Title Timing and magnitude of Miocene eustasy derived from the mixed siliciclastic- carbonate stratigraphic record of the northeastern Australian margin
Author John, C.M.; Karner, G.D.; Browning, E.; Leckie, R.M.; Mateo, Z.; Carson, B.; Lowery, C.
Author Affil John, C.M., Imperial College London, Department of Earth Science and Engineering, London, United Kingdom. Other: ExxonMobil Upstream Research Company; University of Massachusetts at Amherst; Integrated Ocean Drilling Program; Chevron Corporation
Source Earth and Planetary Science Letters, 304(3-4), p.455-467. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012- 821X
Publication Date Apr. 15, 2011
Notes In English. Supplementary data available in online version. 60 refs. GeoRef Acc. No: 308666
Index Terms Australia; Antarctica--East Antarctic ice sheet; Coral Sea--Marion Plateau; Ocean Drilling Program--ODP Site 1192; Ocean Drilling Program--ODP Site 1193; Ocean Drilling Program--ODP Site 1194; Ocean Drilling Program--ODP Site 1195; aggradation; Antarctic ice sheet; Antarctica; Australasia; backstripping; biostratigraphy; carbonate platforms; carbonate ramps; carbonate rocks; Cenozoic; continental margin sedimentation; Coral Sea; cores; correlation; East Antarctic ice sheet; eustacy; isotope ratios; isotopes; Leg 194; Marion Plateau; middle Miocene; Miocene; Neogene; northeastern Australia; O- 18/O-16; Ocean Drilling Program; ODP Site 1192; ODP Site 1193; ODP Site 1194; ODP Site 1195; oxygen; Pacific Ocean; progradation; sea-level changes; sedimentary rocks; sedimentation; sequence stratigraphy; siliciclastics; South Pacific; Southwest Pacific; stable isotopes; Tertiary; West Pacific
Abstract Eustasy is a key parameter to understand sedimentary sequences on continental margins and to reconstruct continental ice volume in the Cenozoic, but timing and magnitude of global sea level changes remain controversial, especially for the Miocene Epoch. We analyzed sediment cores recovered from the Marion Plateau, offshore northeastern Australia, during Ocean Drilling Program (ODP) Leg 194 to define the mechanisms and timing of sequence formation on mixed carbonate-siliciclastic margins, and to estimate the amplitude of Miocene eustatic adjustments. We identified sequence boundaries on seismic reflection lines, significantly revised the existing biostratigraphic age models, and investigated the sedimentary response to sea-level changes across the Marion Plateau. We subdivided the Miocene sediments into three sequence sets comprising a set of prograding clinoforms, a muddy prograding carbonate ramp evolving into an aggrading platform, and a lowstand ramp evolving into a backstepping ramp. We recognized eight individual sequences dated at 18.0 Ma, 17.2 Ma, 16.5 Ma, 15.4 Ma, 14.7 Ma, 13.9 Ma, 13.0 Ma, and 11.9 Ma. We demonstrate that sequences on the Marion Plateau are controlled by glacio-eustasy since sequence boundaries are marked by increases in delta 18O (deep-sea Miocene isotope events Mi1b, Mbi-3, Mi2, Mi2a, Mi3a, Mi3, Mi4, and Mi5, respectively), which reflects increased ice volume primarily on Antarctica. Our backstripping estimates suggest that sea-level fell by 26-28 m at 16.5 Ma, 26-29 m at 15.4 Ma, 29-38 m at 14.7 Ma, and 53-81 m at 13.9 Ma. Combining backstripping with delta 18O estimates yields sea-level fall amplitudes of 271 m at 16.5 Ma, 271 m at 15.4 Ma, 333 m at 14.7 Ma, and 596 m at 13.9Ma. We use a similar approach to estimate eustatic rises of 191 m between 16.5 and 15.4 Ma, 233 m between 15.4 and 14.7 Ma, and 333 m between 14.7 and 13.9 Ma. These estimates can be combined into a eustatic curve that suggests that sea-level fell by 53-69 m between 16.5 and 13.9 Ma. This implies that at least 90% of the East Antarctic Icesheet was formed during the middle Miocene. The new independent amplitude estimates are crucial as the Miocene is the geologic Epoch for which the New Jersey margin sea-level record is poorly constrained.
URL http://hdl.handle.net/10.1016/j.epsl.2011.02.013
Publication Type journal article
Record ID 91059