Stratigraphic constraints for Miocene-age vertical motion along the Santa Clara fault, Espanola Basin, north-central New Mexico
— Koning, Daniel, J., Sean D. Connell, Janet L. Slate, and Elmira Wan

We examine the middle to late Miocene tectonic history of the Santa Clara fault (SCF) in the Española Basin, north-central Rio Grande rift. A part of the Embudo fault system, the northeast-trending SCF transfers strain between the San Luis and Española Basins. This fault dips to the southeast and exhibits a normal, east-down sense of offset and significant leftlateral slip. Comparing thickness changes of dated stratigraphic intervals across the SCF allows us to document the development of this structure during middle and late Miocene time. Our thickness comparisons indicate an increase in fault activity at ca. 12.7 Ma and suggest a prior increase in fault activity between 15 and 13 Ma. Between 11 and 10 Ma, the southward-flowing river associated with the Cejita Member (Chamita Formation) lapped westward 3 km onto the Santa Clara footwall, suggesting diminished subsidence during that time or increased sediment supply to this river. Approximately 430-500 m of stratigraphic separation of post-10 Ma Chamita Formation strata and lesser vertical offset of the Pliocene Puye Formation indicates that significant vertical motion along the SCF occurred after 10 Ma.