MARKS, EDWARD, and SATISH K. SRIVASTAVA, Marks and Associates, Whittier, CA
ABSTRACT: Hydrostratigraphy of the Orange County Water District HBM-1 Well, Westminster, Orange County, California
A lithological, micropaleontological, palynological, and palynofacial examination of 32 cuttings and bit samples from 65 to 2010 ft depth in the Orange County Water District HBM-1 water well, Orange County, California, documented 17 biohorizons. These markers are useful in separating 11 aquifers and interstitial aquicludes in Orange County. Samples between 2010 and 1822 ft are of late Pliocene age, representing the upper Pico Formation. Six horizons and four depositional environments of alternating bathyal and outer neritic were documented in this interval. The 1442-1238 ft interval represents the early Pleistocene lower San Pedro Formation and consists of 3 biohorizons of outer neritic environment. The 1204-820 ft interval, with an unconformity near the top at about 880 ft, represent the upper San Pedro Formation of early Pleistocene age and consists of 3 biohorizons indicating a shallow marine deposition with a terrestrial influence. The 820-65 ft interval of the late Pleistocene Lakewood Formation contains two biohorizons, an outer neritic environment (820-810 ft), an inner neritic environment (810-412 ft), and three biohorizons (260-65 ft) indicative of shallow open marine deposition.
Recycled palynormorphs of Maestrichtian age at 1952 ft depth, of Senonian age at 1197 ft depth, and of Turonian age at 250 ft depth indicate an Upper Cretaceous source of deposition. Picea and Sequoia occurrence in the interval 2010-910 ft indicates a temperate climate in the area during the deposition. An erosional unconformity at about 880 ft indicates a regression-erosion-transgression cycle.
The well's lithology was examined and plotted as a percentage log. Wood occurrence were displayed to pinpoint water coloration. A clastic analysis chart was prepared to show reservoir geometry, sand transport, porosity, facies, 7 and environments.
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Discovery Article #90992©1993 AAPG Pacific Section Meeting, Long Beach,
California, May 5-7, 1993.