Geologic map of the Goodnews and Hagemeister Island quadrangles region, southwestern Alaska

Hoare, J.M.; Coonrad, W.L.

doi:10.3133/ofr789b

Cited by 27 publications

(145 citation statements)

References 0 publications

Supporting

Mentioning

144

Contrasting

Order By: Relevance

“…In the center of the map area, at the join of four quadrangles, map trends suggest that the volcaniclastic sedimentary rocks of the Koksetna River sequence of Wallace and others (1989;KJkr herein), the Graywacke of Kulukak Bay of Hoare and Coonrad (1978;Jkw herein), the Jurassic to Cretaceous volcanic and sedimentary rock sequence of Hoare and Coonrad (1978;KJvs herein), and the Kuskokwim Group (Kk herein) come together. In the northeast Dillingham quadrangle Wilson and others (2003) mapped the latter three units, whereas Wallace and others (1989) showed only their Koksetna River sequence in this vicinity on their sketch map.…”

Section: Map Units Not Assigned To a Provincementioning

confidence: 99%

“…microfossil fauna in the Mulchatna River region. Within the map area, data is not always sufficient to distinguish these rocks from the Koksetna River sequence of Wallace and others (1989) (Hoare and Coonrad, 1978). This rock unit was mapped by Hoare and Coonrad (1978) in the western Dillingham and adjacent Goodnews Bay quadrangles.…”

Section: Qsmentioning

confidence: 99%

“…Within the map area, data is not always sufficient to distinguish these rocks from the Koksetna River sequence of Wallace and others (1989) (Hoare and Coonrad, 1978). This rock unit was mapped by Hoare and Coonrad (1978) in the western Dillingham and adjacent Goodnews Bay quadrangles. According to Hoare and Coonrad (1978), "the volcanic rocks range in composition and type from mafic pillow basalts to more abundant andesitic and trachytic flows, tuff, and breccia.…”

Section: Qsmentioning

confidence: 99%

“…Condon dating from 1953 through 1970. Hoare and Coonrad (1978) mapped these rocks as Early Ordovician to Early Cretaceous unit MzPz in the southwestern Taylor Mountains and northwestern Dillingham quadrangles, as well as in the western Goodnews Bay quadrangle; unit MzPz included a wide range of lithologies. We have attempted to subdivide the Togiak-Tikchik complex into lithologic packages; in general, the nature of the boundaries between the lithologic packages is not known and clarification of this awaits further mapping.…”

Section: Ahklun Mountains Provincementioning

confidence: 99%

“…Wallace (Wallace and others, 1989;Wallace, written commun., 2003), and additional interpretation by the authors of this map. In the Taylor Mountains and Dillingham quadrangles, previously unmapped apparent bedrock exposures, where appropriate, are assigned to map units based on outcrop patterns on the maps of Hoare and Coonrad (1978) and from the earlier unpublished maps of J.N. Platt and E.H. Muller of the U.S. Geological Survey, dating from the 1950s (J.N.…”

Section: Introduction and Previous Workmentioning

confidence: 99%

See 4 more Smart Citations

Bedrock geologic map of the northern Alaska Peninsula area, southwestern Alaska

2017

View full text Add to dashboard Cite

Section: Map Units Not Assigned To a Provincementioning

confidence: 99%

Section: Qsmentioning

confidence: 99%

Section: Qsmentioning

confidence: 99%

Section: Ahklun Mountains Provincementioning

confidence: 99%

Section: Introduction and Previous Workmentioning

confidence: 99%

See 3 more Smart Citations

Bedrock geologic map of the northern Alaska Peninsula area, southwestern Alaska

2017

View full text Add to dashboard Cite

The Last Interglacial to Glacial Transition, Togiak Bay, Southwestern Alaska

Kaufman¹,

Manley

Wolfe

et al. 2001

Quat. res.

View full text Add to dashboard Cite

An 18-m-high coastal bluff at Togiak Bay (northwestern Bristol Bay, southwestern Alaska) exposes marine, lacustrine, fluvial, glacial, volcanic, and organic deposits that record the ∼50,000-year-long transition from the peak of the last interglaciation to the early Wisconsin glaciation. The base of the section is dominated by stratified sand and silt extending up to 4.3 m above sea level; marine diatoms are present, and pollen assemblages are characterized by relatively high percentages of Picea, Alnus, and Betula and low percentages of Poaceae and Cyperaceae. The marine sediment was probably deposited during the peak of marine oxygen-isotope stage (OIS) 5e. An infrared stimulated luminescence (IRSL) age of 151,000±13,000 yr from near the base of the exposure is permissive of this correlation. The marine sand and silt are overlain by 0.8 m of peaty silt with diatoms that record a transition from marine to lacustrine conditions. During this interval, Poaceae and Cyperaceae dominate the pollen assemblages, and Picea and shrubs are nearly absent, suggesting that herb tundra occupied the landscape. This interval probably encompasses OIS 5d on the basis of the herb tundra and an IRSL age of 119,000±10,000 yr from 60 cm below the marine/lacustrine transition. The organic mud is overlain by 3.1 m of stratified sand and organic silt that apparently record shallowing of the lake; reappearance of spruce and shrubs (=OIS 5c?); and subsequent deepening of the lake (=OIS 5b?); followed by aggradation of a floodplain (=OIS 5a?), which was dry at the time basaltic lava buried the site. Thermoluminescence analyses on lava-baked sediment indicate that the eruption occurred 70,000±10,000 yr ago. Sometime thereafter, but prior to 53,600 14C yr B.P. an outlet of the Ahklun Mountains ice cap advanced over the site and deposited ∼7 m of bouldery ice-contact drift. The sedimentary sequence contains at least four tephra beds. Major- and trace-element chemistry provide a basis for correlating two of the tephras with tephra beds at nearby sites. The tephras, luminescence ages, and correlations with marine isotope stages provide the geochronological control to place the Togiak Bay section into a global context. The site serves as an important new reference section for late Pleistocene paleoenvironmental change in eastern Beringia.

show abstract