Cenozoic Basin Development and Strike-Slip Displacement Along the Denali Fault System, Eastern Alaska Range, Alaska: A Provenance Approach

Allen, Wai K.; Ridgway, Kenneth D.; Benowitz, Jeffrey A.; Fasulo, Cooper R.; Keough, Brandon; Warfel, Thomas S.; Fitzgerald, Paul G.; Gillis, Robert J.; Trop, Jeffrey M.

doi:10.1130/abs/2018am-322519

Cited by 2 publications

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“…Another related possibility is that the 10-5 Ma detrital zircon population in our samples is the product of erosion of airfall tephras associated with the Wrangell arc. Similar age detrital zircon populations have been reported from localized Miocene-Pliocene basins in the eastern Alaska Range that are attributed to reworking of tephras into fluvial strata (Allen, 2016;Allen et al, 2018). In addition, in the Upper Miocene strata of the Tanana basin near the town of Healy, Alaska, two thick tephras have been documented, one 8.4 m thick and the other 5.0 m thick (Ridgway et al, 2007).…”

Section: Characterizing the Mesozoic-cenozoic Magmatic Record Along The Southern Alaska Convergent Marginsupporting

confidence: 66%

Detrital zircon geochronology of modern river sediment in south-central Alaska: Provenance, magmatic, and tectonic insights into the Mesozoic and Cenozoic development of the southern Alaska convergent margin

Fasulo

Ridgway

2021

Geosphere

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New and previously published detrital zircon U-Pb ages from sediment in major rivers of south- central Alaska archive several major episodes of magmatism associated with the tectonic growth of this convergent margin. Analysis of detrital zircons from major trunk rivers of the Tanana, Matanuska-Susitna, and Copper River watersheds (N = 40, n = 4870) documents major <250 Ma age populations that are characteristic of the main phases of Mesozoic and Paleogene magmatism in the region as documented from limited U-Pb ages of igneous rocks. Key points from our detrital record include: (1) Major magmatic episodes occurred at 170, 150, 118, 95, 72, 58, and 36 Ma. The overall pattern of these ages suggests that felsic magmatism was episodic with periodicity ranging between ~14 and 32 m.y. with an average of ~22 m.y. (2) Magmatism in south-central Alaska shows similar age trends with both the Coast Mountains batholith and the along-strike Alaska Peninsula forearc basin strata, demonstrating a spatial and temporal relationship of felsic magmatism along the entire northern Cordilleran margin. (3) Topography and zircon fertility appear to influence the presence and/or absence of detrital zircon populations in individual watersheds. Results from this study indicate that regionally integrated detrital zircon populations from modern trunk rivers are faithful recorders of Mesozoic and Paleogene magmatic events along a convergent margin, but there appears to be a lag time for major rivers to record Neogene and ongoing magmatic events.

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Section: Characterizing the Mesozoic-cenozoic Magmatic Record Along The Southern Alaska Convergent Marginsupporting

confidence: 66%

Detrital zircon geochronology of modern river sediment in south-central Alaska: Provenance, magmatic, and tectonic insights into the Mesozoic and Cenozoic development of the southern Alaska convergent margin

Fasulo

Ridgway

2021

Geosphere

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“…18 Ma (Berkelhammer et al, 2019), although some studies postulate that much of this offset could have occurred since ca. 6 Ma (Allen et al, 2018).…”

Section: New Insights On Provenance Of the Wellesly Basin And Implicamentioning

confidence: 99%

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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Cenozoic Basin Development and Strike-Slip Displacement Along the Denali Fault System, Eastern Alaska Range, Alaska: A Provenance Approach

Cited by 2 publications

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Detrital zircon geochronology of modern river sediment in south-central Alaska: Provenance, magmatic, and tectonic insights into the Mesozoic and Cenozoic development of the southern Alaska convergent margin

Detrital zircon geochronology of modern river sediment in south-central Alaska: Provenance, magmatic, and tectonic insights into the Mesozoic and Cenozoic development of the southern Alaska convergent 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

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