Preliminary bedrock geologic map of the Yaquina and Toledo quadrangles, Oregon

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

doi:10.3133/ofr72352

Cited by 3 publications

(4 citation statements)

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“…The holotype of Aetiocetus cotylalveus was collected from the Yaquina Formation as exposed intertidally on the modern marine abrasion platform near the mouth of Deer Creek between Seal Rock State Park and the mouth of Beaver Creek, Lincoln County, Oregon, USA (UO Locality 2503). As reported by Emlong (1966) and Snaveley et al (1976), the Yaquina Formation here consists of a north-west-dipping (19°) sequence of interbedded, grey, fine-grained sandstones, medium-grained sandstones, and siltstones containing fossils of marine molluscs, as well as carbonized wood. Emlong (1966: fig.…”

Section: Location Stratigraphy and Correlationsupporting

confidence: 61%

Skull anatomy of the Oligocene toothed mysticeteAetioceus weltoni(Mammalia; Cetacea): implications for mysticete evolution and functional anatomy

Deméré¹,

Berta²

2008

Zoological Journal of the Linnean Society

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Toothed mysticetes of the family Aetiocetidae from Oligocene rocks of the North Pacific play a key role in interpretations of cetacean evolution because they are transitional in grade between dorudontine archaeocetes and edentulous mysticetes. The holotype skull of Aetiocetus weltoni from the late Oligocene (28–24 Ma) of Oregon, USA, has been further prepared, revealing additional morphological features of the basicranium, rostrum and dentary that have important implications for mysticete evolution and functional anatomy. The palate of Aetiocetus weltoni preserves diminutive lateral palatal foramina and associated delicate sulci which appear to be homologous with the prominent palatal foramina and sulci that occur along the lateral portion of the palate in extant mysticetes. In modern baleen whales these foramina allow passage of branches of the superior alveolar artery, which supplies blood to the epithelia of the developing baleen racks. As homologous structures, the lateral palatal foramina of A. weltoni suggest that baleen was present in this Oligocene toothed mysticete. Cladistic analysis of 46 cranial and dental characters supports monophyly of the Aetiocetidae, with toothed mysticetes Janjucetus and Mammalodon positioned as successive sister taxa. Morawanacetus is the earliest diverging aetiocetid with Chonecetus as sister taxon to Aetiocetus species. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154, 308–352.

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Section: Location Stratigraphy and Correlationsupporting

confidence: 61%

Skull anatomy of the Oligocene toothed mysticeteAetioceus weltoni(Mammalia; Cetacea): implications for mysticete evolution and functional anatomy

Deméré¹,

Berta²

2008

Zoological Journal of the Linnean Society

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“…Snavely and Baldwin (1948) and Snavely et al (1968Snavely et al ( , 1976aSnavely et al ( , 1976bSnavely et al ( , 1976c mapped and described the type area of the SRV between Newport and Corvallis, Oregon (Fig. 1).…”

Section: Newport Areamentioning

confidence: 98%

“…Our analysis is based on our geologic mapping of Siletzia over the past three decades (Wells, 1981(Wells, , 1989aWells et al, 1995Wells et al, , 2000Wells and Sawlan, 2014), building on the earlier framework by Snavely et al (1976aSnavely et al ( , 1976bSnavely et al ( , 1976cSnavely et al ( , 1993bSnavely et al ( , 1996 and Tabor and Cady (1978). Age assignments of marine strata interfi ngering and overlying the basalts of Siletzia are based on the calcareous nannoplankton (coccolith) framework, which is tied to the global biostratigraphic zonation (Bukry, 1971(Bukry, , 1973 CP-Coccolith Paleogene zones of Okada and Bukry, 1980;Bukry andSnavely, 1988, Gradstein et al, 2012).…”

Section: Approachmentioning

confidence: 98%

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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“…Fossil specimens referred to Enaliarctos* described in this report were collected by Douglas Emlong from rock units exposed in the Yaquina Bay area between Newport and Waldport in northwestern Lincoln County, Oregon (Figure 1). This region has been mapped (Snavely et al, 1976) and more detailed descriptions of the regional geology are given in Snavely et al, 1980. The fossils described below come from three successive formations of late Oligocene through early Miocene age.…”

Section: Location Stratigraphy and Correlationmentioning

confidence: 99%

New Enaliarctos* (Pinnipedimorpha) from the Oligocene and Miocene of Oregon and the Role of "Enaliarctids" in Pinniped Phylogeny

Berta¹

1991

Smithsonian Contributions to Paleobiology

117

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.-Three new species of the pinnipedimorph Enaliarctos* are described from the marine late Oligocene and early Miocene (Arikareean and Hemingfordian or early Barstovian correlatives) of coastal Oregon. Enaliarctos tedfordl, new species, is based on a partial cranium from the late Oligocene Yaquina Fonnation. A related new species, Enaliarctos emlongi, is founded on a nearly complete cranium, jaws, and associated skeletal elements from the late Oligocene to early Miocene Nye Mudstone. A third new species, Enaliarctos barnesi, is based on a partial cranium and jaws from late Oligocene or early Miocene rocks near the contact between the Yaquina Formation and the Nye Mudstone. Another skull, from the Nye Mudstone, is referred to a previously described species, Enaliarctos mitchelli Barnes, 1979. Three of these species, E. mitchelli, E. emlongi, and E. tedfordl form a monophyletic clade, united by reduced cheek teeth cingula and short metacone of the upper camassial. The major trend observed in Enaliarctos over 10 million years of history is an intermediate stage in the transformation to homodonty evidenced by premolarization of the upper camassial and molars and reduction and simplification of cusps on the lower camassial.Cladistic analysis of 52 cranial and dental characters suggests the following phylogenetic hypotheses: (1) the subfamily "Enaliarctinae" (= "Enaliarctidae") is paraphyletic, (2) monophyly of the genus Enaliarctos* is questioned although the status of this taxon as sister taxon to other pinnipeds is affirmed, (3) other "enaliarctid" pinnipeds, Pteronarctos and Plnnarctidlon, are assigned to less inclusive pinniped clades {Pteronarctos -I-all other pinnipeds and Pinnarctidion + Desmatophoca, Allodesmus, and the Phocidae).OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: The trilobite Phacops rana Green.

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Preliminary bedrock geologic map of the Yaquina and Toledo quadrangles, Oregon

Cited by 3 publications

References 0 publications

Skull anatomy of the Oligocene toothed mysticeteAetioceus weltoni(Mammalia; Cetacea): implications for mysticete evolution and functional anatomy

Skull anatomy of the Oligocene toothed mysticeteAetioceus weltoni(Mammalia; Cetacea): implications for mysticete evolution and functional anatomy

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

New Enaliarctos* (Pinnipedimorpha) from the Oligocene and Miocene of Oregon and the Role of "Enaliarctids" in Pinniped Phylogeny

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