Abstract

Three general types of composite ichnofabric can be distinguished based on mechanisms responsible for trace-fossil overprinting, number of ichnocoenoses present, and relative timing of ichnocoenosis emplacement. Autocomposite ichnofabrics, which comprise a single ichnocoenosis, form by gradual upward migration of vertically partitioned benthic communities in pace with sedimentation; because they are presumed to reflect paleoenvironmental stasis, they are most useful in assessing aspects of benthic paleoecology (e.g., endobenthic tiering). Heterocomposite ichnofabrics comprise two or more ichnocoenoses produced in response to short- to long-term environmental perturbations within a depositional system; they reflect depositional process (e.g., event sedimentation) and longer-term paleoenvironmental dynamics. Ultracomposite ichnofabrics form by overprinting of ichnocoenoses that are significantly temporally disjunct and reflect bioturbation in disparate depositional systems. Although the latter ichnofabrics are comparatively rare, their recognition is vital for paleoichnologic studies, particularly those that target surface exposures upon which there may be a modern biogenic overprint.

You do not currently have access to this article.