Physical Sciences and Mathematics Commons^™

A Gravity Survey And Analysis Of The Mount Stuart Block Of Washington State, Gregg M. Petrie

WWU Graduate School Collection

Gravity data were gathered in the vicinity of the Mt. Stuart Block, a horst of pre-Tertiary rocks which include the Chiwaukum Schist, the composite Mt. Stuart Batholith, and the Ingalls Complex with its related metasedimentary-volcanic sequence, located in the east central Cascade Mountains of Washington. The final complete Bouguer map suggests the following features: (1) displacement of the Chiwaukum Graben occurs mostly on the west side in a narrow, 4-5 km, block 5.5 to 7.5 km deep, expanding in width to the north; (2) the Ingalls Complex is a relatively shallow feature: certainly a model hypothesizing a deep plug of …