Ca. 13 Ma strike-slip deformation in coastal Sonora from a large-scale, en-echelon, brittle-ductile, dextral shear indicator: implications for the evolution of the California rift

Paleomagnetic Study of the Late Miocene Volcanic Sequence in Sonora, Mexico: Clockwise Vertical Axis Rotation Related to the Oblique Rifting in the Pacific‐North American Plate Boundary

“…12.5 Ma to 6 Ma. This timing coincides with lithospheric rupture and substantial magmatic activity in Sonora and Baja California (Bennett et al., 2017; Darin et al., 2016; Gastil & Krummenacher, 1977; Mora‐Álvarez & McDowell, 2000; Pallares et al., 2007; Till et al., 2009), the appearance of peralkaline magmatism (Vidal‐Solano et al., 2005, 2007), and tectonic deformation due to oblique‐divergent plate motion between PAC‐NAM along both margins of the GOC (Bennett et al., 2013; Darin et al., 2016; Ferrari et al., 2013; Gans et al., 2013; García‐Martínez et al., 2014; Seiler et al., 2010; Velderrain‐Rojas et al., 2021; William‐Herman, 2013). The second phase (spanning from ca.…”

“…The PGC formed between ∼12.5 and 6 Ma, eventually forming the present‐day Gulf of California (GOC; Figure 1). Although the PGC was proposed as a volcano‐tectonic rift zone with orthogonal extension (Karig & Jensky, 1972), at the eastern margin of the GOC (along coastal Sonora), the deformation is widely characterized by clockwise (CW) vertical axis block rotation, strike‐slip faulting, and tilting blocks of volcanic and intrusive rocks (Bennett et al., 2013, 2016, 2017; Bennett & Oskin, 2014; Darin et al., 2016; García‐Martínez et al., 2014; Velderrain‐Rojas et al., 2021; William‐Herman, 2013). This characteristic shear zone development in the GOC is within a region called Gulf Extensional Province (GEP; Figure 1; Gastil et al., 1975; Stock & Hodges, 1989; Martín‐Barajas, 2000; Bennett et al., 2014).…”

Late Miocene extension in coastal Sonora, México: Implications for the evolution of dextral shear in the proto-Gulf of California oblique rift

“…Scattered evidence of proto-Gulf age dextral shear is documented onshore in the northern GEP (e.g., Gans, 1997;Lewis & Stock, 1998;Nourse et al, 2005;Seiler et al, 2010Seiler et al, , 2011Bennett et al, 2013a;Herman, 2013;Vidal-Solano et al, 2013;García-Martínez et al, 2014;Bennett et al, this volume), but the timing, total magnitude, and spatial extent of dextral strain are not fully documented. For example, Bennett et al (2013a) documented a minimum of 41 ± 11 km of dextral shear in the Coastal Sonora fault zone (CSFZ) near Bahía de Kino, most of which likely accumulated during latest proto-Gulf time ca.…”

“…3) reveal clockwise vertical-axis rotations that are interpreted as evidence of ca. 13-12 Ma shear (García-Martínez, et al, 2014). However, the magnitude and geometry of the causative structures are speculative and incompletely documented, the basement dikes that may record dextral warping remain undated and could record pre-Miocene deformation, and no crosscutting relationship (e.g., angular unconformity, undeformed capping unit) has been documented to serve as a minimum age constraint on the deformation.…”

Geology of the Selene perlite deposit in the northern Sierra Madre Occidental, northeastern Sonora, Mexico

“…20 -18 Ma and again after ca. 12.5 Ma when kinematics of rifting became more oblique and strike-slip faults started to developed Bennett and Oskin, 2014;García-Martínez et al, 2014). The active tectonic regime shaping the Gulf of California is defined as a narrow, NNW-trending dextral transtensional belt of strike-slip faults connecting en echelon pull-apart basins all kinematically linked to the strike-slip San Andreas Fault system Bennett and Oskin, 2014).…”