The Aegean region experienced a
series of continental plate collisions from Late Cretaceous to Eocene time.
Post-collisional extension in the region, although controversial in its timing
and nature, caused the exhumation of several metamorphic belts. The largest of
these, the Menderes Massif, accommodated significant crustal extension, which
may have been caused by: (1) tectonic escape and lateral extrusion, in which
the Anatolian plate moves westward along the North and East Anatolian Faults,
(2) back-arc spreading/slab roll back due to the subduction along the Hellenic
Arc, or (3) orogenic collapse of thermally weakened lithosphere that
experienced Paleogene contraction. These hypotheses are tested using
geochronology, making the Menderes Massif a key locale in identifying the
fundamental plate tectonic processes that facilitate extension in the
continental lithosphere. The main goal of the research is to characterize the
petrologic evolution of rocks in the central Menderes Massif to identify the
cause of tectonic transition from compression to extension in the Aegean
Region. The project involves fieldwork and geochemical data acquisition,
including recently developed techniques of in situ ion microprobe monazite
geochronology and argon-argon K-feldspar multi-diffusion domain modeling. The
ion microprobe technique preserves the grain and rock fabric, and, when
combined with electron microprobe chemical analyses, allow for a clear
interpretation of meaning of the age. The argon-argon multi-diffusion domain
model shows that a single K-feldspar sample can reveal a broad segment of a
cooling history, rather than a single datum. This project is collaborative
between a U.S. team including Dr. Elizabeth Catlos, Dr. Ibrahim Cemen (School
of Geology; Oklahoma State University) and Dr. Matt Kohn (Dept. Geological
Sciences; University of South Carolina), and a Turkish team including Dr.
Cemal Goncuoglu (Middle East Technical University, Department of Geological
Engineering, Ankara). The two graduate students participating in this proposal
are exposed to a different culture, intense fieldwork, and a variety of
geochemical methods.
