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DOGAMI Bulletin 108, Geology of the North Half of the Lower Crooked River Basin, Crook, Deschutes, Jefferson, and Wheeler Counties, Oregon, by Jason D. McClaughry, Mark L. Ferns, and Caroline L. Gordon; 286 p. report; 1 map plate, scale 1:63,360; Esri format geodatabase; shapefiles; metadata; spreadsheets.

• Pamphlet only (286 p., 65.3 MB PDF)
• Map plate, with cross sections (georeferenced PDF):
• Plate, Geologic Map of the North Half of the Lower Crooked River Basin, Crook, Deschutes, Jefferson, and Wheeler Counties, Oregon (64" x 60"; 47 MB)
• GIS metadata only bundle (18 .xml files, 1MB .zip) 
• GIS data:
• Full GIS data bundle, geodatabase and shapefiles with metadata (9.2 MB zip file)
• GIS data: geodatabase only, with embedded metadata (Esri® version 10.7 format; 10.7 MB zip file
• GIS data: shapefiles only, with embedded metadata:  (123 KB, zip file)
• Data spreadsheets bundle (5 MB, Microsoft Excel .xlsx format):
• LCB2021_DATA.xlsx
• NEW_40Ar39Ar_ANALYTICALDATA folder
• NEW_UPB_ANALYTICALDATA folder
• Complete publication (report, map plate, geodatabase, shapefiles, metadata, spreadsheets; 124.4MB zip file)

INTRODUCTION [from the report pamphlet]

The north half of the lower Crooked River basin encompasses an area of ~2,338 km² (903 mi²) east of the Cascade Range in central Oregon (Figure 1‑1; plate; Hydrologic Unit Code 8 [HUC8] subbasin 17070305 referred to herein simply as the lower Crooked River basin). Detailed field mapping, integrated with many detailed geologic datasets, has enabled us to reveal a long-lived and complex history of volcanism and sedimentation in this part of central Oregon.

The lower Crooked River basin has been a locus of magmatism for the past 47 million years, including the formation of two large-scale Paleogene rhyolite calderas, deposition of volcaniclastic sedimentary rocks and tuff, and eruption and emplacement of Neogene and Quaternary basaltic lava flows. The earliest magmatism in the lower Crooked River basin is recorded by 46.4 Ma high-MgO alkali-olivine basalt and ~44 to 39 Ma intermediate to silicic calc-alkaline volcanic and intrusive rocks that are part of the Eocene Clarno Formation. Clarno volcanism, focused in the Ochoco volcanic field in the eastern half of the lower Crooked River basin, peaked at 41.8 Ma with the eruption of the tuff of Steins Pillar and formation of the ~16 × 11 km (10 × 7 mi) Wildcat Mountain caldera. The Clarno Formation is overlain in the western half of the lower Crooked River basin by a bimodal assemblage of tholeiitic mafic lava flows and intrusions, rhyolitic tuffs, lava flows and domes, and volcaniclastic sedimentary rocks that are part of the late Eocene to Oligocene John Day Formation. John Day rocks in the lower Crooked River basin make up the lower Crooked volcanic field and include the Crooked River caldera, a large-scale ~41 × 27 km (25.5 × 17 mi) multicyclic caldera formed between 29.7 and 27.6 m.y.a. Sedimentary rocks of the early Miocene Simtustus Formation and ~17- to 16-Ma lava flows of the early Miocene Columbia River Basalt Group unconformably overlie Paleogene rocks in the lower Crooked River basin. In the western part of the basin these rocks infill the central depression of the Crooked River caldera, recording the earliest development of the Crooked River drainage. Late Miocene and Pliocene volcaniclastic sedimentary rocks, ash-flow tuff, and lava flows of the Deschutes Formation, cropping out across the western part of the lower Crooked River basin, record the onset of late High Cascades volcanism, early development of the central Oregon segment of the High Cascades intra-arc graben, and sedimentary and volcanic infilling of the Deschutes Basin on the west. Mafic Deschutes Formation lava flows mapped across the western part of the lower Crooked River basin erupted from vents in the Bowman volcanic field between 8.8 to 3.3 m.y.a. Intracanyon Deschutes Formation mafic lava flows, following channels incised into older rock, record the late Neogene development of ancestral Deschutes and Crooked River channels closely approximating present-day river courses. Pliocene and older rocks are overlain in the western part of the lower Crooked River basin by a broad plain of Quaternary basaltic lava flows erupted from Newberry Volcano between 720 and 400 k.y.a. Bedrock units are locally covered across the lower Crooked River basin by Late Pleistocene and Holocene surficial deposits.

The geology of the lower Crooked River basin, was mapped by the Oregon Department of Geology and Mineral Industries (DOGAMI), with the primary objective to provide an updated and spatially accurate geologic framework for the area (Figure 1‑1; plate). Additional key objectives of the study include: 1) determining the geologic history of volcanic rocks in this part of central Oregon, east of the Cascade Range; 2) characterizing the stratigraphic framework and geologic conditions controlling the distribution of water resources; 3) mapping the distribution of potential aggregate sources and other mineral resources; and 4) describing the nature of geologic hazards in the region. New detailed geologic mapping presented here also provides a basis for future geologic, geohydrologic, and geohazard studies in the lower Crooked River basin (Figure 1‑1; plate).

The core products of this study are this report, accompanying geologic map and cross sections (plate), Esri ArcGIS™ geodatabase, and Microsoft Excel® spreadsheets tabulating point data. The geodatabase presents new geologic mapping in a digital format consistent with the U.S. Geological Survey (USGS) National Cooperative Geologic Mapping Program Geologic Map Schema (GeMS) (U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020). It contains spatial information, including geologic polygons, contacts, structures, as well as data about each geologic unit such as age, lithology, and mineralogy. The geodatabase also includes point feature classes for geochemistry, geochronology, magnetic polarity, orientation points, volcanic vents, and well data. Digitization at scales of 1:24,000 or larger was accomplished using a combination of georeferenced 1:24,000-scale USGS digital raster images, imagery, and where available, high-resolution lidar topography and imagery. Surficial and bedrock geologic units contained in the geodatabase are depicted on the map plate at a scale of 1:63,360 in order to show contrasting bedrock lithology, structural relations, and surficial geology in the lower Crooked River basin. The map plate also includes six geologic cross sections constructed on the basis of the digital data included in the geodatabase. Details in the geodatabase and plottable map plate are referable to this report and accessible in digital appendices.

Geologic mapping in the lower Crooked River basin is a high priority of the Oregon Geologic Map Advisory Committee (OGMAC), supported in part by grants from the STATEMAP component of the USGS National Cooperative Geologic Mapping Program (05HQAG0037, 06HQAG0027, G20AC00202), and by the Oregon Water Resources Department (OWRD) through Interagency Agreement DOGAMI IAA# DASPS-2542-16/OWRD IAA 16 047 (2016). Additional funds were provided by the State of Oregon through the Oregon Department of Geology and Mineral Industries.

GEOGRAPHIC INFORMATION SYSTEM (GIS) DATA
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 PDF is 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.  Geologic Map of the North Half of the Lower Crooked River Basin, Crook, Deschutes, Jefferson, and Wheeler Counties, Oregon, scale 1:63,360, 64" x 60”