USGS Science⌕ Search
Home/Archive/USGS

USGS · 70016233

The Hayes tephra deposits, and upper Holocene marker horizon in south-central Alaska

J.R. Riehle·P.M. Bowers·T. A. Ager
View original source ↗Export metadata ↓

Abstract

The most widespread of all Holocene tephra deposits in the Cook Inlet region of south-central Alaska is a set of deposits from Hayes volcano. Because of their unique phenocryst content-biotite in rare amounts and a high proportion of amphibole to pyroxene-the deposits are readily identifiable at all but the most distant sites where they are very fine grained. Eighteen radiocarbon dates from eight upland sites limit the age of the tephra set to between about 3500 and 3800 yr. The set originated at Hayes volcano in the Tordrillo Mountains 150 km northwest of Anchorage; seven or possibly eight closely succeeding deposits, low-silica dacite in composition, compose two main lobes that extend northeast for 400 km and south for at least 250 km from the vent. We estimate the total tephra volume to be 10 km3; multiple layers imply four to six larger and two or three smaller eruptions. The deposits are a nearly isochronous marker horizon that should be useful in future archeologic, geologic, and palynologic studies in the region. ?? 1990.

Explore related subjects

Quaternary ResearchArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J.R. Riehle, P.M. Bowers, T. A. Ager. 2017-01-20. The Hayes tephra deposits, and upper Holocene marker horizon in south-central Alaska. https://doi.org/10.1016/0033-5894(90)90056-q

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Age reassignment using luminescence dating for the Mammoth Site, Black Hills, South Dakota, USA

The Mammoth Site (MS) at Hot Springs, South Dakota, provides a unique opportunity to reconstruct paleoenvironmental conditions on the Northern Great Plains of the United States. Previous radiocarbon analyses of mammoth bone apatite suggested the MS sinkhole was deposited ∼42–23 cal ka BP. However, two U-series ages and one thermoluminescence (TL) age ranged between 150 and 101 ka, suggesting the bones were considerably older. We analyzed six samples from the bone bed using infrared-stimulated luminescence (IRSL) on feldspars, because the quartz luminescence was saturated; the ages ranged from approximately 232 to 160 ka, showing better agreement with previous U-series and TL analyses. In addition, we dated three samples on two terraces that are at lower elevation than the MS. Our new IRSL ages show that the sediments of the MS were likely well bleached, derived from pond margin runoff events, and deposited as sandy-silt laminae couplets. Our chronology indicates that the 6-m-thick bone-bearing sediments accumulated at a rate of approximately 12 mm/yr and that deposition occurred during Marine Isotope Stage (MIS) 6 and MIS 7, not MIS 2 and MIS 3 as previously published.

South Dakota↗
USGS2026

A multiproxy reconstruction of changes in sea ice and primary productivity at IODP Site U1339 (Umnak Plateau, Bering Sea) during Marine Isotope Stage 11

The extreme warmth of Marine Isotope Stage (MIS) 11 has been extensively studied in the terrestrial realm; however, less is known about its expression in the North Pacific. Here, we present a multiproxy record from Integrated Ocean Drilling Program (IODP) Site U1339 in the southeastern Bering Sea (Umnak Plateau). We use sedimentology, diatoms, and organic geochemistry to reconstruct sea ice and primary productivity from the end of MIS 12 to the beginning of MIS 10 (430–368 ka) at this site. In late MIS 12, the Umnak Plateau experienced extensive seasonal sea ice cover, with spring sea ice concentration near 100%. Based on diatoms and ice-rafted debris, sea ice declined to year-round ice-free conditions during deglaciation but readvanced during the interglacial climatic optimum. In contrast, sea ice has not been present at the Umnak Plateau throughout the Holocene. During MIS 11, sea ice at this site may have persisted due to a more easterly and/or weaker Aleutian Low. Laminated sediments indicate enhanced seasonal productivity during deglaciation. However, productivity does not remain high throughout the interglacial. The decline in productivity during MIS 11 occurs independently of fluctuations in sea ice and upwelling and may be due to increasing nutrient limitation.

Alaska↗