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Strontium isotope stratigraphy was used to date 5 discrete horizons within the CRP-3 drillhole. A single in situ modiolid bivalve fragment at 10.88 mbsf gives an age of 30.9 (±0.8) Ma for the associated sediment. The four remaining well preserved fragments recovered from 29.94-190.31 mbsf are within error of this age, indicating a high sedimentation rate and suggesting little time is missing in disconformities. The diagenetic alteration of carbonate macrofossils by continental fluids (and possibly seawater) is a common feature to 320 mbsf.

Stable isotope analyses of marine bivalve growth increment samples have been used to estimate early Oligocene (29.4 - 31.2) Ma and early Miocene (24.0 Ma) seafloor palaeotemperatures from the southwestern continental margin of the Ross Sea. Measured d18O values average +2.5‰ in the early Miocene and range between +1.26 to +3.24‰ in the early Oligocene. The results show that palaeoceanographic conditions in McMurdo Sound during the mid-Cenozoic were significantly different from those of today. The minimum estimated spring through late summer seasonal temperature range was 3°C during the early Miocene and between 1 and 5°C during the early Oligocene. This compares to the equivalent modern day range of <0.5°C within the sound. Absolute seawater temperatures at <100 m depth were of the order of 5 to 7°C during both time slices, compared to modern day values of -1.4 to -1.9°C in the same area. The results are in broad agreement with early Oligocene Mg/Ca temperature estimates from deep Atlantic foraminifera as well as estimates from local terrestrial palynology and palaeobotany.

Strontium isotope stratigraphy was used to date 5 discrete horizons within the CRP-3 drillhole. A single in situ modiolid bivalve fragment at 10.88 mbsf gives an age of 30.9 (±0.8) Ma for the associated sediment. The four remaining well preserved fragments recovered from 29.94-190.31 mbsf are within error of this age, indicating a high sedimentation rate and suggesting little time is missing in disconformities. The diagenetic alteration of carbonate macrofossils by continental fluids (and possibly seawater) is a common feature to 320 mbsf.

Stable isotope analyses of marine bivalve growth increment samples have been used to estimate early Oligocene (29.4 - 31.2) Ma and early Miocene (24.0 Ma) seafloor palaeotemperatures from the southwestern continental margin of the Ross Sea. Measured d18O values average +2.5‰ in the early Miocene and range between +1.26 to +3.24‰ in the early Oligocene. The results show that palaeoceanographic conditions in McMurdo Sound during the mid-Cenozoic were significantly different from those of today. The minimum estimated spring through late summer seasonal temperature range was 3°C during the early Miocene and between 1 and 5°C during the early Oligocene. This compares to the equivalent modern day range of <0.5°C within the sound. Absolute seawater temperatures at <100 m depth were of the order of 5 to 7°C during both time slices, compared to modern day values of -1.4 to -1.9°C in the same area. The results are in broad agreement with early Oligocene Mg/Ca temperature estimates from deep Atlantic foraminifera as well as estimates from local terrestrial palynology and palaeobotany.

Gravel-free, high-resolution (1-metre spacing, 32 channel) particle size data from the CRP-2/2A drill core indicate that many of the diamictites were likely deposited from floating ice. Textural dislocations occur at most sequence boundaries and provide independent corroboration of the sequence stratigraphic interpretation. Likewise the data largely support the correlation drawn (Fielding et al., this volume) between the sequence stratigraphic cycles and the regional seismic stratigraphy (an alternative correlation to Reflector ‘f’ is also suggested). The gravel-free data appear to be reflecting predominantly regional (global?) forcing with some possible local effects, and long-term trends persisting through gravelly textural dislocations.

Strontium isotope stratigraphy was used to date 16 discrete horizons within the CRP-2/2A drillhole. Reworked Quaternary (<1.7 Ma) and possible Pliocene (<2.4 Ma) sediments overlie a major sequence boundary at 25.92 metres below sea floor (mbsf). This hiatus is estimated to account for c. 16 Myr of missing section. Early Miocene to ?earliest Oligocene (c. 18.6 to >31 Ma) deposits below this boundary were cut by multiple erosion surfaces of uncertain duration. Strontium isotope ages are combined with 40Ar/39Ar dates, diatom and calcareous nannofossil datums and a palaeomagnetic polarity zonation, to produce an age model for the core.

Strontium isotope stratigraphy was used to date 16 discrete horizons within the CRP-2/2A drillhole. Reworked Quaternary (<1.7 Ma) and possible Pliocene (<2.4 Ma) sediments overlie a major sequence boundary at 25.92 metres below sea floor (mbsf). This hiatus is estimated to account for c. 16 Myr of missing section. Early Miocene to ?earliest Oligocene (c. 18.6 to >31 Ma) deposits below this boundary were cut by multiple erosion surfaces of uncertain duration. Strontium isotope ages are combined with 40Ar/39Ar dates, diatom and calcareous nannofossil datums and a palaeomagnetic polarity zonation, to produce an age model for the core.

Strontium isotope stratigraphy was used to date five discrete horizons within CRP- 1. Early and late Quaternary (0 87- 1 3 Ma and 0-0 67 Ma respectively) age sediments overlie a major sequence boundary at 43.15 meters below sea floor (mbsf) This hiatus is estimated to account for -16 m y of missing section. Early Miocene (16 6-20 8-25 Ma) age deposits below this boundary are in turn cut by multiple erosion surfaces representing hiatuses of between 0.2 and 1.2 m.y. Estimated minimum sedimentation rates range between 0.9 and 2.8 cm/k.y. in the Quaternary, and 1.5 and 6.4 cm/k.y. in the lower Miocene.

Vertical facies associations within the CRP- 1 drillcorc reveal a strong cyclicity and facilitate the development of a sequence stratigraphic framework. The sedimentary record appears to be punctuated by a series of erosional sequence boundaries which are here inferred to be the product of cycles of glacial advance and retreat. This is further supported by the absence of thick (preglacial) progradational sequences within the drill core. Eight Miocene and at least two Quaternary sequences are identified on the basis of facies and textural association. The core is dominated by transgressive (local glacial retreat) and high stand (local glacial minimum) deposits, with regressive (local glacial advance) and lowstand (local glacial maximum) events being under represented.

Strontium isotope stratigraphy was used to date five discrete horizons within CRP- 1. Early and late Quaternary (0 87- 1 3 Ma and 0-0 67 Ma respectively) age sediments overlie a major sequence boundary at 43.15 meters below sea floor (mbsf) This hiatus is estimated to account for -16 m y of missing section. Early Miocene (16 6-20 8-25 Ma) age deposits below this boundary are in turn cut by multiple erosion surfaces representing hiatuses of between 0.2 and 1.2 m.y. Estimated minimum sedimentation rates range between 0.9 and 2.8 cm/k.y. in the Quaternary, and 1.5 and 6.4 cm/k.y. in the lower Miocene.

Vertical facies associations within the CRP- 1 drillcorc reveal a strong cyclicity and facilitate the development of a sequence stratigraphic framework. The sedimentary record appears to be punctuated by a series of erosional sequence boundaries which are here inferred to be the product of cycles of glacial advance and retreat. This is further supported by the absence of thick (preglacial) progradational sequences within the drill core. Eight Miocene and at least two Quaternary sequences are identified on the basis of facies and textural association. The core is dominated by transgressive (local glacial retreat) and high stand (local glacial minimum) deposits, with regressive (local glacial advance) and lowstand (local glacial maximum) events being under represented.