The vertical distribution of lithofacies from glacimarine sequences recovered during the Cape Rob... more The vertical distribution of lithofacies from glacimarine sequences recovered during the Cape Roberts Project displays a cyclicicty which is interpreted as the sedimentary response to changes in relative sea-level. The changes are associated with climatic cycles and/or cycles of glacial advance and retreat (CRP Science team, 2000). Based on available bio- and magnetostratigraphic data (CRP Science Team, 2001; Florindo et al., 2005) the CRP-3 core spans the upper part of Chron C13r to the uppermost Chron C12r. The sequence is, therefore, a unique archive containing information on ice-sheet volume changes across a major step of glaciation as revealed by the stable isotope record from oceanic sequences. Image analysis data from CRP-3 core reveals a cyclical pattern, which based on the current age interpretation of the surveyed interval, appear to be orbitally controlled. These results are compared with simulated long-term (104-106 yr) behavior of the ice sheet using a coupled GCM-ice sheet-sediment model accounting for lower Oligocene boundary conditions and orbital forcing.
The magnetic properties of late Quaternary hemipelagic sediment from piston core BS77-15 taken i... more The magnetic properties of late Quaternary hemipelagic sediment from piston core BS77-15 taken in the Tyrrhenian Sea were investigated and the results compared with paleoclimatic records. The magnetic mineralogy of the sediment was studied and the magnetic carriers were identified by their spectra of coercivity and unblocking temperature. Investigations of rock magnetic parameters such as the Natural Remanent Magnetization (NRM), the low field magnetic susceptibility x, the frequency dependent susceptibility xFD, the acquisition of Anhysteretic Magnetization (ARM) and Isothermal Magnetization (IRM) and the Median Destructive Field (MDF) have established the downcore variations in terms of magnetic mineralogy, grain size and coercivity in the sediments. The rock magnetic parameters were compared with an alternative climatic record from the same core based on the faunal association of planktonic foraminifera. A significant correlation was found between faunal climatic record and...
About 34 million years ago, Earth's climate cooled and an ice sheet formed on Antarctica as a... more About 34 million years ago, Earth's climate cooled and an ice sheet formed on Antarctica as atmospheric carbon dioxide (CO2) fell below ~750 parts per million (ppm). Sedimentary cycles from a drill core in the western Ross Sea provide direct evidence of orbitally controlled glacial cycles between 34 million and 31 million years ago. Initially, under atmospheric CO2 levels of ≥600 ppm, a smaller Antarctic Ice Sheet (AIS), restricted to the terrestrial continent, was highly responsive to local insolation forcing. A more stable, continental-scale ice sheet calving at the coastline did not form until ~32.8 million years ago, coincident with the earliest time that atmospheric CO2 levels fell below ~600 ppm. Our results provide insight into the potential of the AIS for threshold behavior and have implications for its sensitivity to atmospheric CO2 concentrations above present-day levels.
Milankovitch cycle stratigraphy has become an important method of calibrating the geomagnetic pol... more Milankovitch cycle stratigraphy has become an important method of calibrating the geomagnetic polarity time scale in the Neogene. The resulting geochronological con- straints can be used to interpret the timing of sea level changes and the long-term rate of subsidence in the Venice area, which is located at the northern end of the Adri- atic Sea in a foreland setting
The vertical distribution of lithofacies from glacimarine sequences recovered during the Cape Rob... more The vertical distribution of lithofacies from glacimarine sequences recovered during the Cape Roberts Project displays a cyclicicty which is interpreted as the sedimentary response to changes in relative sea-level. The changes are associated with climatic cycles and/or cycles of glacial advance and retreat (CRP Science team, 2000). Based on available bio- and magnetostratigraphic data (CRP Science Team, 2001; Florindo et al., 2005) the CRP-3 core spans the upper part of Chron C13r to the uppermost Chron C12r. The sequence is, therefore, a unique archive containing information on ice-sheet volume changes across a major step of glaciation as revealed by the stable isotope record from oceanic sequences. Image analysis data from CRP-3 core reveals a cyclical pattern, which based on the current age interpretation of the surveyed interval, appear to be orbitally controlled. These results are compared with simulated long-term (104-106 yr) behavior of the ice sheet using a coupled GCM-ice sheet-sediment model accounting for lower Oligocene boundary conditions and orbital forcing.
The magnetic properties of late Quaternary hemipelagic sediment from piston core BS77-15 taken i... more The magnetic properties of late Quaternary hemipelagic sediment from piston core BS77-15 taken in the Tyrrhenian Sea were investigated and the results compared with paleoclimatic records. The magnetic mineralogy of the sediment was studied and the magnetic carriers were identified by their spectra of coercivity and unblocking temperature. Investigations of rock magnetic parameters such as the Natural Remanent Magnetization (NRM), the low field magnetic susceptibility x, the frequency dependent susceptibility xFD, the acquisition of Anhysteretic Magnetization (ARM) and Isothermal Magnetization (IRM) and the Median Destructive Field (MDF) have established the downcore variations in terms of magnetic mineralogy, grain size and coercivity in the sediments. The rock magnetic parameters were compared with an alternative climatic record from the same core based on the faunal association of planktonic foraminifera. A significant correlation was found between faunal climatic record and...
About 34 million years ago, Earth's climate cooled and an ice sheet formed on Antarctica as a... more About 34 million years ago, Earth's climate cooled and an ice sheet formed on Antarctica as atmospheric carbon dioxide (CO2) fell below ~750 parts per million (ppm). Sedimentary cycles from a drill core in the western Ross Sea provide direct evidence of orbitally controlled glacial cycles between 34 million and 31 million years ago. Initially, under atmospheric CO2 levels of ≥600 ppm, a smaller Antarctic Ice Sheet (AIS), restricted to the terrestrial continent, was highly responsive to local insolation forcing. A more stable, continental-scale ice sheet calving at the coastline did not form until ~32.8 million years ago, coincident with the earliest time that atmospheric CO2 levels fell below ~600 ppm. Our results provide insight into the potential of the AIS for threshold behavior and have implications for its sensitivity to atmospheric CO2 concentrations above present-day levels.
Milankovitch cycle stratigraphy has become an important method of calibrating the geomagnetic pol... more Milankovitch cycle stratigraphy has become an important method of calibrating the geomagnetic polarity time scale in the Neogene. The resulting geochronological con- straints can be used to interpret the timing of sea level changes and the long-term rate of subsidence in the Venice area, which is located at the northern end of the Adri- atic Sea in a foreland setting
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