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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.

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.

Geodatabas .zip (geodatabase only, with embedded metadata, Esri® version 10.7 format; 9.2 MB zip file)

Feature dataset classes

 

 

Name

Description

Metadata bundle .(zip)

AlteredGeochemPoints

This feature class represents point locations where alteration-zone samples have been analyzed by ICP-MS and ICP-AES methods. Includes data collected by the authors during this study or compiled from previous studies. These data are also contained in the alteredgeochempoints spreadsheet.

.xml

CartographicLines

Vector lines that have no real-world physical existence and do not participate in map-unit topology. The feature class includes cross section lines used for cartography.

.xml

ContactsAndFaults

The vector lines in this feature class contain geologic content including contacts and fault locations used to create the map unit polygon boundaries. The existence and location confidence values for the contacts and faults are provided in the feature class attribute table.

.xml

DataSourcePolys

This feature class contains polygons that delineate data sources for all parts of the geologic map. These sources may be a previously published map, new mapping, or mapping with a certain technique. For a map with one data source, for example all new mapping, this feature class contains one polygon that encompasses the map area.

.xml

GeochemPoints

This feature class represents point locations where whole-rock samples have been analyzed by X-ray fluorescence (XRF) techniques. Includes data collected by the authors during this study or compiled from previous studies. These data are also contained in the geochemistry spreadsheet.

.xml

GeochronPoints

This feature class represents point locations where isotopic ages have been obtained for rock samples in the map area. Data collected by the authors or compiled during the course of this study. These data are also contained in the geochronology spreadsheet.

.xml

GeologicLines

These vector lines represent known fold axis locations in the quadrangle. The existence and location confidence for the fold axes are provided in the feature class attribute table.

.xml

MagneticPoints

This feature class represents point locations where measurements of natural remanent magnetization have been obtained for strongly magnetized lavas. Includes data collected by the authors during the course of this study. These data are also contained in the magnetic polarity spreadsheet.

.xml

MapUnitPoints

This feature class represents points used to generate the MapUnitPolys feature class from the ContactsAndFaults feature class.

.xml

MapUnitPolys

This polygon feature class represents the geologic map units as defined by the authors.

.xml

OrientationPoints

This feature class represents point locations in the map area where structural measurements were made or were compiled from previous studies. These data are also contained in the bedding (strike and dip) spreadsheet described in more detail below.

.xml

OverlayPolys

This feature class holds the reference map outline for each map plate.

.xml

WellPoints

This feature class represents point locations of wells in the map area. Includes data obtained by the authors from the Oregon Department of Water Resources (OWRD). These data are also contained in the Wells Points spreadsheet.

.xml

VentPoints

This feature class represents point locations of volcanic vents in the map area. These data are also contained in the Vent Points spreadsheet.

.xml

Tables

 

 

DataSources

Data table that contains information about data sources used to compile the geology of the area.

.xml

DescriptionOfMapUnits

Data table that captures the content of the Description of Map Units (DMU), or equivalent List of Map Units and associated pamphlet text, included in a geologic map.

.xml

GeoMaterialDict

Data table providing definitions and hierarchy for GeoMaterial names prescribed by the GeMS database schema.

.xml

Glossary

Data table that contains information about the definitions of terms used in the geodatabase.

.xml

Shapefiles (GIS shapefiles only bundle, with metadata; 652 KB, zip file)

 

LCB2021_AlteredGeochemPoints.shp

See descriptions above

.xml

LCB2021_AlteredZones.shp

.xml

LCB2021_GeochemPoints.shp

.xml

LCB2021_GeochronPoints.shp

.xml

LCB2021_MagneticPoints.shp

.xml

LCB2021_OrientationPoints.shp

.xml

LCB2021_RefMap.shp

.xml

LCB2021_VentPoints.shp

.xml

LCB2021_WellPoints.shp

.xml

LCB2021_XSectionLines.shp

.xml

 

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”