The Yellowstone Magmatic System from the Mantle Plume to the Upper Crust Hsin-Hua Huang, Fan-Chi Lin, Brandon Schmandt, Jamie Farrell, Robert B. Smith, Victor C. Tsai PDF Download
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Author: Hsin-Hua Huang
Publisher:
ISBN:
Category : Snake River Plain (Idaho and Or.)
Languages : en
Pages : 4
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Book Description
The Yellowstone supervolcano is one of the largest active continental silicic volcanic fields in the world. An understanding of its properties is key to enhancing our knowledge of volcanic mechanisms and corresponding risk. Using a joint local and teleseismic earthquake P-wave seismic inversion, we revealed a basaltic lower-crustal magma body that provides a magmatic link between the Yellowstone mantle plume and the previously imaged upper-crustal magma reservoir. This lower-crustal magma body has a volume of 46,000 cubic kilometers, ~4.5 times that of the upper-crustal magma reservoir, and contains a melt fraction of ~2%. These estimates are critical to understanding the evolution of bimodal basaltic-rhyolitic volcanism, explaining the magnitude of CO2 discharge, and constraining dynamic models of the magmatic system for volcanic hazard assessment.
Author: Hsin-Hua Huang
Publisher:
ISBN:
Category : Snake River Plain (Idaho and Or.)
Languages : en
Pages : 4
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Book Description
The Yellowstone supervolcano is one of the largest active continental silicic volcanic fields in the world. An understanding of its properties is key to enhancing our knowledge of volcanic mechanisms and corresponding risk. Using a joint local and teleseismic earthquake P-wave seismic inversion, we revealed a basaltic lower-crustal magma body that provides a magmatic link between the Yellowstone mantle plume and the previously imaged upper-crustal magma reservoir. This lower-crustal magma body has a volume of 46,000 cubic kilometers, ~4.5 times that of the upper-crustal magma reservoir, and contains a melt fraction of ~2%. These estimates are critical to understanding the evolution of bimodal basaltic-rhyolitic volcanism, explaining the magnitude of CO2 discharge, and constraining dynamic models of the magmatic system for volcanic hazard assessment.
Author: Fan-Chi Lin
Publisher:
ISBN:
Category :
Languages : en
Pages : 4
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Author:
Publisher:
ISBN:
Category : Geology, Structural
Languages : en
Pages : 218
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Author: Eugene D. Humphreys
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ISBN:
Category : Geology, Structural
Languages : en
Pages : 7
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Author: Robert Baer Smith
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ISBN:
Category : Calderas
Languages : en
Pages : 122
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Book Description
Direct evidence for a plume-plate interaction as the mechanism responsible for the Yellowstone-Snake River Plain (YSRP), 16 Ma volcanic system is observation of a linear age-progression of silicic volcanic centers along the Snake River Plain 800 km to the Yellowstone caldera-- the track of the Yellowston hotspot. Caldera-forming rhyolitic volcanism, active crustal deformation, extremely high heat flow (30 times the continental average), and intensive earthquake activity in Yellowstone National Park mark the surface manifestations of the hotspot. Anomalously low, P-wave velocities in the upper-crust of the Yellowstone caldera are interpreted as solidified but still hot granitic rocks, partial melts, hydrothermal fluids and sediments. Unprecedented deformation of the Yellowstone caldera of up to 1 m of uplift from 1923 to 1984, followed by subsidence of as much as ~12 cm from 1985 to 1991, clearly reflects a giant caldera unrest. The regional signature of the Yellowstone hotspot is highlighted by an anomalous, 600 m high, topographic bulge centered on the caldera and that extends across a ~600 km-wide region. We suggest that this feature reflecs long-wavelength tumescence of the hotspot. Yellowstone is also the center of a +20 m geoid anomaly, the largest in North America, and extends ~500 km laterally from the caldera, similar in width to the geoid anomalies of many oceanic hotspots and swells. The 16 Ma trace of the Yellowstone hotspot, the seismically quiescent Snake River Plain, is surrounded by "bow-wave" or parabolic shaped regions of earthquakes and high topography. Whereas systematic topographic decay along the Snake River Plain, totaling 1,300 m, fits a model of lithospheric cooling and subsidence which is consistent with passage of the North American plate across a mantle heat source. We note that the rate of 4.5 cm/yr silicic, volcanic age progression of the YSRP includes a component of southwest motion of the North American plate, modeled at ~2.5 cm/yr, and a component of concomitant crustal extension estimated to be 1 to 2 cm/yr. The USRP also exhibits anomalous crustal structure which we believe is inherited from magmatic and thermal processes associated which the Yellowstone hotspot. This includes a thin, 2-5 km-thick surface layer compses of basalts and rhyolites and an unusually high-velocity, 6.5 km/s, mid-crustal mafic layer that we suggest reflects extinct "Yellowstone" magma systems that have replaced much of the normal granite upper-crust. Direct evidence for a mantle connection for the YSRP system is from anomalously low, P-wave velocities which extend from the crust to depths of ~200km. These properties and the kinematics of teh YSRP are consistent with an analytic model for plume-plate interaction that produces a "bow-wave" or parabolic patter of upper-mantle flow southwesterly from the hotspot, similar to the systematic patterns of regional topography and seismicity. Our unified model for the origin of the YSRP is consistent with the geologic evidence where basaltic magmas ascend from a mantle plume to interact with a silicic-rich continental crust producing partial melts of rhyolite composition and the characteristic caldera-forming volcanism of Yellowstone. Cooling and contraction of the lithosphere follows the passage of the plate over the hotspot with continuing episodic eruptions of mantle-derived basalts along the SRP.
Author: Robert L. Christiansen
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 12
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Fundamental features of the geology and tectonic setting of the northeast-propagating Yellowstone hotspot are not explained by a simple deep-mantle plume hypothesis and, within that framework, must be attributed to coincidence or be explained by auxiliary hypotheses. These features include the persistence of basaltic magmatism along the hotspot track, the origin of the hotspot during a regional middle Miocene tectonic reorganization, a similar and coeval zone of northwestward magmatic propagation, the occurrence of both zones of magmatic propagation along a first-order tectonic boundary, and control of the hotspot track by preexisting structures. Seismic imaging provides no evidence for, and several contraindications of, a vertically extensive plume-like structure beneath Yellowstone or a broad trailing plume head beneath the eastern Snake River Plain. The high helium isotope ratios observed at Yellowstone and other hotspots are commonly assumed to arise from the lower mantle, but upper-mantle processes can explain the observations. The available evidence thus renders an upper-mantle origin for the Yellowstone system the preferred model; there is no evidence that the system extends deeper than 200 km, and some evidence that it does not. A model whereby the Yellowstone system reflects feedback between upper-mantle convection and regional lithospheric tectonics is able to explain the observations better than a deep-mantle plume hypothesis. --Abstract.
Author: Georg S. Reuber
Publisher:
ISBN:
Category : 3D model
Languages : en
Pages : 17
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Book Description
The Yellowstone magmatic system is one of the largest magmatic systems on Earth, and thus an ideal location to study magmatic processes. Whereas previous seismic tomography results could only image a shallow magma reservoir, a recent study using more seismometers showed that a second and massive partially molten mush reservoir exists above the Moho (Huang et al., 2015). To understand the measurable surface response of this system to visco-elasto-plastic deformation, it is thus important to take the whole system from the mantle plume up to the shallow magma reservoirs into account. Here, we employ lithospheric-scale 3D visco-elasto-plastic geodynamic models to test the influence of parameters such as the connectivity of the reservoirs and rheology of the lithosphere on the dynamics of the system. A gravity inversion is used to constrain the effective density of the magma reservoirs, and an adjoint modeling approach reveals the key model parameters affecting the surface velocity. Model results show that a combination of connected reservoirs with plastic rheology can explain the recorded slow vertical surface uplift rates of around 1.2 cm/year, as representing a long term background signal. A geodynamic inversion to fit the model to observed GPS surface velocities reveals that the magnitude of surface uplift varies strongly with the viscosity difference between the reservoirs and the crust. Even though stress directions have not been used as inversion parameters, modeled stress orientations are consistent with observations. However, phases of larger uplift velocities can also result from magma reservoir inflation which is a short term effect. We consider two approaches: (1) overpressure in the magma reservoir in the asthenosphere and (2) inflation of the uppermost reservoir prescribed by an internal kinematic boundary condition. We demonstrate that the asthenosphere inflation has a smaller effect on the surface velocities in comparison with the uppermost reservoir inflation. We show that the pure buoyant uplift of magma bodies in combination with magma reservoir inflation can explain (varying) observed uplift rates at the example of the Yellowstone volcanic system.
Author: Dylan P. Colon
Publisher:
ISBN:
Category : Geophysics
Languages : en
Pages : 18
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Book Description
Geophysical imaging of the Yellowstone supervolcano shows a broad zone of partial melt interrupted by an amagmatic gap at depths of 15-20 km. We reproduce this structure through a series of regional-scale magmatic-thermomechanical forward models which assume that magmatic dikes stall at rheologic discontinuities in the crust. We find that basaltic magmas accumulate at the Moho and at the brittle-ductile transition, which naturally forms at depths of 5-10 km. This leads to the development of a 10-15 km thick mid-crustal sill complex with a top at a depth of approximately 10 km, consistent with geophysical observations of the pre-Yellowstone hotspot track. We show a linear relationship between melting rates in the mantle and rhyolite eruption rates along the hotspot track. Finally, melt production rates from our models suggest that the Yellowstone plume is ~175°C hotter than the surrounding mantle and that the thickness of the overlying lithosphere is ~80 km.
Author: Robert b Smith
Publisher:
ISBN:
Category :
Languages : en
Pages : 5
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Author: Kenneth Lee Pierce
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Category : Earth movements
Languages : en
Pages : 25
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Geophysical imaging of a tilted mantle plume extending at least 500 km beneath the Yellowstone caldera provides compelling support for a plume origin of the entire Yellowstone hotspot track back to its inception at 17Mawith eruptions of flood basalts and rhyolite. The widespread volcanism, combined with a large volume of buoyant asthenosphere, supports a plume head as an initial phase. Estimates of the diameter of the plume head suggest it completely spanned the upper mantle and was fed from sources beneath the transition zone, We consider a mantle?plume depth to at least 1,000 km to best explain the large scale of features associated with the hotspot track. The Columbia River?Steens flood basalts form a northward-migrating succession consistent with the outward spreading of a plume head beneath the lithosphere. The northern part of the inferred plume head spread (pancaked) upward beneath Mesozoic oceanic crust to produce flood basalts, whereas basalt melt from the southern part intercepted and melted Paleozoic and older crust to produce rhyolite from 17 to 14 Ma. The plume head overlapped the craton margin as defined by strontium isotopes; westward motion of the North American plate has likely ?scraped off? the head from the plume tail. Flood basalt chemistries are explained by delamination of the lithosphere where the plume head intersected this cratonic margin. Before reaching the lithosphere, the rising plume head apparently intercepted the east-dipping Juan de Fuca slab and was deflected ~250 km to the west; the plume head eventually broke through the slab, leaving an abruptly truncated slab. Westward deflection of the plume head can explain the anomalously rapid hotspot movement of 62 km/m.y. from 17 to 10 Ma, compared to the rate of ~25 km/m.y. from 10 to 2 Ma. A plume head-to-tail transition occurred in the 14-to-10-Ma interval in the central Snake River Plain and was characterized by frequent (every 200?300 ka for about 2 m.y. from 12.7 to 10.5 Ma) ?large volume (N7000 km3)?, and high temperature rhyolitic eruptions (N1000 °C) along a ~200?km-wide east?west band. The broad transition area required a heat source of comparable area. Differing characteristics of the volcanic fields here may in part be due to variations in crustal composition but also may reflect development in differing parts of an evolving plume where the older fields may reflect the eruption from several volcanic centers located above very large and extensive rhyolitic magma chamber(s) over the detached plume head while the younger fields may signal the arrival of the plume tail intercepting and melting the lithosphere and generating a more focused rhyolitic magma chamber. The three youngest volcanic fields of the hotspot track started with large ignimbrite eruptions at 10.21, 6.62, and 2.05 Ma. They indicate hotspot migration N55° E at ~25 km/m.y. compatible in direction and velocity with the North American Plate motion. The Yellowstone Crescent of High Terrain (YCHT) flares outward ahead of the volcanic progression in a pattern similar to a bow-wave, and thus favors a sub-lithospheric driver. Estimates of YCHT-uplift rates are between 0.1 and 0.4mm/yr.Drainage divides havemigrated northeastwardwith the hotspot. The Continental Divide and a radial drainage pattern nowcenters on the hotspot. The largest geoid anomaly in the conterminous U.S. is also centered on Yellowstone and, consistent with uplift above a mantle plume. Bands of late Cenozoic faulting extend south and west from Yellowstone. These bands are subdivided into belts based both on recency of offset and range-front height. Fault history within these belts suggests the following pattern: Belt I ? starting activity but little accumulated offset; Belt II ? peak activity with high total offset and activity younger than 14 ka; Belt III?waning activitywith large offset and activity younger than 140 ka; and Belt IV ? apparently dead on substantial range fronts (south side of the eastern Snake River Plain only). These belts of fault activity have migrated northeast in tandem with the adjacent hotspot volcanism. On the southern arm of the YCHT, fault activity occurs on the inner, western slope consistent with driving by gravitational potential energy, whereas faulting has not started on the eastern, outer, more compressional slope. Range fronts increase in height and steepness northeastward along the southern-fault band. Both the belts of faulting and the YCHT are asymmetrical across the volcanic hotspot track, flaring out 1.6 times more on the south than the north side. This and the southeast tilt of the Yellowstone plumemay reflect southeast flow of the upper mantle.
