The nature of the sequence boundary between the Normanville and Kanmantoo Groups on Fleurieu Peninsula, South Australia

The late Early to Middle Cambrian Kanmantoo Group is a very thick succession of fine to medium‐grained clastic sedimentary rocks with minor conglomerate and carbonate that outcrops in the Mt Lofty Ranges, Fleurieu Peninsula and Kangaroo Island region of South Australia. The Kanmantoo Group represents the youngest succession within the southern part of the major Late Precambrian to Cambrian sedimentary basin known as the Adelaide Geosyncline. The basal unit of the Kanmantoo Group, the Carrickalinga Head Formation rests unconformably on the underlying Normanville Group rocks, with an erosional surface with a relief of over 300 m. It is thought that the erosional surface at the base of the Kanmantoo Group represents a Type 1 sequence boundary and is the first sequence boundary to be documented in detail from the Cambrian rocks of the southern Adelaide Geosyncline. It is suggested that the top of the lowest sequence of the Kanmantoo Group is at the top of the Backstairs Passage Formation rather than the bottom as previously proposed.

Key words:

• Cambrian
• Kanmantoo Group
• Normanville Group
• sequence stratigraphy
• South Australia