Detrital zircon geochronology of Cordilleran retroarc foreland basin strata, western North America

Abstract

[1] We present a compilation of 8717 U-Pb analyses from 95 detrital zircon samples of Jurassic-Eocene North American Cordillera foreland basin strata. Of these samples, 30 are new and previously unpublished. Variation in detrital zircon age spectra between samples records erosion or recycling of basement and cover rocks within the Cordilleran orogenic wedge. Each sample can be classified into one of six major provenance groups, whose age spectra suggest derivation from (1) Mesozoic eolianites of the western United States, (2) Paleozoic passive margin strata of the western United States, (3) Paleozoic passive margin strata of western Canada, (4) the Mogollon Highlands, (5) the Cordilleran magmatic arc, or (6) Yavapai-Mazatzal Province crystalline basement rocks. Referencing these provenance interpretations to their location and stratigraphic deposition age produces a detailed spatial and temporal record of sediment dispersal within the foreland basin system. Late Jurassic provenance is dominated by recycling of Mesozoic eolianites from sources in the Sevier thrust belt. Cretaceous-Eocene provenance is dominated by recycling of the passive margin, with increasing complexity upsection. We interpret that this provenance transition records a basin-wide unroofing sequence. A composite age-probability plot of 1539 young (<250 Ma) detrital zircons reveals at least four age-abundance peaks that we interpret to represent periodic high-flux magmatism in the Cordilleran arc.

A Late Jurassic to Early Cretaceous record of orogenic wedge evolution in the Western Interior basin, USA and Canada

“…The distribution of zircon populations is consistent with recycling of sedimentary strata uplifted along the Mogollon highlands and incipient Cordilleran foldthrust belt in the southwestern United States ( Fig. 7; Dickinson andGehrels, 2008a, 2009b;Leier and Gehrels, 2011;Laskowski et al, 2013;May et al, 2013). Group 1 samples are also characterized by a Jurassic detrital zircon population from primary igneous sources in the Cordillera (Fig.…”

“…7) are characterized by broad detrital zircon populations derived from the Appalachian orogeny (populations at 615 and 420 Ma) and the Grenville orogeny (populations at 1160 and 1055 Ma) (Dickinson andGehrels, 2008a, 2009b;Laskowski et al, 2013). Paleozoic and Proterozoic detrital zircon populations in Group 1 samples are similar to the Mesozoic eolianites (Fig.…”

Quickening the Pulse: Fractal Tempos in Continental Arc Magmatism

“…The double peak in the volcanic record together with the correlative peak in the detrital fore-arc data, when contrasted with the irregular plutonic curve, also illustrates the longitudinal asymmetry of the arc. Over a longer time scale, as much as 100 My, the distal back-arc record possibly mimics the greater flux curve for the Sierra Nevada batholith in FIGURE 3B (Laskowski et al 2013).…”

“…By extension, detrital zircons should record magmatic addition rates and provide a first approximation of the volume of zircon-bearing magmatic rock, with short-lived magmatic pulses and lulls also being apparent (e.g. Barth et al 2012;Laskowski et al 2013). Nonetheless, caution is warranted when using the zircon record as a proxy because seldom does the sedimentary record isolate a single part of a magmatic arc: sedimentary successions probably represent longer-term integrated "average" records.…”

Evolution of the Jura-Cretaceous North American Cordilleran margin: Insights from detrital-zircon U-Pb and Hf isotopes of sedimentary units of the North Cascades Range, Washington

“…Jurassic to Eocene convergence along the western margin of the North American continent resulted in the accretion of multiple oceanic-arc terranes, intrusion of arc plutons, and formation of large sedimentary basins (e.g., Saleeby and Busby-Spera, 1992;Dickinson, 2004). The U-Pb age spectra of detrital zircons from western North American Cor dilleran sedimentary rocks have been used to help understand episodic high-flux magmatism (Paterson and Ducea, 2015), the timing at which sediment sources were uplifted and when basins subsided (e.g., DeGraaff-Surpless et al, 2003;Laskowski et al, 2013;Surpless et al, 2014), paleogeography, and terrane mobility (e.g., Gehrels et al, 1995;Housen and Beck, 1999;Barbeau et al, 2005). Hafnium-isotope analyses of detrital zircons are used as an additional fingerprint of sedimentary provenance (e.g., Gehrels and Pecha, 2014;Surpless et al, 2014;Holland et al, 2015) by comparing to zircon Hf-isotope compositions of potential source rocks (e.g., Goodge and Vervoort, 2006;Gaschnig et al, 2011;Lackey et al, 2012;Shaw et al, 2014).…”