T107 Earth Surface Processes in Tectonically Active and Unstable Regions (Posters)

Monday, 23 September 2024
8:00 AM - 5:30 PM
Hall D

GEOLOGIC MAPPING AND ANALYSIS OF THE NORTHERN ELSINORE FAULT, NORTHERN SANTA ANA MOUNTAINS, SOUTHERN CALIFORNIA

Paper number: T107-14
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

The Glen Ivy fault segment of the Elsinore fault zone bifurcates into the Whittier fault and Chino fault in Corona, California. Geologic slip rates for the Elsinore fault zone range from 2-9 mm/yr, with limited slip rate studies on this portion of the fault. Access to new airborne LiDAR (Light Detection and Ranging) datasets and improvements in Quaternary dating methods have motivated a re-examination of the previously mapped fault, with objectives to: (1) differentiate the geologic units, (2) establish the geometry and kinematics of the faults, and (3) establish slip magnitudes and rates. The high-resolution (1.0 m2) LiDAR topographic data are paired with NAIP (National Agriculture Imagery Program) data and historical aerial photography to produce a detailed (1:10,000) geologic map of the Glen Ivy fault segment of the Elsinore fault zone in Corona, California over portions of the Corona South, Corona North, Black Star Canyon, and Prado Dam 7.5-minute quadrangles. Furthermore, the use of LiDAR allows for detailed surface analysis to improve surface visualization and derive topographic information through terrain ruggedness index and topographic surface roughness analysis. Preliminary mapping shows that the southern portion of the Glen Ivy fault segment is primarily a single stranded fault. As the fault progresses northward, it becomes a complex, multi-stranded fault zone with some dip-slip component. While the Whittier fault segment is thought to be the primary extension of the Elsinore fault zone, preliminary mapping shows that paleochannels of the Santa Ana River have been displaced along the fault, with the farthest channel offset approximately ~13 km. The magnitude of the displacement is consistent with offsets recorded by a range of markers in the bedrock, suggesting the total lateral slip for this portion of the fault is 13-15 km. The results also suggest that the Chino fault segment is the primary extension of the Elsinore fault. On-going efforts focus on obtaining new geochronological constraints for Pliocene to Quaternary deposits in the foothills of the Santa Ana Mountains for slip rate analysis.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-405510

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