Abstract: Documentation of Cretaceous Depositional Cycles by Graphic Correlation

R. W. Scott, R. W. Aurisano, J. A. Bergen, M. A. Evetts, B. A. Masters, F. X. Miller, J. A. Stein, R. J. White

The widespread acceptance of global Mesozoic and Cenozoic cycles of coastal onlap and eustatic change is a major synthesis in stratigraphy. It has promoted research about the timing, amplitude and causes of relative changes in sea level. The concept of depositional cycles avoids the question of cause by emphasizing the two-dimensional facies succession of deepening-shoaling and the displacement of shore line relative to the continental margin.

Consistent recognition of timing of depositional cycles requires a methodology that generates an internally consistent and globally identifiable time scale. The quantitative technique of graphic correlation provides a high-precision scale based upon the maximum known ranges of diverse sets of taxa. This scale can be readily converted to any of the time scales by the precise placement of stadial boundary stratotypes in the composite standard data base.

Depositional cycles defined and correlated from upon the shelf into the basin and correlated precisely between basins on separate tectonic plates provide the basis of recognizing globally synchronous events. Cycle boundaries are consistently identified within the Valanginian, within the Hauterivian, in the latest early Aptian, within the early Albian, at the early-medial Albian contact, in the early part of the late Albian, at the Albian-Cenomanian contact, at the early-medial Cenomanian contact, within the latest Cenomanian, within the late medial Turonian, in the earliest Coniacian, at the Coniacian-Santonian contact, at the Santonian-Campanian contact, at the Campanian-Maastrichtian contact, and within the Maastrichtian. Shorter-term, 1-2 Ma cycles can be consistently recognized wi hin some cycles, and Milankovitch-scale cycles are recorded in many depositional settings. Additional cycles may be proven to be globally synchronous by future work.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994