Pattern of extensional faulting in pelagic carbonates of the Umbria-Marche Apennines of central Italy

Research Article| May 01, 1990 Pattern of extensional faulting in pelagic carbonates of the Umbria-Marche Apennines of central Italy Walter Alvarez Walter Alvarez 1Department of Geology and Geophysics, University of California, Berkeley, California 94720 Search for other works by this author on: GSW Google Scholar Author and Article Information Walter Alvarez 1Department of Geology and Geophysics, University of California, Berkeley, California 94720 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1990) 18 (5): 407–410. https://doi.org/10.1130/0091-7613(1990)018<0407:POEFIP>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Walter Alvarez; Pattern of extensional faulting in pelagic carbonates of the Umbria-Marche Apennines of central Italy. Geology 1990;; 18 (5): 407–410. doi: https://doi.org/10.1130/0091-7613(1990)018<0407:POEFIP>2.3.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 SocietyGeology Search Advanced Search Abstract The Umbria-Marche Apennines provide a new region in which the nature of passive-margin extensional faulting can be studied in outcrop. In these dominantly pelagic carbonate rocks of Jurassic and Cretaceous age, horsts acted as shallow, nonvolcanic seamounts, while tilted half grabens formed deeper basins. One well-exposed seamount-basin transition agrees in general with the model of listric normal faulting and tilted half grabens, but shows interesting and significant divergences when studied in detail. A small sedimentary wedge at the faulted margin of a horst-block seamount thickens unexpectedly toward the adjacent basin. This wedge developed because of local convex-upward curvature of the shallowest part of a fault which at depth must have concave-up, listric geometry. The local sedimentary wedge resulted from deposition on the hanging wall as it tilted, followed by differential compaction of younger limestones that lapped onto the gentle slope leading from the horst-block seamount toward the basin. The map pattern of listric normal faulting in the Umbria-Marche Apennines suggests that both principal strain axes were extensional, in contrast to the usual pattern of listric faults crossed by transfer faults. 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.