| Abstract: | The Coastal belt of the Franciscan Complex represents a Late Cretaceous to Miocene accretionary prism and overlying slope deposits. Its equivalents may extend from the offshore outer borderland of southern California to north of the Mendocino Triple Junction under the Eel River Basin and in the offshore of Cascadia. The Coastal belt is exposed on land in northern California, yet its structure and stratigraphy are incompletely known because of discontinuous exposure, structural disruption, and lithologically non-distinctive clastic rocks. The intent of this report is to make available, in map form, aeromagnetic data covering the Coastal belt that provide a new dataset to aid in mapping, understanding, and interpreting the incompletely understood geology and structure in northern California. The newly merged aeromagnetic data over the Coastal belt of the Franciscan Complex reveal long, linear anomalies that indicate remarkably coherent structure within a terrane where mapping at the surface indicates complex deformation and that has been described as "broken formation" and, even locally as "melange". The anomalies in the Coastal belt are primarily sourced by volcanic-rich graywackes and exotic blocks of basalt. Some anomalies along the contact of the Coastal belt with the Central belt are likely caused by local interleaving of components of the Coast Ranges ophiolite. These data can be used to map additional exotic blocks within the Coastal belt and to distinguish lithologically indistinct graywackes within the Coastal terrane. Using anomaly asymmetry allows projection of these "layers" into the subsurface. This analysis indicates predominant northeast dips consistent with tectonic interleaving of blocks within a subduction zone. |
| Genre: | USGS Numbered Series |
| ProdID: | 70007344 |
| Citation Author: | Langenheim, V. E.; Jachens, R. C.; McLaughlin, R. J. |
| Citation Contributing Office: | Geology, Minerals, Energy, and Geophysics Science Center-Menlo Park |
| Citation Datum: | NAD27 |
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| Citation Language: | English |
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| Citation LatN: | 0404000 |
| Citation LatS: | 0381500 |
| Citation LonE: | -1224500 |
| Citation LonW: | -1243000 |
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| Citation Number Of Pages: | |
| Citation Online Only Flag: | Y |
| Citation Phsyical Description: | Pamphlet: i, 8 p.; Figures, Tables; 3 Plates; Sheet 1: 29.2 x 28.3 inches; Sheet 2: 26.7 x 48.4 inches; Sheet 3: 26.7 x 48.4 inches; TXT Download of Readme File; Metadata Folder; ZIP Download of GIS Database |
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| Citation Publisher: | U.S. Geological Survey |
| Citation Series: | Scientific Investigations Map |
| Citation Series Code: | SIM |
| Citation Series Number: | 3188 |
| Citation Search Results Text: | Aeromagnetic and aeromagnetic-based geologic maps of the Coastal Belt, Franciscan Complex, northern California; 2011; SIM; 3188; Langenheim, V. E.; Jachens, R. C.; McLaughlin, R. J. |
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| Citation Year: | 2011 |
| Type: | citation/reference |
| Text: | Aeromagnetic and aeromagnetic-based geologic maps of the Coastal Belt, Franciscan Complex, northern California; 2011; SIM; 3188; Langenheim, V. E.; Jachens, R. C.; McLaughlin, R. J. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/sim_3188.gif |
| URL (INDEX PAGE): | http://pubs.usgs.gov/sim/3188/ |
| Date Other: | Thu, 9 Feb 2012 00:00 -0600 |
| Publisher: | U.S. Geological Survey |
