Lusardi Formation: A Post-Batholithic Cretaceous Conglomerate North of San Diego, California

Abstract

Research Article| February 01, 1970 Lusardi Formation: A Post-Batholithic Cretaceous Conglomerate North of San Diego, California CHARLES E NORDSTROM CHARLES E NORDSTROM Ocean Research Division, Scripps Institution of Oceanography, La Jolla, California 92037 Search for other works by this author on: GSW Google Scholar Author and Article Information CHARLES E NORDSTROM Ocean Research Division, Scripps Institution of Oceanography, La Jolla, California 92037 Publisher: Geological Society of America Received: 26 May 1969 Revision Received: 25 Sep 1969 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1970, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1970) 81 (2): 601–606. https://doi.org/10.1130/0016-7606(1970)81[601:LFAPCC]2.0.CO;2 Article history Received: 26 May 1969 Revision Received: 25 Sep 1969 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation CHARLES E NORDSTROM; Lusardi Formation: A Post-Batholithic Cretaceous Conglomerate North of San Diego, California. GSA Bulletin 1970;; 81 (2): 601–606. doi: https://doi.org/10.1130/0016-7606(1970)81[601:LFAPCC]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Lusardi Formation, a previously undescnbed Cretaceous conglomerate, is discontinuously exposed over an area of 25 sq mi near Rancho Santa Fe, California. It unconformably overlies Late Jurassic to Early Cretaceous igneous and metamorphic rocks, and is unconformably overlain by the Eocene La Jolla Formation.The Lusardi Formation is predominantly a reddish-brown boulder-to-cobble conglomerate with clasts that range up to 30 ft in diameter. Clast types include plutomc rocks, volcanic and volcanic-clastic rocks, and metasedimentary rocks derived from the underlying rock units. Thin lenses of well-sorted, medium-grained arkosic sandstone are locally present in the otherwise massive conglomerate.The large size of the clasts, their local provenance, and color of the unit suggest terrestrial deposition, probably by fluvial and mass transport processes on alluvial fans. Many clasts are deeply weathered and friable, and the iron bearing minerals of the matrix are commonly altered to oxides, indicating lengthly subaerial weathering in a semi-arid climate after deposition. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.