High-resolution reconstructions of Pacific–North America plate motion: 20 Ma to present

DeMets, Charles; Merkouriev, S.

doi:10.1093/gji/ggw305

Cited by 69 publications

(93 citation statements)

References 116 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The viscosity estimates of Freed, Bürgmann, Calais, Freymueller, and Hreinsdóttir (), Freed, Bürgmann, Calais, and Freymueller () apply to a similar region but are weighted more heavily toward the asthenosphere beneath central Alaska because of the geographic location of the earthquake and the sampling sites. Southeast Alaska is a former subduction zone, with a long history of subduction and mantle hydration, but has been a dominantly strike‐slip boundary over the last 20 Ma (DeMets & Merkouriev, ). Our asthenospheric viscosity estimate here is higher by a factor of 1–3 than the long‐term viscosities estimated by these nearby postseismic studies.…”

Section: Discussionmentioning

confidence: 99%

Geodetic Observations of Time‐Variable Glacial Isostatic Adjustment in Southeast Alaska and Its Implications for Earth Rheology

Freymueller

2019

JGR Solid Earth

View full text Add to dashboard Cite

Global Positioning System observations in Southeast Alaska show evidence for interannual variations in uplift rates, which are consistent with an acceleration of mass loss rates across the region from the 1990s to 2012. We constructed an updated regional loading model based on updated twentieth century average deglaciation estimates. This model features a larger mass loss rate overall than the model used in previous studies. We adopted a viscosity model with an upper and lower mantle viscosity from VM5a but with a low viscosity asthenosphere as in previous regional studies. We varied the asthenospheric thickness, asthenospheric viscosity, and lithospheric thickness to find the Earth model that best fits the data, which has a lithospheric thickness of 55 km and an asthenosphere with thickness 230 km and viscosity 3 × 1019 Pa s. There is a strong tradeoff between the asthenosphere thickness and viscosity, and different estimates or assumptions about the asthenospheric thickness is one of the main causes of the varying viscosity estimates of previous studies. We find a higher viscosity than previous studies in part because we find that a thicker asthenosphere fits the data better than a thinner one and also because the higher twentieth century mass loss rate compared to earlier studies requires a higher viscosity to predict the same uplift rates. Vertical velocities predicted by the model drop rapidly with distance from the ice masses, while horizontal velocities are smaller but extend for a longer distance.

show abstract

Section: Discussionmentioning

confidence: 99%

Geodetic Observations of Time‐Variable Glacial Isostatic Adjustment in Southeast Alaska and Its Implications for Earth Rheology

Freymueller

2019

JGR Solid Earth

View full text Add to dashboard Cite

show abstract

“…For example, Kluane Ranges samples that record Phase III cooling and exhumation at ~15–10 Ma (61115‐2A and 15‐SI‐012; Figure ) may reflect a response to microplate collision, which is also inferred in the St. Elias Mountains (Falkowski et al, ; O'Sullivan & Currie, ; Spotila & Berger, ). Alternatively, exhumation in the Kluane Ranges may reflect other factors such as changing plate convergence angle with respect to EDFZ orientation (e.g., DeMets & Merkouriev, ). Oligocene‐Miocene cooling and (or) deformation is documented along the broader Denali fault system, although variable in timing, and also attributed to flat‐slab subduction of the Yakutat microplate (Figure b; Benowitz et al, ; Benowitz et al, ; Lease et al, ; Trop et al, ; Waldien et al, ).…”

Section: Geological Interpretations Of Thermal History Exhumation Amentioning

confidence: 99%

Thermotectonic History of the Kluane Ranges and Evolution of the Eastern Denali Fault Zone in Southwestern Yukon, Canada

et al. 2019

View full text Add to dashboard Cite

Exhumation and landscape evolution along strike‐slip fault systems reflect tectonic processes that accommodate and partition deformation in orogenic settings. We present 17 new apatite (U‐Th)/He (He), zircon He, apatite fission‐track (FT), and zircon FT dates from the eastern Denali fault zone (EDFZ) that bounds the Kluane Ranges in Yukon, Canada. The dates elucidate patterns of deformation along the EDFZ. Mean apatite He, apatite FT, zircon He, and zircon FT sample dates range within ~26–4, ~110–12, ~94–28, and ~137–83 Ma, respectively. A new zircon U‐Pb date of 113.9 ± 1.7 Ma (2σ) complements existing geochronology and aids in interpretation of low‐temperature thermochronometry data patterns. Samples ≤2 km southwest of the EDFZ trace yield the youngest thermochronometry dates. Multimethod thermochronometry, zircon He date‐effective U patterns, and thermal history modeling reveal rapid cooling ~95–75 Ma, slow cooling ~75–30 Ma, and renewed rapid cooling ~30 Ma to present. The magnitude of net surface uplift constrained by published paleobotanical data, exhumation, and total surface uplift from ~30 Ma to present are ~1, ~2–6, and ~1–7 km, respectively. Exhumation is highest closest to the EDFZ trace but substantially lower than reported for the central Denali fault zone. We infer exhumation and elevation changes associated with ~95–75 Ma terrane accretion and EDFZ activity, relief degradation from ~75–30 Ma, and ~30 Ma to present exhumation and surface uplift as a response to flat‐slab subduction and transpressional deformation. Integrated results reveal new constraints on landscape evolution within the Kluane Ranges directly tied to the EDFZ during the last ~100 Myr.

show abstract

“…The return to open‐ocean seawater 187 Os/ 188 Os values in Davidson and Taney Seamount Fe‐Mn crusts ∼4.5 Ma coincided with the Pliocene orogeny in western California (DeMets & Merkouriev, ; Page et al, ). Reconstruction of plate slip and rotation of the Sierra Nevada and Great Valley blocks with reference to the Pacific plate show that from 9 to 5.2 Ma the plates were parallel to the San Andreas Fault, but that from 5.2 Ma onward progressive clockwise rotation from the San Andreas Fault has occurred (DeMets & Merkouriev, ). The Sierra Nevada‐Great Valley block and the Pacific plate began to converge at an angle orthogonal to the San Andreas Fault from 5.2 to 4.2 Ma (DeMets & Merkouriev, ).…”

Section: Discussionmentioning

confidence: 97%

“…Reconstruction of plate slip and rotation of the Sierra Nevada and Great Valley blocks with reference to the Pacific plate show that from 9 to 5.2 Ma the plates were parallel to the San Andreas Fault, but that from 5.2 Ma onward progressive clockwise rotation from the San Andreas Fault has occurred (DeMets & Merkouriev, ). The Sierra Nevada‐Great Valley block and the Pacific plate began to converge at an angle orthogonal to the San Andreas Fault from 5.2 to 4.2 Ma (DeMets & Merkouriev, ). That coincided with the onset of the orogeny of the Santa Lucia Range starting around 6 Ma and estimated onset of shortening in central California at around 3.9 to 3.4 Ma (Ducea et al, ; Page et al, ).…”

Section: Discussionmentioning

confidence: 99%

Reconstructing the Evolution of the Submarine Monterey Canyon System From Os, Nd, and Pb Isotopes in Hydrogenetic Fe‐Mn Crusts

Conrad

Nielsen

Peucker‐Ehrenbrink

et al. 2017

Geochem Geophys Geosyst

View full text Add to dashboard Cite

The sources of terrestrial material delivered to the California margin over the past 7 Myr were assessed using 187Os/188Os, Nd, and Pb isotopes in hydrogenetic ferromanganese crusts from three seamounts along the central and southern California margin. From 6.8 to 4.5 (±0.5) Ma, all three isotope systems show more radiogenic values at Davidson Seamount, located near the base of the Monterey Canyon System, than in Fe‐Mn crusts from the more remote Taney and Hoss Seamounts. At the Taney Seamounts, approximately 225 km farther offshore from Davidson Seamount, 187Os/188Os values, but not Pb and Nd isotope ratios, also deviate from the Cenozoic seawater curve toward more radiogenic values from 6.8 to 4.5 (±0.5) Ma. However, none of the isotope systems in Fe‐Mn crusts deviate from seawater at Hoss Seamount located approximately 450 km to the south. The regional gradients in isotope ratios indicate that substantial input of dissolved and particulate terrestrial material into the Monterey Canyon System is responsible for the local deviations in the seawater Nd, Pb, and Os isotope compositions from 6.8 to 4.5 (±0.5) Ma. The isotope ratios recorded in Fe‐Mn crusts are consistent with a southern Sierra Nevada or western Basin and Range provenance of the terrestrial material which was delivered by rivers to the canyon. The exhumation of the modern Monterey Canyon must have begun between 10 and 6.8 ± 0.5 Ma, as indicated by our data, the age of incised strata, and paleo‐location of the Monterey Canyon relative to the paleo‐coastline.

show abstract

High-resolution reconstructions of Pacific–North America plate motion: 20 Ma to present

Cited by 69 publications

References 116 publications

Geodetic Observations of Time‐Variable Glacial Isostatic Adjustment in Southeast Alaska and Its Implications for Earth Rheology

Geodetic Observations of Time‐Variable Glacial Isostatic Adjustment in Southeast Alaska and Its Implications for Earth Rheology

Thermotectonic History of the Kluane Ranges and Evolution of the Eastern Denali Fault Zone in Southwestern Yukon, Canada

Reconstructing the Evolution of the Submarine Monterey Canyon System From Os, Nd, and Pb Isotopes in Hydrogenetic Fe‐Mn Crusts

Contact Info

Product

Resources

About