Preliminary bedrock geologic map of the Cape Foulweather and Euchre Mountain quadrangles, Oregon

Snavely, Parke Detweiler; MacLeod, N.S.; Wagner, H.C.

doi:10.3133/ofr72350

Cited by 2 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2,3) which occur above the Siletz River Volcanic Series and below the volcanics of the Nestucca Formation have been designated the "Strata of Cascade Head" in this investigation. The "Strata of Cascade Head" represent a coarse-grained, somewhat volcaniclastic facies of the finer-grained siltstones and mudstones of the "Yamhill Formation" of Snavely, et al (1972). Although the lateral relationships of this unit are unknown, it seems probable that these rocks become interbedded with or grade laterally into strata of the "Yamhill Formation" of Snavely, et al (1972) The following discussion refers to the stratigraphic sections measured during the present investigation.…”

Section: "Strata Of Cascade Head"mentioning

confidence: 86%

“…1-B). This sequence had previously been included within the Tyee Formation (Snavely and Vokes, 1949;Snavely, et al, 1972) but in this investigation it is assigned to the "Strata of Cascade Head". Lithologically, the rocks exposed in the Salmon River Section differ from the rhythmically-bedded sandstone and mudstone of the Tyee Formation in that siltstone comprises most of the section.…”

Section: Neskowin Creek Sectionmentioning

confidence: 98%

“…The lower member is assigned to the "Yamhill Formation". Thus, strata previously mapped as the lower Nestucca Formation (Snavely and Vokes, 1949) along the coast between Cape Kiwanda and Cape Foulweather are now referable to the "Yamhill Formation" of Snavely, MacLeod, and Wagner (1972). It should be noted however, that rocks assigned to the "Yamhill Formation" of Snavely, et al (1972) which occur inunediately to the north and south of the Cascade Head area, differ somewhat from the sediments of the type Yamhill Formation exposed some 25 miles to the east along Mill Creek.…”

Section: "Strata Of Cascade Head"mentioning

confidence: 99%

“…Thus, strata previously mapped as the lower Nestucca Formation (Snavely and Vokes, 1949) along the coast between Cape Kiwanda and Cape Foulweather are now referable to the "Yamhill Formation" of Snavely, MacLeod, and Wagner (1972). It should be noted however, that rocks assigned to the "Yamhill Formation" of Snavely, et al (1972) which occur inunediately to the north and south of the Cascade Head area, differ somewhat from the sediments of the type Yamhill Formation exposed some 25 miles to the east along Mill Creek. Strata of the type Yamhill Formation are predominately massive to thick-bedded and weather to a reddish-brown color whereas the outcrops along the Nestucca River and near Devils Lake are typically thin-bedded, more tuffaceous, and weather yellow-orange.…”

Section: "Strata Of Cascade Head"mentioning

confidence: 99%

“…Strata of equivalent age, but different lithology, are exposed to the north along the Nestucca River and to the south near Devils Lake. Snavely, MacLeod, and Wagner (1972) The thickest, most complete section of the "Strata of Cascade Head" is exposed along Neskowin Creek. Although the subjacent and superjacent units are exposed in the section, the contacts with them are covered, and consequently are best described in areas to the east and west of the creek (Fig.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Middle and upper Eocene biostratigraphy (Foraminifera) of the Cascade Head area, Lincoln and Tillamook Counties, Oregon

Callender¹,

Arden²

2000

View full text Add to dashboard Cite

Section: "Strata Of Cascade Head"mentioning

confidence: 86%

Section: Neskowin Creek Sectionmentioning

confidence: 98%

Section: "Strata Of Cascade Head"mentioning

confidence: 99%

Section: "Strata Of Cascade Head"mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Middle and upper Eocene biostratigraphy (Foraminifera) of the Cascade Head area, Lincoln and Tillamook Counties, Oregon

Callender¹,

Arden²

2000

View full text Add to dashboard Cite

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

View full text Add to dashboard Cite

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.

show abstract

Preliminary bedrock geologic map of the Cape Foulweather and Euchre Mountain quadrangles, Oregon

Cited by 2 publications

References 0 publications

Middle and upper Eocene biostratigraphy (Foraminifera) of the Cascade Head area, Lincoln and Tillamook Counties, Oregon

Middle and upper Eocene biostratigraphy (Foraminifera) of the Cascade Head area, Lincoln and Tillamook Counties, Oregon

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

Contact Info

Product

Resources

About