Gravity of the Reno Basin Jeffrey Pulliam, Evan Saint-Pierre, Will Struble

Gravity in the Reno Basin – Previous Work Large portion of previously available gravity data from Abbott and Louie (2000) and other previous studies. Data provides insight on depth of Reno basin, yet some holes present around the periphery of the basin. Abbott and Louie (2000)

Abbott and Louie and Previous Interpretations

Previous Work Data also available from the Paces Database at the University of Texas – El Paso. Map provides visualization of all previously collected data and exposes holes in dataset. Derived from Abbott and Louie (2000)

Newly Updated Database Our data further complements the data collected by Abbott and Louie (2000) and data available from the Paces database. Key: Greyscale points: Abbott and Louie (2000) Orange: Paces database Green: Newly collected points Derived from Abbott and Louie (2000)

Data Collection Data collection begins with measurement at base station, on UNR campus for our study. Proper data collection technique requires collection of points over two hour period before returning to base station to account for instrumental and tidal drift. Instrumental drift due to environmental changes in and outside of the gravimeter. If possible, multiple measurements taken at each location; gravimeter sensitive to environment, so multiple measurements preferable.

Data Collection GPS measurements taken with Trimble R10 unit to find elevation accurate to ~0.3 m. Measurement difficulties: Weather including wind and precipitation Uneven terrain and soft surfaces Significant lag time in gravimeter Significant time requirement on our survey made following proper protocol challenging.

Courtesy of John Louie

Gravity Calculations Bouguer Correction Bouguer Slab Equation John Louie and Gary Oppliger

Results Station Basin/Bedrock Depth (m) GB1 (SEM) Basin 423±159 Edge 1 336 Edge 2 21 Edge 3 142 Edge 4 472 Edge 5 188 Edge 6 325 Edge 7 133 Edge 8 1358±509 JVTV 9 495±186 RFMA 10 Bedrock? 763 SKYF 11 748±281 REDF 12 1168±320 SPHI 13 565±212

Abbott and Louie (2000) For points RFMA 10, SKYF 11, JVTV 9, SPHI 13, and the average of all edge stations projected onto a horizontal transect across the basin.

Discussion and Conclusions Collection of data points provides further resolution for basin depth determination throughout the Reno basin. Difficulty in following data collection protocol may bring into question the quality of new data. Results suggest that previous studies have reasonably determined basin depth. Our collected data seems to match contour map from Abbott and Louie (2000). Gaps still exist in the dataset, as measurements taken during the course of this project were largely for correlation with other geophysical methods (ReMi, H/V).

Questions?