LATE CRETACEOUS THROUGH CENOZOIC CONTRACTIONAL IMBRICATION, EXTENSIONAL DETACHMENT AND STRIKE SLIP DISMEMBERMENT/ROTATION OF THE RAND THRUST COMPLEX, NORTHWESTERN MOJAVE DESERT, CALIFORNIA
We present a map compilation of geologic and structural data acquired since 1983; including observations from the western Rand Mountains, inaccessible for the past two decades due to tortoise preserve status. Interpretation of the movement history is complicated by kinematic indicators with different lineation directions and contradictory shear senses at various structural levels. Another factor is likelihood that the eastern California shear zone has rotated all or parts of the area up to 90 degrees CW. Macro and microstructural analyses of greenschist to lower amphibolite grade mylonites yield the following pattern of transport directions (present day geography), from deep to shallow: 1) NW and N-vergent shear along Fault 1 and uppermost Rand Schist, 2) penetrative top-to-SW shear fabrics within thicker portions of Plate 2, overprinted by asymmetric folds with northerly vergence, 3) localized NE-vergent shear zones within Plate 3, and 4) NNE directed transport of Plate 4 across Plates 1-3 along Fault 3. These movement directions require adjustment for vertical and horizontal axis rotations to fully understand true tectonic transport geometry. Overall structural patterns and age relations are consistent with east over west imbrication of the batholith with Rand Schist during Laramide convergence, followed by Miocene extensional detachment, then left-lateral displacement accompanied by CW rotation that may be ongoing.