Sarsapkin Tonalite. Name proposed for unit in /Toats Coulee magma series [informal] (new). Mapped in Toats Coulee Creek region, Okanogan Range, Washington, in T. 39 and 40 N., R. 25 E. Described as light-gray, fine- to medium-grained; very similar to Loomis granodiorite (new) of Toats Coulee magma series. Age is Late Triassic, based on radiometric (K-Ar, hornblende) age of 194 +/-6 Ma of Loomis granodiorite (new) of Toats Coulee magma series (citing Rinehart and Fox [1972]). [Age is Early Jurassic, based on 1983 DNAG Geologic Time Scale and 1986 USGS Geologic Time Chart.]
Type locality stated to be in T. 39 and 40 N., R. 25 E., Okanogan Range, WA. Origin of name not stated.
["Toats Coulee magma series" considered informal. Term "Series" is applied formally only to chronostratigraphic units (ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). US geologic names lexicon (USGS Bull. 1520, p. 271) lists Sarsapkin Tonalite of Toats Coulee Group (explanation not given).]
Source: GNU records (USGS DDS-6; Menlo GNULEX); US geologic names lexicon (USGS Bull. 1520, p. 271).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
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