Franciscan Assemblage

The Franciscan Assemblage is a term in geology that describes a group of rocks near the peninsula of San Francisco, California.

Franciscan Assemblage Media

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  Map modified from Irwin (1990) showing distribution of Great Valley Sequence and Franciscan Complex (in blue).

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  Diagram (modified from Fig 3.11 in Irwin, 1990) showing the depositional setting of the Franciscan Assemblage and the contemporaneous Great Valley Sequence,.

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  Shale matrix mélange with clasts of sandstone and greenstone on Marshall's Beach, San Francisco

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  Ribbon Chert of the Marin Headlands Terrane, exposed at Marshall's Beach, San Francisco.

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  Pillow structures preserved in greenschist-facies metamorphosed basalts of the FranciscanComplex, Black Sands Beach, Marin Headlands, California. Field of view is approximately 2 m wide.

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  Folded blue metacherts with glaucophane-rich layers, exposed in outcrops on Kayak Beach, Angel Island, northern San Francisco Bay.

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  Sheared block-in-matrix fabric composed of serpentinite blocks in serpentinite matrix, exposed on Perles Beach, Angel Island, Marin County, California. Pencil for scale. The strong anastomosing foliation is folded, sub-vertical in the lower part of the photo and more gently dipping in the upper part of the photo.

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  Shale matrix mélange of the Franciscan Complex at Marshall's Beach, San Francisco, California. Sandstone blocks (light grey) contain white mineral veins. Dark grey shale matrix displays strongly foliated anastomosing scaly fabric. Geologist John Wakabayashi for scale.