Geochemical confirmation of the Kula-Farallon slab window beneath the Pacific Northwest in Eocene time

Breitsprecher, K.; Thorkelson, Derek J.; Groome, Wesley G.; Dostál, J.

doi:10.1130/0091-7613(2003)031<0351:gcotkf>2.0.co;2

Cited by 128 publications

(83 citation statements)

References 29 publications

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“…Others considered the coastal basalts to be the product of marginal rifting of North America during ridge subduction (Wells et al, 1984;Massey, 1986;Clowes et al, 1987;Snavely, 1987), producing slab window volcanism (Babcock et al, 1992;Thorkelson, 1996;Groome et al, 2003;Haeussler et al, 2003;Breitsprecher et al, 2003). Sheeted dikes in the Metchosin igneous complex of Vancouver Island and locally in the Crescent Formation, along with their transitional chemistry (Massey, 1986), are consistent with marginal rifting, as is the tholeiitic and alkalic volcanism in the Coast Range that continued for 20 m.y.…”

Section: Introductionmentioning

confidence: 77%

Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot

et al. 2014

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Siletzia is a basaltic Paleocene and Eocene large igneous province in coastal Oregon, Washington, and southern Vancouver Island that was accreted to North America in the early Eocene. New U-Pb magmatic, detrital zircon, and 40 Ar/ 39 Ar ages constrained by detailed fi eld mapping, global nannoplankton zones, and magnetic polarities allow correlation of the volcanics with the 2012 geologic time scale. The data show that Siletzia was rapidly erupted 56-49 Ma, during the Chron 25-22 plate reorganization in the northeast Pacifi c basin. Accretion was completed between 51 and 49 Ma in Oregon, based on CP11 (CP-Coccolith Paleogene zone) coccoliths in strata overlying onlapping continental sediments. Magmatism continued in the northern Oregon Coast Range until ca. 46 Ma with the emplacement of a regional sill complex during or shortly after accretion. Isotopic signatures similar to early Columbia River basalts, the great crustal thickness of Siletzia in Oregon, rapid eruption, and timing of accretion are consistent with offshore formation as an oceanic plateau. Approximately 8 m.y. after accretion, margin parallel extension of the forearc, emplacement of regional dike swarms, and renewed magmatism of the Tillamook episode peaked at 41.6 Ma (CP zone 14a; Chron 19r). We examine the origin of Siletzia and consider the possible role of a long-lived Yellowstone hotspot using the reconstruction in GPlates, an open source plate model. In most hotspot reference frames, the Yellowstone hotspot (YHS) is on or near an inferred northeast-striking KulaFarallon and/or Resurrection-Farallon ridge between 60 and 50 Ma. In this confi guration, the YHS could have provided a 56-49 Ma source on the Farallon plate for Siletzia, which accreted to North America by 50 Ma. A sister plateau, the Eocene basalt basement of the Yakutat terrane, now in Alaska, formed contemporaneously on the adjacent Kula (or Resurrection) plate and accreted to coastal British Columbia at about the same time. Following accretion of Siletzia, the leading edge of North America overrode the YHS ca. 42 Ma. The voluminous high-Ti basaltic to alkalic magmatism of the 42-35 Ma Tillamook episode and extension in the forearc may be related to the encounter with an active YHS. Clockwise rotation of western Oregon about a pole in the backarc has since moved the Tillamook center and underlying Siletzia northward ~250 km from the probable hotspot track on North America. In the reference frames we examined, the YHS arrives in the backarc ~5 m.y. too early to match the 17 Ma magmatic fl are-up commonly attributed to the YHS. We suggest that interaction with the subducting slab may have delayed arrival of the plume beneath the backarc.

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Section: Introductionmentioning

confidence: 77%

Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot

et al. 2014

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“…In terms of tectonic evolution, ridge subduction is usually accompanied by shearing, faulting, uplifting and extension [18,23]. Furthermore, when the subducting ocean ridge is not perpendicular to the subduction zone, magmatic zone moves laterally with time [96,97].…”

Section: Ridge Subduction and Porphyry Cu Depositsmentioning

confidence: 99%

Ridge subduction and porphyry copper-gold mineralization: An overview

Sun

Ling

Yang

et al. 2010

Sci. China Earth Sci.

281

132

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“…When a ridge intersects with a subduction zone, a slab window may form between the subducted parts of the diverging oceanic plates and result in upwelling of asthenospheric mantle through the slab window with particular magmatic products, e.g. adakite, tholeiite, high-Mg andesite (Breitsprecher et al, 2003;Delong et al, 1979;Dickinson and Snyder, 1979;Guivel et al, 1999;Thorkelson, 1996). Such special magmatic rock associations are interpreted to characterize the onset of ridge subduction and formation of a slab window (Thorkelson, 1996).…”

Section: Evidence For Late Carboniferous Ridge Subduction and Slab Wimentioning

confidence: 99%

“…It is suggested that most subduction zones would eventually interact with a spreading ridge and result in opening of slab windows (Sisson et al, 2003;Thorkelson, 1996). The upwelling of asthenospheric mantle through the slab window may produce specific magmas, including adakites, high-Mg andesites, MORB or OIB-like tholeiite (Abratis and Wörner, 2001;Breitsprecher et al, 2003;Cole and Stewart, 2009;Guivel et al, 1999;Hole et al, 1991;Rogers et al, 1985). Based on the occurrence of adakites, boninites, near-trench magmatism, Alaskantype mafic-ultramafic complexes and high-temperature metamorphic belts, some authors inferred that several Paleozoic ocean ridges have been subducted in the CAOB (e.g.…”

Section: Introductionmentioning

confidence: 99%

A Late Carboniferous–Early Permian slab window in the West Junggar of NW China: Geochronological and geochemical evidence from mafic to intermediate dikes

Yin¹,

Long²,

Yuan³

et al. 2013

Lithos

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Geochemical confirmation of the Kula-Farallon slab window beneath the Pacific Northwest in Eocene time

Cited by 128 publications

References 29 publications

Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot

Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot

Ridge subduction and porphyry copper-gold mineralization: An overview

A Late Carboniferous–Early Permian slab window in the West Junggar of NW China: Geochronological and geochemical evidence from mafic to intermediate dikes

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