Guide to geophysical data for the northern Rocky Mountains and adjacent areas, Idaho, Montana, Washington, Oregon, and Wyoming

Mankinen, Edward A.; Hildenbrand, Thomas G.; Zientek, Michael L.; Box, Stephen E.; Bookstrom, Arthur A.; Carlson, M.H.; Larsen, Jeremy C.

doi:10.3133/ofr20041413

Cited by 10 publications

(16 citation statements)

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“…This idea is supported by long-wavelength isostatic residual gravity and magnetic potential maps (figs 8 & 18 of Mankinen et al 2004) that effectively illuminate positive mass and magnetic anomalies at midcrustal depths beneath much of the SRP and show that these anomalies are largely confined to the physiographic province (c. 100 km wide by 600 km long). Magmatic densification of the crust is also supported by available seismic refraction studies (Hill & Pakiser 1967;Pakiser 1991).…”

Section: Evidence For Basalt Intrusion In the Middle -Upper Crustmentioning

confidence: 82%

Snake River Plain – Yellowstone silicic volcanism: implications for magma genesis and magma fluxes

Leeman

Annen

Dufek

2008

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The origin of large-volume, high-temperature silicic volcanism associated with onset of the Snake River Plain -Yellowstone (SRPY) hotspot track is addressed based on evolution of the well-characterized Miocene Bruneau-Jarbidge (BJ) eruptive centre. Although O -Sr-Pb isotopic and bulk compositions of BJ rhyolites exhibit strong crustal affinity, including strong 18 O-depletion, Nd isotopic data preclude wholesale melting of ancient basement rocks and implicate involvement of a juvenile component -possibly derived from contemporaneous basaltic magmas. Several lines of evidence, including limits on 18 O-depletion of the rhyolite source rocks due to influx of meteoric/hydrothermal fluids, constrain rhyolite generation to depths shallower than mid-upper crust (,20 km depth). For crustal melting driven by basaltic intrusions, sustenance of temperatures exceeding 900 8C at such depths over the life of the BJ eruptive centre requires incremental intrusion of approximately 16 km of basalt into the crust. This minimum basaltic flux (c. 4 mm year 21 ) is about one-tenth that at Kilauea. Nevertheless, emplacement of such volumes of magma in the crust creates a serious room problem, requiring that the crust must undergo significant extensional deformation -seemingly exceeding present estimates of extensional strain for the SRPY province. This paper addresses two related issues -each of which carries important broader implications. The first concerns the origin of large-volume, hightemperature silicic magmas associated with the Yellowstone hotspot track. Assuming they form largely in response to intrusion of voluminous basaltic magma into the crust, we are interested in knowing how much basalt is required, and at what depths that magma is emplaced. Our approach is to evaluate the conditions required to elevate crustal temperatures to magmatic values over volumes that are sufficiently large to generate the quantities of magma produced. Also, many rhyolites from this province exhibit 18 O-depletion, and this characteristic is widely attributed to involvement of low-d18 O meteoric waters. Assuming that this anomaly is source-related, the depths to which surface fluids can plausibly circulate and effectively alter the oxygen isotopic composition of large volumes of crust provide an important constraint on maximum depth of crustal melting. Thus, a second issue concerns how and where the magmas acquire this signal, and what significance this holds regarding both rhyolite petrogenesis and fluid flow in the crust. Although we focus mainly on the physical processes involved, an important side issue concerns the relative contributions of pre-existing crustal rocks v. basalt-derived components in forming the rhyolite magmas; this, in turn, bears on how much older crust is melted.As a framework for the problem, discussion is centred mainly on the relatively well-characterized Miocene Bruneau -Jarbidge (BJ) volcanic field in the central Snake River Plain (cf. Bonnichsen et al. 2008). This area is examined because, unlike Yellows...

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Section: Evidence For Basalt Intrusion In the Middle -Upper Crustmentioning

confidence: 82%

Snake River Plain – Yellowstone silicic volcanism: implications for magma genesis and magma fluxes

Leeman

Annen

Dufek

2008

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“…Flexure in the Teton Range and adjoining basins for (a) 10% and (b) 100% of depth to pre‐Cenozoic basement reported by Mankinen et al [2004]. Black, bold line shows Teton Fault trace, 20 m vertical deflection contours (positive (upward), white; negative (downward), black), bold white line denotes zero contour.…”

Section: Resultsmentioning

confidence: 97%

“…Although we focus our interpretations of the model on isostatic uplift of the Teton Range, we also incorporate estimates of sediment loading in the adjacent Teton Basin and Jackson Hole to avoid potential edge effects that may come from their omission. Estimates of sediment thickness in Jackson Hole and Teton Basin are taken from the regional gravity survey of Mankinen et al [2004], who estimated the depth to the pre‐Cenozoic basement using a gravity inversion method [after Jachens and Moring , 1990]. A mass redistribution grid is created by combining these two data sets (Figure 4), to which we apply a relatively simple three‐dimensional model of flexure, assuming a thin elastic plate with a constant thickness, T e .…”

Section: Methodsmentioning

confidence: 99%

Glacial‐topographic interactions in the Teton Range, Wyoming

2010

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[1] Understanding interactions among tectonics, topography, climate, and erosion is fundamental to studies of mountainous landscapes. Here, we combine topographic analyses with modeled distributions of precipitation, insolation, and flexural isostasy to present a conceptual model of topographic evolution in the Teton Range, Wyoming, and test whether efficient glacial relief production has contributed to summit elevations. The conceptual model reveals a high degree of complexity inherent in even a relatively small, glaciated, mountain range. Back tilting has caused topographic asymmetry, with the greatest relief characterizing eastern catchments in the center of the range. Two high summits, Grand Teton and Mount Moran, rise hundreds of meters above the surrounding landscape; their elevations set by the threshold hillslope angle and the spacing between valleys hosting large, erosionally efficient glaciers. Only basins >20 km 2 held glaciers capable of eroding sufficiently rapidly to incise deeply and maintain shallow downvalley gradients on the eastern range flank. Glacial erosion here was promoted by (1) prevailing westerly winds transporting snow to high-relief eastern basins, leading to cross-range precipitation asymmetry; (2) the wind-blown redistribution of snow from open western headwaters into sheltered eastern cirques, with the associated erosion-driven migration of the drainage divide increasing eastern accumulation areas; and (3) tall, steep hillslopes providing shading, snow influx from avalanching, and insulating debris cover from rockfalls to valley floor glaciers. In comparison, the topographic enhancement of glacial erosion was less pronounced in western, and smaller eastern, basins. Despite dramatic relief production, insufficient rock mass is removed from the Teton Range to isostatically raise summit elevations.

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“…At 11-9 Ma, silicic and basaltic volcanism accompanied further development of the western Snake River Plain graben coeval with a later position of the Yellowstone hotspot in the central Snake River Plain (Shervais et al 2002;Wood & Clemmens 2002). Seismic refraction, gravity and magnetic data suggest mafic densification of the crust beneath the western Snake River Plain and beyond its southern boundary into the Owyhee Plateau in Idaho (Hill & Pakiser 1967;Mabey 1976;Pakiser 1989;Mankinen et al 2004). Seismic refraction, gravity and magnetic data suggest mafic densification of the crust beneath the western Snake River Plain and beyond its southern boundary into the Owyhee Plateau in Idaho (Hill & Pakiser 1967;Mabey 1976;Pakiser 1989;Mankinen et al 2004).…”

Section: T E C T O N I C S E T T I N Gmentioning

confidence: 99%

A new interpretation of deformation rates in the Snake River Plain and adjacent basin and range regions based on GPS measurements

Payne

McCaffrey

King

et al. 2012

Geophysical Journal International

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SUMMARY Within the Northern Basin and Range Province, USA, we estimate horizontal velocities for 405 sites using Global Positioning System (GPS) phase data collected from 1994 to 2010. The velocities, together with geologic, volcanic, and earthquake data, reveal a slowly deforming region within the Snake River Plain in Idaho and Owyhee–Oregon Plateau in Oregon separated from the actively extending adjacent Basin and Range regions by shear. Our results show a NE‐oriented extensional strain rate of 5.6 ± 0.7 × 10−9 yr−1 in the Centennial Tectonic Belt and an ∼E‐oriented extensional strain rate of 3.5 ± 0.2 × 10−9 yr−1 in the Great Basin. These extensional rates contrast with the very low strain rate within the 125 km × 650 km region of the Snake River Plain and Owyhee–Oregon Plateau, which is indistinguishable from zero (−0.1 ± 0.4 × 10−9 yr−1). Inversions of the velocities with dyke‐opening models indicate that rapid extension by dyke intrusion in volcanic rift zones, as previously hypothesized, is not currently occurring in the Snake River Plain. This slow internal deformation, in contrast to the rapidly extending adjacent Basin and Range regions, indicates shear along the boundaries of the Snake River Plain. We estimate right‐lateral shear with slip rates of 0.3–1.4 mm yr−1 along the northwestern boundary adjacent to the Centennial Tectonic Belt and left‐lateral oblique extension with slip rates of 0.5–1.5 mm yr−1 along the southeastern boundary adjacent to the Intermountain Seismic Belt. The fastest lateral shearing evident in the GPS occurs near the Yellowstone Plateau where strike‐slip focal mechanisms and faults with observed strike‐slip components of motion are documented. The regional velocity gradients are best fit by nearby poles of rotation for the Centennial Tectonic Belt, Snake River Plain, Owyhee–Oregon Plateau, and eastern Oregon, indicating that clockwise rotation is not locally driven by Yellowstone hotspot volcanism, but instead by extension to the south across the Wasatch fault due to gravitational collapse and by shear in the Walker Lane belt resulting from Pacific–Northern America relative plate motion.

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Guide to geophysical data for the northern Rocky Mountains and adjacent areas, Idaho, Montana, Washington, Oregon, and Wyoming

Cited by 10 publications

References 0 publications

Snake River Plain – Yellowstone silicic volcanism: implications for magma genesis and magma fluxes

Snake River Plain – Yellowstone silicic volcanism: implications for magma genesis and magma fluxes

Glacial‐topographic interactions in the Teton Range, Wyoming

A new interpretation of deformation rates in the Snake River Plain and adjacent basin and range regions based on GPS measurements

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