Late Cenozoic structure and stratigraphy of south-central Washington

Abstract

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Second Quarter Hanford Seismic Report for Fiscal Year 2000

“…Continued subsidence in this area during the Miocene resulted in thicker CRE3Gcompared to that on the craton. Subsidence continues today but at a greatly reduced rate (Reidel et al 1994). …”

Third Quarter Hanford Seismic Report for Fiscal Year 2000

“…These boreholes provided accurate measurements of the physical properties of the CRBG and the pre-basah sediments (Reidel et al 1994(Reidel et al , 1998, but the thickness of the pre-basalt sediments and nature of the crystalline basement are still poorly understood. The difference between the thicknesses listed in Table 4.1 and the thicknesses of the crustal layers in the velocity model in Table 3.1 reflect data specific to the UW's crustal velocity model for eastern Washington.…”

“…Continued subsidence in this area during the Mic}cene resulted in thicker CRBG compared to that on the craton. Subsidence continues today but at a greatly reduced rate (Reidel et al 1994). …”

Hanford Site National Environmental Policy Act (NEPA) Characterization

“…The principal characteristics of the Yakirna Fold Belt area series of segmented, narrow, asymmetric anticlines that have wavelengths between 5 and 31 km (3 and 19 mi) and amplitudes commonly <1 km (0.6 mi) (Reidel 1984;Reidel et al 1989Reidel et al , 1994. These anticlinal ridges are separated by broad synclines or basins that, in many cases, contain thick accumulations of Neogene-to Quatemary-age sediments.…”

“…It is generally steepest on the north, with a gently dipping southern limb. A major thrust or high-angle reverse fault occurs on the north side (Reidel 1984;Reidel et al 1994).…”