期刊名称：IOP Conference Series: Earth and Environmental Science
印刷版ISSN：1755-1307
电子版ISSN：1755-1315
出版年度：2008
卷号：2
出版社：IOP Publishing
摘要：In the Anatolides of Turkey the neotectonic (post collisional) phase of
deformation embraces the period since final closure of the southern arm of
Neotethys in mid-Miocene times. The Arabian Shield indenter has continued to
deform into the weak Anatolian accretionary collage resulting from subduction of
this ocean by a combination of differential movement relative to the African
Plate and counterclockwise (CCW) rotation. Much of resulting deformation has
been accommodated by slip along major transforms comprising the North Anatolian
Fault Zone (NAFZ), the East Anatolian Fault Zone (EAFZ) and the northward
extension of the Dead Sea Fault Zone (DSFZ) but has also been distributed as
differential block rotations through the zone of weak crust in between. Facets
of this deformation comprise crustal thickening and uplift to produce the
Anatolian Plateau, establishment of transform faults and tectonic escape as
Arabia has continued to impinge into the Anatolian collage. Paleomagnetic
analysis of this deformation is facilitated by the widespread distribution of
neotectonic volcanism and graben infills, and rotations relative to the Eurasian
reference frame are recognised on two scales. Rapid rotation (up to 5°/10,000
years) of small fault blocks is identified between master faults along the
intracontinental transforms but deformation does not extend away from these
zones and shows that seismogenic upper crust is decoupled from a lower
continental lithosphere undergoing continuum deformation. The broad area of weak
accreted crust between the transforms is dissected into large fault blocks which
exhibit much lower rotation rates (mostly < 1°/100,000 years) that vary
systematically across the Anatolides. Large CCW rotations near the Arabian
indenter diminish westwards to become zero then CW near the limit of tectonic
escape in western Turkey. The view that the collage has rotated anticlockwise as
a single plate, either uniformly or episodically, during the Neotectonic era is
refuted. Instead, deformation has been distributed and differential as the
collage has adapted to changing tectonic regimes. Crustal extrusion to the west
and south has expanded the curvature of the Tauride Arc and combined with
retreat of the Hellenic Arc to produce the extensional horst and graben province
in western Turkey. A challenge of present work is to resolve the temporal
framework of tectonic rotation. Evidence from the Cappadocian volcanic province
and Sivas Basin in central Anatolia indicates that rotation has been
concentrated within the last 2–3 million years of the neotectonic era and
therefore correlates with establishment of the intracontinental transform
framework. Thus we recognise two phases to the evolution of this sector of the
orogen: the first embraces crustal thickening and uplift with initiation defined
specifically by transition from marine to terrestrial deposition in the
Serravallian at ~12 Ma, and the second embraces crustal extrusion to the west
motivated by continuing northward movement of Arabia and roll back on the
Hellenic Arc since late Pliocene times. Latitudinal motions detected by
paleomagnetism are close to confidence limits and consistent with small
northward motion of the Anatolides since Eocene times including up to a few
hundred km of closure linked to crustal thickening since the demise of
NeoTethys. The driving motion from the Arabian indenter can be partially
resolved from the widespread basaltic volcanism that occurred along the
periphery of the Arabian Shield at 12–18 Ma during final stages of collision
along the Bitlis Suture. This defines CCW rotation of 13–21° with respect to
Eurasia. An average CCW rotation of 0.9°/Myr since closure of the Bitlis Suture
in mid-Miocene times is unlikely to have been uniform because it has been linked
to three adjoining interactions namely episodic opening of the Red Sea, a
transition from crustal thickening to tectonic escape in the Anatolian collage
and variable rates of strike slip motion on the DSFZ.
