The influence of bioerosion on taphonomy - a case stuy using Nautilus macromphalus

Conference contribution


Publication Details

Author(s): Seuß B, Hembree DI, Wisshak M, Mapes RH
Publication year: 2017
Language: English


Abstract

Bioerosion, i.e., chemical and mechanical degradation of largely
carbonate skeletal material, was studied in detail in shells of Nautilus
for the first time. Nautilus typically lives along slopes of coral
reefs in water depths between 300-400 m, with a range of 100-700 m and
occurs in the Indo-Pacific Ocean exclusively. After death of the animal
its conch will either float (up to hundreds of km until it sinks or is
washed onto the beach) or it will rapidly sink to the seafloor close to
where Nautilus has lived and died. Two sets of N. macromphalus shells
from New Caledonia are included in this study: 1) Backshore collected
(from two beaches on Lifou (Loyalty Islands)) and 2) Deep-sea dredged
(395 m: halfway from Grand Terre and the Isle of Pines; 589 m: western
edge of the Lansdowne Bank west of Grand Terre). After preparing
synthetic resin casts these were analyzed with the SEM and ichnotaxa
were categorized semi-quantitatively in the plan view. In total, 30
ichnotaxa were identified, some of them are new. Seven ichnotaxa were
produced by cyanobacteria and five traces by chlorophytes. Further
traces were produced by sponges, fungi, foraminifers, and by
rhodophytes. Six traces were produced by some unknown heterotroph and
two have an unknown affinity so far. The 23 ichnotaxa occurring in the
backshore ichnocoenosis contain eleven traces that are produced by
phototrophic and ten by heterotrophic organisms; two forms are of
unknown origin. The 15 traces from the 395 m sample contain both, traces
of photoautotroph producers and those of heterotrophs. All of the eight
taxa recorded from 589 m water depth are of heterotrophic origin.
Interpretation of the results is largely based on the ichnobathymetrical
scheme combining the key ichnospecies and the mode of penetration: 1)
Backshore: Shallow euphotic zone III to the deep euphotic zone; key
ichnotaxa of the intertidal are present as well reflecting transport
from nearshore to backshore. 2) 398 m: Transport must have taken place
from the deep euphotic zone down into the aphotic zone. 3) 589 m: The
shell had rapidly sunk to the seafloor after death of the specimen into
aphotic conditions and had likely stayed close to the living site of the
animal.


FAU Authors / FAU Editors

Seuß, Barbara Dr.
Lehrstuhl für Paläoumwelt


How to cite

APA:
Seuß, B., Hembree, D.I., Wisshak, M., & Mapes, R.H. (2017). The influence of bioerosion on taphonomy - a case stuy using Nautilus macromphalus. In Proceedings of the GSA Annual meeting. Seattle, US.

MLA:
Seuß, Barbara, et al. "The influence of bioerosion on taphonomy - a case stuy using Nautilus macromphalus." Proceedings of the GSA Annual meeting, Seattle 2017.

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Last updated on 2019-22-07 at 07:22

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