Variations In Cascade Arc Magmatism Through Space And Time; A Comparison Of Geochemical And Geographic Trends In Volcanic And Plutonic Rocks From The Chilliwack-mt. Baker And Fifes Peaks-bumping Lake Areas, Washington
Abstracts With Programs - Geological Society Of America
Volcanic and plutonic rocks of the Cascade arc extend from northern California to British Colombia and preserve a record of subduction-related magmatism over the past approximately 44 Ma. During this interval the arc has experienced variations in several parameters that have the potential to influence magmatism including the rate of subduction, the age and volatile content of the subducting plate, and the stress regime, thickness and composition of the overlying continental crust. This study compares spatial and temporal patterns of magmatic activity in two areas of the Washington Cascades with the goals of: (1) identifying trends that may be related to changing subduction parameters, and (2) contrasting the records of plutonic versus volcanic rocks. The two areas under study are the Chilliwack-Mt. Baker area (CMB), which includes >40 plutons of the Chilliwack batholith (35 Ma to 40, Y < 15 ppm) and define a younger-to-the-SE progression. The presence of adakites in the FPBL but not the CMB may reflect a difference between the two areas in the age of the subducting slab. Preliminary results of this study suggest that many of the temporal and spatial trends observed in CMB and FPBL are strongly influenced by local variations in subduction parameters including slab age and geometry.
Tepper, Jeffrey H., and Paul E. Hammond. 2003. "Variations in Cascade arc magmatism through space and time; a comparison of geochemical and geographic trends in volcanic and plutonic rocks from the Chilliwack-Mt. Baker and Fifes Peaks-Bumping Lake areas, Washington." Abstracts With Programs - Geological Society Of America 35(4; 4): 57-57.