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Geology

All Faculty Scholarship for the College of the Sciences

2018

Articles 1 - 6 of 6

Full-Text Articles in Physical Sciences and Mathematics

The Three-Stage Petrochemical Evolution Of The Steens Basalt [Southeast Oregon, Usa] Compared To Large Igneous Provinces And Layered Mafic Intrusions, N. E. Moore, A. L. Grunder, Wendy A. Bohrson Sep 2018

The Three-Stage Petrochemical Evolution Of The Steens Basalt [Southeast Oregon, Usa] Compared To Large Igneous Provinces And Layered Mafic Intrusions, N. E. Moore, A. L. Grunder, Wendy A. Bohrson

All Faculty Scholarship for the College of the Sciences

The Steens Basalt, southeast Oregon, USA, initiated at 17 Ma as the earliest pulse of the Columbia River Flood Basalt of the northwestern USA. New and existing stratigraphically controlled data reveal temporal changes in lava flow character, and whole-rock and mineral compositions, which we use to evaluate how the balance of magma differentiation processes change in time. Temporal petrochemical variations in the Steens Basalt are analogous to the transition from Imnaha Basalt to Grande Ronde Basalt units of the Columbia River Flood Basalt and have parallels to the temporal evolution of the Deccan and Siberian traps, in India and Russia, …

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The Crust And Upper Mantle Structure Of Central And West Antarctica From Bayesian Inversion Of Rayleigh Wave And Receiver Functions, Weisen Shen, Audrey D. Huerta, J. Paul Winberry Sep 2018

The Crust And Upper Mantle Structure Of Central And West Antarctica From Bayesian Inversion Of Rayleigh Wave And Receiver Functions, Weisen Shen, Audrey D. Huerta, J. Paul Winberry

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We construct a new seismic model for central and West Antarctica by jointly inverting Rayleigh wave phase and group velocities along with P wave receiver functions. Ambient noise tomography exploiting data from more than 200 seismic stations deployed over the past 18 years is used to construct Rayleigh wave phase and group velocity dispersion maps. Comparison between the ambient noise phase velocity maps with those constructed using teleseismic earthquakes confirms the accuracy of both results. These maps, together with P receiver function waveforms, are used to construct a new 3-D shear velocity (Vs) model for the crust and uppermost mantle …

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The 2015 Landslide And Tsunami In Taan Fiord, Alaska, Bretwood Higman, Breanyn Macinnes, Colin Bloom Sep 2018

The 2015 Landslide And Tsunami In Taan Fiord, Alaska, Bretwood Higman, Breanyn Macinnes, Colin Bloom

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Glacial retreat in recent decades has exposed unstable slopes and allowed deep water to extend beneath some of those slopes. Slope failure at the terminus of Tyndall Glacier on 17 October 2015 sent 180 million tons of rock into Taan Fiord, Alaska. The resulting tsunami reached elevations as high as 193 m, one of the highest tsunami runups ever documented worldwide. Precursory deformation began decades before failure, and the event left a distinct sedimentary record, showing that geologic evidence can help understand past occurrences of similar events, and might provide forewarning. The event was detected within hours through automated seismological …

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On The Interaction Of The North Andes Plate With The Caribbean And South American Plates In Northwestern South America From Gps Geodesy And Seismic Data, Omar J. Pérez, Steven G. Wesnousky, Roberto De La Rosa, Julio Márquez, Redescal Uzcátegui, Christian Quintero, Luis Liberal, Héctor Mora-Páez, Walter Szeliga Sep 2018

On The Interaction Of The North Andes Plate With The Caribbean And South American Plates In Northwestern South America From Gps Geodesy And Seismic Data, Omar J. Pérez, Steven G. Wesnousky, Roberto De La Rosa, Julio Márquez, Redescal Uzcátegui, Christian Quintero, Luis Liberal, Héctor Mora-Páez, Walter Szeliga

All Faculty Scholarship for the College of the Sciences

We examine the hypocentral distribution of seismicity and a series of geodetic velocity vectors obtained from Global Positioning System observations between 1994 and 2015 both offshore and mainland northwestern South America (66°W–77°W; 8°N–14°N). Our analysis, that includes a kinematic block modelling, shows that east of the Caribbean–South American–North Andes plates’ triple junction at ∼68°W; 10.7°N, right-lateral easterly oriented shear motion (∼19.6 ± 2.0 mm yr−1) between the Caribbean and South America plates is split along two easterly striking, right-lateral strike-slip subparallel fault zones: the San Sebastián fault that runs off-shore the Venezuelan coast and slips about 17.0±0.5mm …

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Phase Equilibrium Modelling And Implications For P-T Determinations Of Medium-Temperature Uhp Eclogites, North Qaidam Terrane, China, David Hernández‐Uribe, Chris G. Mattinson, Jianxin Zhang Jul 2018

Phase Equilibrium Modelling And Implications For P-T Determinations Of Medium-Temperature Uhp Eclogites, North Qaidam Terrane, China, David Hernández‐Uribe, Chris G. Mattinson, Jianxin Zhang

All Faculty Scholarship for the College of the Sciences

In contrast to low-T eclogites (garnet growth zoning preserved) or high-T eclogites (garnet diffusionally homogenized at peak conditions), medium-temperature eclogites pose additional challenges to P-T determinations due to the partial preservation of garnet zoning. The Dulan area, in the southeastern part of North Qaidam ultrahigh-pressure terrane, exposes minor eclogites hosted by ortho- and paragneisses. Four fresh, medium-temperature eclogites contain the paragenesis Grt+Omp+Rt+Qz/Coe+Ph +/- Ky +/- Zo. In all samples, garnet X-Mg shows little zoning, suggesting diffusional modification, and precludes the use of pyrope+almandine+grossular isopleth intersections to determine a P-T path. However, in one sample, sharp zoning in grossular content suggests …

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Gps Vertical Land Motion Corrections To Sea-Level Rise Estimates In The Pacific Northwest, Jean-Philippe Montillet, Timothy I. Melbourne, Walter M. Szeliga Feb 2018

Gps Vertical Land Motion Corrections To Sea-Level Rise Estimates In The Pacific Northwest, Jean-Philippe Montillet, Timothy I. Melbourne, Walter M. Szeliga

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We construct coastal Pacific Northwest profiles of vertical land motion (VLM) known to bias long-term tide-gauge measurements of sea-level rise (SLR) and use them to estimate absolute sea-level rise with respect to Earth’s center of mass. Multidecade GPS measurements at 47 coastal stations along the Cascadia subduction zone show VLM varies regionally but smoothly along the Pacific coast and inland Puget Sound with rates ranging from +4.9 to –1.2 mm/yr. Puget Sound VLM is characterized by uniform subsidence at relatively slow rates of +0.1 to –0.3 mm/yr. Uplift rates of 4.5 mm/yr persist along the western Olympic Peninsula of northwestern …

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