Mesozoic and Cenozoic extension recorded by metamorphic rocks in the Funeral Mountains, California

The Funeral Mountains metamorphic core complex contains early ductile structures related to Mesozoic compressional tectonics that have been overprinted by structures related to later extension. The core-bounding detachment system formed in late Miocene time, and ductile extensional fabrics in its footwall have been viewed as evidence of a higher-temperature stage in the same event. Integrated structural analysis and geochronology, however, indicate that ductile fabrics with a transport direction similar to the northwest direction of movement on the detachment are part of an older extensional event of Late Cretaceous age. This event produced mylonitic fabrics, a dominant foliation, and well-developed mineral and stretching lineations. Further extensional events are described. -from Authors