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New perspectives on graptolite distributions and their use as indicators of platform margin dynamics

1997; Geological Society of America; Volume: 25; Issue: 10 Linguagem: Inglês

10.1130/0091-7613(1997)025 2.3.co;2

1943-2682

Stanley C. Finney, William B. N. Berry,

Geological formations and processes

Research Article| October 01, 1997 New perspectives on graptolite distributions and their use as indicators of platform margin dynamics Stanley C. Finney; Stanley C. Finney 1Department of Geological Sciences, California State University, Long Beach, California 90840 Search for other works by this author on: GSW Google Scholar William B. N. Berry William B. N. Berry 2Department of Geology and Geophysics, University of California, Berkeley, California 94720 Search for other works by this author on: GSW Google Scholar Geology (1997) 25 (10): 919–922. https://doi.org/10.1130/0091-7613(1997)025 2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Stanley C. Finney, William B. N. Berry; New perspectives on graptolite distributions and their use as indicators of platform margin dynamics. Geology 1997;; 25 (10): 919–922. doi: https://doi.org/10.1130/0091-7613(1997)025 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 Graptolite distributions in Ordovician shelf, slope, and basinal facies in the Great Basin indicate that graptolites were scarce in open oceanic waters oceanward of the Cordilleran shelf margin and that they thrived in waters above the margin. This pattern is consistent with that of most zooplankton in modern oceans. It follows from these observations that the depositional setting of typical graptolitic shale was the area of the sea floor under continental-margin upwelling zones where graptolites flourished and within the oxygen-minimum zone where their rhabdosomes were preserved. With changes over time in relative sea level, deep oceanic circulation, and wind-driven surface circulation, the upwelling and oxygen-minimum zones may have thickened or thinned, migrated landward or oceanward, and expanded laterally, contracted, or even disappeared. The observed graptolite occurrences suggest that the primary graptolite biotope—that is, the habitat of diverse and abundant faunas—was a relatively narrow belt of upwelling waters along, and extending somewhat open oceanward from, the continental margin. Provinces were maintained only to the extent that species could disperse along continental margins. Distribution of typical graptolitic strata may be used to interpret development of continental margins, because such distribution incorporates a signal of sea-level rise or fall, oceanographic changes (especially upwelling), and tectonic events that led to creation and deterioration of upwelling conditions in which graptolites flourished. 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.