 |
| Titel |
Late Pleistocene glacial chronology of the Retezat Mts, Southern Carpathians, using 10Be exposure ages |
| VerfasserIn |
Zsófia Ruszkiczay-Rüdiger, Zoltán Kern, Petru Urdea, Régis Braucher, Balázs Madarász, Irene Schimmelpfennig |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104560
|
| Publikation (Nr.) |
 EGU/EGU2015-5593.pdf |
|
|
|
|
|
| Zusammenfassung |
| Our knowledge on the timing of glacial advances in the Southern Carpathians is limited.
Recently, some attempts have been made to develop an improved temporal framework for the
glaciations of the region using cosmogenic 10Be exposure dating. However, glacial
chronology of the Romanian Carpathians remains contradictory. E.g. the timing of the
maximum ice advance appears to be asynchronous within the area and also with other dated
glacial events in Europe.
Main objective of our study is to utilize cosmogenic in situ produced 10Be dating to
disentangle the contradictions of the Southern Carpathian Late Pleistocene glacial
chronology. Firstly, previously published 10Be data are recalculated in accordance with the
new half-life, standardization and production rate of 10Be. The recalculated 10Be
exposure ages of the second largest (M2) moraines in the Retezat Mts. appear to be ca.
19-24% older than exposure ages calculated by Reuther et al. (2007, Quat. Int.
164-165, 151-169). This contradicts the earlier conclusions suggesting post LGM
age of M2 glacial advance and suggests that M2 moraines can be connected to
the end of the LGM with final stabilization possibly at the beginning of the Late
Glacial. We emphasize that it is ambiguous to correlate directly the exposure-dated
glacier chronologies with millennial scale climate changes due to uncertainties in
sample collection and in computation of exposure ages from measured nuclide
concentrations.
New 10Be samples were collected in order to determine the 10Be exposure age of
moraines outside the most prominent generation (M2) including the largest and
oldest moraine (M1) and the landforms connected to the smallest ice advances (M4),
which remained undated so far. The new exposure ages of M2 moraines are well in
harmony with the recalculated ages of Reuther at al. (2007). 10Be exposure age of
boulders on the smallest moraine suggest that the last glaciers disappeared in the area
during the Late Glacial, indicating no glaciation during the Younger Dryas and
Holocene.
Previous works, based on geomorphologic analogies and pedological properties
suggested that the M1 ice advance was older than LGM, and possibly occurred during the
MIS4. Our 10Be exposure dating provided LGM ages for boulders on the M1 side moraine. It
is question of further research whether these ages show the time when the glacier abandoned
the moraine or they only indicate an LGM erosional event affecting an older moraine. If we
accept the LGM age of maximum ice extent (M1), our 10Be exposure age data enables the
calculation of a mean glacier retreat rate of 1.3 m/a for the period between M1 and M4 (21.4
to 13.6ka). Alternatively, considering only the oldest 10Be exposure age of the M2
moraine, the M2 to M4 (20.2–13.6ka) glacier retreat rate was slightly lower: 1.1
m/a.
Our research was supported by the OTKA PD83610, by the MTA-CNRS cooperation
(NKM-96/2014), by the Bolyai Scholarship, and by the “Lendület” program of the HAS
(LP2012-27/2012). The 10Be measurements were performed at the ASTER AMS national
facility (CEREGE, Aix en Provence, France). |
|
|
|
|
|
|