CONCLUSIONS

  1. Neogene planktonic foraminifers in sediments from the Great Australian Bight are dominated by southern temperate species, with abundant G. woodi in the early Miocene, G. trilobus and G. conoidea in the middle and late Miocene, and G. crassaformis and Globoconella puncticulata in the Pliocene.
  2. Warm subtropical species are rare, and they are mainly confined to the later early Miocene and younger intervals; their high abundance especially during the latest early to early middle Miocene indicates climatic warming and a vigorous flow of the Leeuwin Current from the northwest during the Miocene climatic optimum.
  3. New planktonic foraminiferal Zones SAN1 to SAN25 were proposed for refining the southern Australian Neogene. They can be recognized on first or last occurrence datum levels of marker species that have been widely used in the region. These datums also provide the base for correlating the SAN zones with other zonation schemes, especially the standard N zones from the tropics and subtropics (Fig. F2).
  4. All Neogene sections in Holes 1126B and 1126C, 1128B and 1128C, 1130A and 1130B, 1132B, and 1134A and 1134B are bounded by hiatuses of ~0.5 to >3 m.y. in duration. The longer gaps in Holes 1128B and 1128C and 1130A and 1130B eradicated a record of >20 and ~16 m.y., respectively.
  5. Most slumps coincide with hiatuses, and their concentration in the late Miocene and Pliocene indicates region-wide slope failure at times of low sea level and/or intense tectonic activities.
  6. Fifteen hiatuses represent 15 synchronous erosional events from the base of the Miocene to the lower part of the Pleistocene. These are local manifestations of major third-order boundaries at about (1) 23.8, (2) 22.3, (3) 20.5, (4) 18.7, (5) 16.4, (6) 14.8, (7) 13.5, (8) 11.5, (9) 9.3, (10) 7.0, (11) 6.0, (12) 4.5, (13) 3.5, (14) 2.5, and (15) 1.5 Ma, respectively (Fig. F12).
  7. The Neogene succession from the Great Australian Bight samples the regional transgressions and stages that were defined previously on the neritic record. An onshore and offshore correlation helps understand better the evolution of southern Australian margin during the Neogene.

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