Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Part A. Integrated Mesozoic biochronology and magnetochronology. Part B. Studies of Cretaceous black shales

Thesis/Dissertation ·
OSTI ID:6449007
In Part A, an integrated Mesozoic timescale has been constructed combining the biochronology of numerous fossil groups and magnetochronology. The nannofossil biostratigraphy of numerous European and DSDP sections with magnetostratigraphic control has been investigated and the results enable direct biostratigraphic correlation of Chrons CMO to CM22. In most cases nannofossil stratigraphy resembles previously proposed zonations. A new, higher resolutions nannofossil biostratigraphy is proposed for the Jurassic-Cretaceous boundary interval consisting of six zones, eleven subzones and 48 biohorizons in an interval previously divided into six zones. Part B concerns the paleoceanography, biostratigraphy and geochemistry of Middle Cretaceous black shale. Transition metal accumulation rates have been estimated for Aptian-Cenomanian DSDP intervals and are higher than in most Holocene environments. Possible reasons for these high rates include hydrothermal input, precipitation of metal sulfides in a euxinic water column or diagenetic enrichment. The nannofossil biostratigraphy of Cenomanian-Turonian boundary sequences has been studied and a higher resolution zonation proposed. This zonation is used to compare lithologic variability, the timing of black shale deposition and of carbon isotopic excursions in different sequences. Nannofossil assemblages and preservation change markedly in the Cenomanian-Turonian boundary interval.
Research Organization:
California Univ., San Diego (USA)
OSTI ID:
6449007
Country of Publication:
United States
Language:
English