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| Titel |
Glaciation and erosion of Eastern Greenland at the Eocene-Oligocene transition: Insights from low-temperature thermochronology |
| VerfasserIn |
Thomas Bernard, Philippe Steer, Kerry Gallagher, Adam Szulc, Andrew Whittam |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250132975
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| Publikation (Nr.) |
 EGU/EGU2016-13532.pdf |
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| Zusammenfassung |
| Climate cooling through the Late Cenozoic was important in the evolution of glaciated
mountain ranges. While the onset of accelerated Cenozoic exhumation is generally associated
with the Quaternary at mid-latitudes, coincident with the local onset of glaciation, some
high-latitude passive margins may have experienced earlier glaciation starting at 30-38 Ma or
even 45 Ma. To address this issue, we use a set of new AFT data from 16 sub-vertical profiles
sampled along the fjords of the central Eastern Greenland margin between 68˚
and 76˚ N, combined with new apatite (U-Th-Sm)/He (AHe) data from selected
profiles. To infer thermal histories and exhumation from these profiles, we use the
software QTQt. The modeling results show a major phase of exhumation in the
East Greenland margin between 68˚ and 76˚ N starting at 30±5 Ma. The spatial
distribution of the exhumation shows that normal faulting on East Greenland margin had
no resolvable influence on exhumation related to the cooling phase. However, the
timing is coincident with the dramatic worldwide fall of surface temperature at
the Eocene-Oligocene transition. We therefore suggest that a transition from an
Eocene fluvial to an Oligocene glacial-dominated landscape triggered a period of
enhanced erosion. We infer from the thermal histories that around 2.7±1.9 km of
erosion occurred close to the coast since the Eocene-Oligocene transition. This
amount of erosion is consistent with the incision of the fjords and with the effective
removal of 2.3±1.5 km of basalt thickness, deduced by the thermal modeling of a
heating phase at 55±5 Ma. This phase of erosion is most strongly evidenced near the
coast, suggesting either that continental ice extent was limited to the coastal areas or
that erosion was less efficient outside these areas, leading to no obvious signal in
thermochronometric data further north. Overall, this study provides the first onshore evidence
of the onset of continental ice in East Greenland margin at the Eocene-Oligocene
transition (∼34 Ma), contemporary with the onset of Antarctica glaciation and erosion.
Our interpretation is consistent with that based on of the oldest ice-rafted debris
found in the sedimentary records offshore the Eastern Greenland and implies East
Greenland exhibits the oldest onshore record of Cenozoic glacial erosion on Earth. |
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