EVIDENCE FOR LARGE SCALE FOLD AND FAULT IMBRICATION OF A PERMIAN TO MID-CRETACEOUS VOLCANO-SEDIMENTARY ASSEMBLAGE IN THE MINERAL KING PENDANT, SOUTHERN SIERRA NEVADA, CALIFORNIA

The Mineral King pendant is a late Permian to mid-Cretaceous volcano-sedimentary assemblage that forms one of the largest exposures of intrabatholithic wall rocks in the southern Sierra Nevada. Northwest-striking, steeply dipping lithologic units are characterized by well-developed layer-parallel cleavage and flattening foliation and steeply northwest-plunging stretching lineation. Pendant rocks are structurally imbricated by a combination of km-scale tight to isoclinal folding and cryptic thrust(?) faulting, accentuated by, and eventually obscured by, pervasive flattening and vertical stretching that preceded and accompanied emplacement of the bounding mid-Cretaceous plutons. Three prominent structural/stratigraphic discontinuities are present: (1) Between middle Permian strata and late Triassic units; this may represent a late Permian unconformity, complicated by repeated slices of Triassic rocks suggesting fault imbrication. (2) At the base of prominent felsic volcanic rocks dated at ~135 Ma; contact with older rocks was originally depositional and is now exposed as a tightly folded angular unconformity. (3) Discordant vertical contacts between 105 to 100 Ma felsic volcanic units and all older strata, indicating fault imbrication into older units during vertical extension. These discontinuities are interpreted to result from: (a) at least one phase of contractional deformation post-late Triassic time, possibly resulting in folding and thrust imbrication of Permian and Triassic strata; (b) major contractional deformation post-135 Ma, resulting in km-scale tight to isoclinal folding of early Cretaceous felsic volcanic strata as well as the previously deformed Permo-Triassic and Jurassic sections; and (c) mid-Cretaceous ductile flattening and vertical stretching superimposed on all units during emplacement of the enclosing granite plutons. Much of the stratigraphic and structural complexity in the Mineral King pendant is identifiable only through detailed dating, and the fortuitous presence of a distinctive stratigraphic marker that allows identification of km-scale isoclinal folds. Detailed dating in other Sierran pendants will likely also indicate much more complex structural histories than are presently documented.