“…Although considerable work has been done on these two similar rhyolite ignimbrites (e.g., Rowley et al, 1995;Gromme et al, 1997), full understanding of their stratigraphic relations, distribution, and compositional variations is incomplete. Further paleomagnetic and chronologic analyses will be needed to distinguish them throughout their extent in the eastern Great Basin (Figs.…”

Section: Stratigraphymentioning

confidence: 99%

“…Available modal data do not unequivocally distinguish between the Racer Canyon and Hiko because of overlap in proportions of phenocrysts (Rowley et al, 1995, their fi gure 15;Gromme et al, 1997, their fi gure 3). But in an attempt to possibly clarify differences we have plotted Hiko modes from samples well into Nevada and Racer Canyon modes from samples well into Utah, both from Rowley et al (1995); these selected samples avoid uncertain stratigraphic identities near the state line as just described.…”

Section: Petrography and Compositionmentioning

confidence: 99%

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The 36–18 Ma Indian Peak–Caliente ignimbrite field and calderas, southeastern Great Basin, USA: Multicyclic super-eruptions

et al. 2013

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“…In principle, it seems unlikely that pyroclasts would vent uniformly around the perimeter of the ring-fracture to create a radially uniform outflow sheet. Among others, Gromme et al (1997) have documented lobate emplacement of ash flows vented from adjacent sectors of a caldera system. Topographic influences on ash-flow dispersal as well as differential post-emplacement erosion of the outflow sheet can also create an eccentric source-outflow sheet relationship.…”

Section: Eccentricity Of Source Calderas Within Their Corresponding Omentioning

confidence: 99%

The Great Basin Altiplano during the middle Cenozoic ignimbrite flareup: insights from volcanic rocks

Best

Barr

Christiansen

et al. 2009

International Geology Review

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125

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Uncertainty surrounds the fate of the orogenic plateau in what is now the Great Basin in western Utah and Nevada, which resulted from the Mesozoic and earliest Cenozoic contractile deformations and crustal thickening. Although there is some consensus regarding the gravitational collapse of the plateau by extensional faulting and consequent crustal thinning, whether or not the plateau existed during the middle Cenozoic Great Basin ignimbrite flareup -one of the grandest expressions of continental volcanism in the geologic record -had remained in doubt. We use compositions of contemporaneous calc-alkaline lava flows as well as configurations of the ignimbrite sheets to show that the Great Basin area during the middle Cenozoic was a relatively smooth plateau underlain by unusually thick crust. We compare analyses of 376 intermediate-composition lava flows in the Great Basin that were extruded at 42 -17 Ma with compositions of .6000 analyses of the late Cenozoic lava flows in continental volcanic arcs that correlate roughly with known crustal thickness. This comparison indicates that the middle Cenozoic Great Basin crust was much thicker than the present ca. 30 km thickness, likely as much as 60 -70 km. If isostatic equilibrium prevailed, this unusually thick continental crust must have supported high topography. This high terrain in SE Nevada and SW Utah was progressively smoothed as successive ignimbrite outflow sheets were emplaced over areas currently as much as tens of thousands of square kilometres to aggregate thicknesses of as much as hundreds of metres. The generally small between-site variations in the palaeomagnetic directions of individual sheets lend further support for a relatively smooth landscape over which the sheets were draped. We conclude that during the middle Cenozoic, especially towards the close of the ignimbrite flareup, this Great Basin area was a relatively flat plateau, and because it was also high in elevation, we refer to it as an Altiplano. It was not unlike the present-day Altiplano-Puna in the tectonically similar central Andes, where an ignimbrite flareup comparable to that in the Great Basin occurred at ca. 9-3 Ma. Outflow ignimbrite sheets that were deposited from 35 to 23 Ma on the progressively smoothed Altiplano in south-eastern Nevada were derived from source calderas to the west. Of the 12 major sheets from seven sources, nine are distributed unevenly east of their sources while the remaining three sheets are spread about as far east as west of their sources. This eccentricity of sources near the western margin of 75% of the sheets indicates the existence of a NS-trending topographic barrier in central Nevada that restricted westward dispersal of ash flows. In a symmetric manner, eastward dispersal of ash flows from sources farther west seemed to have been impeded by this same topographic barrier. The westward dispersal was controlled in part by westward-draining stream valleys incised in the sloping flank of the Great Basin Vol. 51, Nos. 7 -8, July-August 2009, 589-633 A...

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Geochronologic and paleomagnetic evidence defining the relationship between the Miocene Hiko and Racer Canyon tuffs, eccentric outflow lobes from the Caliente caldera complex, southeastern Great Basin, USA

Cited by 6 publications

References 26 publications

The 36–18 Ma Central Nevada ignimbrite field and calderas, Great Basin, USA: Multicyclic super-eruptions

The 36–18 Ma Central Nevada ignimbrite field and calderas, Great Basin, USA: Multicyclic super-eruptions

The 36–18 Ma Indian Peak–Caliente ignimbrite field and calderas, southeastern Great Basin, USA: Multicyclic super-eruptions

The Great Basin Altiplano during the middle Cenozoic ignimbrite flareup: insights from volcanic rocks

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