Reinterpreting the Tectonic Model of the Southern Part of the Taconic Orogeny through a Provenance Study of Late Ordovician Sandstones

Guerrero, Juan Carlos

doi:10.31390/gradschool_theses.5022

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“…Grain size and sampling biases are of great concern for detrital zircon record interpretations [35]. Analyzing two different sandstone samples from the Horseleg Mountain location yielded no major differences in age distribution (see Table 2 in [13]). No grain size analyses were performed.…”

Section: Samplingmentioning

confidence: 99%

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Testing Tectonostratigraphic Hypotheses of the Blountian Phase of the Taconic Orogeny in the Southern Appalachians through an Integrated Geochronological and Sedimentological Study of Ordovician K-Bentonites and Quartz Arenites

et al. 2023

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The tectonic setting of the southernmost part of the eastern margin of Laurentia during the Blountian tectophase (~472–452 Ma) of the Ordovician Taconic Orogeny remains unresolved. Tephras produced by explosive volcanism during this early phase of the orogeny are now K-bentonites, and in many locations, they are interbedded with mature to supermature quartz arenites. We conducted U-Pb analyses of detrital zircons from the sandstones, and of zoned magmatic zircons from the K-bentonites, to constrain the tectonostratigraphic setting with more precision. We also used geochemical fingerprinting of apatite phenocrysts to correlate the K-bentonites in these sandstones along the tectonic front, and we then integrated these results with a depositional systems study of the quartz arenites to further constrain and test competing models of the regional tectonomagmatic setting during that time. The general dearth of detrital zircons that have ages contemporaneous with the volcanic activity, coupled with the predominantly Precambrian ages of the zircons in these Lower Paleozoic quartz arenites that otherwise lack volcaniclastic components—such as detrital VRFs or a muddy matrix derived from an eroding volcanic arc—suggests that magmatic zircons from the tephra layers entered the depositional system only occasionally, and that the volcanic centers were separated geographically from where these quartzose sands were being deposited. Our findings support a tectonostratigraphic and tectonomagmatic model analogous to a combination of select modern settings in the western Pacific and Indonesia, specifically (1) New Guinea, where mature quartz arenites occur in the Cenozoic foreland succession, and (2) Sumatra, where the enormous Toba caldera formed in association with subduction beneath the Cretaceous-aged continental crust of Sumatra.

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Section: Samplingmentioning

confidence: 99%

“…All ages reported herein are less than 20% discordant. Zircon age data for the Alexander Gap, Dirtseller Mountain, and Hanging Rock locations were taken from [13], and analytical details for those analyses can be obtained from there.…”

Section: Apatite Phenocryst "Fingerprinting" Using Laser Ablation Ind...mentioning

confidence: 99%

Testing Tectonostratigraphic Hypotheses of the Blountian Phase of the Taconic Orogeny in the Southern Appalachians through an Integrated Geochronological and Sedimentological Study of Ordovician K-Bentonites and Quartz Arenites

et al. 2023

View full text Add to dashboard Cite

show abstract

Reinterpreting the Tectonic Model of the Southern Part of the Taconic Orogeny through a Provenance Study of Late Ordovician Sandstones

Cited by 1 publication

References 0 publications

Testing Tectonostratigraphic Hypotheses of the Blountian Phase of the Taconic Orogeny in the Southern Appalachians through an Integrated Geochronological and Sedimentological Study of Ordovician K-Bentonites and Quartz Arenites

Testing Tectonostratigraphic Hypotheses of the Blountian Phase of the Taconic Orogeny in the Southern Appalachians through an Integrated Geochronological and Sedimentological Study of Ordovician K-Bentonites and Quartz Arenites

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