Gravity Analysis in the Truckee Meadows Basin and Hidden Valley Sub-basin
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This study enhances the NE portion of the Truckee Meadows Basin gravity dataset by employing gravimetry to fill data gaps and analyze the Hidden Valley sub-basin. Utilizing tools such as the LaCost and Rhomberg gravimeters, Grav2D, GM-SYS, and Trimble GPS, we identified key gravity anomalies, including a ~14 mGal anomaly in Prater and a -6 mGal anomaly in Hidden Valley. The research addresses various error factors, outlines future work for verifying findings, and emphasizes the necessity of completing regional infrastructure for data integrity.
Gravity Analysis in the Truckee Meadows Basin and Hidden Valley Sub-basin
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Presentation Transcript
Gravity Janice Kukuk Rob Ghigieri Ross Whitmore http://sciencefun.wordpress.com/2008/04/
Takehome Message • Bolstered NE portion of the Truckee Meadows Basin (TMB) Gravity dataset • Hidden Valley Sub-basin
Purpose • Learn how to use a Gravimeter • Fill data gaps in TMB dataset • Profile a smaller sub-basin in Hidden Valley
Methods • LaCost and Rhomberg Gravimeter • Grav2d • GM-SYS • Trimble GPS • Theodolite
Results for Prater Grav2d W E GM-SYS ~14 mGal anomaly Distance in km
Results for Hidden Valley Grav2d W E Tolerance 2 mGal Density contrast-0.33 g/cc GM-SYS -6 mGal Anomaly Distance in km
Comparison of results Prater W E (Modified from Widmer et al., 2007)
Error • Non-equilibrated spring • Terrain corrections • Elevation error • Inconsistent temperature • User error • Instrument drift
Future Work • Verification of Hidden Valley anomaly • Completion of D’Andreapkwy line to bolster dataset
TakehomeMessage • Bolstered NE portion of the Truckee Meadows Basin (TMB) Gravity dataset • Hidden Valley Sub-basin
References • Abbot, R.E., and Louie, J.N., 2000, Depth to bedrock using gravimetry in the Reno and Carson City, Nevada, Area basins: Geophysics, V. 65, p. 430-450. • Anderson, J., Su, F., Zeng, Y., 1999, Seismic Hazards in the vicinity of Las Vegas and Reno: Final Technical Report GS# 1434-HQ-97- GR-03044 (paper copy, 15 p.) • Telford, W.M., Geldhart, L.P., and Sheriff, R.E., 1990, Applied Geophysics: New York, Cambridge University Press, 770 p. • Widmer, M.C., Cashman, P.H., Benedict, F.C., Trexler, J.H., 2007, Neogene through Quaternary stratigraphy and structure in a portion of the Truckee Meadows Basin; a record of recent tectonic history: Geological Society of America Abstracts with programs, v. 39, no. 4 p.9