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Fabric Study And Structural History Of Deformed Plutonic And Metamorphic Rocks In The Holden Area, North Cascades, Washington, Gary K. Hurban
Fabric Study And Structural History Of Deformed Plutonic And Metamorphic Rocks In The Holden Area, North Cascades, Washington, Gary K. Hurban
WWU Graduate School Collection
The Holden area, in the Crystalline Core of the North Cascades, contains deformed and undeformed plutons ranging from Triassic to Eocene in age.
Two deformational styles have been identified in the Holden area. Contractional deformation is indicated by steeply-plunging, down-dip, mineral and stretching lineations in the syn-tectonic Seven Fingered Jack pluton (estimated midLate Cretaceous), and in the pre-tectonic Dumbell Mountain pluton (220 Ma), associated with apparent flattened fabrics. Strike-slip shear deformation is represented by gently-plunging to subhorizontal, strike-parallel mineral and stretching lineations, which are commonly associated with constricted fabrics. These fabrics occur prominently in the Dumbell Mountain pluton, and crosscut …