West Antarctic Ice Sheet grounding events on the Ross Sea outer continental shelf during the middle Miocene

Chow, J. M.; Bart, Philip J.

doi:10.1016/s0031-0182(03)00400-0

Cited by 55 publications

(31 citation statements)

References 28 publications

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“…Adopting the ages of the seismostratigraphic units and unconformities on the Ross Sea shelf, which are relatively well constrained by DSDP Leg 28 and ANDRILL records (e.g., De Santis et al, 1999;McKay et al, 2009), the shelf basin formation model (Figure F5) for the ASE shows the development from a Cretaceous synrift basin to glacially dominated strata in the Neogene and Quaternary . The seismostratigraphic record from the ASE shelf is consistent with records from the Ross Sea (Bartek et al, 1991;Chow and Bart, 2003) and James Ross Basin in the northwestern Weddell Sea (Smith and Anderson, 2010), indicating a Miocene intensification of glaciation (De Santis et al, 1997) in accordance with findings from the Core AND-2A (Warny et al, 2009;Passchier et al, 2011) and the Shallow Scientific Drilling on The Antarctic Continental Margin (SHALDRIL)-II drill cores .…”

Section: Geological Settingsupporting

confidence: 78%

Untitled

Gohl¹,

Wellner²,

Klaus³

2017

International Ocean Discovery Program Scientific Prospectus

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The West Antarctic Ice Sheet (WAIS) is largely marine based and thus highly sensitive to both climatic and oceanographic changes. Therefore, the WAIS has likely had a very dynamic history over the last several million years. A complete collapse of the WAIS would result in a global sea level rise of 3.3-4.3 m, yet the world's scientific community is not able to predict its future behavior. Moreover, knowledge about past behavior of the WAIS is poor, in particular during geological times with climatic conditions similar to those expected for the near and distant future. Reconstructions and quantifications of partial or complete WAIS collapses in the past are urgently needed for constraining and testing ice sheet models that aim to predict future WAIS behavior and the potential contribution of the WAIS to global sea level rise. Large uncertainties exist regarding the chronology, extent, rates, and spatial and temporal variability of past advances and retreats of the WAIS across the continental shelves. These uncertainties largely result from the fundamental lack of data from drill cores recovered proximal to the WAIS. The continental shelf and rise of the Amundsen Sea are prime targets for drilling because the records are expected to yield archives of pure WAIS dynamics unaffected by other ice sheets and the WAIS sector draining into the Amundsen Sea Embayment (ASE) currently experiences the largest ice loss in Antarctica (Paolo et al., 2015).We propose a series of drill sites for the ASE shelf where seismic data reveal seaward-dipping sedimentary sequences that span from the preglacial depositional phase to the most recent glacial periods. Our strategy is to drill a transect from the oldest sequences close to the bedrock/basin boundary at the middle-inner shelf transition to the youngest sequences on the outer shelf in the eastern ASE. If the eastern ASE is inaccessible due to sea ice cover, a similar transect of sites can be drilled on the western ASE. The core transect will provide a detailed history of the glacial cycles in the Amundsen Sea region and allow comparison to the glacial history from the Ross Sea sector. In addition, deep-water sites on the continental rise of the Amundsen Sea are selected for recovering continuous records of glacially transported sediments and detailed archives of climatic and oceanographic changes throughout glacial-interglacial cycles. We will apply a broad suite of analytical techniques, including multiproxy analyses, to address our objectives of reconstructing the onset of glaciation in the greenhouse to icehouse transition, processes of dynamic ice sheet behavior during the Neogene and Quaternary, and ocean conditions associated with the glacial cycles.The five principal objectives of Expedition 379 are as follows:1. To reconstruct the glacial history of West Antarctica from the Paleogene to recent times and the dynamic behavior of the WAIS during the Neogene and Quaternary, especially possible partial or full WAIS collapses, and the WAIS contribution to past sea level...

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Section: Geological Settingsupporting

confidence: 78%

Untitled

Gohl¹,

Wellner²,

Klaus³

2017

International Ocean Discovery Program Scientific Prospectus

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“…At DSDP Site 272, a ~400 m thick middle-upper Miocene sequence of glaciomarine mudstones was recovered ( Figure F6). Combined with the presence of numerous outwash channels above Unconformity RSU4, up to 250 m of till delta foreset and aggrading bottomset strata suggest that glaciomarine sedimentation was dominated by the release of abundant erosive sediment-laden meltwater during the middle Miocene (~14 Ma; Figure F9) (Anderson and Bartek, 1992;Chow and Bart, 2003). This meltwater release was likely associated with extensive channellevee systems above Unconformity RSU4 on the continental slope and rise .…”

Section: Geological Setting and Previous Drillingmentioning

confidence: 99%

“…Unconformity RSU3 (key target of proposed Site EBOCS-03C) provides the first evidence for a major cross-shelf paleotrough eroded by an expanded WAIS, although the age of this event(s) is poorly constrained (~14-4 Ma; Figures F6, F8) (Bart, 2003;De Santis et al, 1995. Large meltwater and outwash features are absent and laminated seismic facies are progressively thinner/less common in strata younger than Unconformity RSU3, suggesting sediment starvation and a transition to a colder glacial regime.…”

Section: Geological Setting and Previous Drillingmentioning

confidence: 99%

“…Major hiatuses are likely to occur in continental shelf sequences, but the existing sediments provide critical snapshots into past interglacial intervals. The timing of major hiatuses will allow us to determine if widespread WAIS advances coincided with major global cooling steps (e.g., Anderson, 1999;Zachos et al, 2001;Bart, 2003;Fielding et al, 2011;Bart et al, 2011).…”

Section: Continental Shelf (Ebocs) Sitesmentioning

confidence: 99%

“…The MMCO was immediately followed by an interval of Antarctic ice growth and cooling, termed the Middle Miocene Climate Transition (MMCT; 14.2-13.8 Ma), as observed in both far-field benthic foraminifer δ 18 O records and ice-proximal data ( Figure F1) (Cramer et al, 2009;Flower and Kennett, 1994;Holbourn et al, 2007;Kennett, 1977;Shevenell et al, 2008Shevenell et al, , 2004Zachos et al, 2001) and is believed to have resulted in the extinction of the Antarctic tundra vegetation (Lewis et al, 2008). Although ice expansion has traditionally been inferred in East Antarctica, Ross Sea seismic evidence also suggests WAIS expansion (Bart, 2003). However, the timing of the Ross Sea event, WAIS development, and forcings and feedbacks involved in the MMCT remain enigmatic .…”

Section: Introductionmentioning

confidence: 99%

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McKay¹,

Santis²,

Kulhanek³

2017

International Ocean Discovery Program Scientific Prospectus

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Observations from the past several decades indicate that the Southern Ocean is warming significantly and that Southern Hemisphere westerly winds have migrated southward and strengthened due to increasing atmospheric CO 2 concentrations and/or ozone depletion. These changes have been linked to thinning of Antarctic ice shelves and marine terminating glaciers. Results from geologic drilling on Antarctica's continental margins show late Neogene marine-based ice sheet variability, and numerical models indicate a fundamental role for oceanic heat in controlling this variability over at least the past 20 My. Although evidence for past ice sheet variability has been observed in marginal settings, sedimentological sequences from the outer continental shelf are required to evaluate the extent of past ice sheet variability and the role of oceanic heat flux in controlling ice sheet mass balance.

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Impact of Weddell Sea shelf progradation on Antarctic bottom water formation during the Miocene

et al. 2017

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The Weddell Sea is a main location of bottom water formation and, thus, an important component of global ocean circulation. In this study we examine the ocean and climatic responses to a shelf progradation induced by ice sheet advance and glacially transported sediments during the Miocene, using a general circulation model. Our investigations show that relative to a Miocene standard bathymetry, a farther southerly placed shelf break, as reconstructed in a state‐of‐the‐art bathymetry for the Weddell Sea, enables enhanced Antarctic Bottom Water (AABW) formation and gyre transport during the middle Miocene for both relatively high and low atmospheric CO2 concentrations. Furthermore, CO2 sensitivity experiments show that an atmospheric CO2 decline for a setup with the southerly placed shelf break of a new bathymetry has only a minor impact on AABW formation, while the standard setup shows an increase. In combination, these impacts may explain the pronounced deep water formation in the southern high latitudes from the middle Miocene to the late Miocene.

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West Antarctic Ice Sheet grounding events on the Ross Sea outer continental shelf during the middle Miocene

Cited by 55 publications

References 28 publications

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Impact of Weddell Sea shelf progradation on Antarctic bottom water formation during the Miocene

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