Teredinid-bored Araucariaceae logs preserved in shoreface sediments, Wangaloa Formation (Paleocene), Otago, New Zealand

Abstract

Bored, calcite-cemented, and partly carbonised Araucariaceae logs (?Agathis sp.) occur within a concretionary shellbed in Wangaloa Formation shallow marine sandstone exposed near Mitchells Rocks, southeast Otago. Dense concentrations of carbonate-lined and sand-infilled teredinid tubes occur in the sapwood of four logs.

Conspicuous sedimentation features such as shell lags, truncated and reworked Ophiomorpha burrows, and low-angle hummocky and swaley crossstratification exposed in strata at Mitchells Rocks, indicate shoreface or storm deposition close to fairweather wave base. The logs probably endured only a brief period of sea-floor exposure and decay before final burial and cementation.

Keywords:

• ichnofossils
• Teredinidae
• Ophiomorpha
• shoreface sediments
• storm deposits
• cementation
• diagenesis
• concretions
• Wangaloa Formation
• Mitchells Rocks
• Otago
• Teurian Stage
• Paleocene