Zircon grain selection reveals (de)coupled metamictization, radiation damage, and He diffusivity

Ault, Alexis K.; Guenthner, William R.; Moser, Amy C.; Miller, Gifford H.; Refsnider, Kurt A.

doi:10.1016/j.chemgeo.2018.04.023

Cited by 44 publications

(65 citation statements)

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“…Understanding sources of intrasample dispersion in grain cooling ages is important for evaluating uncertainties in thermochronometric interpretations and optimizing sampling design. Most samples in this study displayed greater dispersion in ZHe grain ages (typical 1σ ~10% of mean age) than expected for analytical uncertainty (~4% of grain age), similar to results of other studies (e.g., Wolfe & Stockli, ; Guenthner et al, ; Powell et al, ; Ault et al, ), partly related to varying radiation damage that affects He diffusion (Guenthner et al, ). Grains were selected for ZHe analysis based on similar eU contents (mostly 30 to 300 ppm) and U‐Pb ages (mostly 2.0–1.0 Ga), and thus similar values of maximum accumulated radiation damage.…”

Section: Discussionsupporting

confidence: 89%

Fault Slip and Exhumation History of the Willard Thrust Sheet, Sevier Fold‐Thrust Belt, Utah: Relations to Wedge Propagation, Hinterland Uplift, and Foreland Basin Sedimentation

et al. 2019

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Zircon (U‐Th)/He (ZHe) and zircon fission track thermochronometric data for 47 samples spanning the areally extensive Willard thrust sheet within the western part of the Sevier fold‐thrust belt record enhanced cooling and exhumation during major thrust slip spanning approximately 125–90 Ma. ZHe and zircon fission track age‐paleodepth patterns along structural transects and age‐distance relations along stratigraphic‐parallel traverses, combined with thermo‐kinematic modeling, constrain the fault slip history, with estimated slip rates of ~1 km/Myr from 125 to 105 Ma, increasing to ~3 km/Myr from 105 to 92 Ma, and then decreasing as major slip was transferred onto eastern thrusts. Exhumation was concentrated during motion up thrust ramps with estimated erosion rates of ~0.1 to 0.3 km/Myr. Local cooling ages of approximately 160–150 Ma may record a period of regional erosion, or alternatively an early phase of limited (<10 km) thrust slip. Propagation of the Sevier wedge front and major thrust slip during the late Early to mid‐Cretaceous were synchronous with increasing subsidence and deposition of thick synorogenic strata in the foreland, crustal thickening in the hinterland, growing igneous activity in the Sierran magmatic arc, and increasing plate convergence rates. Along‐strike, other parts of the Cordilleran retroarc fold‐thrust belt also experienced major shortening during the late Early to mid‐Cretaceous, following a period of earlier Cretaceous quiescence. Late Jurassic shortening was concentrated nearer the arc, and thus mostly in the hinterland at the latitude of northern Utah, related to width and location of the passive‐margin sedimentary wedge relative to the plate margin.

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Section: Discussionsupporting

confidence: 89%

Fault Slip and Exhumation History of the Willard Thrust Sheet, Sevier Fold‐Thrust Belt, Utah: Relations to Wedge Propagation, Hinterland Uplift, and Foreland Basin Sedimentation

et al. 2019

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“…Recent work extends the low-temperature thermal history of cratonic North American into deeper geologic time (Figures 8a and 8c; Ault et al, 2018;DeLucia et al, 2018;McDannell, Zeitler, & Schneider, 2018;Orme et al, 2016). For example, zircon He thermochronometry date-eU patterns from the North American midcontinent cratonic basement reveal~850-to 680-Ma cooling and exhumation associated with the development of the Great Unconformity, an erosion surface representing~100-1,000 Ma of missing geologic time between Precambrian and Phanerozoic rocks (DeLucia et al, 2018).…”

Section: 1029/2018tc005312mentioning

confidence: 78%

“…Zircon He dates can yield positive and/or negative relationships with eU and increasing visual metamictization (see zircon images) tracks with increased eU . Young, uniform zircon He dates at high eU (and thus high radiation damage) define a date-eU "pediment," reflecting residence at temperatures low enough to accumulate sufficient damage to yield low closure temperatures combined with subsequent heating followed by relatively rapid cooling across a range of closure temperature (T c )-equivalent to apatite fission track and apatite He T c (e.g., Ault et al, 2018;DeLucia et al, 2018;Johnson et al, 2017;Mackintosh et al, 2017). High eU zircon He dates can be younger than apatite He dates reflecting low T c .…”

Section: Radiation Damage and Chemistry Controls On (U-th)/he And Ft mentioning

confidence: 99%

“…Apatite, zircon, and titanite date-eU relationships (e.g., Figure 3) are a powerful tool for reconstructing protracted thermal histories characteristic of ancient bedrock (Ault et al, 2009(Ault et al, , 2013Ault et al, 2018;Baughman & Flowers, 2018;DeLucia et al, 2018;Flowers, 2009;Flowers et al, 2007;Guenthner et al, 2013Guenthner et al, , 2014Guenthner et al, , 2017Johnson et al, 2017;Mackintosh et al, 2017;Orme et al, 2016;Powell et al, 2016;Weisberg et al, 2018). Damage-diffusivity patterns can be predicted given a thermal history or inverted to derive a thermal history using HeFTy or QTQt.…”

Section: 1029/2018tc005312mentioning

confidence: 99%

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Innovations in (U–Th)/He, Fission Track, and Trapped Charge Thermochronometry with Applications to Earthquakes, Weathering, Surface‐Mantle Connections, and the Growth and Decay of Mountains

2019

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A transformative advance in Earth science is the development of low‐temperature thermochronometry to date Earth surface processes or quantify the thermal evolution of rocks through time. Grand challenges and new directions in low‐temperature thermochronometry involve pushing the boundaries of these techniques to decipher thermal histories operative over seconds to hundreds of millions of years, in recent or deep geologic time and from the perspective of atoms to mountain belts. Here we highlight innovation in bedrock and detrital fission track, (U–Th)/He, and trapped charge thermochronometry, as well as thermal history modeling that enable fresh perspectives on Earth science problems. These developments connect low‐temperature thermochronometry tools with new users across Earth science disciplines to enable transdisciplinary research. Method advances include radiation damage and crystal chemistry influences on fission track and (U–Th)/He systematics, atomistic calculations of He diffusion, measurement protocols and numerical modeling routines in trapped charge systematics, development of 4He/3He and new (U–Th)/He thermochronometers, and multimethod approaches. New applications leverage method developments and include quantifying landscape evolution at variable temporal scales, changes to Earth's surface in deep geologic time and connections to mantle processes, the spectrum of fault processes from paleoearthquakes to slow slip and fluid flow, and paleoclimate and past critical zone evolution. These research avenues have societal implications for modern climate change, groundwater flow paths, mineral resource and petroleum systems science, and earthquake hazards.

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“…Radiation damage effects expand the effective T c range of apatite and zircon He systems and can be exploited to better constrain thermal histories (e.g., Ault et al, ; Flowers, ; Guenthner et al, ; Orme et al, ). Available radiation damage‐diffusivity models for apatite and zircon assume damage annealing occurs at the temperatures and rates that FTs anneal in each system, although recent work suggests that α‐damage annealing may require higher temperatures (Ault et al, ; Flowers, ; Fox & Shuster, ; Gautheron et al, ; Gerin et al, ; Ginster et al, ; Guenthner et al, ; Willett et al, ). In addition to radiation damage effects, possible sources of overdispersion in He dates include strong eU zonation and associated errors in correcting for grain edge α ejection, parentless He implanted by “bad neighbors” or hosted in unrecognized U‐Th‐rich inclusions, and crystal defects that create fast diffusion pathways (e.g., Farley, ; Flowers & Kelley, ).…”

Section: Low‐temperature Thermochronometry and Methodsmentioning

confidence: 99%

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

et al. 2019

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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.

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Zircon grain selection reveals (de)coupled metamictization, radiation damage, and He diffusivity

Cited by 44 publications

References 50 publications

Fault Slip and Exhumation History of the Willard Thrust Sheet, Sevier Fold‐Thrust Belt, Utah: Relations to Wedge Propagation, Hinterland Uplift, and Foreland Basin Sedimentation

Fault Slip and Exhumation History of the Willard Thrust Sheet, Sevier Fold‐Thrust Belt, Utah: Relations to Wedge Propagation, Hinterland Uplift, and Foreland Basin Sedimentation

Innovations in (U–Th)/He, Fission Track, and Trapped Charge Thermochronometry with Applications to Earthquakes, Weathering, Surface‐Mantle Connections, and the Growth and Decay of Mountains

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

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