Lithospheric topography, tilted plumes, and the track of the Snake River-Yellowstone hot spot (original) (raw)
Related papers
Yellowstone plume–continental lithosphere interaction beneath the Snake River Plain
Geology, 2008
The Snake River Plain represents 17 m.y. of volcanic activity that took place as the North American continent migrated over a relatively fi xed magma source, or hotspot. The identifi cation of a clear seismic image of a plume beneath Yellowstone is compelling evidence that the Miocene to recent volcanism associated with the Columbia Plateau, Oregon High Lava Plains, Snake River Plain, Northern Nevada Rift and Yellowstone Plateau represents a single magmatic system related to a mantle plume. A remaining enigma is, why do radiogenic isotope signatures from basalts erupted over the Mesozoic-Paleozoic accreted terrains suggest a plume source while basalts erupted across the Proterozoic-Archean craton margin indicate an ancient subcontinental mantle lithosphere source? We show that ancient cratonic lithosphere like that of the Wyoming province superimposes its inherent isotopic composition on sublithospheric plume and/or asthenospheric melts. The results show that Yellowstone plume could have a radiogenic isotope composition similar to the mantle source of the early Columbia River Basalt Group and that the plume source composition has persisted to the present day.
GSA Field Guide 10: Roaming the Rocky Mountains and Environs: Geological Field Trips, 2008
This fi eld trip highlights various stages in the evolution of the Snake River Plain-Yellowstone Plateau bimodal volcanic province, and associated faulting and uplift, also known as the track of the Yellowstone hotspot. The 16 Ma Yellowstone hotspot track is one of the few places on Earth where time-transgressive processes on continental crust can be observed in the volcanic and tectonic (faulting and uplift) record at the rate and direction predicted by plate motion. Recent interest in young and possible renewed volcanism at Yellowstone along with new discoveries and synthesis of previous studies, i.e., tomographic, deformation, bathymetric, and seismic surveys, provide a framework of evidence of plate motion over a mantle plume.
Journal of Geophysical Research: Solid Earth, 2004
The High Lava Plains province (HLP) is a late Cenozoic bimodal volcanic field at the northern margin of the Basin and Range province in southeastern Oregon that hosts a westward younging trend of silicic volcanism that crudely mirrors northeastward migration of silicic volcanism along the Yellowstone-Snake River Plain (YSRP) trend. We present 40 Ar/ 39 Ar ages for 19 rhyolite domes, 5 rhyolite ash flow tuffs, and 34 basaltic lavas from the HLP. The previously identified trend of westward migration of HLP rhyolites is confirmed. The rate of propagation is 33km/m.y.from10to5Ma,slowingto33 km/m.y. from 10 to 5 Ma, slowing to 33km/m.y.from10to5Ma,slowingto13 km/m.y. after 5 Ma. The duration of silicic volcanism at any locus is 2m.y.ThreeolderHLPdacitedomesyieldedagesof2 m.y. Three older HLP dacite domes yielded ages of 2m.y.ThreeolderHLPdacitedomesyieldedagesof15.5 Ma. Basalts are not age progressive. We identify several episodes of increased basaltic activity at 7.5-7.8, 5.3-5.9, and 2-3 Ma, with the younger episode likely continuing into the Recent. The HLP and YSRP trends emerged from the axis of middle Miocene basaltic volcanism of the Columbia River and Steens basalts. We propose a model in which (1) Miocene flood basalts and widespread silicic rocks are the result of emplacement of a plume head near the craton margin, enhanced by flow up a topographic gradient along the base of the lithosphere at the craton margin; (2) the HLP trend is the result of westward flow originating at the craton margin; and (3) the YSRP trend is the trace of the motion of the North American plate over the tail of the plume.
Open-File Report
We trace the Yellowstone hotspot track back to an apparent inception centered near the Oregon-Nevada border. We and others have concluded this is the locus of a starting plume or plume head. Consid eration of this plume-head model leads us to discuss the following three implications. (1) The apparent center of the relic plume head is about 250 km west of the location where both the trend of the younger hotspot track and the inferred plate motions would place the hotspot at 16 Ma. A possible explanation for this discrepancy is the westward deflection of the plume up the inclined Vancouver slab. Plate tectonic reconstructions and an intermediate dip for the Vancouver slab indicate a plume head would have encountered the Vancouver slab. (2) The postulated arrival of the plume head at the base of the lithosphere is temporally associated with eruption of the Columbia River and Oregon Plateau flood basalts at 14-17 Ma; however, these basalts were erupted several hundred kilometers north of the apparent plume center. The postulated plume center is symmetrically located near the midpoint of the 1,100-km-long Nevada-Oregon rift zone (see fig. 1). Strontium isotopic variations reflect crustal and mantle lithosphere variations along the trend of this rift zone, with the basalt area of Oregon and Washington lying west of the 0.704 line in oceanic crust, the apparent center in northern Nevada between the 0.704 and 0.706 line in intermediate crust, and the area of central and southern Nevada east of the 0.706 line in Precambrian continental crust. Geophysical model ing is consistent with a dense crust north of the Nevada-Oregon border and an asthenospheric low-density body that extends several hundred kilometers south and north of the Nevada-Oregon boundary. A recon struction of the initial contact of the plume head with the lithosphere suggests relatively thin lithosphere at 17 Ma beneath Oregon and Washington, which would favor the spreading of the plume northward in this direction, more decompression melting in this "thinspot" area, and the eruption of basalt through dense, oceanic lithosphere. Thus, preferential extrusion of flood basalts north of the plume center may be the result of differences in the pre-plume lithosphere, and not the location of the center of the plume head. (3) A plume head rising into the base of the lithosphere is expected to produce uplift, which we estimate to be on the order of 1 km with a north-south dimension of 1,000 km. This plume-head uplift, followed by subsidence, is consistent with Cenozoic paleobotanical altitude estimates. Other climatic indicators show major aridity about 15 Ma in areas in the inferred precipitation shadow east of the in ferred uplift. Indicators of climate about 7 Ma are compatible with an eastward migration of uplift to a site between the plume-head area and the present Yellowstone crescent of high terrain. The warm Neo gene "climate optimum" correlates with 14-17-Ma flood basalt and rhyolite volcanism. The continued effects of Yellowstone plume-head uplift and ensuing plume tail uplift, if real, could provide regional uplift that is geophysically plausible. Climatic modeling has shown that uplift of the age and latitude of the postulated Yellowstone plume-head uplift, if allied with Himalayan and perhaps other uplifts could result in the late Cenozoic cooling leading to the Pliocene-Pleistocene ice ages (Kutzbach and others, 1989; Ruddiman and others, 1989, 1997). Thus, the postulated Yellowstone plume head could have played an important role in the late Ceno zoic geologic history of the northern, interior part of the U.S. Cordillera. Future studies of the kind briefly discussed here should provide a better evaluation of the Yellowstone plume head concept.
Geophysical Journal International
The Yellowstone-East Snake River Plain hotspot track has been intensely studied since several decades and is widely considered to result from the interaction of a mantle plume with the North American plate. An integrated conclusive geodynamic interpretation of this extensive data set is however presently still lacking, and our knowledge of the dynamical processes beneath Yellowstone is patchy. It has been argued that the Yellowstone plume has delaminated the lower part of the thick Wyoming cratonic lithosphere. We derive an original dynamic model to quantify delamination processes related to mantle plume-lithosphere interactions. We show that fast (∼300 ka) lithospheric delamination is consistent with the observed timing of formation of successive volcanic centres along the Yellowstone hotspot track and requires (i) a tensile stress regime within the whole lithosphere exceeding its failure threshold, (ii) a purely plastic rheology in the lithosphere when stresses reach this yield limit, (iii) a dense lower part of the 200 km thick Wyoming lithosphere and (iv) a decoupling melt horizon inside the median part of the lithosphere. We demonstrate that all these conditions are verified and that ∼150 km large and ∼100 km thick lithospheric blocks delaminate within 300 ka when the Yellowstone plume ponded below the 200 km thick Wyoming cratonic lithosphere. Furthermore, we take advantage of the available extensive regional geophysical and geological observation data sets to design a numerical 3-D upper-mantle convective model. We propose a map of the ascending convective sheets contouring the Yellowstone plume. The model further evidences the development of a counter-flow within the lower part of the lithosphere centred just above the Yellowstone mantle plume axis. This counter-flow controls the local lithospheric stress field, and as a result the trajectories of feeder dykes linking the partial melting source within the core of the mantle plume with the crust by crosscutting the lithospheric mantle. This counter-flow further explains the 50 km NE shift observed between the mantle plume axis and the present-day Yellowstone Caldera as well as the peculiar shaped crustal magma chambers.
Upper-mantle origin of the Yellowstone hotspot
Geological Society of America Bulletin, 2002
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 ϳ200 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.
The Role of the Ancestral Yellowstone Plume in the Tectonic Evolution of the Western United States
Geoscience Canada
Plate reconstructions indicate that if the Yellowstone plume existed prior to 50 Ma, then it would have been overlain by oceanic lithosphere located to the west of the North American plate (NAP). In the context of models supporting long-lived easterly directed subduction of oceanic lithosphere beneath the NAP, the Yellowstone plume would have been progressively overridden by the NAP continental margin since that time, the effects of which should be apparent in the geological record. The role of this ‘ancestral’ Yellowstone plume and its related buoyant swell in influencing the Late Mesozoic–Cenozoic tectonic evolution of the southwestern United States is reviewed in the light of recent field, analytical and geophysical data, constraints provided by more refined paleogeographic constructions, and by insights derived from recent geodynamic modeling of the interaction of a plume and a subduction zone. Geodynamic models suggesting that the ascent of plumes is either stalled or destroy...