Petrologic constraints on the unroofing history of the Funeral Mountain metamorphic core complex, California

The northern Funeral Mountains, southeastern California, comprise a metamorphic core complex that lies within a region of extreme Neogene extension but did not experience a significant late Cenozoic thermal event. Available geochronologic data indicate that peak metamorphism occurred in Early Cretaceous time and that the decompression path developed over the Early to Late Cretaceous interval. The maximum pressures indicated by the petrologic data require substantial Late Jurassic(?) - Early Cretaceous tectonic burial even though most recognized thrust faults at this latitude that have large stratigraphic throws are assumed or demonstrated to have early Mesozoic ages. We postulate that post-Early Cretaceous extensional faults may have excised the necessary middle Mesozoic thrust structures. While the majority of extensional structures responsible for this excisement is likely to be of Neogene age, associated with Basin and Range extension, the Cretaceous decompression path described in this paper is similar to the theoretical P-T paths derived from numerical modeling of extensional unroofing. -from Authors