δ18O and Marion Plateau backstripping; combining two approaches to constrain late middle Miocene eustatic amplitude

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doi: 10.1130/G20580.1
Author(s): John, Cédric M.; Karner, Garry D.; Mutti, Maria
Author Affiliation(s): Primary:
Universität Potsdam, Institut für Geowissenschaften, Potsdam, Federal Republic of Germany
Other:
Lamont-Doherty Earth Observatory, United States
Volume Title: Geology (Boulder)
Source: Geology (Boulder), 32(9), p.829-832. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613 CODEN: GLGYBA
Note: In English. 22 refs.; illus., incl. sects., sketch map
Summary: δ18Obenthic values from Leg 194 Ocean Drilling Program Sites 1192 and 1195 (drilled on the Marion Plateau) were combined with deep-sea values to reconstruct the magnitude range of the late middle Miocene sea-level fall (13.6-11.4 Ma). In parallel, an estimate for the late middle Miocene sea-level fall was calculated from the stratigraphic relationship identified during Leg 194 and the structural relief of carbonate platforms that form the Marion Plateau. Corrections for thermal subsidence induced by Late Cretaceous rifting, flexural sediment loading, and sediment compaction were taken into account. The response of the lithosphere to sediment loading was considered for a range of effective elastic thicknesses (10<Te<40 km). By overlapping the sea-level range of both the deep-sea isotopes and the results from the backstripping analysis, we demonstrate that the amplitude of the late middle Miocene sea-level fall was 45-68 m (56.5±11.5 m). Including an estimate for sea-level variation using the δ18Obenthic results from the subtropical Marion Plateau, the range of sea-level fall is tightly constrained between 45 and 55 m (50.0±5.0 m). This result is the first precise quantitative estimate for the amplitude of the late middle Miocene eustatic fall that sidesteps the errors inherent in using benthic foraminifera assemblages to predict paleo-water depth. The estimate also includes an error analysis for the flexural response of the lithosphere to both water and sediment loads. Our result implies that the extent of ice buildup in the Miocene was larger than previously estimated, and conversely that the amount of cooling associated with this event was less important.
Year of Publication: 2004
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Ancient ice ages; Anomalinidae; Australasia; Australia; Backstripping; Benthic taxa; Biochemistry; Carbonate platforms; Cassidulinacea; Cenozoic; Cibicidoides; Coral Sea; Deep-sea environment; Eustasy; Flexure; Foraminifera; Geochemistry; Geophysical methods; Geophysical profiles; Geophysical surveys; Glacial environment; Glaciomarine environment; Invertebrata; Isotope ratios; Isotopes; Leg 194; Lithosphere; Loading; Marine environment; Marion Plateau; Mechanical properties; Microfossils; Middle Miocene; Miocene; Neogene; O-18/O-16; ODP Site 1192; ODP Site 1193; ODP Site 1194; ODP Site 1195; Ocean Drilling Program; Oceanic lithosphere; Oxygen; Pacific Ocean; Paleobathymetry; Paleoecology; Plateaus; Protista; Queensland Australia; Reflection methods; Rotaliina; Sea-level changes; Seismic methods; Seismic profiles; South Pacific; Southwest Pacific; Stable isotopes; Surveys; Tertiary; West Pacific
Coordinates: S203500 S203400 E1522500 E1522400
S201500 S201400 E1514800 E1514700
S201500 S201400 E1515900 E1515800
S202500 S202400 E1524100 E1524000
Record ID: 2004070980
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States