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Aeromagnetic Map with Geology of the Los Angeles 30 x 60 Minute Quadrangle, Southern California

October 30, 2006

Introduction: An important objective of geologic mapping is to project surficial structures and stratigraphy into the subsurface. Geophysical data and analysis are useful tools for achieving this objective. This aeromagnetic anomaly map provides a three-dimensional perspective to the geologic mapping of the Los Angeles 30 by 60 minute quadrangle. Aeromagnetic maps show the distribution of magnetic rocks, primarily those containing magnetite (Blakely, 1995). In the Los Angeles quadrangle, the magnetic sources are Tertiary and Mesozoic igneous rocks and Precambrian crystalline rocks. Aeromagnetic anomalies mark abrupt spatial contrasts in magnetization that can be attributed to lithologic boundaries, perhaps caused by faulting of these rocks or by intrusive contacts. This aeromagnetic map overlain on geology, with information from wells and other geophysical data, provides constraints on the subsurface geology by allowing us to trace faults beneath surficial cover and estimate fault dip and offset. This map supersedes Langenheim and Jachens (1997) because of its digital form and the added value of overlaying the magnetic data on a geologic base. The geologic base for this map is from Yerkes and Campbell (2005); some of their subunits have been merged into one on this map.

Citation Information

Publication Year 2006
Title Aeromagnetic Map with Geology of the Los Angeles 30 x 60 Minute Quadrangle, Southern California
DOI 10.3133/sim2950
Authors V. E. Langenheim, T. G. Hildenbrand, R. C. Jachens, R. H. Campbell, R. F. Yerkes
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Scientific Investigations Map
Series Number 2950
Index ID sim2950
Record Source USGS Publications Warehouse
USGS Organization Geophysics Unit of Menlo Park, CA (GUMP)