A Comparison of Terrestrial Heat Flow and Transient Geomagnetic Fluctuations in the Southwestern United States

Warren, Robert E.; Sclater, John G.; Vacquier, Victor D.; Roy, Robert F.

doi:10.1190/1.1440023

Cited by 37 publications

(12 citation statements)

References 6 publications

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“…Only in the southwest U. S. A. is the density of heat-flow and GDS stations sufficient for valid estimates of spatial correlation between the geomagnetic low-Z zone and this CTAZ. At latitude 32N the change in heat flow (from 1.1kcal/cm2 sec in the Texas Foreland to a mean of 2.21+0.43 in the Basin and Range Province) occurs in close agreement with the location of the GDS discontinuity (Warren et al, 1969). At latitude 35N the relation is not clear; Caner et al (1967) inferred an eastward swing of the GDS discontinuity, which is not in agreement with the heat-flow data.…”

Section: Heat Flowcontrasting

confidence: 33%

Electrical Conductivity Structure in Western Canada and Petrological Interpretation

Caner

1970

J. geomagn. geoelec

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An integrated approach using both geomagnetic depth-sounding (GDS) and magnetotellurics (MT) is applied to the determination of the electrical conductivity structure in western Canada; 42 GDS stations and 6 broad-band MT stations are used. These data are combined with other geophysical information to provide self-consistent petrological models. Excluding geochemically improbable solutions, it can be shown that: a) temperatures at depth 35km must be at least 750C in the entire western region (eastwards extent undefined); b) in a smaller, sharply defined, region (eastern boundary within about +50 km of the Rocky Mountain Trench) the lower crust and possibly uppermost 10-25km of the mantle are hydrated, probably with partial melting.

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Section: Heat Flowcontrasting

confidence: 33%

Electrical Conductivity Structure in Western Canada and Petrological Interpretation

Caner

1970

J. geomagn. geoelec

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“…For rocks not too close to their melting point this ratio should be close to 1:2 rather than the 1: 4 ratio observed. The heat flow evidence also supports the hypothesis that the electrical anomalies are essentially due to temperature anomalies (Warren, et al, 1969). The thickness of the anomalous zone cannot be determined from the present electrical measurements, as the increased conductivity reduces the depth of penetration of the electric currents.…”

supporting

confidence: 65%

Geoelectric Upper Mantle Anomalies in the United States

Madden

1970

J. geomagn. geoelec

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Geoelectric studies have shown that a pronounced high conductivity region exists in the upper mantle of the Southwestern United States. This anomaly is well correlated with other geophysical anomalies. Tne electrical measurements can be interpreted togive upper mantle temperatures very close to the melting point. Preliminary measurements near the California ocean-continent boundary indicate even higher conductivities exist in the mantle under the ocean.

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“…Areas of high heat flow such as midocean ridges would therefore present ideal sites for geomagnetic variation studies. Correlation of high heat flow with transient geomagnetic variations on land has been demonstrated in the case of Schmucker's Rio Grande anomaly (Warren et al 1969) as well as by Porath and his co-workers.…”

Section: Introductionmentioning

confidence: 92%

A Geomagnetic Variation Anomaly Across the Northern Gulf of California

White

1973

Geophysical Journal International

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Vanations in the geomagnetic field have been observed along a profile PeFPendCUlar to the oorthern Gulf of California. The profile extends from the Pacific Ocean (including two sea-floor stations off the coast) to Tucson, Arizona, and includes stations at San Felipe and Puerto Penasco on opposite sides of the Gulf. At these two stations there is a large anomaly in the vertical component variations in the frequency range 0.25-4 c hr-which amounts to almost complete reversal from one station to the other at the higher frequencies. Analysis of the variations demonstrates that the anomaly is due to induced currents flowing in or beneath the Gulf of California. Using a modelling technique developed by Greenhouse, Parker and White the anomaly may be interpreted either in terms of very high Gulf sediment conductivity or an uplifted zone of hot mantle material beneath the Wagner basin. A suitable combination of these models is compatible with the horizontal field observations.Both of these factors support the suggestion that the Wagner basin is the site of a spreading centre similar to those found at ocean ridges. Observations along a profile of stations across the Imperial Valley indicate that the upwelling of mantle material does not necessarily occur continnously along the Gulf of California-Salton Trough mi xi s 2nd is probably a local phenomenon associated only with such spreading centres. Because of the consequent lack of two-dimensionality ic the actual situation, the predicted height of the upwelling will be too small. It is thou& that a conductivity of 0.02 (am)-' could be present at 20-30 km depth in such areas.

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A Comparison of Terrestrial Heat Flow and Transient Geomagnetic Fluctuations in the Southwestern United States

Cited by 37 publications

References 6 publications

Electrical Conductivity Structure in Western Canada and Petrological Interpretation

Electrical Conductivity Structure in Western Canada and Petrological Interpretation

Geoelectric Upper Mantle Anomalies in the United States

A Geomagnetic Variation Anomaly Across the Northern Gulf of California

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