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| Titel |
Uplift of the southern Central Anatolian Plateau from 87Sr/86Sr stratigraphy on margin-capping marine sediments |
| VerfasserIn |
Taylor Schildgen, Frank Dudas, Gianluca Frijia, Domenico Cosentino, Cengiz Yıldırım, Manfred Strecker |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250037122
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| Zusammenfassung |
| The Central Anatolian Plateau is at the crux of one of the most complicated tectonic regions
on Earth, bounded by the Aegean extensional province to the west, enigmatic subduction to
the south, the Bitlis-Zagros collisional zone to the east, and the continental-scale North
Anatolian Fault Zone (NAFZ) to the north. Possible mechanisms for generating the 1.5-km
average elevations include lithospheric delamination, crustal scale thickening, climate-driven
surface processes, or any combination of these. Critical for understanding the mechanism of
surface uplift and how it fits within the regional tectonic setting is deriving better constraints
on the temporal framework and pattern of surface uplift. The southern margin of
the plateau, which is extensively overlain by Miocene marine sediments, offers
some of the best potential to identify both the timing and magnitude of surface
uplift.
We present 87Sr/86Sr data on some of the highest and youngest marine sediments that
presently cap the southern plateau margin. Analyzed samples, including oysters and
foraminifera, cover a region of >150 km along the southern margin, from the Antalya Basin
to the Ermenek Basin. Measured ratios average 0.708888 in the west (1450 m elevation),
0.708832 at the middle site (1885 m elevation, ~200 m below the highest marine sediments),
and 0.708813 at our eastern-most site (1845 m elevation). Comparing these values to the
global sea water 87Sr/86Sr curve (LOWESS IV) suggests ages of ~10 Ma in the west, ~12.5
Ma at the middle site, and ~13 Ma in the east. However, a potential complication concerns
the late Miocene Mediterranean sea water 87Sr/86Sr curve, which shows a major departure
from the global 87Sr/86Sr curve when the Mediterranean became isolated from
global ocean circulation (e.g., McCulloch and De Deckker, 1989). Whether or not
our samples are young enough to have been affected by this event (and thus ratios
should be interpreted as late Tortonian to early Messinian in age) will be tested by
comparing 87Sr/86Sr data to micro- and nannofossil stratigraphic analyses of the same
sections.
If our measurements can be interpreted using the global ocean 87Sr/86Sr curve, the trend
of younger capping marine sediments from east to west suggests that initiation of uplift also
followed an east to west trend. Such a pattern correlates with the history of development of
the NAFZ, which is interpreted to have an eastward-younging trend, based on a late Miocene
initiation of fault-related sedimentary basins in the east (e.g., Refahiye and Erzinkan Basins),
and successively younger basins to the west. Surface uplift along the southern margin may
therefore be closely associated with development of the NAFZ and the onset of
regional “escape tectonics”. One potential mechanism for southern margin uplift
could be internal deformation of the Anatolian plate, leading to counter-clockwise
rotation and subsequent compression along the southern margin. Such internal
rotation is suggested by GPS velocity data from Central Anatolia, which show a
counter-clockwise rotation of vectors when plotted in an Arabia-fixed reference frame.
Alternatively, changes in subduction along the Cyprus arc (e.g., the geometry and
integrity of the subducting slab) may have led to local surface uplift along the southern
margin. |
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