DOGAMI Geologic Map Series

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GMS-129, Geologic map of the Athena 7.5′ Quadrangle, Umatilla County, Oregon, by Jason D. McClaughry, and Carlie J.M. Azzopardi; 2 map plates, scale 1:24,000; Esri format geodatabase; shapefiles; metadata.

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INTRODUCTION [from the report pamphlet]

The Athena 7.5′ quadrangle in Umatilla County of northeast Oregon includes an area of 135 square kilometers (km2) at the eastern edge of the Columbia Plateau, a broad depression forming the northwestern flank of the Blue Mountains (Figure 1). The oldest rocks in the map area are part of the ~17 to 6 Ma (mega annum) Columbia River Basalt Group (CRBG), a succession of tholeiitic basalt and basaltic andesite lava flows cropping out over more than 210,000 km2 in parts of Washington, Oregon, Idaho, and Nevada (Plate 1; Figures 1 and 2; Reidel and others, 2013a). In the Athena 7.5′ quadrangle, the CRBG is locally intermittently overlain by upper Miocene and lower Pleistocene sedimentary rocks, a regionally widespread and thick blanket of lower Pleistocene to Holocene loess, and Upper Pleistocene and Holocene alluvial units on valley floors (Plate 1). Three major fault zones converge in this part of the Columbia Plateau, including the WNW-striking Wallula fault zone, NNW-striking Milton Freewater fault zone, and the NNE-striking Hite fault zone (Hooper and Conrey, 1989; Kuehn, 1995; Reidel and others, 2013b; Reidel and others, 2021; Madin and others, 2023; Figures 1 and 3). The geology and structure of the Athena 7.5′ quadrangle was mapped by the Oregon Department of Geology and Mineral Industries (DOGAMI) between 2021 and 2022. Detailed geologic mapping in the Athena 7.5′ quadrangle is a high priority of the Oregon Geologic Map Advisory Committee, supported in part by grants from the STATEMAP component of the U.S. Geological Survey (USGS) National Cooperative Geologic Mapping Program (NCGMP) under cooperative agreement G21AC00647. Additional funds were provided by the State of Oregon through DOGAMI.

The chief objective of this investigation is to provide an updated and spatially accurate geologic framework for the area as part of a multiyear study of the geology of the larger Walla Walla River basin. Additional key objectives of this project are to: 1) map individual CRBG lava flows and crosscutting faults to determine flow distribution, fault offsets, and fault history in this part of the Walla Walla River basin of northeast Oregon; and 2) characterize the stratigraphic framework and geologic conditions controlling the distribution of water resources within the CRBG. CRBG-hosted aquifers provide a critical water supply in the map area and more widely across the Pacific Northwest (Piersol and Sprenke, 2015). New detailed geologic data presented here also provides a basis for future geologic, geohydrologic, and geohazard studies in the region.

Primary sources of map information consulted during this study include previous works by Hogenson (1964), Newcomb (1965), Walker (1973), Swanson and others (1981), Kuehn (1995), Hutter (1997), Ferns and others (2006 a, b), Derkey and others (2006), and Madin and Geitgey (2007). Soil information from Johnson and Makinson (1988) aided with mapping Quaternary surficial units. Additional sources of information are cited in the Explanation of Map Units and in the DataSourcePolys feature class in the geodatabase.

The core publication products of this study are a plottable geologic map and cross section (Plate 1), Esri ArcGIS™ geodatabase, and Microsoft Excel® spreadsheets tabulating point data for geochemistry, orientation points, and well data. The geodatabase presents new geologic mapping in a digital format consistent with the USGS NCGMP Map Schema (GeMS level 3; USGS NCGMP, 2020). It contains spatial information, including map unit polygons, contacts and faults, geologic lines, geochemistry points, orientation points, and well data, as well as data about each geologic unit such as age, lithology, mineralogy, and structure. Surficial and bedrock units in the geodatabase are depicted on Plate 1 at a scale of 1:24,000. Plate 1 includes: 1) a detailed geologic map showing the relationship of both bedrock and surficial units, including concealed bedrock contacts; 2) a simplified bedrock geologic map showing the distribution of contrasting bedrock lithologies and critical structural relationships; and 3) a geologic cross section labeled A-A′.


Geodatabase is Esri® version 10.7 format.
Metadata is embedded in the geodatabase and in the shapefiles and is also provided as separate .xml formatted files.

MAP PLATES (georeferenced PDFs)

Note: The map plate PDFs are in geospatial PDF format, allowing you to turn on and off layers in the map frame and to find geographic coordinates in the PDF.

Plate 1. Geologic Map of the Athena 7.5′ Quadrangle, Umatilla County, Oregon, scale 1:24,000, 44" x 41"


Plate 2. Geologic Map of the Athena 7.5′ Quadrangle, Umatilla County, Oregon, scale 1:24,000, 45.26" x 46"