Age and progression of volcanism, Wrangell volcanic field, Alaska

Richter, Donald H.; Smith, J. G.; Lanphere, Marvin A.; Dalrymple, G. Brent; Reed, Bruce L.; Shew, Nora B.

doi:10.1007/bf00680318

Cited by 77 publications

(114 citation statements)

References 17 publications

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“…These combined associations suggest that the ~12.5-5.3 Ma central WA Frederika lavas reflect the effects of subduction and minor intra-arc extensional processes on magma genesis. Lavas in the eastern section have ages of ~12.5-9.3 Ma (coeval with the latest St. Clare Creek volcanism, e.g., Skulski et al 1992), and lavas in the western section have ages of ~9.6-5.3 Ma, reflecting the northwestward migration of WA magmatism suggested by Richter et al (1990). The late Miocene subduction of thickened oceanic crust (Yakutat microplate), and the resulting intra-arc extension of the upper plate, are similar processes that operated to produce the trend 2a calcalkaline and trend 1 transitional-tholeiitic series of Preece and Hart (2004) in the <5 Ma western WA.…”

Section: Central Wrangell Arc Volcanism: Frederika Formationmentioning

confidence: 90%

“…Mountains of south-central Alaska has been active since at least ~30 Ma, based on calc-alkaline to transitional geochemistries of sampled eruptive products (Nye, 1983;Richter et al, 1990;Skulski et al, 1991Skulski et al, , 1992Preece and Hart, 2004;Trop et al, 2012), and the presence of a geophysically imaged northward-dipping subducting slab (Eberhart-Phillips et al, 2006;Bauer et al, 2014) ( Fig. 1.1).…”

Section: Regional Tectonic Frameworkmentioning

confidence: 99%

“…Further inboard is a broad province of alkaline volcanism that formed in response to changes in Pacific plate convergence angles and rates (Edwards and Russel, 1999;. Richter et al, (1990) demonstrated that calc-alkaline volcanism in the Wrangell Mountains has shown a northwestward migration from ~26-0.2 Ma, and Preece and Hart (2004) showed that subduction, slab-edge effects, and intra-arc extension controlled magma geochemistries of <5 Ma volcanic rocks. Changes in the relative locations of volcanism in the upper plate, as controlled by the position of the subducting slab and strike-slip faults, as well as variations in magma geochemistry, are common features of volcanic fields in arc-transform transition zones (Park et al, 2002).…”

Section: Regional Tectonic Frameworkmentioning

confidence: 99%

“…1.1; Richter et al, 1990;. Mount Wrangell (4317 m), and andesitic shield, is the largest volcano in the WA by volume and has shown occasional historic activity (~1800 A.D.) at the summit caldera, and fumarole activity is common (Nye, 1983;Richter et al, 1990).…”

Section: Wrangell Arc Geology-underlying Rocks and Wrangell Arc Volcamentioning

confidence: 99%

“…The late Miocene subduction of thickened oceanic crust (Yakutat microplate), and the resulting intra-arc extension of the upper plate, are similar processes that operated to produce the trend 2a calcalkaline and trend 1 transitional-tholeiitic series of Preece and Hart (2004) in the <5 Ma western WA. Richter et al (1990) proposed a model of northwesterly progression of WA volcanism through time, from 26.3 Ma near the Alaska-Yukon border to ~0.2 Ma at the northwest edge of the WA. The oldest age documenting the inception of the WA was based on K-Ar dating of one lava sample from the Sonya Creek volcanic field.…”

Section: Central Wrangell Arc Volcanism: Frederika Formationmentioning

confidence: 99%

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Initiation of the Wrangell Arc: A Record of Tectonic Changes in an Arc-Transform Junction Revealed by New Geochemistry and Geochronology of the ~29–18 Ma Sonya Creek Volcanic Field, Alaska

Berkelhammer¹

2017

Geological Society of America Abstracts With Programs

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The Sonya Creek volcanic field (SCVF) contains the oldest in situ magmatic products in the ~29 Ma-modern Wrangell arc (WA) in south-central Alaska. The WA is located within a transition zone between Aleutian subduction to the west and dextral strike-slip tectonics along the Queen Charlotte-Fairweather and Denali-Duke River fault systems to the east. WA magmatism is due to the shallow subduction (11-16°) WA, and no alkaline lavas that characterize the ~18-10 Ma Yukon WA are present. Sr-Nd-Pb-Hf radiogenic isotope data suggest the SCVF data were generated by contamination of a depleted mantle wedge by ~0.2-4% subducted terrigenous sediment, agreeing with geologic evidence from many places along the southern Alaskan margin. Our combined dataset reveals geochemical and spatial transitions through the lifetime of the SCVF, which record changing tectonic processes during the early evolution of the WA. The earliest SCVF phases suggest the initiation of Yakutat microplate subduction. Early SCVF igneous rocks are also chemically similar to hypabyssal intrusive rocks of similar ages that crop out to the west; together these ~29-20 Ma rocks imply that WA initiation occurred over a <100 km belt, ~50-60 km inboard from the modern WA and current loci of arc magmatism that extends from Mt. Drum to Mt.Churchill.iv

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Section: Central Wrangell Arc Volcanism: Frederika Formationmentioning

confidence: 90%

Section: Regional Tectonic Frameworkmentioning

confidence: 99%

Section: Regional Tectonic Frameworkmentioning

confidence: 99%

Section: Wrangell Arc Geology-underlying Rocks and Wrangell Arc Volcamentioning

confidence: 99%

Section: Central Wrangell Arc Volcanism: Frederika Formationmentioning

confidence: 99%

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Initiation of the Wrangell Arc: A Record of Tectonic Changes in an Arc-Transform Junction Revealed by New Geochemistry and Geochronology of the ~29–18 Ma Sonya Creek Volcanic Field, Alaska

Berkelhammer¹

2017

Geological Society of America Abstracts With Programs

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Constraining the area of rapid and deep‐seated exhumation at the St. Elias syntaxis, Southeast Alaska, with detrital zircon fission‐track analysis

2014

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The Chugach-St. Elias orogen, Southeast Alaska/Southwest Yukon, formed in response to the ongoing Yakutat microplate subduction-collision with the North American Plate. Due to heavy glaciation, the region is a prime location to study active convergent orogenesis and climate-tectonic interactions. This study focuses on the long-term distribution of deformation in the St. Elias syntaxis area, where dextral motion along the plate-bounding Fairweather Fault transitions into convergence. We present 2718 new zircon fission-track single-grain ages from 26 glaciofluvial outwash samples. The grain ages range from 293 Ma to 0.2 Ma, and each sample contains two to five age populations with peaks between 267 ± 64 Ma and 1.2 ± 0.7 Ma (1σ). The rocks of the Yakutat microplate are dominated by latest Cretaceous and Eocene fission-track ages, while the rocks of the North American Plate in the syntaxis region reveal two exhumation phases at~5.1 Ma and 2.7 Ma. The spatial pattern of ≤5 Ma cooling ages shows that the area of rapid and deep exhumation at the St. Elias syntaxis is more extensive than previously known and confined to the south by the Fairweather Fault, to the west by the Seward Glacier catchment, and to the east possibly by the inferred Connector Fault. The area seems to be~4800 km 2 large and may extend farther to the north. The new zircon fission-track data further suggest a transpressional plate boundary since~30 Ma and the onset of plate collision 15-12 Ma.

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Seismic velocity structure and anisotropy of the Alaska subduction zone based on surface wave tomography

Wang

Tape

2014

JGR Solid Earth

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Southcentral Alaska is a complex tectonic region that transitions from subduction of Pacific crust to flat slab subduction—and collision—of overthickened Yakutat crust. Because much of the Yakutat crust has been subducted, seismic imaging is needed in order to understand the crustal and upper mantle structural framework for this active tectonic setting. Here we use teleseismic Rayleigh waves to image large‐scale variations in shear wave structure. Our imaging technique employs a two‐plane wave representation with finite frequency sensitivity kernels. Our 3‐D isotropic model reveals several features: the subducting Pacific/Yakutat slab, slow wave speeds characterizing the onshore Yakutat collision zone, slow wave speeds of the Wrangell subduction zone, and a deep tomographic contrast at the eastern edge of the Pacific/Yakutat slab. We produce anisotropic phase velocity maps that exhibit variations in the fast direction of azimuthal anisotropy. These maps show the dominance of the Yakutat slab on the observed pattern of anisotropy. West of the Yakutat slab the fast directions are approximately aligned with the plate convergence direction. In the region of the Yakutat slab the pattern is more complicated. Along the margins of the slab the fast directions are roughly parallel to the margins. We identify notable differences and similarities with published SKS splitting measurements. Integrative modeling using 3‐D anisotropy models and different seismic measurements will be needed in order to establish a detailed 3‐D anisotropic velocity model for Alaska. This study provides a large‐scale starting point for such an effort.

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Age and progression of volcanism, Wrangell volcanic field, Alaska

Cited by 77 publications

References 17 publications

Initiation of the Wrangell Arc: A Record of Tectonic Changes in an Arc-Transform Junction Revealed by New Geochemistry and Geochronology of the ~29–18 Ma Sonya Creek Volcanic Field, Alaska

Initiation of the Wrangell Arc: A Record of Tectonic Changes in an Arc-Transform Junction Revealed by New Geochemistry and Geochronology of the ~29–18 Ma Sonya Creek Volcanic Field, Alaska

Constraining the area of rapid and deep‐seated exhumation at the St. Elias syntaxis, Southeast Alaska, with detrital zircon fission‐track analysis

Seismic velocity structure and anisotropy of the Alaska subduction zone based on surface wave tomography

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