Elemental abundance anomalies in the late Cenomanian extinction interval; a search for the source(s)

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doi: 10.1016/0012-821X(93)90126-T
Author(s): Orth, Charles J.; Attrep, Moses, Jr.; Quintana, Leonard R.; Elder, William P.; Kauffman, Erle G.; Diner, Richard; Villamil, Tomas
Author Affiliation(s): Primary:
Los Alamos National Laboratory, Isotope and Nuclear Chemistry Division, Los Alamos, NM, United States
Other:
U.S. Geological Survey, Menlo Park, CA, United States
University of Colorado, Boulder, CO, United States
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 117(1-2), p.189-204. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 51 refs.; illus. incl. strat. cols., 1 table, sketch maps
Summary: Elemental abundances have been measured by neutron activation methods across the Cenomanian-Turonian (late Cretaceous) extinction interval in samples collected from sixteen sites in the Western Interior Basin of North America and from twelve widely separated locations around the globe, including six ODP/DSDP sites. In most Western Interior Basin sites, in Colombia, and in western Europe (weaker), two closely spaced elemental abundance peaks occur in the upper Cenomanian (∼92 m.y.), spanning the ammonite zones of Sciponoceras gracile through Neocardioceras juddii. Elements with anomalously high concentrations include Sc, Ti, V, Cr, Mn, Co, Ni, Ir, Pt and Au. The lower peak coincides with the disappearance (extinction) of the foraminifer Rotalipora cushmani. In North American sections R. greenhornensis also disappears at or just below this horizon, but in Europe it disappears considerably earlier than R. cushmani. A series of molluscan extinction and speciation or migration events also begins near the stratigraphic level of the lower elemental abundance peak. The well-documented positive δ 13C excursion begins just before the extinctions and the elemental anomalies, and continues into the lower Turonian, well above the upper anomaly. This carbon isotope excursion has been observed in East European sections where we find little or no evidence of the elemental anomalies, suggesting that the two phenomena may not be tightly coupled. Elemental abundance ratios in the anomalies closely resemble those of Mid-Atlantic Ridge basalt or Hawaiian lava (tholeiitic), but not those of C1 chondrite, black shale, average crustal rocks, or lamproite and kimberlite of roughly similar age in southeastern Kansas. The excess Ir and other siderophiles hint at possible large-body impact(s) for the source. However, we have not located microspherules (other than biogenic calcispheres) or shocked mineral grains in any of our samples. Furthermore, Sc, Ti, V and Mn are not enriched in differentiated Solar-System bodies. Although the weak geochemical signal from comet impact(s) could be masked by the strong terrestrial-like overprint, these anomalies more likely resulted either from intense seafloor spreading activity or merely from increased circulation of deep, metal-rich water associated with the large late Cenomanian through early Turonian eustatic rise and deep-water opening of the South Atlantic. The flooding of continental seaways and margins also could have contributed to the anomalies by preventing much continental detritus from diluting the normal background marine geochemical component.
Year of Publication: 1993
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Ammonoidea; Atlantic Ocean; Beachy Head; C-13/C-12; Carbon; Caribbean Sea; Cenomanian; Central Europe; Cephalopoda; Chispa Summit; Chromium; Cobalt; Colombia; Cores; Cretaceous; DSDP Site 367; Deep Sea Drilling Project; Distribution; Eastbourne England; England; Europe; Eustasy; Extinction; Foraminifera; Geochemical anomalies; Gold; Great Britain; Indian Ocean; Invertebrata; Iridium; Isotopes; Leg 41; Lower Turonian; Manganese; Mesozoic; Metals; Microfossils; Mollusca; Neutron activation analysis data; Nickel; North America; North American Atlantic; North Atlantic; Ocean Drilling Program; Pacific Ocean; Paleo-oceanography; Platinum; Platinum group; Poland; Protista; Rare earths; Scandium; Sea-floor spreading; South America; Stable isotopes; Stratigraphic boundary; Stratigraphy; Tetrabranchiata; Texas; Titanium; Turonian; United Kingdom; United States; Upper Cenomanian; Upper Cretaceous; Vanadium; Western Europe; Western Interior
Coordinates: N122913 N122913 W0200250 W0200250
Record ID: 1993023054
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands