Geology Reports⌕ Search

Geology topics

Research about Idaho, Oregon

Source-linked reports with geographic coverage including Idaho, Oregon.

At least 37 records · Page 2Linked to original sources
USGS2015

Composite Sunrise Butte pluton: Insights into Jurassic–Cretaceous collisional tectonics and magmatism in the Blue Mountains Province, northeastern Oregon

The composite Sunrise Butte pluton , in the central part of the Blue Mountains Province, northeastern Oregon, preserves a record of subduction-related magmatism, arc-arc collision, crustal thickening, and deep-crustal anatexis. The earliest phase of the pluton (Desolation Creek unit) was generated in a subduction zone environment, as the oceanic lithosphere between the Wallowa and Olds Ferry island arcs was consumed. Zircons from this unit yielded a 206 Pb/ 238 U age of 160.2 ± 2.1 Ma. A magmatic lull ensued during arc-arc collision, after which partial melting at the base of the thickened Wallowa arc crust produced siliceous magma that was emplaced into metasedimentary rocks and serpentinite of the overthrust forearc complex. This magma crystallized to form the bulk of the Sunrise Butte composite pluton (the Sunrise Butte unit; 145.8 ± 2.2 Ma). The heat necessary for crustal anatexis was supplied by coeval mantle-derived magma (the Onion Gulch unit; 147.9 ± 1.8 Ma). The lull in magmatic activity between 160 and 148 Ma encompasses the timing of arc-arc collision (159-154 Ma), and it is similar to those lulls observed in adjacent areas of the Blue Mountains Province related to the same shortening event. Previous researchers have proposed a tectonic link between the Blue Mountains Province and the Klamath Mountains and northern Sierra Nevada Provinces farther to the south; however, timing of Late Jurassic deformation in the Blue Mountains Province predates the timing of the so-called Nevadan orogeny in the Klamath Mountains. In both the Blue Mountains Province and Klamath Mountains, the onset of deep-crustal partial melting initiated at ca. 148 Ma, suggesting a possible geodynamic link. One possibility is that the Late Jurassic shortening event recorded in the Blue Mountains Province may be a northerly extension of the Nevadan orogeny. Differences in the timing of these events in the Blue Mountains Province and the Klamath-Sierra Nevada Provinces suggest that shortening and deformation were diachronous, progressing from north to south. We envision that Late Jurassic deformation may have collapsed a Gulf of California-style oceanic extensional basin that extended from the Klamath Mountains (e.g., Josephine ophiolite) to the central Blue Mountains Province, and possibly as far north as the North Cascades (i.e., the coeval Ingalls ophiolite). The lull in magmatic activity between 160 and 148 Ma encompasses the timing of arc-arc collision (159–154 Ma), and it is similar to those lulls observed in adjacent areas of the Blue Mountains Province related to the same shortening event. Previous researchers have proposed a tectonic link between the Blue Mountains Province and the Klamath Mountains and northern Sierra Nevada Provinces farther to the south; however, timing of Late Jurassic deformation in the Blue Mountains Province predates the timing of the so-called Nevadan orogeny in the Klamath Mountains. In both the Blue Mountains Province and Klamath Mountains, the onset of deep-crustal partial melting initiated at ca. 148 Ma, suggesting a possible geodynamic link. One possibility is that the Late Jurassic shortening event recorded in the Blue Mountains Province may be a northerly extension of the Nevadan orogeny. Differences in the timing of these events in the Blue Mountains Province and the Klamath–Sierra Nevada Provinces suggest that shortening and deformation were diachronous, progressing from north to south. We envision that Late Jurassic deformation may have collapsed a Gulf of California–style oceanic extensional basin that extended from the Klamath Mountains (e.g., Josephine ophiolite) to the central Blue Mountains Province, and possibly as far north as the North Cascades (i.e., the coeval Ingalls ophiolite).

Idaho, Oregon↗
USGS2013

Water column and bed-sediment core samples collected from Brownlee Reservoir near Oxbow, Oregon, 2012

The U.S. Geological Survey, in cooperation with Idaho Power Company, collected water-column and bed-sediment core samples from eight sites in Brownlee Reservoir near Oxbow, Oregon, during May 5–7, 2012. Water-column and bed-sediment core samples were collected at each of the eight sites and analyzed for total mercury and methylmercury. Additional bed-sediment core samples, collected from three of the eight sites, were analyzed for pesticides and other organic compounds, trace metals, and physical characteristics, such as particle size. Total mercury and methylmercury were detected in each of the water column and bed-sediment core samples. Only 17 of the 417 unique pesticide and organic compounds were detected in bed-sediment core samples. Concentrations of most organic wastewater compounds detected in bed sediment were less than the reporting level. Trace metals detected were greater than the reporting level in all the bed-sediment core samples submitted for analysis. The particle size distribution of bed-sediment core samples was predominantly clay mixed with silt.

Idaho, Oregon↗
USGS2012

Radiometric and paleomagnetic evidence for the Emperor reversed polarity event at 0.46 ± 0.05 M.Y. in basalt lava flows from the eastern Snake River Plain, Idaho

K-Ar and paleomagnetic data from cores through a sequence of basalt flows in the eastern Snake River Plain provide evidence for a brief (0.005 to 0.01 m.y.) reversal of the geomagnetic field 0.46 ± 0.05 m.y. ago. This reversed polarity event has also been found in sea-floor magnetic anomalies and in sediment cores and is probably the Emperor event of Ryan [1972].

Idaho, Oregon↗
USGS2007

A comparison of protocols and observer precision for measuring physical stream attributes

Stream monitoring programs commonly measure physical attributes to assess the effect of land management on stream habitat. Variability associated with the measurement of these attributes has been linked to a number of factors, but few studies have evaluated variability due to differences in protocols. We compared six protocols, five used by the U.S. Department of Agriculture Forest Service and one by the U.S. Environmental Protection Agency, on six streams in Oregon and Idaho to determine whether differences in protocol affect values for 10 physical stream attributes. Results from Oregon and Idaho were combined for groups participating in both states, with significant differences in attribute means for 9 out of the 10 stream attributes. Significant differences occurred in 5 of 10 in Idaho, and 10 of 10 in Oregon. Coefficients of variation, signal-to-noise ratio, and root mean square error were used to evaluate measurement precision. There were differences among protocols for all attributes when states were analyzed separately and as a combined dataset. Measurement differences were influenced by choice of instruments, measurement method, measurement location, attribute definitions, and training approach. Comparison of data gathered by observers using different protocols will be difficult unless a core set of protocols for commonly measured stream attributes can be standardized among monitoring programs.

Idaho, Oregon↗
USGS1998

Double-stocking for overcoming damage to conifer seedlings by pocket gophers

A 5-yr study was conducted on national forests in Idaho and Oregon to evaluate how doubling the seedling stocking rate of lodgepole pine ( Pinus contorta ) would relate to 5-year survival and the uniformity of distribution of seedlings in the presence of northern pocket gopher ( Thomomys talpoides ) damage. Either 4 or 8 seedlings were planted in 40-m 2 subplots (1000 or 2000 seedlings/ha) and monitored for gopher damage. We found that the number of seedlings attacked by gophers, and consequently, the number of seedlings surviving for 5 years, were directly proportional to the stocking rate, but the consistency of seedling distribution within each site (as measured by the proportion of 40-m 2 subplots with ≥ 2 surviving seedlings) did not double with stocking rate. In some situations, increasing the stocking rate should be considered as a method for overcoming pocket gopher damage.

Idaho, Oregon↗
USGS1998

Organochlorine compounds and trace elements in fish tissue and bed sediments in the lower Snake River basin, Idaho and Oregon

Fish-tissue and bed-sediment samples were collected to determine the occurrence and distribution of organochlorine compounds and trace elements in the lower Snake River Basin. Whole-body composite samples of suckers and carp from seven sites were analyzed for organochlorine compounds; liver samples were analyzed for trace elements. Fillets from selected sportfish were analyzed for organochlorine compounds and trace elements. Bed-sediment samples from three sites were analyzed for organochlorine compounds and trace elements. Twelve different organochlorine compounds were detected in 14 fish-tissue samples. All fish-tissue samples contained DDT or its metabolites. Concentrations of total DDT ranged from 11 micrograms per kilogram wet weight in fillets of yellow perch from C.J. Strike Reservoir to 3,633 micrograms per kilogram wet weight in a whole-body sample of carp from Brownlee Reservoir at Burnt River. Total DDT concentrations in whole-body samples of sucker and carp from the Snake River at C.J. Strike Reservoir, Snake River at Swan Falls, Snake River at Nyssa, and Brownlee Reservoir at Burnt River exceeded criteria established for the protection of fish-eating wildlife. Total PCB concentrations in a whole-body sample of carp from Brownlee Reservoir at Burnt River also exceeded fish-eating wildlife criteria. Concentrations of organochlorine compounds in whole-body samples, in general, were larger than concentrations in sportfish fillets. However, concentrations of dieldrin and total DDT in fillets of channel catfish from the Snake River at Nyssa and Brownlee Reservoir at Burnt River, and concentrations of total DDT in fillets of smallmouth bass and white crappie from Brownlee Reservoir at Burnt River exceeded a cancer risk screening value of 10 -6 established by the U.S. Environmental Protection Agency. Concentrations of organochlorine compounds in bed sediment were smaller than concentrations in fish tissue. Concentrations of p,p'DDE, the only compound detected in all three bed-sediment samples, ranged from 1.1 micrograms per kilogram dry weight in C.J. Strike Reservoir to 11 micrograms per kilogram dry weight in Brownlee Reservoir at Burnt River. Data from this study, compared with data collected in the upper Snake River Basin from 1992 to 1994, indicates that, in general, organochlorine concentrations in fish tissue and bed sediment increased from the headwaters of the Snake River in Wyoming downstream to Brownlee Reservoir. The largest trace-element concentrations in fish tissue were in liver samples from carp from Brownlee Reservoir at Burnt River and suckers from the Boise River near Twin Springs. Concentrations of most trace elements were larger in livers than in the sport- fish fillets. However, mercury concentrations were generally larger in the sportfish fillets; they ranged from 0.08 microgram per gram wet weight in yellow perch from C.J. Strike Reservoir to 0.32 microgram per gram wet weight in channel catfish from Brownlee Reservoir at Burnt River. None of the trace-element concentrations in fillets exceeded median international standards or U.S. Food and Drug Administration action levels. Large trace-element concentrations in the upper Snake River Basin were reported in liver samples from suckers from headwater streams, probably a result of historical mining and weathering of metal-rich rocks. Concentrations of most trace elements in the bed-sediment samples were largest in Brownlee Reservoir at Mountain Man Lodge. Concentrations of arsenic, cadmium, chromium, copper, nickel, and zinc in bed sediment from the Mountain Man Lodge site exceeded either the threshold effect level or probable effect level established by the Canadian Government for the protection of benthic life. Arsenic, chromium, copper, and nickel concentrations in bed sediment from Brownlee Reservoir at Burnt River and chromium, copper, and nickel in bed sediment from C.J. Strike Reservoir also exceeded the threshold effect level.

Idaho, Oregon↗
USGS1997

The effects of Vexar® seedling protectors on the growth and development of lodgepole pine roots

The effects on the growth and development of lodgepole pine roots from the Vexar ® tubes used to protect seedlings from pocket gopher damage were studied in the Targhee National Forest, Idaho and the Deschutes National Forest, Oregon. At each site, Vexar-protected and unprotected seedlings, with and without above-ground gopher damage were examined after six growing seasons for root deformities and growth. Undamaged seedlings exhibited greater growth, reflecting the importance of non-lethal gopher damage as a deterrent to tree growth. Protected seedlings with similar damage history as unprotected seedlings had greater root depth than unprotected seedlings, although unprotected seedlings with no above-ground damage generally had the greatest root weight. In general, the percent of seedlings with root deformities was greater for the unprotected seedlings than for the Vexar-protectd seedlings, although this could be largely due to the greater care required to plant protected seedlings. Acute deformities were more common for unprotected seedlings, whereas root deformities with less severe bending were more common for protected seedlings. The incidence of crossed roots was similar for protected and unprotected seedlings on the Deschutes site, where enough occurrences of this deformity permitted analyses. Protected seedlings were similar in root abundance, root distribution, root size and vigor to the unprotected seedlings, with some indication from the Deshutes study site that root distribution was improved with Vexar protection.

Idaho, Oregon↗
USGS1995

Mapping the response of riparian vegetation to possible flow reductions in the Snake River, Idaho

This study was initiated to determine the general effects of potential flow reductions in the middle Snake River (Swan Falls Dam downstream to the Idaho-Oregon border) on its riparian vegetation. Considerable water from the river is currently used to irrigate the adjacent Snake River Plain, and increased demand for water in the future is likely. The problem was subdivided into several research components including: field investigation of the existing riparian vegetation and river environment, hydrological modeling to calculate the effects of one flow scenario on hydrological regime, and integration of vegetation and hydrological modeling results with a Geographic Information System (GIs) to map the riverbed, island, and bank conditions under the scenario flow. Field work was conducted in summer 1990. Riparian vegetation along 40 U.S. Geological Survey cross-sections was sampled at approximately 1.25 mile intervals within the 50 mile long study area. Cross-section and flow data were provided by the U.S. Geological. Survey. GIs mapping of land/water cover using ARC/INFO was based on 1987 aerial photographs. Riverbed contour maps were produced by linking cross-section data, topographic contouring software ( anudem ), and GIs. The maps were used to spatially display shallow areas in the channel likely to become vegetated under reduced flow conditions. The scenario would reduce flow by approximately 20% (160 MAF) and lower the river an average of 0.5 ft. The scenario flow could cause a drop in the elevation of the riparian zone comparable to the drop in mean river level and expansion of the lower riparian zone into shallow areas of the channel. The GIs maps showed that the shallow areas of the channel more likely to become vegetated under the scenario flow are located in wide reaches near islands. Some possible ecological consequences of the scenario flow include a greater area of riparian habitat, reduced flow velocity and sedimentation in shallow channels leading to channel deactivation, increased island visitation and nest predation by predatory mammals due to loss of a water barrier between some islands and banks, and larger populations of alien plant species in the new riparian vegetation.

Idaho, Oregon↗
USGS1993

Summary of the Snake River plain Regional Aquifer-System Analysis in Idaho and eastern Oregon

The 15,600 sq mi Snake River Plain in southern Idaho and eastern Oregon was studied as part of the U.S. Geological Survey's Regional Aquifer-System Analysis program. Quaternary basalt of the Snake River Group underlies most of the 10,800 square mile eastern plain and constitutes the most productive aquifers. Transmissivity of the upper 200 feet of the basalt aquifer commonly ranges from 100,000 to 1,000,000 square feet per day. Vertical hydraulic conductivity is several orders of magnitude lower than horizontal hydraulic conductivity and is related to the degree of jointing. Alluvial sand and gravel in the Boise River valley constitutes the most productive aquifers in the 4,800 square mile western plain. Along much of its length, the Snake River gains groundwater. Between Milner and King Hill, the river gained 4.7 million acre-ft in 1980, most as spring flow from the north side. The chemical composition of groundwater in the plain is essentially the same as that in streams and groundwater from tributary drainage basins. The use of surface water for irrigation for 100 years has caused major changes in the hydrologic system on the plain. During that time, recharge on the main part of the eastern plain increased about 70 percent, discharge about 80 percent. In 1980, about 8.9 million acre-ft of Snake River water was diverted and 2.3 million acre-ft of groundwater was pumped from 5,300 wells for irrigation.

Idaho, Oregon↗
USGS1992

Streamflow gains and losses in the Snake River and ground-water budgets for the Snake River Plain, Idaho and eastern Oregon

The Snake River is the regional drain for streams and aquifers in the Snake River basin upstream from Weiser, Idaho. The interaction between the river and ground water was quantified as streamflow gains from and losses to the aquifers. Upstream from Milner, Idaho, the Snake River both gains and loses water. Some reaches gain or lose throughout the year; other reaches gain during the irrigation season when ground-water levels rise as a result of application of surface water for irrigation but lose during the rest of the year. The largest continuous streamflow gain upstream from Milner is from springs between Blackfoot and Neeley, where, in 1980, the Snake River gained 1.9 million acre-feet of ground water. Downstream from Milner, the Snake River is a gaining stream. Gains arc largest between Milner and King Hill where numerous springs discharge to the river. In 1980, the Snake River gained 4.7 million acre-feet of ground water between Milner and King Hill. Although large springs were present in the Blackfoot-to-Neeley and Milner-to-King Hill reaches before irrigation began on the plain, the application of surface water for irrigation increased recharge to the Snake River Plain aquifer; therefore, spring discharge to both reaches also increased. However, despite changes in irrigated acreage and corresponding changes in the amount of water potentially available for recharge, spring discharge between Blackfoot and Neeley has remained relatively stable for 69 years (1912-80). During the same period, discharge from individual springs and total ground-water discharge between Milner and King Hill have increased and decreased substantially in quantities that can be attributed to changes in irrigation. The changes in ground-water recharge and discharge and ground-water storage generally are the net result of 100 successive years of irrigation on the Snake River Plain. Water-budget analyses indicate that the total volume of ground water in storage in the main part of the eastern Snake River Plain increased about 24 million acre-feet from 1880 to 1952, largely as a result of increased recharge in areas irrigated with surface water. The total volume of ground water in storage decreased about 6 million acre-feet from 1952 to 1980 as a result of several years of below-normal precipitation, increased pumping of ground water for irrigation, and other changes in irrigation practices. Ground-water storage in parts of the western plain increased about 3 million acre-feet from 1930 to 1972 but generally has decreased since 1972.

Idaho, Oregon↗
USGS1987

Solute geochemistry of the Snake River plain regional aquifer system, Idaho and eastern Oregon

Three geochemical methods were used to determine chemical reactions that control solute concentrations in the Snake River Plain regional aquifer system: (1) Calculation of a regional solute balance within the aquifer and of mineralogy in the aquifer framework to identify solute reactions, (2) comparison of thermodynamic mineral saturation indices with plausible solute reactions, and (3) comparison of stable-isotope ratios of the ground water with those in the aquifer framework. The geothermal ground-water system underlying the main aquifer system was examined by calculating thermodynamic mineral saturation indices, stable-isotope ratios of geothermal water, geothermometry, and radiocarbon dating. Water budgets, hydrologic arguments, and isotopic analyses for the eastern Snake River Plain aquifer system demonstrate that most, if not all, water is of local meteoric and not juvenile or formation origin. Solute-balance, isotopic, mineralogic, and thermodynamic arguments suggest that about 20 percent of the solutes are derived from reactions with rocks forming the aquifer framework. Solute reactions indicate that calcite and silica are precipitated in the aquifer. Mineralogic evidence and thermodynamic arguments suggest that olivine, pyroxene, pyrite, and anhydrite are being dissolved and plagioclase is being weathered. Large amounts of sodium and chloride, relative to their concentration in the igneous rock, are being removed from the aquifer. Release of fluids from inclusions in the igneous rocks, and initial flushing of grain boundaries and pores of detrital marine sediments in interbeds are believed to be the source of the sodium chloride. Identification and quantification of reactions controlling solute concentrations in ground water in the eastern plain indicate that the aquifer is not a large mixing vessel that simply stores and transmits water and solutes but is undergoing diagenesis and is both a source and sink for solutes. Evaluation of solute concentrations and stable-isotope ratios of hydrogen, oxygen, carbon, and sulfur along ground-water flowpaths that transect irrigated areas suggests that irrigation water may have altered solute concentrations and isotope ratios in the eastern Snake River Plain aquifer system. The changes, however, have been small, owing to similarity of solute concentrations in applied irrigation water and in native ground water and rapid movement and large dispersivity of the aquifer. Reactions controlling solutes in the western Snake River basin are believed to be similar to those in the eastern basin but, because of different hydrologic conditions, a definitive analysis could not be made. The regional geothermal system that underlies the Snake River Plain contains total dissolved solids similar to those in the overlying Snake River Plain aquifer system but contains higher concentrations of sodium, bicarbonate, silica, fluoride, sulfate, chloride, arsenic, boron, and lithium, and lower concentrations of calcium, magnesium, and hydrogen. These solutes are believed to be derived from reactions similar to those in the Snake River Plain aquifer system, except that ion exchange may be a significant mechanism controlling solute concentrations in the geothermal system. Geothermometry calculations of selected ground-water samples from known geothermal areas throughout the basin suggest that the geothermal system is large in areal extent but has relatively low temperatures. Approximately half of the silica-quartz calculated water temperatures are greater than 90 degrees Celsius. Radiocarbon dating of geothermal water in the Salmon Falls and Bruneau-Grand View areas in the south-central part of the Snake River basin suggests that residence time of the geothermal water is about 17,700 years.

Idaho, Oregon↗