Stratigraphic analysis of the Vaqueros Formation, Southeastern Cuyama Valley, California

Rocks mapped as Vaqueros Formation within southeastern Cuyama Valley, California crop out near Santa Barbara Canyon (SBC) and in the Cuyama Badlands (CB). Measurem~nt of nine stratigraphic sections indicates thickness decreases westward in the SBC area and increases westward in the CB area. Three members of the marine Vaqueros Formation (lower Quail Canyon Sandstone, middle Soda Lake Shale, and upper Painted Rock Sandstone) are recognized, but each member does not occur throughout the study area. Paleontological and stratigraphic evidence suggests the Vaqueros Formation in SBC ranges between 20 and 17 Ma, whereas the Vaqueros Formation in the CB is older and ranges between 24 and 19 Ma. The Vaqueros Formation and associated rocks are divided into seven lithosomes: 1) upper delta plain and bay-margin deposits of lithesome A (interbedded sandstone anq variegated mudstone), 2) restricted interdistributary bay deposits of lithesome B (white limestone), 3) bay-margin invertebrate communities of lithesome C (non-fragmented-fossil-bearing sandstone), 4) interdistributary bay, prodelta, transition zone, and offshore deposits of lithesome D (silty mudstone), 5) lower/upper delta plain, distributary mouth bar, delta front, shoreface, and transition zone deposits of lithesome E (fine to medium sandstone), 6) lower/upper delta plain and shoreface/foreshore deposits of lithosome F (interbedded coarse to very coarse sandstone and conglomerate), and 7) multi-environmental storm deposits of lithesome G (fragmented-fossil-bearing sandstone). The Vaqueros Formation in the SBC area conformably overlies the nonmarine Simmler Formation, and is conformably overlain by the deep-marine Saltos Shale Member of the Monterey Formation, which indicates a transgressive sequence. The vertical sequence of environments in the SBC area includes (from base to top) alluvial fan and fluvial, upward to transgressive river-dominated deltaic. In the western CB area, the marine Vaqueros Formation unconformably overlies the nonmarine Simmler Formation, and is conformably overlain by the marine to nonmarine Caliente Formation, which indicates a transgressive/regressive sequence. The vertical sequence of environments in the western CB area includes (from base to top) transgressive erosional wave-dominated coastline, upward to regressive wave-dominated deltaic, and finally to fluvial. In the eastern CB only an erosional remnant of the initial transgressive sequence is preserved due to an unconformity at the base of the Caliente Formation.