Palinspastic reconstruction of southeastern California and southwestern Arizona for the Middle Miocene

Abstract

A paleogeographic reconstruction of southeastern California and southwestern Arizona at 10 Ma has been made based on available geologic and geophysical data. Clockwise rotation of 39° has been reconstructed in the eastern Transverse Ranges, consistent with paleomagnetic data from late Miocene volcanic rocks, and with slip estimates for left‐lateral faults within the eastern Transverse Ranges and NW‐trending right‐lateral faults in the Mojave Desert. This domain of rotated rocks is bounded by the Pinto Mountain fault on the north. The model requires that the western part of the late Miocene Pinto Mountain fault was a thrust fault, which gained displacement to the west, because of the absence of evidence for rotation of the San Bernardino Mountains or for significant right slip faults within the San Bernardino Mountains. The Squaw Peak thrust system of Meisling and Weldon (1989) may be a western continuation of this fault system. The Sheep Hole fault bounds the rotating domain on the east. East of this fault an array of NW‐trending right slip faults and south‐trending extensional transfer zones has produced a basin and range physiography while accumulating up to 16 km of right slip. This maximum is significantly less than the 37.5 km of right slip required in this region by a recent reconstruction of the central Mojave Desert (Dokka and Travis, 1990a). Geologic relations along the southern boundary of the rotating domain are poorly known, but this boundary is interpreted to involve a series of curved strike slip faults and linking normal faults that accommodated noncoaxial extension. Quaternary movement on the Pinto Mountain and nearby faults is unrelated to the rotation of the eastern Transverse Ranges, and a hiatus during part of Pliocene time followed the deformation which produced the rotation. The reconstructed Clemens Well fault in the Orocopia Mountains, proposed as a major early Miocene strand of the San Andreas fault, projects eastward towards Arizona, where early Miocene rocks and structures are continuous across its trace, making large displacements on this structure unlikely. The model predicts a 14° clockwise rotation and 32% extension during late Miocene and early Pliocene time along a NW‐trending line parallel to the present trace of the San Andreas fault. Palinspastic reconstructions of the San Andreas system based on this proposed reconstruction may be significantly modified from current models.

CVM-S4.26

“…In the western Transverse Ranges, paleomagnetic data suggest cumulative clockwise rotation of about 70 o -90 o (e.g., Kamerling and Luyendyk 1985; Terres and Luyendyk 1985;Hornafius et al 1986;Luyendyk 1991), which is in agreement with earlier geological studies of disrupted lithotectonic belts (e.g., Jones et al 1976;Crouch 1979) and sediments of the Eocene Poway Group (Yeats et al 1974). For the eastern Transverse Ranges, paleomagnetic data record about 40 o of clockwise rotation between 10 and 4.5 Ma (Carter et al 1987;Powell 1993;Richard 1993;Dickinson 1996) which is in agreement with geophysical constraints in (Langenheim and Powell 2009). In Pliocene to Pleistocene, the southern segment of the Pacific-North America plate boundary shifted eastward into the Gulf of California and the plate boundary had to break a new path across southern California (e.g., Atwater and Stock 1998).…”

“…The southern boundary is approximately along the Salton Creek Fault between the Orocopia Mountains on the north and the Chocolate Mountains on the south. Previous studies suggest that the southern boundary is a zone of complex distributed strain with possibly nonrigid deformation (e.g., Richard 1993;Dickinson 1996). In the Chocolate Mountains south of the Salton Creek Fault, there still exist east-west-trending sinistral faults that are typical in the eastern Transverse Ranges (e.g., Darin and Dorsey 2013).…”

Quantifying Dextral Shear on the Bristol-Granite Mountains Fault Zone: Successful Geologic Prediction from Kinematic Compatibility of the Eastern California Shear Zone

“…Dextral shear in the Mojave portion of the ECSZ should be kinematically linked to tectonism in surrounding regions, which includes rotation of the eastern transverse ranges from 10 to 4 Ma (Carter et al 1987;Richard 1993), extension and shear north of the Garlock fault between 11 and 3 Ma (Snow and Lux 1999;Snow and Wernicke 2000;Niemi et al 2001), and the northwesterly motion of the Sierra Nevada-Great Valley block (Wernicke and Snow 1998;McQuarrie and Wernicke 2005). The left-lateral Garlock fault acts as a continental transform by separating large magnitudes of oblique extension in the north from dextral shear and contraction in the ECSZ to the south (Davis and Burchfiel 1973;Bartley et al 1990).…”

Paleotectonics of a complex Miocene half graben formed above a detachment fault: The Diligencia basin, Orocopia Mountains, southern California

“…1 and 2). Clockwise vertical-axis rotation of ~41° affected several blocks of the eastern Transverse Ranges between 10 and 4.5 Ma, with the Diligencia basin being rotated ~110° and rotations of individual blocks of up to 180° near the Clemens Well fault (Carter et al, 1987;Richard, 1993;Dickinson, 1996;Law et al, 2001). The increase in magnitude of vertical-axis rotation of basalt within the Diligencia Formation from ~110° to 180° is best explained by having most of the regional rotation take place prior to local shortening by faulting and folding, which locally increased clockwise rotation (Terres, 1984;Law et al, 2001).…”