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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 67 (1983)

Issue: 8. (August)

First Page: 1355

Last Page: 1355

Title: Trace Fossils as Environment Indicators in the Rocky Mountains: ABSTRACT

Author(s): Betsy Shepard

Article Type: Meeting abstract


Ichnology is the study of the traces ancient organisms have left in or on the substrate. These traces, or lebensspuren, are in the form of tracks, burrows, trails, or borings, and are important clues in determining ancient rock environments.

Throughout time, organisms have left various types of traces while engaged in different activities. The two major types of lebensspuren were made by suspension feeders found in turbulent water where organic matter is held in suspension, and by deposit feeders whose habitat is found in quiet, deeper waters where large quantities of organic matter settle from suspension.

The different activities which occur in these two environments are the cause of the traces found in sediments. These include escape structures resulting from degradation or aggradation of sediments, feeding structures, dwelling structures, grazing traces, crawling traces, and resting traces.

The use of trace fossils in hydrocarbon exploration is especially helpful in the Cretaceous sandstones of the Rocky Mountains because of the relative abundance of outcrops and the scarcity of body fossils. By combining the interpretation of physical processes with the biological traces, one more tool is made available in the determination of rock environments as an aid in hydrocarbon exploration.

Materials exhibited include 8 × 10 color prints of different Cretaceous lebensspuren, hand-drawn "cartoons" of the six different trace activities, and a regional cross section of the Eagle sandstone illustrated by photographs of different traces near each location, as well as a variety of rock samples.

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