A Structural and Paleomagnetic Analysis of the Basalts of Summit Creek

This study is a detailed analysis of the structural geology and paleomagnetism of the Basalts of Summit Creek. Located southeast of Mount Rainier, this section of layered basaltic flows formed during the Eocene Epoch (55 to 45 Ma). The exact origin of the Basalts of Summit Creek is unknown, but there appears to be a growing connection between the Basalts of Summit Creek and the Crescent Basalts, which are Eocene flood basalts located on the Olympic Peninsula (Clark, 1989). This study attempts to provide a greater understanding of the emplacement and deformation of the Basalts of Summit Creek and any possible relationship with the Crescent Basalts. Once paleomagnetic directions were corrected for core orientation and bedding tilt, none of the flows yielded orientations consistent enough to provide reliable magnetic directions for the section. The scattered magnetic orientations are quite similar to those observed in the Crescent Basalts. This is does not demonstrate a definite connection between the two chemically similar Eocene volcanic sequences, but it does provide another similarity on the growing list. These two sections require further study to obtain the information needed to show a conclusive relationship beyond just their likeness in age, chemical and degree of alteration