The middle Pleistocene transition by frequency locking and slow ramping of internal period

Abstract. Based on sparse data, Titan Dome has been identified as having a higher probability of containing ice that would capture the middle Pleistocene transition (1.25 to 0.7 Ma). New aerogeophysical observations (radar and laser altimetry) collected over Titan Dome, located about 200 km from the South Pole within the East Antarctic Ice Sheet, were used to characterize the region (e.g., geometry, internal structure, bed reflectivity, and flow history) and assess its suitability as a paleoclimate ice core site. The radar coupled with an available ice core chronology enabled the tracing of dated internal reflecting horizons throughout the region, which also served as constraints on basal ice age modeling. The results of the survey revealed new basal topographic detail and better constrain the ice topographical location of Titan Dome, which differs between community datasets. Titan Dome is not expected to be relevant to the study of the middle Pleistocene transition due to a combination of past fast flow dynamics, the basal ice likely being too young, and the temporal resolution likely being too coarse if 1 Ma ice were to exist.

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Characterization of Titan Dome, East Antarctica, and potential as an ice core target

10.5194/tc-2020-210 ◽

2020 ◽

Cited By ~ 1

Author(s):

Lucas H. Beem ◽

Duncan A. Young ◽

Jamin S. Greenbaum ◽

Donald D. Blankenship ◽

Jingxue Guo ◽

...

Keyword(s):

Ice Core ◽

Ice Age ◽

Middle Pleistocene ◽

South Pole ◽

Basal Ice ◽

Core Site ◽

Age Model ◽

Middle Pleistocene Transition ◽

Paleoclimate Proxy

Abstract. Titan Dome is located about 200 km from the South Pole along the 180◦ meridian within the East Antarctic Ice Sheet. Based on sparse data, it is a region that is identified as having a higher probability of containing ice that would capture the middle Pleistocene transition (1.25 to 0.7 Ma) as a paleoclimate proxy. New aerial geophysical observations collected over Titan Dome were used to characterize the region and assess its suitability as a paleoclimate ice core site. The radar coupled with an available ice core age model enabled the tracing of isochronal layers throughout the region which also served as constraints on basal ice age modeling. The results of the survey revealed new basal topographic detail, constrained the location of Titan Dome, which differs between community datasets, and suggests that the basal ice beneath Titan Dome is too young to be relevant to study of the middle Pleistocene transition.

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Review of the Early–Middle Pleistocene boundary and Marine Isotope Stage 19

Progress in Earth and Planetary Science ◽

10.1186/s40645-021-00439-2 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Martin J. Head

Keyword(s):

North Atlantic ◽

Meridional Overturning Circulation ◽

Middle Pleistocene ◽

Orbital Eccentricity ◽

Middle Pleistocene Transition ◽

Meridional Overturning ◽

Asian Pacific ◽

Low Amplitude ◽

The Antarctic ◽

Insolation Forcing

AbstractThe Global Boundary Stratotype Section and Point (GSSP) defining the base of the Chibanian Stage and Middle Pleistocene Subseries at the Chiba section, Japan, was ratified on January 17, 2020. Although this completed a process initiated by the International Union for Quaternary Research in 1973, the term Middle Pleistocene had been in use since the 1860s. The Chiba GSSP occurs immediately below the top of Marine Isotope Substage (MIS) 19c and has an astronomical age of 774.1 ka. The Matuyama–Brunhes paleomagnetic reversal has a directional midpoint just 1.1 m above the GSSP and serves as the primary guide to the boundary. This reversal lies within the Early–Middle Pleistocene transition and has long been favoured to mark the base of the Middle Pleistocene. MIS 19 occurs within an interval of low-amplitude orbital eccentricity and was triggered by an obliquity cycle. It spans two insolation peaks resulting from precession minima and has a duration of ~ 28 to 33 kyr. MIS 19c begins ~ 791–787.5 ka, includes full interglacial conditions which lasted for ~ 8–12.5 kyr, and ends with glacial inception at ~ 774–777 ka. This inception has left an array of climatostratigraphic signals close to the Early–Middle Pleistocene boundary. MIS 19b–a contains a series of three or four interstadials often with rectangular-shaped waveforms and marked by abrupt (< 200 year) transitions. Intervening stadials including the inception of glaciation are linked to the calving of ice sheets into the northern North Atlantic and consequent disruption of the Atlantic meridional overturning circulation (AMOC), which by means of the thermal bipolar seesaw caused phase-lagged warming events in the Antarctic. The coherence of stadial–interstadial oscillations during MIS 19b–a across the Asian–Pacific and North Atlantic–Mediterranean realms suggests AMOC-originated shifts in the Intertropical Convergence Zone and pacing by equatorial insolation forcing. Low-latitude monsoon dynamics appear to have amplified responses regionally although high-latitude teleconnections may also have played a role.

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