Abstract
Laumontite of hydrothermal origin occurs in veins and as a replacement of the anorthite component of plagioclase in granitic and gneissic basement and overlying arkosic sandstone and conglomerate of the San Francisquito(?), Vaqueros and Cajon formations exposed in Cajon Pass north of the San Andreas fault. Accompanying alteration includes exsolution of albite from plagioclase, conversion of orthoclase to microcline and perthite, and oxidation of iron in biotite and magnetite to form a disseminated hematite stain. These changes are pervasive within 1 km of the fault but diminish to no alteration at 4 km. Granitic rocks close to the fault are crushed to highly fractured and contain a mosaic of laumontite veins. Veins occur along joints and minor faults in sedimentary rocks. Most veins are nearly vertical and trend northwest at a more northerly angle than the San Andreas. This mineralization is attributed to deep circulation of ground water in fractured and frictionally heated rocks along the San Andreas fault.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
