Geologic map and structure sections of the Loma Prieta 7 1/2' quadrangle, Santa Clara and Santa Cruz Counties, California

Abstract

Open-file Map 88-752This map is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. Any use of trade names is for descriptive purposes only and does not imply endorsement by the U.S. Geological Survey.

Neogene Contraction between the San Andreas Fault and the Santa Clara Valley, San Francisco Bay Region, California

“…The timing of this thrusting coincides with transten- sion-linked deposition that was occurring to the northeast in the Cupertino basin, which also seems to have become younger northwestward from the Gilroy-Morgan Hill area. Observed com ponents of reverse and dextral-slip from slickensides in the Sargent fault zone (McLaughlin et al, 1988) further suggest that the hanging-wall block of the Sargent fault could be translated northwest ward relative to its position at the time of Miocene basin development (Fig. 10A).…”

“…A moderate com ponent of strike-slip, therefore, seems necessary to explain stratigraphic differences across the Sargent and Berrocal faults. A component of late strike-slip along the Sargent fault and along nu merous small, subparallel, adjacent faults, fur thermore, is supported by rake measurements of 50° or less on shear surfaces (McLaughlin et al, 1988(McLaughlin et al, , 1991Clark et al, 1989).…”

“…This lower Eocene to Oligocene or lower Miocene conformable sequence, in turn, is thrust northeastward over a different sequence of coeval lower Eocene and older rocks (Fig. 1B;McLaughlin et al, 1988). No conformable se quence of deep-marine Miocene-Eocene rocks of comparable depositional setting is present at the surface northeast of the Sargent or Berrocal faults.…”

“…Components of displacement on the Sargent and Hooker Gulch faults were measured from sev eral structure sections oriented normal to the trend of the faults (structure sections are in McLaughlin et al, 1988McLaughlin et al, , 1991. To help constrain the displacement com ponents we compared the structure sections with several similarly oriented gravity and magnetic models (Jachens and Griscom, in press;K.…”

Checklist of Mesozoic macrofossil localities in the Santa Cruz Mountains and vicinity

“…The rocks at Pigeon Point are of a similar age (Hall et al, 1959); recendy discovered fossils from this area and listed in this report suggest that the entire Pigeon Point Formation straddles the Campanian-Maastrichtian boundary and does not range into the lower Campanian as suggested by Saul (1978). The Mesozoic Great Valley-like strata of the Santa Cruz Mountains have a lower interval of Tithonian to Valanginian age which is separated from an upper interval of late Campanian to early Maastrichtian age by a low angle normal fault (McLaughlin et al, 1988).…”