TiO2 and Geophysical Logging Criteria for Yakima Basalt Correlation, Columbia Plateau

Borehole geophysical techniques to define stratigraphy, alteration and aquifers in basalt

“…The aquifer beneath the INEEL ranges in thickness from less than 100 m to about 400 m, similar to aquifer thickness on the Columbia River Plateau in northwestern Washington State (Crosby and Anderson, 1971;Siems, 1973;Siems et al, 1974). Compared to other basalt-hosted aquifers, the Snake River Plain aquifer is one of the thickest basalt-hosted aquifers in the world (cf.…”

“…8). In unsaturated conditions, neutron logs can sometimes be sufficient to delineate flow interiors (Siems, 1973;Siems et al, 1974), though in some areas like the East Snake River Plain, the neutron log needs to be supplemented by a natural gamma or gamma -gamma log to avoid misinterpretation (e.g., Fig. 6).…”

Results of Downhole Geophysical Logging Hole 396B, DSDP Leg 46

“…The downhole logging of Hole 396B on Deep Sea Drilling Project Leg 46 was the first attempt to obtain in situ physical property data in Layer 2 of the oceanic crust, and one of the few published logging attempts in basaltic rocks (Zablocki et al, 1974;Keller et aL, 1974;Siems et al, 1973Siems et al, , 1974Crosby and Anderson, 1971). Hole 396B is about 160 km east of the Mid-Atlantic Ridge at 22°59.14'N, 43°30.90'W.…”

Neutron Log Measurement of Moisture in Unsaturated Basalt: Progress and Problems

“…Previous logging studies in basalts by Crosby and Anderson (1971), Siems (1973), Siems et al (1974), and Morin et al (1993) have improved our understanding of neutron log data in unsaturated conditions, although these authors did not compare detailed physical properties to log response in a quantitative manner. Presently, no successful published calibration exists between neutron log response and moisture for unsaturated continental basalt despite some previous noteworthy attempts.…”

“…Most hydrous minerals in basalt may be qualitatively identified by an increase in passive γ flux measured by a natural γ logging tool coupled with a decrease in the attenuated neutron flux measured by a neutron logging tool (Crosby and Anderson, 1971; Siems, 1973; Siems et al, 1974). In saturated basalts, quantitative separation of the effects of free water vs. hydrous minerals has been demonstrated using neutron and other logs from the Ocean Drilling Program (Broglia and Ellis, 1990), a method that depends on correctly estimating the amounts of all elements present in the borehole environment and modeling their contribution to neutron moderation.…”