Cretaceous, Tertiary, and Early Pleistocene Rocks from the Continental Margin in the Bering Sea

Hopkins, David M.; Scholl, David W.; Addicott, Warren O.; Pierce, Richard L.; Smith, Patsy Beckstead; Wolfe, Jack A.; Gershanovich, D. Ye.; Kotenev, B. N.; Lohman, Kenneth E.; Lipps, Jere H.; Obradovich, John D.

doi:10.1130/0016-7606(1969)80[1471:ctaepr]2.0.co;2

Cited by 40 publications

(8 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The sublittoral group, dominated by Eliphidium clavatum, is very similar to that occurring in sediments deposited during late Wisconsin time on what is now the outer shelf of the Bering Sea (Knebel et al, in press). The outer sublittoral and bathyal group is very similar to that reported by Smith {In Hopkins et al, 1969) in lower Pleistocene rocks dredged from the Pribilof Canyon on the continental slope of the Bering Sea. During times of low sea level, the inner shelf species group would have inhabited the present outer shelf, while the outer shelf bathal species group probably was confined beyond the shelf break.…”

Section: Foraminiferasupporting

confidence: 84%

Site 191

1973

Initial Reports of the Deep Sea Drilling Project

View full text Add to dashboard Cite

Section: Foraminiferasupporting

confidence: 84%

Site 191

1973

Initial Reports of the Deep Sea Drilling Project

View full text Add to dashboard Cite

“…The continental margin in the Bering Sea, informally known as the Beringian margin (Hopkins et al 1969), extends about 1500 km northwestward from the Alaska Peninsula to eastern I Siberia (Fig. 1).…”

Section: Geologic Settingmentioning

confidence: 99%

Petrology and age of volcanic-arc rocks from the continental margin of the Bering Sea: implications for Early Eocene relocation of plate boundaries

Davis¹,

Pickthorn²,

Valuer³

et al. 1989

Can. J. Earth Sci.

View full text Add to dashboard Cite

Eocene volcanic flow and dike rocks from the Beringian margin have arc characteristics, implying a convergent history for this region during the early Tertiary. The extrusive rocks are basalt, basaltic andesite, andesite, and minor dacite and rhyolite. The intrusive sample is from a quartz diorite dike intruding serpentinized peridotite. Major-element oxide contents, particularly FeO*/MgO versus SiO,, identify both tholeiitic and calc-alkalic basalt; more silicic lavas have calc-alkalic affinities. Consistent with volcanic-arc compositions, spidergrams show pronounced Nb-Ta depletion and alkali enrichment relative to light-rare-earth-element (LREE) abundance. Chondrite-normalized REE plots show relatively flat patterns, with only slight LREE enrichment for tholeiitic compositions and greater LREE enrichment and lower heavy-rare-earth-element (HREE) abundance for calc-alkalic compositions. The samples, particularly those with calc-alkalic compositions, are rich in plagioclase that is strongly zoned; the more silicic samples contain orthopyroxene, clinopyroxene, and primary amphibole. The quartz diorite dike contains iron-rich almandine phenocrysts that appear to be magmatic, suggesting emplacement at great depth near the base of the crust or upper mantle.Chemical and mineralogical compositions are similar to those of modem Aleutian-arc lavas. They also resemble volcanicarc compositions from western mainland Alaska, although greater chemical diversity and a stronger continental influence are observed in the Alaskan mainland rocks.Early Eocene ages of 54.4-50.2 Ma for the Beringian samples are well constrained by conventional K-Ar ages of nine plagioclase separates and by concordant 40Ar/39Ar incremental heating and total-fusion experiments. A concordant U -Pb zircon age of 53 Ma for the quartz-diorite dike is in good agreement with the K-Ar data.Plate motion studies of the North Pacific Ocean indicate more northerly directed subduction prior to the Tertiary and a continuous belt of arc-type volcanism extending from Siberia, along the Beringian margin, into mainland Alaska. Around 56 Ma (chron 25 -24), subduction changed to a more westerly direction and subduction-related volcanism ceased for most of mainland Alaska. The increasingly oblique angle of convergence should have ended subduction along the Beringian margin as well. However, consistent ages of 54-50 Ma indicate a final pulse in arc-type magmatism during this period of plate adjustment, which may be explained by three different models: (1) The northern and central part of the Beringian margin maintained a higher angle of convergence, allowing a final pulse of arc-type magmatism. (2) The rocks erupted in an early, or proto, Aleutian arc and were rafted against the continental margin along transform faults. (3) The rocks erupted along a leaky transform fault, analogous to calc-alkalic volcanism in the southern California borderland.Les roches d'bge kockne d'une coulee volcanique et d'un dyke de la marge bkringienne prksentent les caractkristiques d'un arc, ce...

show abstract

“…Sructure-contours of acoustic basement beneath the southern Bering Sea shelf. Derived in part from Scholl and others (1968), Scholl and Hopkins (1969), others (1976a,b, 1977). Heavy solid line shows location of seismic-reflection profile interpreted in Figure 9.…”

Section: Structure Contoursmentioning

confidence: 99%