Constraints on the amplitude of Mid-Pliocene (3.6–2.4 Ma) eustatic sea-level fluctuations from the New Zealand shallow-marine sediment record

Abstract

Ice-volume calibrations of the deep-ocean foraminiferal d18 O record imply orbitally influenced sea-level fluctuations of up to 30 m amplitude during the Mid-Pliocene, and up to 30 per cent loss of the present-day mass of the East Antarctic Ice Sheet (EAIS) assuming complete deglaciation of the West Antarctic Ice Sheet (WAIS) and Greenland. These sea-level oscillations have driven recurrent transgressions and regressions across the world's continental shelves. Wanganui Basin, New Zealand, contains the most complete shallow-marine Late Neogene stratigraphic record in the form of a continuous cyclostratigraphy representing every 41 and 100 ka sea-level cycle since ca 3.6 Ma. This paper presents a synthesis of faunally derived palaeobathymetric data for shallow-marine sedimentary cycles corresponding to marine isotope stages M2-100 (ca 3.4-2.4 Ma). Our approach estimates the eustatic sea-level contribution to the palaeobathymetry curve by placing constraints on total subsidence and decompacted sediment accumulation. The sea-level estimates are consistent with those from d18 O curves and numerical ice sheet models, and imply a significant sensitivity of the WAIS and the coastal margins of the EAIS to orbital oscillations in insolation during the Mid-Pliocene period of relative global warmth. Sea-level oscillations of 10-30 m were paced by obliquity.

Antarctic bedrock topography uncertainty and ice sheet stability

“…The simulated retreat is equivalent to a sea level rise of 12.6-17.9 m, in an ice sheet model with mechanisms for ice shelf hydrofracturing and ice cliff failure after 3 kyrs of forcing. If the Greenland ice sheet also completely melted during the mid-Pliocene, this would create a total sea level rise of 20.0-25.3 m, which is comparable to some estimates of the Pliocene sea level highstand [e.g., Naish and Wilson, 2009;Miller et al, 2012]. This model sensitivity is also relevant to long-term simulations of a future warm climate.…”

Biogeography and conservation in Southeast Asia: how 2.7 million years of repeated environmental fluctuations affect today’s patterns and the future of the remaining refugial-phase biodiversity

“…During the first half of the Tertiary, when sea levels were higher than today's, the Thai-Malay peninsula comprised an island chain with water gaps separating the pre-Tertiary mountains of continental Asia from those in peninsula Malaysia, Sumatra and Borneo. During much of the Miocene (23-5.3 Ma) and Pliocene (5.3-2.6 Ma) conditions were hot (3°C warmer), perhumid (wetter than today and covered with rainforest), and sea levels were higher (C25 m relative to today's level) Naish and Wilson 2009). Air temperatures began to decline 3.2 Ma and the Northern Hemisphere continental ice sheets began to form 2.7 Ma.…”

Neotectonics of mainland Portugal: state of the art and future perspectives

“…Worldwide data of Quaternary sea-level changes have been combined to build eustatic sea-level curves that can be used as references for research studies (e.g. Shackleton et al, 1984;Haq et al, 1987;Dowsett and Cronin, 1990;Naish and Wilson, 2009;Raymo et al, 2011, for the late Pliocene-early Pleistocene sea-level, and Shackleton and Opdyke, 1973;Bloom et al, 1974;Chappell, 1974;Bender et al, 1979;Bloom, 1980;Chappell and Shackleton, 1986;Siddall et al, 2006, among others, for the Pleistocene eustatic sealevel curves).…”