Integrated biostratigraphy of Cretaceous-Paleogene strata on Campbell Island, southwest Pacific

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Hollis, C.J.; Beu, A.G.; Raine, J.I.; Strong, C.P.; Turnbull, I.M.; Waghorn, D.B.; Wilson, G.J. 1997 Integrated biostratigraphy of Cretaceous-Paleogene strata on Campbell Island, southwest Pacific. Lower Hutt: Institute of Geological & Nuclear Sciences. Institute of Geological & Nuclear Sciences science report 97/25 47 p.

Abstract: At 52 degrees South, Campbell Island provides the southernmost exposures of Cretaceous and Paleogene strata in the Pacific Ocean. As such, these exposures provide a valuable stratigraphic link between mainland New Zealand and drill cores in the Pacific sector of the Antarctic Ocean. However, it has not been possible to undertake detailed biostratigraphic sampling of the sequence. This report links together a series of paleontological collections made in course of general mapping over the last fifty years with two collections recently undertaken at the request of the authors of the report. The results presented significantly upgrade the biostratigraphy of the Cretaceous-Paleogene sequence but they also highlight significant gaps in knowledge which will only be removed by a detailed stratigraphic sampling programme. The Campbell Island Cretaceous-Paleogene sequence comprises two formations - Garden Cove and Tucker Cove formations - which are overlain by the Pliocene Shoal Point Formation. Garden Cove Formation is a 30-100 m-thick fining-upwards sequence of conglomerate, sandstone and mudstone. The sediments are perhaps nonmarine in the lower part but mainly marginal to fully marine and contain abundant and often well-preserved miospores and dinoflagellates. Agglutinated foraminifera and rare radiolarians occur in the uppermost unit. The Formation ranges in age from latest Cretaceous (late Haumurian) to early Paleocene (early-mid Teurian) and may include a near-complete Cretaceous-Tertiary boundary. The Tucker Formation is a 100-200 m-thick micritic limestone sequence with a thin sand- and glauconite-rich basal interval and several nodular chert horizons. The basal unit is of early Eocene (Mangaorapan) age and contains rare miospores, common dinoflagellates, calcareous nannofossils, foraminifera and radiolarians. The same microfossils occur in varying abundance in the upper part of the formation and indicate an age range of early Eocene to Oligocene (Mangaorapan to Landon series). An angular unconformity observed in the sea cliffs of Northwest Bay is of middle Eocene age (rather than late Eocene as was initially reported by Beggs [1978]) and may not represent a major time gap; it separates Porangan and Bortonian strata. It is likely that a middle Eocene to Oligocene succession is preserved on Campbell Island although we have not been able to locate a stratigraphic section between Late Eocene and Oligocene strata; late Eocene strata have been identified only in Tucker Cove (Perseverance harbour) while Oligocene strata have been identified only in the western part of the island (Penguin Bay, Rocky Bay). (auth)