The diachronous formation of the Enmyvaam and Amguema-Kanchalan volcanic fields in the Okhotsk-Chukotka volcanic belt (NE Russia): Evidence from isotopic data
[No abstract available]
Geology topics
Publications and source records attributed to E. J. Moll-Stalcup.
[No abstract available]
Introduction The Nulato quadrangle encompasses approximately 17,000 km2 (6,500 mi2) of west-central Alaska within the Yukon River drainage basin. The quadrangle straddles two major geologic features-the Yukon-Koyukuk sedimentary basin, a huge triangle-shaped Cretaceous depression that stretches across western Alaska from the Brooks Range to the Yukon delta; and the Ruby geanticline,a broad uplift of pre-Cretaceous rocks that borders the Yukon-Koyukuk basin on the southeast. The Kaltag Fault crosses the quadrangle diagonally from northeast to southwest and dextrally offsets all major geologic features as much as 130 km.
Bering Sea basalt province consists of at least 15 late Cenozoic (less than 6 Ma) volcanic fields that occur on islands in the Bering Sea and along the adjacent west coast of Alaska. The fields are composed of widespread flows of tholeiitic and alkali olivine basalt and small cones, flows, and maar craters of more alkalic basalt, basanite, and rare nephelinite. Although the volcanic fields do not lie along a hot-spot trace, the rocks are compositionally similar to ocean island basalts. Although the rocks show some evidence for fractionation, the dominant control on composition is by varying degrees of partial melting of a mantle source. Trace-element and isotopic data further constrain the mantle source.
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