Magnetotelluric Imaging of a Carbonatite Terrane in the Southeast Mojave Desert, California and Nevada

Jared R. Peacock; Kevin M. Denton; David A. Ponce

doi:10.1071/ASEG2016ab148

25th International Conference and Exhibition – Interpreting the Past, Discovering the Future

ISSN: 2202-0586
E-ISSN:

oa Magnetotelluric Imaging of a Carbonatite Terrane in the Southeast Mojave Desert, California and Nevada
Authors Jared R. Peacock^a, Kevin M. Denton^b and David A. Ponce^c
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^a U.S. Geological Survey, Menlo Park, , California, , USA, [email protected] ^b U.S. Geological Survey, Menlo Park, , California, , USA, [email protected] ^c U.S. Geological Survey, Menlo Park, , California, , USA, [email protected]
Publisher: Australian Society of Exploration Geophysicists
Source: ASEG Extended Abstracts, Volume 2016, Issue 25th International Conference and Exhibition – Interpreting the Past, Discovering the Future, Dec 2016, p. 1 - 5
DOI: https://doi.org/10.1071/ASEG2016ab148
- Published online: 01 Dec 2016

Abstract

The southeast Mojave Desert hosts one of the world’s largest rare earth element (REE) deposits at Mountain Pass, California. Although surface geology has been studied, a full understanding of the carbonatite and associated intrusive suite complex requires subsurface geophysical characterization. In this study, a combination of geophysical methods, including magnetotelluric (MT), magnetics, and gravity are used to create a two-dimensional (2D) geophysical model to a depth of about 10 km. An electrically conductive body is found 2-3 km below and west of the deposit that is associated with a magnetic high that could be connected to a deeper (10 km) conductive body related to possible intrusions or hydrothermal systems. The carbonatite body coincides with a steep magnetic gradient and a bench or terrace in the gravity data that may reflect relative lower-density intrusive rocks. Although carbonatite rocks are typically magnetic, the carbonatite rocks, associated intrusive suite, and host rocks in this area are essentially non-magnetic. Combined geophysical data indicate that the enriched REE deposit may be related to a regional extensive hydrothermal alteration event.

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References

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Article Type: Research Article

Keyword(s): Carbonatite deposits; Magnetotellurics; Potential Fields; Rare Earth Element

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oa Magnetotelluric Imaging of a Carbonatite Terrane in the Southeast Mojave Desert, California and Nevada

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