Environmental Engineering Reference
In-Depth Information
Chapter 21
Deep-Sea Fans
Alfred Uchman * ,1 and Andreas Wetzel
*Institute of Geological Sciences, Jagiellonian University, Krako´w, Poland, Geologisch-
Pala¨ontologisches Institut der Universita¨t, Basel, Switzerland
1 Corresponding author: e-mail: alfred.uchman@uj.edu.pl
1. INTRODUCTION
Bioturbational structures and trace fossils are important components of turbi-
dites since late Cambrian to early Ordovician times, when endobenthic animals
began to colonize the deep-sea floor more intensively (e.g., Crimes and
Fedonkin, 1994 ). The variable but still poorly understood burrowing activity
in the abyssal habitat was and is influenced by many environmental factors,
such as pore water oxygenation, trophic level, and sediment properties.
Research into deep-sea ichnology developed more slowly than work in
shallow-water settings, because of a general lack of knowledge about the
deep-sea environments until the 1950s. In the nineteenth century, trace fossils
occurring in deep-marine deposits were often described as algae (fucoids)
without any recognition of their true origin (e.g., Heer, 1876/1877;
von Fischer-Ooster, 1858 ). Once the true nature of trace fossils had been
recognized ( Nathorst, 1881 ), they were increasingly studied ( Abel, 1935;
Richter, 1928; Seilacher, 1953, 1955 ; see Uchman, 2007a , for partial review).
The potential use of bioturbational structures as ecological indicators dramat-
ically increased with the study of modern environments about 50 years ago.
In the following, an overview is given of the ichnology of deep-marine
settings that are considerably affected by turbidite deposition, and a state-of-
the-art compilation is provided regarding the interpretation of the main trace-
fossil groups. Additionally, some ichnological processes and phenomena in
the deep sea are illustrated by some examples.
2. CLASSIFICATION OF DEEP-SEA TRACE FOSSILS
In the fossil record, two main behavioral and, hence, often variably preserved
groups of trace fossils can be distinguished with respect to the time of sedimen-
tation of the bed in which they occur. Trace fossils that are produced on or very
close to the sediment surface become preserved only when they are partly
 
 
 
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