Gravity and magnetic maps of the Santa Maria province, California

Conference · Fri Feb 01 04:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5171303

Griscom, A; Sauer, P E ^[1]

---

1. Geological Survey, Menlo Park, CA (United States)

In this paper the authors display an isostatic residual gravity map, contour interval 5 mGal, and an aeromagnetic map, which is a mosaic of existing data . Two computer-derived maps, also at a scale of 1:250,000 display the locations of the steepest gravity gradients and of the steepest gradients on the pseudogravity transform of the magnetic map. These gradients indicate boundaries between rock masses with differing physical properties. The gradient boundaries, where steep and linear, are presumably cause by faults. The gravity reduction removes the isostatic effects of the continental margin, a 60 mGal gradient across the Santa Maria basin, leaving a maximum basin low of 40-50 mGal caused by the low-density basin rocks and bounded by various steep gradients at the basin margin faults. Offshore gravity lows indicate local sedimentary basins trending north to north-west. The magnetic anomalies are caused primarily by serpentinite in the basement of Franciscan assemblage and form irregular belts trending northwest across the basin and basin margins, terminating against the offshore Hosgri fault. The magnetic patterns west of the Hosgri are more irregular in character and may reflect a different basement. The Hosgri fault appears to extend south beyond Point Arguello (about 2 km offshore) according to the gravity map. The right-lateral slip on this fault is thus presumably accommodated on north-dipping thrust faults on the north side of the Santa Barbara Channel and perhaps along the south side of the Santa Maria basin as well. Along the east side of the Hosgri fault, high gravity values indicate local uplift.

• OSTI ID: 5171303
• Report Number(s): CONF-9103128--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 75:2
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
BASEMENT ROCK
CALIFORNIA
DEVELOPED COUNTRIES
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
GRAVITY SURVEYS
MAGNETIC SURVEYS
MAPPING
MAPS
MINERALS
NORTH AMERICA
OFFSHORE SITES
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SERPENTINE
SILICATE MINERALS
SURVEYS
USA