Columbia River Basalt Flows Research Articles

3-D crustal structure of the western United States: application of Rayleigh-wave ellipticity extracted from noise cross-correlations

We present a new 3-D seismic model of the western United States crust derived from a joint inversion of Rayleigh-wave phase velocity and ellipticity measurements using periods from 8 to 100 s. Improved constraints on upper-crustal structure result from use of short-period Rayleigh-wave ellipticity, or Rayleigh-wave H/V (horizontal to vertical) amplitude ratios, measurements determined using multicomponent ambient noise cross-correlations. To retain the amplitude ratio information between vertical and horizontal components, for each station, we perform daily noise pre-processing (temporal normalization and spectrum whitening) simultaneously for all three components. For each station pair, amplitude measurements between cross-correlations of different components (radial–radial, radial–vertical, vertical–radial and vertical–vertical) are then used to determine the Rayleigh-wave H/V ratios at the two station locations. We use all EarthScope/USArray Tranportable Array data available between 2007 January and 2011 June to determine the Rayleigh-wave H/V ratios and their uncertainties at all station locations and construct new Rayleigh-wave H/V ratio maps in the western United States between periods of 8 and 24 s. Combined with previous longer period earthquake Rayleigh-wave H/V ratio measurements and Rayleigh-wave phase velocity measurements from both ambient noise and earthquakes, we invert for a new 3-D crustal and upper-mantle model in the western United States. Correlation between the inverted model and known geological features at all depths suggests good resolution in five crustal layers. Use of short-period Rayleigh-wave H/V ratio measurements based on noise cross-correlation enables resolution of distinct near surface features such as the Columbia River Basalt flows, which overlie a thick sedimentary basin.

Temperature Effects on the Crystallinity of Synthetic Nontronite and Implications for Nontronite Formation in Columbia River Basalts

AbstractThe formation conditions of the ferric smectite nontronite are not fully understood. The present study couples experimental and analytical data with field observations in an attempt to constrain the rate and temperature of formation of naturally occurring nontronites from Columbia River Basalt flows. Synthetic Fe-Al-Si gels were incubated at temperatures ranging from 4 to 150°C for 4 weeks. Samples were analyzed using Fe K-edge X-ray fluorescence spectroscopy (XAFS). Spectra of the synthesized nontronites were compared with spectra of natural samples collected from weathered Columbia River Basalt flows. Cation ordering in the synthetic samples increased with incubation temperature, but the synthetic clays did not approach the degree of crystal ordering of the natural nontronite samples. These observations suggest that highly ordered natural nontronites require longer crystallization times than are typically used in laboratory experiments. The natural samples were found filling open cracks near flow surfaces, indicating that the clays formed at temperatures below the boiling point of water. A comparison of experimental and field timescales with other estimates of nontronite growth rates suggests that natural nontronite crystallization in the region must have occurred at ambient, near-surface temperatures over timescales of up to millions of years.

Influence of paleorelief on the Mid-Miocene climate variation in southeastern Washington, northeastern Oregon, and western Idaho, USA

Terrestrial climate proxy records repeatedly show spatial heterogeneity because regional climate condition is largely influenced by the relationship between large-scale atmospheric circulation patterns and regional topographic features. The paleosols developed on the top of Columbia River Basalt flows emplaced between 15.3 and 15.8 Ma in the northwestern United States show significant spatial variations in the Mid-Miocene soil-forming processes. The paleosol in the northwestern part of the study area has the least degree of chemical weathering, fine scale and very shallow penetrating depth of root traces with the estimated paleoprecipitation and paleotemperature of about 550 mm and 16 °C, respectively. The paleosols in the southeastern part of the study area indicate more intense chemical weathering with the estimated paleoprecipitation and paleotemperature of approximately 1400 to 1500 mm and 17 °C, respectively. The spatial variations in paleo-pedogenesis were predominantly affected by spatial heterogeneity in the Mid-Miocene regional climate and regional paleotopographic features, taking the other ancient soil-forming factors, including time, parent rock materials, and biological activities, into account. We suggest that intrusions of hot Columbia River Basalt magma into the crust were responsible for the regional surface uplift and the paleoclimate heterogeneity because the major vent systems of the Columbia River Basalt eruptions were located in the area where development of the Mid-Miocene high topography existed within the Blue Mountains. Paleotopography of the Earth's surface can be reconstructed by the paleoprecipitation and paleotemperature estimations from several spatially distributed chrono-stratigraphic paleosols although it is difficult to estimate the magnitude of the paleorelief precisely.

Evaluation of sulfur flow emplacement on Io from Galileo data and numerical modeling

Galileo images of bright lava flows surrounding Emakong Patera have been analyzed and numerical modeling has been performed to assess whether these flows could have resulted from the emplacement of sulfur lavas on Io. Images from the solid‐state imaging (SSI) camera show that these bright, white to yellow Emakong flows are up to 370 km long and contain dark, sinuous features that are interpreted to be lava conduits, ∼300–500 m wide and >100 km long. Near‐Infrared Mapping Spectrometer (NIMS) thermal emission data yield a color temperature estimate of 344 K ± 60 K (≤131°C) within the Emakong caldera. We suggest that these bright flows likely resulted from either sulfur lavas or silicate lavas that have undergone extensive cooling, pyroclastic mantling, and/or alteration with bright sulfurous materials. The Emakong bright flows have estimated volumes of ∼250–350 km3, similar to some of the smaller Columbia River Basalt flows. If the Emakong flows did result from effusive sulfur eruptions, then they are orders of magnitude greater in volume than any terrestrial sulfur flows. Our numerical modeling results show that sulfur lavas on Io could have been emplaced as turbulent flows, which were capable of traveling tens to hundreds of kilometers, consistent with the predictions of Sagan [1979] and Fink et al. [1983]. Our modeled flow distances are also consistent with the measured lengths of the Emakong channels and bright flows. Modeled thermal erosion rates are ∼1–4 m d−1 for flows erupted at ∼140–180°C, which are consistent with the melting rates of Kieffer et al. [2000]. The Emakong channels could be thermal erosional in nature; however, the morphologic signatures of thermal erosion channels cannot be discerned from available images. There are planned Galileo flybys of Io in 2001 which provide excellent opportunities to obtain high‐resolution morphologic and color data of Emakong Patera. Such observations could, along with further modeling, provide additional information to better constrain whether sulfur lavas produced the Emakong flows.

Chemical discrimination of Columbia River basalt flows

The homogeneity and distinctive chemical composition of individual Columbia River basalt flows are illustrated in a series of chemical plots, and the procedure for flow identification is outlined. The unique characterization of many individual eruptions permits units to be mapped from feeder dike to flow margins across the Columbia Plateau for hundreds of kilometers, and so provides critical constraints on the physical and chemical evolution of this continental flood basalt province.

Primary and ‘forced folds’ of the Columbia River basalt province, eastern Washington, USA

Abstract The Yakima fold belt is a series of asymmetric, east-west anticlines separated by much broader synclines in the thick and otherwise horizontal sequence of Columbia River basalt flows. The folds have grown progressively over the last 17 Ma in response to regional north-south compression and east-west extension. This stress and strain pattern is reflected on a regional scale by the highly oriented north-northwest-south-southeast basalt feeder dykes, by the WNW- (right-lateral) and NNE- (left-lateral) trending conjugate fault system, and by the presence of a similar strain field measurable in the basalt flows today. Peripheral to the Yakima fold belt, pre-basalt structures of different orientations project under the basalt pile. Some of these structures have continued to develop during and after basalt extrusion and have influenced structures in the basalt flows which are, therefore, ‘forced’.

Basement heating by a cooling lava: Paleomagiietic constraints

Paleomagnetism can provide quantitative, empirical data on basement heating by cooling lava flows, thereby constraining theoretical models of heat transport processes. We used paleomagnetism to study heating in a Frenchman Springs (FS) lava by the overlying cooling Roza flow. The flows belong to the Miocene Columbia River Basalt (CRB) group, and they recorded very different primary paleomagnetic directions: FS has normal polarity, and Roza is transitional. The solid base of Roza typically rests on a few meters of the brecciated and vesicular top of FS, which is otherwise solid. Thermal demagnetization of FS specimens was usually successful at separating the overprinting due to Roza from the primary FS direction and for establishing limits on the unblocking temperatures of the overprinting. The unblocking temperatures agree well between sites separated by up to 70 km, irrespective of Roza thickness at the sites, which vary from 35–62 m. In specimens from 0.3 to l m below the contact, the overprinting was unblocked in the laboratory between 600 and 300°C and close to 200°C at 4‐m depth. No overprinting was apparent below 6 m. The influence of longer heating times in the field on the unblocking temperatures was estimated by viscous remanence acquisition at elevated temperatures. The results suggest typical reductions of the unblocking temperatures by a few tens of degrees. Our observations imply much less heating of the basement than predicted by simple conductive thermal models. Accounting for the low conductivity breccia in the contact zone results in a better agreement with the experimental temperature profile, but unrealistically low conductivities are needed to sufficiently reduce the absolute temperature. The observed heating is effectively explained by postulating a wet basement at the time of Roza extrusion, as well as groundwater, to maintain a low‐temperature isotherm (∼100°C) a few meters below the contact. The presence of water during the time of Roza extrusion and some other CRB flows has been suggested by field observations.

Structures, textures, and cooling histories of Columbia River basalt flows: Discussion and reply

Research Article| December 01, 1987 Structures, textures, and cooling histories of Columbia River basalt flows: Discussion and reply: Reply PHILIP E. LONG; PHILIP E. LONG 1Geology Group, Basalt Waste Isolation Project, Rockwell Hanford Operations, Richland, Washington 99352 Search for other works by this author on: GSW Google Scholar BERNARD J. WOOD BERNARD J. WOOD 2Department of Geological Sciences, Northwestern University, Evanston, Illinois 60201 Search for other works by this author on: GSW Google Scholar Author and Article Information PHILIP E. LONG 1Geology Group, Basalt Waste Isolation Project, Rockwell Hanford Operations, Richland, Washington 99352 BERNARD J. WOOD 2Department of Geological Sciences, Northwestern University, Evanston, Illinois 60201 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1987) 99 (6): 887–888. https://doi.org/10.1130/0016-7606(1987)99<887:STACHO>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation PHILIP E. LONG, BERNARD J. WOOD; Structures, textures, and cooling histories of Columbia River basalt flows: Discussion and reply: Reply. GSA Bulletin 1987;; 99 (6): 887–888. doi: https://doi.org/10.1130/0016-7606(1987)99<887:STACHO>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract No Abstract Available. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Structures, textures, and cooling histories of Columbia River basalt flows: Discussion and reply

Research Article| December 01, 1987 Structures, textures, and cooling histories of Columbia River basalt flows: Discussion and reply: Discussion ANTHONY R. PHILPOTTS; ANTHONY R. PHILPOTTS 1Department of Geology and Geophysics, and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06268 Search for other works by this author on: GSW Google Scholar DAVID H. BURKETT DAVID H. BURKETT 1Department of Geology and Geophysics, and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06268 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1987) 99 (6): 886–887. https://doi.org/10.1130/0016-7606(1987)99<886:STACHO>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation ANTHONY R. PHILPOTTS, DAVID H. BURKETT; Structures, textures, and cooling histories of Columbia River basalt flows: Discussion and reply: Discussion. GSA Bulletin 1987;; 99 (6): 886–887. doi: https://doi.org/10.1130/0016-7606(1987)99<886:STACHO>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract No Abstract Available. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Structures, textures, and cooling histories of Columbia River basalt flows

Flood basalt flows of the Columbia River Basalt Group commonly exhibit well-developed colonnade and entablature structures formed during cooling of individual flows. The colonnade refers to the well-defined columnar structure of many flows, which appears in the lowermost 10% to 30% and, in places, the uppermost 10% to 20%. Entablature refers to those parts of a flow that have smaller column diameters and more irregular pattern fractures than those of colonnade. Entablature commonly occupies the central 60% to 70% of a flow. In some cases, however, the entablature is interrupted by colonnade; in such cases, the entablature and colonnade may be repeated once or twice within a single flow. In other cases, flows may lack an entablature entirely. Petrographic examination reveals a pronounced correlation between structural and textural features. Thin sections of colonnade basalt have relatively coarse cruciform or octahedral Fe-Ti oxide crystals and ∼20% glassy mesostasis. The central entablature basalt, in contrast, has much more mesostasis (as much as 60%) and has textural features such as feathery Fe-Ti oxide crystals indicative of more rapid cooling. These features are the reverse of what might be expected for normal conductive cooling because cooling rates at the flow margins should be greater than those in the flow interior. We reconciled the observed basalt textures with thermal models by taking into account rainfall and deranged drainage during crystallization of the flow. Downward migration of water through cracks would cause convective cooling of underlying, unsolidified lava. This effect and its consequences have been modeled numerically in order to clarify the physical constraints on the mechanism by which the central part of the lava can be quenched. We have found that a water infiltration front can explain the presence of a thick, quenched, flow interior, provided that the infiltration front moves downward just behind the lava solidification front. Despite heavy rainfall on Hawaii (for example, ∼250 cm/yr at Kilauea Iki), exposed, prehistoric lava flows on that island exhibit only colonnades. We deduce from this that heavy rainfall alone is inadequate to quench flow interiors. Extensive flooding by deranged drainage, or perhaps extremely heavy rainfall (>>250 cm/yr), is apparently required to produce entablatures. The model also can be used to explain the occurrence of repeated entablature and colonnade by considering the effects of intermittent inundation. The imposition of boundary conditions that mimic the removal and reoccurrence of flooding yields cooling histories that are consistent with the development of multiple colonnades and entablatures.

Physical and chemical constraints on the evolution of the Columbia River basalt

Physical and chemical constraints require that Columbia River basalt flows were fed from a large (>700 km 3 ) magma reservoir near the crust-mantle boundary and prohibit significant crystal fractionation or crustal assimilation between reservoir and surface. Demonstrable fractionation of plagioclase + olivine ± pyroxene in the reservoir largely obviates the need for an unusual iron-rich pyroxenite source. Variation of Sr and Nd isotope ratios with age in the main series of Columbia River basalt and variation in such incompatible trace-element ratios as Ba/P suggest lower crustal assimilation at the top of the reservoir combined with crystal fractionation. However, decoupling between isotope ratios and incompatible element ratios implies two separate processes in addition to crystal fractionation, of which lower crustal assimilation may be one. The other process may involve the participation of a vertically heterogeneous mantle resulting from metasomatism in the continental lithosphere.

Paleomagnetic correlation of Columbia River basalt flows using secular variation

A statistical method is developed to evaluate stratigraphic correlations that are based on the similarity of paleomagnetic directions. It involves comparison of the probabilities that such directions could have arisen by either simultaneous or random samplings of the ancient magnetic field. To calculate these probabilities one must estimate the effects of paleomagnetic errors and paleosecular variation, respectively. The method is tested successfully on sections of 8–10 Grande Ronde Basalt (Columbia River Basalt Group) flows at Sentinel Gap and Umtanum Ridge, which are separated by only 25 km and contain two flows thought to be the same on geological grounds. More significantly, for widely separated sections at Sentinel Gap and Butler Canyon the analysis again shows that simultaneous magnetization is a much more likely explanation of the general similarity of paleomagnetic directions than chance agreement of ancient field directions. The simplest interpretation of this result is that many of the flows at the two sites are the same, implying that series of Grande Ronde flows extended over distances of several hundred kilometers.

Contrasting Compositions of the Youngest Columbia River Basalt Flows in Union and Wallowa Counties, Northeastern Oregon

Note: This paper is dedicated to Aaron and Elizabeth Waters on the occasion of Dr. Waters' retirement. Several new chemical analyses of flows confined to a structural downwarp in northeastern Oregon indicate the first reported occurrence of Late-Yakima–type basalt in the region and the close stratigraphic association of Yakima–type and Late-Yakima–type flows, as well as andesite. The andesite is the most silicic flow rock yet found on the Columbia Plateau.

Flow directions in Columbia River Basalt flows and paleocurrents of interbedded sedimentary rocks, South-Central Washington

More than 150 flow directions measured mainly in inclined pipe vesicles and, more rarely, vesicle cylinders, spiracles, and inclined foreset beds in pillowpalagonits-complexes) of the upper 12 widespread Yakima Basalt flows on the Columbia River Plateau in south-central Washington indicate rather uniform transport directions from southeast to northwest. This strongly supports former ideas that the large Grande Ronde-Cornucopia dike swarm in northeast Oregon fed the huge lava floods. It is shown that all previous evidence indicating eruption centers for the basalts in the Cascada Range to the west is inconclusive. Cross-bedding directions, maximum pebble sizes, and distribution of heavy mineral suites in sedimentary deposits interbedded with the basalt sheets delineate in more detail two main paleoslopes whose deposits interfinger: a) the Cascade paleoslope to the west with east-southeast paleocurrents and a predominance of volcanic heavy minerals (hornblende, oxyhornblende, hypersthene, and clinopyroxene). b) the Columbia paleoslope with south-southwest paleocurrents and chiefly sphene, epidote, clinozoisite, blue-green hornblende, garnet, sillimanite, kyanite, and staurolite. Distribution of conglomerats, current directions, and heavy mineral suites support former hypotheses that the ancestral Columbia River flowed about 50 km farther west in early Pliocene time than it does today in the area of lower Yakima Valley.

Resurrected Erosion Surface in Central Washington

Results obtained in mapping the geology of the Wenatchee-Chelan and of the Okanogan district suggest modifications of the earlier interpretations regarding the erosional history: 1) The existence of a “Methow Plain” or “Cascade Peneplain” is questioned. Most of the areas formerly considered to be remnants of this peneplain are surfaces controlled by the structure of the Columbia River basalt flows without regard to a widespread base level of erosion. One remnant, which bevels the Columbia River basalt and the Ellensburg formation on the flanks of an anticline in the Yakima district, is believed to be a pediment of very local extent. 2) The mature surface of the “Entiat stage” is well developed only on resistant granodiorite and gneiss and is exceedingly fragmentary or absent in areas underlain by greenstone, phyllite, schist, and Tertiary sedimentary rocks. It has not been recognized in areas underlain by the Columbia River basalt. The writer interprets nearly all the residuals of the “Entiat surface” described in the literature as resurrected fragments of a widespread late mature erosion surface buried beneath the Miocene Columbia River lavas and associated sediments and then partially exhumed in post-Miocene time. Certain fragmentary remnants of this surface on massive crystalline rocks beyond the limit reached by the basalt flows are believed to have been similarly preserved by burial under andesitic pyroclastics erupted from volcanoes in the Cascade Range.