Fracture-controlled magma conduits in an obliquely convergent continental magmatic arc

Magnetic fabric patterns of two mid-Cretaceous nested plutons in the central Sierra Nevada batholith provide evidence that felsic magma emplacement (and ascent?) occurred via north-trending, steeply dipping, planar fracture conduits oriented obliquely to the arc. U-Pb geochronology data indicate that emplacement of the plutons was separated by 2 to 10 m.y. and that they were emplaced in part via the same conduit. Formation of the north-trending conduits at ~100 Ma can be related to a small, arc-parallel, dextral-shear component. By ~90 Ma, convergence had become sufficiently oblique for the development of nearly arc-parallel structures. -from Authors