How to translate text using browser tools
1 December 2006 Implication of spatiotemporal distribution of black shales deposited during the Cretaceous Oceanic Anoxic Event-2
Author Affiliations +

Oceanic Anoxic Events (OAEs) mark the contemporaneous deposition of organic-rich marine sediments termed “black shales” in the wide areas of the oceans. An anoxic event that occurred at the Cenomanian-Turonian boundary, OAE-2, has been recognized as one of the largest events in the Cretaceous. Carbon isotopic compositions (δ13C) of sedimentary carbonate and organic matter exhibit a positive excursion across the OAE-2, reflecting an enhanced burial rate of 13C-depleted organic carbon during the event. Here we compile a spatiotemporal distribution of black shales on the basis of their onset timings relative to the δ13C excursion as a time-control reference, and discuss the “spreading patterns” of black shale deposition. The patterns suggest that the deposition of black shales started from marginal regions of the southern North Atlantic and the Western Interior Seaway in North America, and spread to the northern North Atlantic and Tethys Sea. Strangely, the black shales whose onset corresponds to that of the δ13C excursion have not been found in many locations. Furthermore, extensive deposition of black shales in the Tethys and some sites in the North Atlantic occurred significantly after the major shift of the δ13C excursion. Sediments in the largely unexplored Pacific basin may be the missing link in the temporal relationship between the black shale deposition and the isotopic excursion.

JUNICHIRO KURODA and NAOHIKO OHKOUCHI "Implication of spatiotemporal distribution of black shales deposited during the Cretaceous Oceanic Anoxic Event-2," Paleontological Research 10(4), 345-358, (1 December 2006).
Received: 28 April 2006; Accepted: 1 August 2006; Published: 1 December 2006
black shale
carbon isotopic excursion
Cenomanian-Turonian boundary
Oceanic Anoxic Event
Get copyright permission
Back to Top