Tecuya Formation
Tecuya Formation
early Miocene to Eocene
Consists of interbedded pebble to boulder conglomerate, sandstone, siltstone, and mudstone occurring at moderate to higher elevations of the San Emigdio Mountains near southwestern map extent. Pebble to boulder conglomerates have varying abundances of granitic, quartzite, metavolcanic, and marble clasts in a matrix of coarse sand (Nilsen and others, 1973; Chapman and Saleeby, 2012).
Contains or is interstratified with Tunis Volcanics member (map unit tuv). Locally (west of Tecuya Canyon) includes a basal granitic breccia that Nilsen and others (1973) interpreted as a landslide deposit.
Conformably overlies the Tejon Formation; interfingers the San Emigdio and Pleito Formations (map unit sep); interfingers and is overlain by the Temblor Formation (map unit tmb), and is generally interpreted as a time-equivalent proximal alluvial fan complex of the same system (e.g., Nilsen and others, 1973). Attains maximum thickness of ~700 m near eastern extent and thins westward, pinching out near Pleito Creek (Nilsen and others, 1973; Kellogg and others, 2008).
Late Eocene to early Miocene age indicated by late Oligocene to early Miocene K-Ar ages on interbedded Tunis volcanics, locally occurring mammalian fossils, and interfingering relations to more distal marine units (Nilsen and others, 1973; Kellogg and others, 2008). Roughly similar in age and depositional environment to the Walker Formation (map unit wlk), which occurs across the San Joaquin Valley to the northeast.