Schlager, Wolfgang¹ 
(1) Vrije Universiteit, Amsterdam, Netherlands

ABSTRACT: Fractal View of Sequence Stratigraphy

The succession of stratigraphic sequences is traditionally viewed as a hierarchy of orders, defined by duration but also characterized by a specific depositional architecture. I propose that stratigraphic sequences are better described by scale-invariant fractals. This "fractal model" pertains to the time range of (at least) 10³ – 10⁶ yr, where sequence stratigraphy is mainly applied, and rests on four principal arguments: 
(1) Surveys of published data show that estimated or assumed duration of orders vary widely, sometimes even within one study. 
(2) Detailed studies on surfaces in carbonate rocks indicate that units bounded by exposure surfaces (standard sequences) and units bounded by flooding surfaces (parasequences) are about equally likely among sequences of 10³ – 10⁶ yr duration. 
(3) Extensive published data on sea-level fluctuations and sedimentation rates, two principal controls on sequence architecture, revealed that both are fractals over more than 10 orders of magnitude in time. 
(4) Migration paths of shelf edges of depositional systems that prograde and step up and down under the influence of fluctuating sea level are fractals in a certain range of spatial scales. 
The proposed model treats sequences and systems tracts as universal patterns that are scale-invariant fractals in the time range of (at least) 10³ – 10⁶ yr. It assumes that the parasequence pattern of units bounded by flooding surfaces, and the standard sequence pattern of units bounded by exposure surfaces are both common in this time range.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.