ABSTRACT
The Ankara volcanics comprise a small volcanic field immediately
to
the north of Ankara, Turkey. This volcanic field is composed of a
mixture
of flows, tuffs, and agglomerates, with the flows ranging in
composition
from high-K basaltic andesite to rhyolite. Dacitic flows are the
most
common.
A potassium-argon date gives a Middle Eocene age of 42.0 ±
1.6
m.y.
The volcanics unconformably overlie Paleozoic sediments of the
"Cimmerian
continent" to the south and Mesozoic rocks of the Ankara melange
to the
north.
Results of analyses on 25 samples for major elements and Y, Sr,
Rb,
Ni, Cr, V, Co, Zn, Cu, Nb, and Zr are presented. Major elements
and
most
trace elements show well defined trends when plotted on SiO2
variation
diagrams, indicating a chemical consanguinity. The processes of
partial
melting, fractional crystallization, and mixing/contamination are
evaluated
in terms of the roles they may have played in the generation of
these
magmas.
A model based on fractional crystallization best explains the
observed
chemical trends; xenocrystic phases and disequilibrium phenomena
in
plagioclase
indicate that mixing/contamination processes may have played a
lesser
role.
Comparison of major and trace element abundances of the Ankara
rocks
to those of other suites of calc-alkaline rocks reveals that these
volcanic
rocks most resemble those that have been produced by magmatic arcs
built
upon continental basement. This is consistent with the hypothesis
that
these rocks are related to the Eocene subduction and convergence
which
closed the northern branches of Neo-Tethys.
Ach, J.A., 1982. The Petrochemistry of the Ankara Volcanics,
Central
Turkey.
Unpublished MSc. thesis, State University of New York at Albany.
146
pp., +x; 1 folded plate (map)
University at Albany Science Library call number: SCIENCE
Oversize
(*) QE 40 Z899 1982 A34
thesis (scanned
text) - 3.8MB pdf file
Plate 1 - Generalized
geology
and sample locations, Ankara region, Turkey
(uncoloured geological map, scale 1: 50,000) -
2.4MB pdf file
Return to MS Theses completed in the
Geological
Sciences Program, University at Albany