Structural analysis of Mesozoic deformations in the central Slate Range, eastern California

Eastern Sierran wall rocks in the central portion of the Slate Range have undergone several phases of Mesozoic deformation resulting in the folding and faulting of Permian (?) - Triassic (?) metasedimentary and metavolcanic rocks. Additionally, five phases of pre-, syn- and(or) post-tectonic intrusion occurred in the study area. Five generations of folding are recognized, several of which are correlative with regionally recognized structures. Early-formed fold generations, F1 , F2 and F3, are oriented in a northeasterly direction. Axial plane cleavage is developed only in the F1 generation. Fold trends changed to a northwesterly direction during the F4 generation which also has a poorly developed axial plane cleavage. The F5 generation is pervasive and is represented by kink folds, warps and minor folds. F1 folds are cut by west-trending strike- and oblique-slip faults, and both folds and faults are truncated by the northwest-striking Ophir thrust fault, which has been refolded about a N.50°W. orientation by the F4 fold generation. Three other minor thrust faults associated with this compressional phase also developed. Minor folds and mineral lineations present in Triassic (?) metavolcanic rocks indicate a northeastward direction of tectonic transport of the thrust plates. (See more in text.)