U-PB AND <sup>40</sup>AR/<sup>39</sup>AR DETRITAL GEOCHRONOLOGY OF MODERN RIVER SEDIMENTS IN THE WRANGELL MOUNTAINS, ALASKA: IMPROVED CONSTRAINTS ON THE AGE AND TECTONIC EVOLUTION OF JURASSIC-QUATERNARY MAGMATISM

Trop, Jeffrey M.; Benowitz, Jeff; Davis, Kailyn N.; Layer, Paul W.; Brueseke, Matthew E.

doi:10.1130/abs/2016am-278082

Cited by 3 publications

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“…2). U-Pb zircon analyses from the Chitina arc yield ages of 153-150 Ma, while detrital zircon grains from modern river sands draining from Chitina arc plutons yield ages between 156 and 130 Ma (Plafker et al, 1989;Roeske et al, 2003;Day et al, 2016;Trop et al, 2016). The Chitina arc is interpreted as an oceanic arc that is the southeastern continuation of the Talkeetna arc to the northwest (Plafker et al, 1989;Trop et al, 2005).…”

Section: Potential Magmatic Sources Of Sediment On the Wrangellia Commentioning

confidence: 97%

Detrital zircon geochronology and Hf isotope geochemistry of Mesozoic sedimentary basins in south-central Alaska: Insights into regional sediment transport, basin development, and tectonics along the NW Cordilleran margin

2020

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The Jurassic–Cretaceous Nutzotin, Wrangell Mountains, and Wellesly basins provide an archive of subduction and collisional processes along the southern Alaska convergent margin. This study presents U-Pb ages from each of the three basins, and Hf isotope compositions of detrital zircons from the Nutzotin and Wellesly basins. U-Pb detrital zircon ages from the Upper Jurassic–Lower Cretaceous Nutzotin Mountains sequence in the Nutzotin basin have unimodal populations between 155 and 133 Ma and primarily juvenile Hf isotope compositions. Detrital zircon ages from the Wrangell Mountains basin document unimodal peak ages between 159 and 152 Ma in Upper Jurassic–Lower Cretaceous strata and multimodal peak ages between 196 and 76 Ma for Upper Cretaceous strata. Detrital zircon ages from the Wellesly basin display multimodal peak ages between 216 and 124 Ma and juvenile to evolved Hf compositions. Detrital zircon data from the Wellesly basin are inconsistent with a previous interpretation that suggested the Wellesly and Nutzotin basins are proximal-to-distal equivalents. Our results suggest that Wellesly basin strata are more akin to the Kahiltna basin, which requires that these basins may have been offset ~380 km along the Denali fault. Our findings from the Wrangell Mountains and Nutzotin basins are consistent with previous stratigraphic interpretations that suggest the two basins formed as a connected retroarc basin system. Integration of our data with previously published data documents a strong provenance and temporal link between depocenters along the southern Alaska convergent margin. Results of our study also have implications for the ongoing discussion concerning the polarity of subduction along the Mesozoic margin of western North America.

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Section: Potential Magmatic Sources Of Sediment On the Wrangellia Commentioning

confidence: 97%

Detrital zircon geochronology and Hf isotope geochemistry of Mesozoic sedimentary basins in south-central Alaska: Insights into regional sediment transport, basin development, and tectonics along the NW Cordilleran margin

2020

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“…U-Pb zircon ages from these potential sources of sediment range in age from 190 to 153 Ma with the highest volume of plutonic rocks with ages between 177 and 153 Ma . Day et al, 2016;Plafker et al, 1989;MacKevett, 1978;Roeske et al, 1992Roeske et al, , 2003Trop et al, 2016;Winkler et al, 1980). Contemporaneous arc-related plutons from the Saint Elias plutonic suite to the southeast (present coordinates) contain U-Pb ages on zircon between 155 and 147 Ma (Beranek et al, 2017).…”

Section: Upper Matanuska Formationmentioning

confidence: 97%

“…More distal potential sources include Upper Jurassic‐Lower Cretaceous plutons of the Chitina arc located south of the Wrangell Mountains and Middle Cretaceous plutons of the Chisana arc, located north of the Wrangell Mountains. Direct measurement of the Chitina arc plutons yield 153–150 Ma U‐Pb zircon ages; however, U‐Pb zircon ages of modern river sands draining the Chitina Valley batholith range between 156 and 130 Ma (E. M. Day et al, ; Plafker et al, ; MacKevett, ; Roeske et al, , ; Trop et al, ; Winkler et al, ). Contemporaneous arc‐related plutons from the Saint Elias plutonic suite to the southeast (present coordinates) contain U‐Pb ages on zircon between 155 and 147 Ma (Beranek et al, ).…”

Section: Provenancementioning

confidence: 99%

“…This interpretation could extend Talkeetna arc magmatism into Early Cretaceous time, but more geologic mapping and geochronology are needed to properly address this hypothesis. Alternatively, 153-131 Ma detrital zircons may reflect contributions from more distant sources located >150 km along strike to the east in the Wrangell Mountains, where the Chitina Valley batholith yields 153-150 Ma U-Pb zircon ages (Plafker et al, 1989;Roeske et al, 2003) and adjacent modern rivers in this area yield detrital zircons with 155-130 Ma U-Pb ages (E. M. Day et al, 2016;Trop et al, 2016). An even more distant potential source is the Saint Elias plutonic suite, which yields U-Pb zircon ages between 155 and 147 Ma (Beranek et al, 2017).…”

Section: 1002/2017tc004825mentioning

confidence: 99%

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Detrital Zircon Record of a Mesozoic Collisional Forearc Basin in South Central Alaska: The Tectonic Transition From an Oceanic to Continental Arc

2018

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The collision of oceanic arcs with continental margins is an important mechanism for the growth of continents. Ancient forearc basin strata in collisional orogens provide a record of the upper crustal response to this tectonic process. In south central Alaska, Mesozoic forearc basin strata are exposed in a complete crustal section. U‐Pb detrital zircon geochronology from the forearc basin strata was analyzed within a ~107 Ma stratigraphic framework. The Jurassic strata contain unimodal detrital zircon populations that become progressively younger upsection and range from 175 to 151 Ma. These strata are derived from the active oceanic Talkeetna arc. The Cretaceous strata were deposited above multiple unconformities that collectively represent as much as ~30 Ma of nondeposition and/or erosion in the forearc basin. Erosion in the forearc basin and a general absence of detrital zircon ages between 140 and 120 Ma are interpreted as a hiatus of magmatism triggered by collision of the oceanic arc with the former continental margin. The Cretaceous strata have two main detrital zircon populations: a Cretaceous population ranging from 90 to 68 Ma that becomes progressively younger upsection and a Jurassic population with a broad range of peak ages from 194 to 144 Ma. The Cretaceous population marks the establishment of an active Cretaceous continental arc following the collisional event, and the older population reflects continued erosion of the remnant Jurassic oceanic arc plutons. Our results show that detrital zircon geochronology provides a powerful approach for delineating stages of forearc basin collision and the erosion of multiple magmatic arcs.

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“…Along strike in the Wrangell Mountains, Late Jurassic‐Early Cretaceous plutons of the Chitina arc have 153–150 Ma U‐Pb zircon ages (Plafker et al, ; Roeske et al, , ). U‐Pb zircon ages of modern river sands draining the Chitina Valley batholith, however, range between 156–130 Ma (Day et al, ; Trop et al, ). Jurassic‐Cretaceous detrital zircon ages, 4% of the total population, fall within the age range associated with the Chitina arc (175–135 Ma), whereas Cretaceous detrital zircon ages, 7% of the total population, fall within the age range associated with the Chisana arc (140–115 Ma) (Plafker et al, ; Snyder & Hart, ).…”

Section: U‐pb Geochronology and Hf Isotope Interpretations: Ancestralmentioning

confidence: 99%

Geology, U‐Pb Geochronology, and Hf Isotope Geochemistry Across the Mesozoic Alaska Range Suture Zone (South‐Central Alaska): Implications for Cordilleran Collisional Processes and Tectonic Growth of North America

2020

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The Mesozoic Alaska Range suture zone is defined by a transition from oceanic to continental terranes and is part of a 2000-km-long tectonic boundary throughout the northern Cordillera. Surface geologic mapping of the rock types across this suture zone provides critical information about the upper crustal configuration but provides little insight into the sedimentary, igneous, and metamorphic processes that occurred in deeper levels of the collisional zone. To better constrain the timing and mantle-crust sources of collision-related magmatism, we combine U-Pb ages and Hf isotope compositions of detrital zircons from the three main components of the suture zone. U-Pb/Hf data sets from inboard, continental margin samples have Precambrian-Paleozoic ages with epsilon Hf (t) values ranging between +10 and −20. U-Pb/Hf data sets from the outboard, oceanic terrane samples have Pennsylvanian-Permian detrital zircon ages with epsilon Hf (t) values between +16 and +10. The U-Pb/Hf data set of detrital zircons from Mesozoic strata that represent intervening sedimentary basin(s) that formed between the continental margin and oceanic terranes record Precambrian-Mesozoic detrital zircon ages with epsilon Hf (t) values between +14 and −20. Results of the study document four Archean and Proterozoic global crustal magmatic events that are correlated to the tectonic growth of Laurentia. Also, three Phanerozoic magmatic events have been identified that represent more regional tectonic events. This study demonstrates that the combination of U-Pb geochronology and Hf isotope geochemistry applied to detrital zircons is a powerful tool to define sediment provenance in collisional zones and delineate episodes of global and regional magmatism along convergent plate boundaries.

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U-PB AND ⁴⁰AR/³⁹AR DETRITAL GEOCHRONOLOGY OF MODERN RIVER SEDIMENTS IN THE WRANGELL MOUNTAINS, ALASKA: IMPROVED CONSTRAINTS ON THE AGE AND TECTONIC EVOLUTION OF JURASSIC-QUATERNARY MAGMATISM

Cited by 3 publications

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Detrital zircon geochronology and Hf isotope geochemistry of Mesozoic sedimentary basins in south-central Alaska: Insights into regional sediment transport, basin development, and tectonics along the NW Cordilleran margin

Detrital zircon geochronology and Hf isotope geochemistry of Mesozoic sedimentary basins in south-central Alaska: Insights into regional sediment transport, basin development, and tectonics along the NW Cordilleran margin

Detrital Zircon Record of a Mesozoic Collisional Forearc Basin in South Central Alaska: The Tectonic Transition From an Oceanic to Continental Arc

Geology, U‐Pb Geochronology, and Hf Isotope Geochemistry Across the Mesozoic Alaska Range Suture Zone (South‐Central Alaska): Implications for Cordilleran Collisional Processes and Tectonic Growth of North America

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U-PB AND 40AR/39AR DETRITAL GEOCHRONOLOGY OF MODERN RIVER SEDIMENTS IN THE WRANGELL MOUNTAINS, ALASKA: IMPROVED CONSTRAINTS ON THE AGE AND TECTONIC EVOLUTION OF JURASSIC-QUATERNARY MAGMATISM

Cited by 3 publications

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Detrital zircon geochronology and Hf isotope geochemistry of Mesozoic sedimentary basins in south-central Alaska: Insights into regional sediment transport, basin development, and tectonics along the NW Cordilleran margin

Detrital zircon geochronology and Hf isotope geochemistry of Mesozoic sedimentary basins in south-central Alaska: Insights into regional sediment transport, basin development, and tectonics along the NW Cordilleran margin

Detrital Zircon Record of a Mesozoic Collisional Forearc Basin in South Central Alaska: The Tectonic Transition From an Oceanic to Continental Arc

Geology, U‐Pb Geochronology, and Hf Isotope Geochemistry Across the Mesozoic Alaska Range Suture Zone (South‐Central Alaska): Implications for Cordilleran Collisional Processes and Tectonic Growth of North America

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U-PB AND ⁴⁰AR/³⁹AR DETRITAL GEOCHRONOLOGY OF MODERN RIVER SEDIMENTS IN THE WRANGELL MOUNTAINS, ALASKA: IMPROVED CONSTRAINTS ON THE AGE AND TECTONIC EVOLUTION OF JURASSIC-QUATERNARY MAGMATISM