Pliocene and early Pleistocene planktic foraminifera : important taxa and bioevents in ODP Hole 1123B, Chatham Rise, New Zealand

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Crundwell, M.P. 2015 Pliocene and early Pleistocene planktic foraminifera : important taxa and bioevents in ODP Hole 1123B, Chatham Rise, New Zealand. Lower Hutt, N.Z.: GNS Science. GNS Science report 2015/51 70 p.

Abstract: ODP Site 1123 has one of the most complete sequences of Pliocene to early Pleistocene calcareous biogenic sediments that has so far been recovered in the temperate Southwest Pacific. The sequence of planktic foraminiferal taxa and bioevents closely matches the one in DSDP Site 284 and allows a good correlation between these oceanic sequences and the New Zealand timescale. A total of 37 planktic foraminiferal bioevents and 1 calcareous nannofossil event were identified in Site 1123 and of these, 21 are shared by Site 284 and all but two maintain homotaxy. A number of bioevents in the Waipipian section of Site 1123 are missing in Site 284, whereas other shared bioevents occur at the same stratigraphic level in Site 284, alluding to the possibility that most of the Waipipian is missing at a hiatus in Site 284, with an estimated duration of 0.5 Myr to 0.7 Myr. Five new taxa are described: . Lower Hutt, N.Z.: GNS Science. Globoconella puncticuloides subsp. A (vaulted) and subsp. B (compressed), . Lower Hutt, N.Z.: GNS Science. Truncorotalia aff. . Lower Hutt, N.Z.: GNS Science. crassaconica, . Lower Hutt, N.Z.: GNS Science. Truncorotalia cf. . Lower Hutt, N.Z.: GNS Science. crassula (ventroconical), and . Lower Hutt, N.Z.: GNS Science. Truncorotalia sp. A (pyramidalis). The latter species is provisionally included in the genus Truncorotalia, but its broad arched aperture distinguishes it from typical truncorotalids and this is perhaps justification for it being included in a new genus. It is restricted to the Opoitian, and based on morphological similarities, it appears to be the ancestral form from which . Lower Hutt, N.Z.: GNS Science. Truncorotalia triangula (formerly . Lower Hutt, N.Z.: GNS Science. Globorotalia inflata triangula) evolved in the Waipipian. The proposed phylogenetic relationship between these taxa has major implications for the generic composition of Pliocene and early Pleistocene faunas and the history of planktic foraminiferal evolution in the temperate Southwest Pacific. (auth)