摘要: The Tyonek Quadrangle in south-central Alaska was evaluated to identify geologic environments favorable for the occurrence of uranium deposits. Published geologic maps and reports, aerial radiometric surveys, geochemical surveys, ... 展开 The Tyonek Quadrangle in south-central Alaska was evaluated to identify geologic environments favorable for the occurrence of uranium deposits. Published geologic maps and reports, aerial radiometric surveys, geochemical surveys, and ground geologic examination were used in the evaluation. The western two-thirds of the Tyonek Quadrangle is a part of the Alaska Range orogenic belt. It consists largely of a Mesozoic flysch and mafic volcanic sequence and Mesozoic and Tertiary granitic plutonic rocks. The eastern one-third of the quadrangle is mainly underlain by rocks and deposits of the Cook Inlet-Susitna Basin of Tertiary age. No areas or units in the quadrangle were found to be favorable for uranium deposits. Sediment samples from streams draining the Mount Estelle pluton in the northwest corner of the quadrangle contained up to 40 ppM U sub 3 O sub 8 . In addition, radiometric data and high geochemical factor scores characterized the Mount Estelle unit, but no uranium occurrences were found in reconnaissance-level ground examination. Radiometric and geochemical levels in the rest of the exposed bedrock environments in the quadrangle were low. The Cenozoic basins of the quadrangle have some similarity to those which host sandstone uranium deposits elsewhere. Their potential, however, remains unevaluated because of their water-saturated surficial cover. Placer occurrences of uranium likewise remain unevaluated. (ERA citation 07:045845) 收起