USGS Open-File Report 2014–1043: Magnetic and Gravity Studies of Mono Lake, East-central California

Magnetic and Gravity Studies of Mono Lake, East-central California

By Noah D. Athens, David A. Ponce, Angela S. Jayko, Matt Miller, Bobby McEvoy, Mae Marcaida, Margaret T. Mangan, Stuart K. Wilkinson, James S. McClain, Bruce A. Chuchel, and Kevin M. Denton

Introduction

From August 26 to September 5, 2011, the U.S. Geological Survey (USGS) collected more than 600 line-kilometers of shipborne magnetic data on Mono Lake, 20 line-kilometers of ground magnetic data on Paoha Island, 50 gravity stations on Paoha and Negit Islands, and 28 rock samples on Paoha and Negit Islands, in east-central California. Magnetic and gravity investigations were undertaken in Mono Lake to study regional crustal structures and to aid in understanding the geologic framework, in particular regarding potential geothermal resources and volcanic hazards throughout Mono Basin. Furthermore, shipborne magnetic data illuminate local structures in the upper crust beneath Mono Lake where geologic exposure is absent.

Magnetic and gravity methods, which sense contrasting physical properties of the subsurface, are ideal for studying Mono Lake. Exposed rock units surrounding Mono Lake consist mainly of Quaternary alluvium, lacustrine sediment, aeolian deposits, basalt, and Paleozoic granitic and metasedimentary rocks (Bailey, 1989). At Black Point, on the northwest shore of Mono Lake, there is a mafic cinder cone that was produced by a subaqueous eruption around 13.3 ka. Within Mono Lake there are several small dacite cinder cones and flows, forming Negit Island and part of Paoha Island, which also host deposits of Quaternary lacustrine sediments. The typical density and magnetic properties of young volcanic rocks contrast with those of the lacustrine sediment, enabling us to map their subsurface extent.

First posted March 24, 2014

Report (PDF, 1 MB)

For additional information, contact:
Contact Information, Geology, Minerals, Energy, & Geophysics Science Center—Menlo Park, California
U.S. Geological Survey
345 Middlefield Road
Menlo Park, CA 94025-3591
http://geomaps.wr.usgs.gov/

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Suggested citation:

Athens, N.D., Ponce, D.A., Jayko, A.S., Miller, M., McEvoy, B., Marcaida, M., Mangan, M.T., Wilkinson, S.K., McClain, J.S., Chuchel., B.A., and Denton, K.M., 2014, Magnetic and gravity studies of Mono Lake, east-central, California: U.S. Geological Survey Open-File Report 2014–1043, 14 p., https://dx.doi.org/10.3133/ofr20141043.

ISSN 2331-1258 (online)

Contents

Introduction

Physical-Property, Magnetic, and Gravity, Data

Shipborne Magnetic Data Processing

Discussion

Acknowledgments

References Cited

Appendix--Gravity Base Station Description