Abstract:
Quaternary sediment deposits of the Eastern coast of Sri Lanka were studied for the first
time to understand the taphonomy of tube burrows and the impact of structure and
mineralogy of the wall on the preservation of burrows, was interpreted. Photography
and interpretations were made and described during the field observations on exposed
trace fossils. Fine structures were identified using Scanning electron microscopy with
energy dispersive x-ray spectroscopy. Simple vertical tube burrows were observed in a
fine to medium sandy sediment bed which was above 4 m from the present mean sea
level. The average diameter of the tubes was about 1 cm and the recorded maximum
length was about 20 cm. Specimens are significant with circular color rims around the
central holes. The internal wall of the tube was ornamented by microscopic
honeycomb-like sclerite and fecal material secreted by the burrower and rich in iron
oxide and clay minerals. Microbial activities on the wall have enhanced the early
consolidation of the sediments of shallow marine environments, leading to filming
cuticular organic matter, pyritization and aluminosilicatization processes. The
environmental change from reducing to fully oxidizing conditions has strengthened the
tubes commonly rimmed by iron oxides.
