Caitlin Leslie ACF Abstract FY13

Recent Folding, Geomorphic Evolution, and Paleoclimate: Apsheron Peninsula Azerbaijan

2012 Geological Society of America (GSA) Annual Meeting and Exposition

The Apsheron Peninsula, Azerbaijan in the southern foreland of the
Caucasus Mountains exposes the Pliocene clastic Productive Series and
Pleistocene-Quaternary flanking carbonate-rich units in a number of
long, narrow oil-saturated anticlines. We are beginning to study the
tectonics, geomorphology, and exhumation history of the Apsheron
Peninsula and Yasamal and Kirmaky anticlines using GIS, apatite
U-Th-He and fission-track thermochronology, and 10Be and 26Cl surface
exposure dating. With GIS (digital elevation models, Google Earth,
aerial photos, and digital geologic maps), we investigated the
morphology, gradients, and relative timing of streams flanking and
crossing these two anticlines and how they vary along, across, and
between the two structures. Drainage density varies systematically
along and across the Yasamal anticline. The higher drainage density of
streams on the eastern flank of the anticline may be associated with
steeper surface slopes and/or steeper bedrock dips along this flank.
The systematic decrease in drainage density toward the southern fold
nose probably indicates that the anticline recently propagated to the
south during an older (T1) wet climate. The flanking “dry” Yasamal
valley post-dates earlier (fold-related) streams which are left as
“hanging valleys” on west side of Yasamal valley and east side of the
Yasamal anticline. Yasamal valley has a non-standard rectangular
cross-sectional shape, trends N-S, parallel to today’s prevailing
winter and summer winds, and slopes southward toward the Caspian Sea.
Yasamal valley appears to be wind sculpted, and likely formed during a
dry period, T2, that followed T1. Kirmaky Valley appears to be a
similar T2 N-S, wind-sculpted, rectangular valley. Kirmaky anticline
has no T1 fold-affected streams, suggesting that it may be younger
than Yasamal anticline. Results from a suite of ~30 U-Th-He, apatite
fission-track samples, and several 26Cl and 10Be samples will be
forthcoming; these, and links to calibrated paleoclimate records, will
help us establish the absolute timing of the exhumation (unburial) of
the rocks in the two Apsheron anticlines and that of the wet/dry
climate cycles that helped sculpt the landscapes of the Apsheron
peninsula.

 

 

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