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New kinematic and geochronologic evidence for the Quaternary evolution of the Central Anatolian Fault Zone (CAFZ)

Authors:

Abstract

As the kinematics of active faults that bound the Anatolian Plate are well studied, it is now essential to improve our understanding of the style and rates of intraplate deformation to constrain regional strain partitioning and improve seismic risk assessments. One of these internal structures, the Central Anatolian Fault Zone (CAFZ) was originally defined as a regionally significant left-lateral ‘tectonic escape’ structure, stretching for 700 km in a NE direction across the Anatolian plate. We provide new structural, geomorphic and geochronologic data for several key segments within the central part of the CAFZ that suggest the sinistral motion has been overstated. The Ecemiş fault, the southernmost part of the CAFZ, has a Late-Quaternary minimum slip rate of 1.1 ± 0.4 mm a−1, slower than originally proposed. Further north, the Erciyes fault has fed a linear array of monogenetic vents of the Erciyes stratovolcano and 40Ar/39Ar dating shows a syn-eruptive stress field of ESE-WNW extension from 580 ± 130 ka to 210 ± 180 ka. In the Erciyes basin, and central part of the CAFZ, we mapped and re-characterized the Erkilet and Gesi faults as predominantly extensional. These long-term geological rates support recent GPS observations that reveal ESE-WNW extension, which we propose as the driver of faulting since 2.73 ± 0.08 Ma. The slip-rates and kinematics derived in this study are not typical of an ‘escape tectonic’ structure. The CAFZ is a transtensional fault system that re-activates paleotectonic structures and accommodates E-W extension associated with the westward movement of Anatolia.
New kinematic and geochronologic evidence
for the Quaternary evolution of the Central
Anatolian fault zone (CAFZ)
Mark Higgins
1
, Lindsay M. Schoenbohm
1
, Gilles Brocard
2
, Nuretdin Kaymakci
3
,
John C. Gosse
4
, and Michael A. Cosca
5
1
Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada,
2
Department of Earth and Environmental
Science, University of Pennsylvania, Philadelphia, Pennsylvania, USA,
3
Department of Geological Engineering, Middle East
Technical University, Ankara, Turkey,
4
Department of Earth Sciences, Dalhousie University, Halifax, Nova Scotia, Canada,
5
Central Mineral and Environmental Resources Science Center, U.S. Geological Survey, Denver, Colorado, USA
Abstract As the kinematics of active faults that bound the Anatolian plate are well studied, it is now
essential to improve our understanding of the style and rates of intraplate deformation to constrain regional
strain partitioning and improve seismic risk assessments. One of these internal structures, the Central Anatolian
fault zone (CAFZ), was originally dened as a regionally signicant left-lateral tectonic escapestructure,
stretchingfor 700km in a NE direction across the Anatolian plate. We provide new structural, geomorphic, and
geochronologic data for several key segments within the central part of the CAFZ that suggest that the sinistral
motion has been overstated. The Ecemişfault, the southernmost part of the CAFZ, has a late-Quaternary
minimum slip rate of 1.1 ± 0.4 mm a
1
, slower than originally proposed. Farther north, the Erciyes fault has fed a
linear array of monogenetic vents of the Erciyes stratovolcano and
40
Ar/
39
Ar dating shows a syneruptive stress
eld of ESE-WNW extension from 580 ± 130 ka to 210 ± 180 ka. In the Erciyes basin, and central part of the CAFZ,
we mapped and recharacterized the Erkilet and Gesi faults as predominantly extensional. These long-term
geological rates support recent GPS observations that reveal ESE-WNW extension, which we propose as the
driver of faulting since 2.73± 0.08Ma. The slip rates and kinematics derived in this study are not typical of an
escape tectonicstructure. The CAFZ is a transtensional fault system that reactivates paleotectonic structures
and accommodates E-W extension associated with the westward movement of Anatolia.
1. Introduction
Lateral escape of microplates is a common feature of active collisional tectonics and has been described in
various regions including Tibet [Tapponnier et al., 1982], Anatolia [McKenzie,1972;Şengör,1985;Dewey et al.,
1986], Alaska [Redeld et al., 2007], and Taiwan [Lacombe et al., 2001]. In each case, microplates move away
from a zone of collision toward a free boundary or an extending domain [Burke and Sengör, 1986]. A debate
exists about the driving forces behind the lateral escape of the Anatolian plate, where Arabian plate collision
in the Eastern Anatolian combined with ongoing extension in the Western Anatolia associated with retreat of
the Hellenic trench (Figure 1) result in rapid westward extrusion. Recent research on the Anatolian plate has
focused primarily on its bounding faults, the North and East Anatolian faults, while the style and magnitude of
internal deformation have received less attention. Improved understanding of intraplate strain is required to
test competing hypotheses.
Conceptual models of the geodynamics of the eastern Mediterranean are complex and varied. Şengör [1985]
invoked tectonic escapein which the westward movement of the Anatolian plate is accommodated
by major strike-slip faults, the North Anatolian fault and East Anatolian fault, with relatively insignicant
internal deformation. Early GPS studies suggested that present-day motion of the Anatolian plate is explained
by coherent extrusion of a rigid tectonic block, driven by the pull of the African slab rollback beneath the
Hellenic-Cyprus subduction zones with minimal internal deformation of the plate [McClusky et al., 2000;
Reilinger et al., 2006]. Other models call for signicant internal deformation of the Anatolian plate, in which
smaller strike-slip-bounded crustal wedges move independently, each accommodating some of the relative
motion between the Arabian and Eurasian plates [Şengör, 1985; Koçyiğit and Beyhan, 1998; Koçyiğit and Erol, 2001;
Jaffey and Robertson, 2001; Bozkurt, 2001]. The Anatolian plate experienced signicant internal deformation
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 1
PUBLICATION
S
Tectonics
RESEARCH ARTICLE
10.1002/2015TC003864
Key Points:
The CAFZ is a weakly active
transtensional fault system
Minimum sinistral slip rate of
1.1 ± 0.3 mm a
1
Evidence is presented which reveals
ESE-WNW extension since 2.73 Ma
Supporting Information:
Text S1 and Tables S1S10
Correspondence to:
M. Higgins,
mark.higgins@mail.utoronto.ca
Citation:
Higgins, M., L. M. Schoenbohm, G. Brocard,
N. Kaymakci, J. C. Gosse, and M. A. Cosca
(2015), New kinematic and geochronologic
evidence for the Quaternary evolution of
the Central Anatolian fault zone (CAFZ),
Tectonics,34, doi:10.1002/2015TC003864.
Received 10 MAR 2015
Accepted 2 SEP 2015
Accepted article online 5 SEP 2015
©2015. American Geophysical Union.
All Rights Reserved.
throughout the late Cenozoic, prior to and after the initiation of escape tectonics,but its contribution to the
lateral translation is rarely considered in regional geodynamic models.
In this study, we focus on what is potentially the most signicant of these second-order, internal structures,
the Central Anatolian fault zone (CAFZ; Figure 1). Previous studies [Koçyiğit and Beyhan, 1998; Toprak, 1998;
Koçyiğit and Erol, 2001] classify the CAFZ as a major intracontinental shear zone accommodating compressive
strain from the Eastern Anatolian compressional province and have argued for up to 24km of Pliocene-
Quaternary left-lateral displacement [Koçyiğit and Beyhan, 1998]. However, its proposed history, connectivity,
activity levels, and total left-lateral displacement have been disputed [Westaway, 1999; Westaway et al.,
2002]. Improved understanding of its activity, kinematics, and tectonic signicance is therefore clearly
needed. Here we use eld mapping, volcanic vent analysis, and terrestrial cosmogenic nuclide and
40
Ar/
39
Ar
dating to estimate slip rates and characterize the kinematics of several key segments of the southern and
central CAFZ. We also compile existing geodetic data and seismic catalogues to help assess the activity of
different parts of the fault zone. We propose a model for the Quaternary kinematics and evolution of the
CAFZ that requires extrusion-related E-W extension.
2. Background
2.1. Tectonic Setting
The Anatolian plate formed by amalgamation of terranes between Arabia-Africa and Eurasia in the Late Mesozoic.
Northward subduction of the African and Arabian plates and closure of distinct Neotethyan seaways are
recorded by several prominent suture zones [Şengör and Yılmaz, 1981; Dewey et al., 1986], including the
Izmir-Ankara-Erzican suture zone (Figure 1) and the Inner Tauride suture zone (Figure 1). The Inner Tauride
suture zone separates the Kırşehir Block in the north from the deformed and uplifted Anatolide-Tauride carbonate
platform in the south [Şengör and Yılmaz, 1981]. The northeastern part of the CAFZ follows this suture zone.
The modern rst-order tectonic structures of Eastern Mediterranean (Figure 1) result from the closure of the
Neotethys Ocean between 30 and 25 Ma and subsequent and ongoing collision of the Arabian plate with
Eurasia along the Bitlis Zagros suture zone [Jolivet and Faccenna, 2000; McQuarrie and van Hinsbergen,
2013; Kaymakci et al., 2010]. Compressional tectonics in the Eastern Anatolia contrasts with rapid back-arc
extension in Western Anatolia and in the Aegean Sea, which began between 35 and 30 Ma [Jolivet and
Faccenna, 2000]. In Central Anatolia, a N-S to NE-SW compressional stress regime persisted until the late
Miocene before giving way to a extensional tectonic regime [Özsayin et al., 2013].
Figure 1. Simplied tectonic map of the eastern Mediterranean showing major plate boundaries and tectonic structures.
WEAP: Western Anatolian extensional province, EACP: Eastern Anatolian contractional province [Şengör, 1985]. Major plate
boundaries in thick black lines, NAFZ: North Anatolian fault zone, EAFZ: East Anatolian fault zone, DSFZ: Dead Sea fault
zone. The thin black lines represent second-order tectonic structures of the Anatolian plate, CAFZ: Central Anatolian fault
zone, TGFZ: Tüz Gölü fault zone, MOFZ: Malatya-Ovacık fault zone, IA: Isparta angle. Tethyan suture zones in white, IAEZ:
Izmir Ankara Erzican suture zone, ITSZ: Inner Tauride suture zone, BZSZ: Bitlis Zagros suture zone, KTJ:Karliova triple junction.
The black arrows indicate plate velocities (in mm a
1
) from Reilinger et al. [2006].
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 2
The rate of Anatolian microplate extrusion, relative to a stable Eurasian plate, increases from 18 mm a
1
in the
east to 25 mm a
1
in the west and appears to be accommodated by major transform faults. Bounding the
Anatolian plate in the north, the North Anatolian fault is >1200 km long dextral strike-slip fault that stretches
from the Karliova triple junction in the east before widening into the north Aegean in the west (Figure 1).
With cumulative offset estimat ed at 85 km [Barka et al., 2000], the North Anatolian fault accommodates
transform motion between the Anatolian and Eurasian plates. GPS-derived slip rates of 24 ± 1 mma
1
have
been estimated from regional block models [McClusky et al., 2000] with local estimate s of 22 ± 3 mm a
1
at
the western end of the fault [Straub et al., 1997]. The North Anatolian fault formed as a result of strain
localization, between 13 and 11 Ma in the east with much younger (<1 Ma) esti mates of strain localization
in the west [Şengör et al., 2005]. Comparisons of geodetic and longer-term, geologic slip rates suggest that
movement along the fault is currently faster than it has in the past [Reilinger et al., 2006] and may not have
formed immediately following the collision of Arabia [Allen, 2010].The East Anatolian fa ult is a 550 km long
plate-bounding transform fault between the Arabian and Anatolian plates (Figure 1). Geodesy reveals that
the East Anatolian fault has a modern slip rate of 9.7 ± 0.9 mm a
1
[Reilinger et al., 2006]. Its poorly resolved
total offset estimated between 8 and 30 km is much less than the North Anatolian fault [Westaway and Arger,
2001], resulting from both lower slip rates and later inception between 5 and 2 Ma ago [Yilmaz et al., 2006].
This northeast trending left-lateral transform fault zone forms a triple junction with the North Anatolian fault
in the northeast and with the Dead Sea fault zone in the southwest. The relative African-Arabian plate
motions have been accommodated by the left-lateral Dead Sea fault zone at a rate of 4.54. 8 mm a
1
[Reilinger et al., 2006].
In addition to Arabian collision and Aegean extension, the tectonics ofCentral Anatolia has been inuenced by
the subduction of the African slab beneath Anatolia. The geochemical signature of postcollisional volcanism
and geophysical estimates of lithospheric thickness in Eastern Anatolia have also led to interpretations of slab
breakoff and delamination of mantle lithosphere in Eastern Anatolia sometime after 11Ma [Şengör et al.,2003;
Keskin, 2003]. This slab break-off event beneath the Eastern Anatolian compressional province (Figure 1) has
been proposed as a potential trigger for the initiation of the North Anatolian fault [Faccenna et al., 2006].
Recent studies of Pn [Gans et al., 2009] and Pwave [Biryol et al., 2011] tomography are consistent with the
CAFZ being a major lithospheric-scale structure be the western extent of and interpretations that it may be
the slab break-off event beneath Eastern Anatolia.
Early GPS studies [McClusky et al., 2000; Reilinger et al., 2006] found that the Anatolian plate extrudes westward
away from the Arabian collision zone as a counterclockwise-rotating coherent rigid body, requiring minimal
internal plate deformation. This contrasts with the geologic record, which reveals a complex history of
deformation within the Anatolian plate along second-order tectonic structures such as the CAFZ [Koçyiğit
and Beyhan, 1998; Umhoefer et al., 2007; Idleman et al., 2014], the Malatya-Ovacık fault zone [Kaymakci
et al., 2006; Westaway et al., 2008], the Sürgu fault [Koç and Kaymakcı, 2013], and the Tüz Gölü fault zone
(TGFZ) [Çemen et al., 1999]. Furthermore, a review of regional paleomagnetic data shows a gradual east to
west transition from counterclockwise to clockwise block rotations between smaller crustal blocks across
Anatolia since 12 Ma [Piper et al., 2010]. Heterogeneous deformation patterns in Central Anatolia have also
been demonstrated by a recent geodetic study. Aktuğet al. [2013] use a dense array (3050 km spacing) of
GPS stations that demonstrate extension rates of up to 2 mm a
1
and 50100 nanostrain a
1
along the middle
part of the CAFZ [Aktuğet al., 2013].
2.2. The Central Anatolian Fault Zone (CAFZ)
Koçyiğit and Beyhan [1998] proposed the existence of the CAFZ (Figure 2), dened as an active major
intracontinental shear zone, linking a system of similarly striking, potentially interconnected faults for 730 km
from the North Anatolian fault across the interior of the Anatolian plate and into the Mediterranean Sea.
They suggested that it nucleated in its southern part by reactivation of the Ecemişfault (Figure 2) and
then propagated to the NE and SW to cross the entire Anatolian plate. They divided the fault system into
three parts (north, central, and south) and 24 distinct fault segments that record up to 24 km left-lateral
displacement since the late early Pliocene. Subsequent studies either disputed the proposed activity and
continuity of the fault zone [i.e., Westaway, 1999; Westaway et al., 2002] or focused on the kinematics and
structure of individual faults [Çetin, 2000; Jaffey and Robertson, 2001; Dirik, 2001; Koçyiğit and Erol, 2001;
Jaffey et al., 2004; Akyuz et al., 2013; Sarıkaya et al., 2015b]. From SW to NE, the following active segments have
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 3
been veried. Two major, recently active fault strands mark the Ecemişcorridor near the town of Demirkazık
[Koçyiğit and Beyhan, 1998, 1999]. At the eastern margin of the Ecemişfault zone, the Cevizlik fault is a steeply
west dipping mountain-front normal fault bounding the west side of the Aladağlar Range. It juxtaposes
Mesozoic carbonates of the Taurides in the footwall against the Oligocene-Miocene Burç and Cukurbağ
formations and overlying Quaternary alluvium in the hanging wall. The Demirkazık-Sulucaova fault runs parallel
to the Cevizlik fault in the center of the valley and shows clear signs of normal and sinistral displacement.
These active fault segments comprise an array of strands that dene the Ecemişcorridor, or graben, a fault
zone that obliquely cuts through the more E-W striking structures of the Tauride platform. The fault was
rst studied by Yetiş[1984], who dated its main phase of activity to the Paleocene-Eocene based on biostra-
tigraphy and inferred 80 km left-lateral displacement. Jaffey and Robertson [2001] proposed a similar total
left-lateral Cenozoic offset of 60 km based on structural and stratigraphic evidence with most of the strike-slip
displacement occurring between 13 and 5 Ma. However, they also identied a younger kinematic phase in
Pliocene-Quaternary deposits, which records mostly east-west extension along the Ecemişfault zone with
a minor strike-slip component. The change in kinematics was attributed to rotation of the fault zone from
NE-SW to its modern NNE-SSW orientation, which more easily accommodates the current E-W extension
associated to the westward extrusion of Anatolia [Jaffey and Robertson, 2001].
North of the Ecemis corridor the CAFZ broadens to 30km in the southern Erciyes extensional basin (Figure 2).
The basin is bounded by the Yeşilhisar and Develi normal faults in the west and east, respectively. The
Dundarlı-Erciyes fault maintains the trend of the Ecemişfault zone through the center of the basin and
continues as the Gesi fault on the north side of Erciyes Dağstratovolcano, where it then bounds the basin
in the SE. The Yeşilhisar fault bends to the NE near the town of Incesu and becomes the Erkilet fault, which
bounds the basin in the NW. The center of the Erciyes basin is occupied by Mount Erciyes, the largest
Figure 2. Composite digital elevation model and shaded relief map of Central Anatolia. The thick black lines indicate major
plate boundaries NAFZ: North Anatolian fault zone and EAFZ: East Anatolian fault zone. The thin black lines represent
second-order tectonic structures, CAFZ: Central Anatolian fault zone, MOFZ: Malatya Ovacık fault zone, TGFZ: Tüz Gölü fault
zone KFZ: Kozan fault zone, major polygenetic volcanoes in oranges ED: Erciyes Dag, KD: Hasan Dag, DD: Develi Dag, MD:
Melendiz Dag, HD: Hasan Dag, metamorphics of the Central Anatolian Crystalline Complex are in purple, including the
Nigde Massif, ND along the Ecemis fault. Xand Zare sinistral piercing points (28 km) proposed in Toprak [1998].
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 4
stratovolcano in Central Anatolia (Figure 2), covering an area of over 555 km
2
and reaching 3917 m above
sea level, nearly 3000 m above the surrounding extensional basin. Mount Erciyes developed in two stages.
Construction of the Koç Dağvolcano in the eastern part of the complex culminated with caldera collapse
and deposition of the regionally extensive Valibaba Tepe Ignimbrite [Şen et al., 2003]. Normal faulting with
a minor strike-slip component is pervasive in these older volcanic units. The second stage of volcanism
(2.6 Ma to present) constructed Mount Erciyes. The slopes of the central volcano are dotted by numerous
andesitic, dacitic, and basaltic lava domes, ows, and cinder cones [Şen et al., 2003]. Many studies have
inferred faults crossing the volcano [Koçyiğit and Beyhan, 1998; Kayseri sheet, Mineral Research and
Exploration General Directorate (MTA),2002;Jaffey et al., 2004], but the accumulation of volcanic products
limits fault exposure. The Erciyes basin has been interpreted as both a releasing bend and a pull-apart
basin [Toprak, 1998; Koçyiğit and Erol, 2001] with estimated offset of 28 km based on the distribution of
volcanoes proposed to have been aligned prior to basin opening ([Toprak, 1998] Xand Yin Figure 2).
Koçyiğit and Erol [2001] suggested that the opening of the basin followed the deposition of the Valibaba
Tepe Ignimbrite, while Jaffey et al. [2004] claimed that the most recent faulting in the Erciyes basin
occurred along the sinistral Dundarlı-Erciyes fault and can be linked with late Quaternary strike-slip faulting
in the Ecemişcorridor.
The northern CAFZ consists of a broad, 2580 km wide zone stretching 200 km from north of the Erciyes basin
toward the North Anatolian fault (Figure 2). It consists of dominantly strike-slip, NE trending sinistral strike-slip
faults and related pull-apart basins [Yılmaz and Yılmaz, 2006]. From north to south, the major left-lateral
structures include the Kızılırmak, Gemerek-Şarkışla, Delier, and Tecer faults (Figure 2). Koçyiğit and Beyhan
[1998] hypothesize that these faults follow a zone of weakness along the Inner Tauride suture zone. The
southernmost Tecer fault has been active during the Holocene as a slow-moving, pure strike-slip fault, with
an estimated slip rate of 1 mm a
1
[Akyuz et al., 2013].
Existing work has not demonstrated clearly the fault zone connectivity or robust offset markers, the lack of
which provides the motivation for this study. We have targeted key sites where different parts of the fault
zone are thought to connect or demonstrate left-lateral offset.
3. Methods
3.1. Mapping
Pliocene and Quaternary fault traces were mapped using high-resolution (50 cm) Digital Globe WV01
panchromatic and WV02 multispectral satellite imagery and Advanced Spaceborne Thermal Emission
and Reection digital topography. Kinematic data and strain markers were measured in the eld on fault
planes and plotted on stereonets. Fault scarp topography was surveyed in the eld using a Trimble R3
GPS System. Data were projected on straight transects perpendicular to the scarps. Land surfaces were
interpolated from elevation points on either side of the fault scarps. To calculate throw and extension, fault
angle was measured in the eld, and the fault plane was assumed to intersect the ground surface at the
midpoint of the fault scarp.
3.2. Volcanic Geomorphology
Linear arrays of vents are common in monogenetic volcanic elds, when multiple vents are sourced from
the same magma feeding dike. Dikes are often in line with the principal compressive stress ([Rubin, 1995]
World Stress Map Project [Heidbach et al., 2001]) and perpendicular to the minimum principal stress (σ
3
)
[Paulsen and Wilson, 2010; Le Corvec et al., 2013]. We employ the azimuth methods of Cebriá et al. [2011]
for statistical identication of meaningful vent alignments. Local-scale alignments are identied statistically
by considering mean intervent distance (X) and standard deviation (σ) for the entire eld. We nd that
preferred orientations are best identied when considering vents within the lower half of the anomalously
short distances (i.e., d(xσ)/2). Best t lines of the center points are determined by linear regression and
dene the alignments azimuth and length.
3.3. Geochronology
3.3.1. Cosmogenic
36
Cl Dating
We combine geomorphic analysis of offset fan and terrace surfaces in the Ecemişcorridor with terrestrial
cosmogenic nuclide exposure dating [Gosse and Phillips, 2001; Gosse, 2011] to estimate prehistoric slip rates.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 5
The lack of large boulders on the surface and
the presence of a >2 m thick petrocalcic
horizonintheshallowsurfacecausedusto
use surface cobbles for modern dating the
fan surface. We collected cobbles from the
well-cemented calcrete surfaces of an alluvial
fan (three cobbles) and of a uvial terrace
(four cobbles). These well-rounded cobbles
range from 10 to 15 cm in diameter. We
selected only samples that were stable within
the cemented surface, extracted from calcrete
exposed through variably thick soil and
regolith. Low surface slopes and high degree
of cementation indicate that the cobbles
have not been moved or otherwise disturbed
since emplacement.
To date the emplacement of the cobbles
within the alluvial units we used in situ-produced
36
Cl generated within the limestone and
marble clasts. The limestone cobbles were
cleaned of pedogenic carbonate by chipping
and leaching in dilute HNO
3
acid, then dried,
crushed, and sieved. Approximately 29 g of
the 355500 μm fraction of single-cobble
samples were prepared at the Dalhousie
Geochronology Centre according to the car-
bonate methodology of Stone et al. [1996].
Approximately 1.8 mg of Cl spike prepared
from an Oak Ridge National Laboratory Cl
salt with
35
Cl/
37
Cl ratio of 0.999 was added
to each sample. The
36
Cl/Cl
T
and
35
Cl/
37
Cl
were measured by accelerated mass spectro-
meter at Purdue Rare Isotope Measurement
Laboratory, Purdue University, against stan-
dard SRM4943. Accelerator mass spectro-
metry (AMS) 1σprecision was between 2
and 4% for the samples, and the process
blank yielded a ratio 2 orders of magnitude
less than values measured in the samples.
Major elements were measured by XRF, and
selected trace elements were measured by
inductively coupled plasmamass spectro-
metry at SGS Mineral Services in Lakeeld,
Ontario, with 5% (1σ) precision. Over 95%
of in situ
36
Cl in our limestone samples was
produced from spallation from Ca. Data
reduction followed the procedure by Marrero
[2012], with calibrated
36
Cl production rates
according to Marrero [2012] and scaling
according to Lifton et al. [2014]. Ages were
computed by the
36
Cl CRONUS-Earth online
calculator Web calculator v. 1.0 accessed in
August 2015 (Cosmic-Ray Produced Nuclide
Table 1. Sample Characteristics and Geochemical and Isotopic Analytical Data for Sample From EcemişFault Zone
Major Elements (wt %)
f
Trace Elements (ppm)
g
Sample
No.
a
Thickness
b
Latitude
(°N)
c
Longitude
(°E)
c
Elevation
(m)
d
Shielding
e
Al
2
0
3
CaO Fe
2
O
3
K
2
O MgO MnO Na
2
OP
2
O
5
SiO
2
TiO CO
2
Cl
h
BSmGd U Th
TIIC-02a 3 cm 37.50 35.05 1759 0.997 0.04 55.2 0.03 0 0.33 0 0 0 0.06 0 43.6 36.6 0 0.2 0.28 0.23 0.3
TIIC-02b 3 cm 37.50 35.05 1759 0.997 0.05 54.8 0.02 0 0.47 0 0.03 0.02 0.13 0 43.9 53.0 0 0.1 0.06 0.16 0.2
TIIC-02d 3 cm 37.50 35.05 1759 0.997 0.07 54.9 0.07 0 0.36 0 0.01 0.02 0.12 0 43.8 48.9 0 0.3 0.29 0.26 0.2
TIIC-06b 3 cm 37.85 35.07 1605 0.998 0.06 55.3 0 0 0.23 0 0.02 0 0.17 0 43.5 21.9 0 0.2 0.29 0.22 0.1
TIIC-06c 3 cm 37.85 35.07 1609 0.998 0.04 55.8 0.04 0 0.34 0 0.03 0 0.19 0 42.9 43.4 0 0 0 0.18 0
TIIC-06e 3 cm 37.85 35.07 1609 0.998 0.04 55 0 0 0.32 0 0.02 0.02 0.11 0 43.8 26.9 0 0.2 0.23 0.14 0
TIIC-06f 3 cm 37.85 35.07 1609 0.998 0.04 55.1 0.03 0 0.33 0 0.02 0.01 0.21 0 43.5 26.5 0 0.1 0.08 0.14 0
a
Water content assumed at 0.05 wt %.
b
Average sample depth used for thickness correction.
c
Decimal degrees, from handheld GPS ± 5 m.
d
Decimal degrees, from handheld GPS ± 15 m.
e
Calculated from 30° measurements of the inclination to the horizon using a handheld clinometer.
f
Major element concentration detection limits are 0.01%.
g
Trace element detection limits are 0.1 ppm.
h
The
36
Cl/Cl(total) ratio measured with AMS on spiked samples and converted back to original rock values.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 6
Systematics on Earth: http://web1.ittc.ku.edu:8888/). All
essential sample information to calculate the ages is
provided in Tables 1 and 2.
3.3.2.
40
Ar/
39
Ar Dating
Additional age constraints on faulting were provided
by dating of ve volcanic samples, including lava
ows, monogenetic volcanoes, and welded ignimbrite
ows. Samples were selected from unweathered inter-
iors of outcrops.
40
Ar/
39
Ar analyses were completed at
U.S. Geological Survey (USGS) in Denver, Colorado
(two analyses) and University of British Columbia in
Vancouver, Canada (three analyses). We use a combi-
nation of incremental heating experiments of whole
rock (three samples) and amphibole (one sample)
and individually fused plagioclase grains (one sample).
Initial data entry and calculations were carried out
using the software ArArCalc [Koppers, 2002]. The plateau
and correlation ages were calculated using Isoplot
v. 3.09 [Ludwig, 2003]. Errors are quoted at the 2 sigma
(95% condence) level and are propagated from all
sources except mass spectrometer sensitivity and age
of the ux monitor. Additional details are given in the
supporting information.
4. Site Analysis
Results and implications are presented from south to north.
4.1. Site 1 EcemişCorridor
The steeply dipping, range-front, Cevizlik fault scarp
(Figure 3) is several hundred meters high in places,
and the fault has ruptured late-Quaternary colluvium
(Figure 4a) with minimal normal displacements (<1m;
Figure 4b). The Cevizlik fault can be traced sporadically
along the entire length of the Ecemişcorridor. The
Demirkazık-Sulucaova fault has a narrow (1050 m),
linear N25°E trending oblique strike-slip trace located
in the center of the Ecemişvalley, with a length of
19.1 km. Shutter ridges, elongated hills, and deected
and offset stream courses are found along its trace,
providing evidence of recent left-lateral displacement
on the Demirkazık-Sulucaova fault. The main east
dipping fault scarp is well exposed in a stream cut
south of Pınarbaşı, where it dips 65° and displaces
both Oligocene-Miocene sediments and a Quaternary
alluvial fan surface. A series of uvial terraces bury
the Demirkazık-Sulucaova fault in several locations and
present an ideal site to constrain short-term slip rates.
4.1.1. Geomorphic Surfaces
Alluvial fans in the study area are extensive in plan
view, have wedge-shaped geometries, and are fed from
both the Yaluk and Emli River drainages (Figure 3). Away
from the mountain front, slopes shallow to 34° in the
middle and distal parts of the fan. The basal, texturally
Table 2.
36
Cl Cosmogenic Isotope Data, Production Rates, and Mean Surface Ages
Sample ID
36
Cl Cosmogenic
(10
4
atoms g
1
sample
1
)
36
Cl Cosmogenic
(atoms g
1
sample
1
)
Production Rate
a
(atoms g
1
yr
1
)
36
Cl Cobble
Age
b
No
Erosion
36
Cl Cobble
Age
b
7mmka
1
36
Cl Cobble Age
b
7mmka
1
a
Inheritance
Correction
d
Surface
Age
c
No
Erosion
Surface Age
c
7mmka
1
Surface Age
c
7mmka
1a
Inheritance
Correction
d
TIIC-02a QAF-1 819 ± 40 8192876 63.7 100 ± 10 ka 108 ± 12 ka 104 ± 12 ka 97.5 ± 10 ka 105 ± 15 ka 98.6 ± 13 ka
TIIC-02b 775 ± 37 7752707 63.7 93 ± 9.5 ka 102 11 ka 92 ± 11 ka
TIIC-02d 830 ± 38 8295015 63.7 94.1 ± 9.6 ka 110 ± 12 ka 101 ± 12 ka
TIIC-06b QFT-1 326 ± 16 3257284 54.0 45.6 ± 4.6 ka 48 ± 5.5 ka 48.2 ± 5.5 ka 42.9 ± 4.4 ka 44.5 ± 4.6 ka 40.3 ± 4.0 ka
TIIC-06c 325 ± 14 3245276 55.0 43.4 ± 3.9 ka 47 ± 5.0 ka 38.1.8 ± 3.6 ka
TIIC-06e 288 ± 19 2879095 53.7 40.5 ± 3.9 ka 42 ± 4.6 ka 42.0 ± 4.3 ka
TIIC-06f 308 ± 13 3079791 53.9 43 ± 3.9 ka 45 ± 4.6 ka 37.9 ± 3.6 ka
a
Total production rate of
36
Cl over the total sample thickness.
b
Uncertainties given at 1σand calculated by AMS reported analytical error on
36
Cl/Cl ratio.
c
Weighted average of cobble ages with uncertainties. Weighted mean uncertainties are analytical, as they were greater than the error due to the spread of the data.
d
Inheritance corrected using inherited component of
36
Cl reported in Sarıkaya et al. [2015b].
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 7
immature clastic intervals of the fan deposits are interpreted as high-energy debris ows formed in response
to steep slopes created by mountain-front extensional faulting on the Cevizlik fault [Jaffey and Robertson,
2005]. Paleocurrent trends within the fan deposits show ow direction perpendicular to the mountain front.
The Quaternary alluvial fan units (QAF-1 to QAF-3) unconformably overlie the heavily deformed Miocene Burç
and Cukurbağformations. Statigraphically higher depositional units within the fans are more texturally
mature, displaying imbrication, good sorting, and strong lamination in distal parts of the fan (Figure 4d).
The conglomerates are monogenetic and coarse grained, comprising well-rounded to subrounded pebble
to cobble-sized clasts sourced almost entirely from the Jurassic limestones of the Aladaǧlar Range. The upper
surface is well cemented by calcrete. The capping lithied horizon increases in thickness from 4 to 5 m in the
distal parts of fan. The surface is generally low relief and well preserved, although thin regolith and localized
incision of up to 30 cm is not uncommon. Similar fossilizedgeomorphic surfaces have been described in
Figure 3. Hillshade base map with a Quaternary geomorphic map of the northern Ecemişfault zone. Ages presented are
from this study (QAF-1 and QFT-1) and Sarıkaya et al. [2015a, 2015b] (QAF-1,QAF-2, and QAF-3).
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 8
SE Spain by Stokes et al. [2007], who attributed calcrete development to a combination of pedogenic and
groundwater processes. Over time, calcrete encasement of these surfaces increases, stabilizing the surfaces
and protecting them from erosion.
Three levels of abandoned river terraces stand 5 (QFT-3), 10 (QFT-2), and 20 m (QFT-1) above the Yaluk stream
(Figure5b).Theirdepositsaremadeofwell-sorted conglomerates and gravels, composed of rounded
limestone clasts 1 to 15 cm in diameter. The degree of cementation of the calcrete horizon capping these surfaces
increases with height (and inferred age) of the abandoned terraces. The youngest (lower) uvial terraces are
unconsolidated at the surface, while the oldest uvial terrace (QFT-1) has a well-cemented horizon down to a
maximum depth of 1 m. Similar surfaces are deeply incised along the Emli River and are described in detail
by Sarıkaya et al. [2015a, 2015b]. At both localities, these surfaces are undeformed where they cross the
Demirkazık-Sulucaova fault and record no vertical or horizontal offset (Figure 5b).
4.1.2. Displacement
Alluvial fans in active tectonic settings can provide excellent piercing points to constrain offset, where
recently active faults displace streams or terrace risers. Interpretation of these geomorphic landforms
can be complex, and careful consideration of multiple piercing points and their reliability is required
for accurate slip rate estimates [Cowgill, 2007]. Deected and beheaded streams, offset terrace risers,
Figure 4. Field photos from the Ecemişfault zone. (a) Mountain front Cevizlik fault. (b) Cevizlik fault rupture of Quaternary
Colluvium. (c) South looking view at the east dipping oblique Demirkazık-Sulucaova fault (DSF). (d) Prole view of the distal
part of the calcrete encased Quaternary alluvial fan (QAF-1). (e) Representative sample of cobble sampled from QFT 1.
Representative sample of cobbles sampled from QAF-1.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 9
and shutter ridges record strong evidence for sinistral displacement of the QAF-1 surface along the 19.1 km
trace of the Demirkazık-Sulucaova fault. However, the study area highlights many of the complexities
associated with offset geomorphic landforms; previous studies have arrived at very different geomorphic
interpretations and estimates of late-Quaternary horizontal offset.
Koçyiğit and Beyhan [1999] cite 70 m of sinistral displacement of QAF-1 along the Demirkazık-Sulucaova fault,
although their piercing point is not explicitly documented. Jaffey and Robertson [2001] argue that for a
minimum offset of 250 m of QAF-1 based on left-lateral deection of the Fenk stream (Figure 5c). Sarıkaya
et al. [2015b] challenge this estimate, pointing out that the geometry of the east dipping Demirkazık-Sulucaova
fault creates a barrier to streams owing west from the Aladağlar Range. Low-order streams without sufcient
hydrological power to overcome the topographic barrier are deected along the fault scarp and may appear as
left-lateral offsets. Instead, Sarıkaya et al. [2015b] prefer a value of 168 ± 2 m based on a reconstruction of the
offset terrace riser immediately to the north of the Yaluk stream (Figure 5b).
We focused on the best preserved offset markers near Ҫukurbağ(Figure 5d; see Figure 3 for location), where
the terrace riser south of the MartıRiver is steeply incised and displaced (Figure 5d). Following displacement
the terrace riser located west of the fault (A in Figure 5d) was sheltered from incision and therefore presents
the clearest and best preserved evidence of recent left-lateral faulting. Lateral offset of QAF-1 was measured
from piercing points on high-resolution satellite imagery. To reconstruct total fault offset we projected both
risers toward the fault, estimating 69 ± 5 m of left-lateral displacement (A-A; Figure 5d). We presume this to
be the same offset cited by Koçyiğit and Beyhan [1999].
Figure 5. (a) Close ups of faulted and unfaulted geomorphic surfaces along the Yaluk Stream. (b) Interpreted with surfaces
with
36
Cl sample locations. (c) Uninterpreted view of the alluvial fan surface near Cukurbag. (d) Interpreted piercing points
from the same surface. Copyright Digital Globe.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 10
Vertical displacement was constrained using six GPS proles across the Demirkazık-Sulucaova fault scarp
(Figure 6). Normal displacement across the east dipping fault in proles 1 to 6 averages 25.7 ±3 m, resulting
in an approximately 3:1 ratio for strike-slip versus dip-slip displacement. Offset predating the deposition of
the QAF-1 is evident in prole 7, where the fault scarp offsets deformed Miocene sediments, which are
draped by QFT-1 deposits. Cumulative offset recorded here is 74 ± 7 m.
4.1.3.
36
Cl Exposure Ages of Geomorphic Surfaces
We dated the QAF-1 and QFT-1 surfaces along the Yaluk River using cosmogenic
36
Cl exposure dating of
surface cobbles. Sample characteristics and compositional data are listed in Table 1. As the pedogenic carbonate
horizonwhich formed at depthis now exposed at the QAF-1 and QFT-1 surfaces (Figures 4e and 4f), we
must account for erosion of the overlying soil cover. An empirical study by Royer [1999] showed that depth to
the top of pedogenic carbonate horizons is <1 m in 95% of cases studied. Field observations also show relief
of noncemented gravel up 30 cm on the QAF-1 surface. This indicates that the cobbles imbedded in the
petrocalcic horizon were previously covered by at least 30 cm. While episodic erosion cannot be excluded,
we assume a gradual and constant surface erosion rate that, depending on exposure age, will account for
0to>50 cm of total erosion. We report
36
Cl ages assuming erosion rates of 0 and 7 mm ka
1
(Table 2 and
Figure 7). Given the age of our surfaces, 7 mm ka
1
erosion rates allow for removal of as much as 60 cm from
QAF-1, a maximum amount of erosion we would expect at this site, and sufcient to exhume pedogenic
carbonate layers. We observed no indication of sediment aggradation after formation of the main petrocalcic
horizon. The lack of aggradation is reasonable considering the depth of incision of these fans, which would
Figure 6. Topographic proles used to constrain normal offset of the DemirkazıkSulucaova fault. Geomorphic surface
slopes and a eld observed fault angle of 65° are used to reconstruct original fault geometry and calculate both throw
and extension. See Figure 3 for prole locations.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 11
have caused the stream to abandon the
surfaces. Thus, we have only considered
surface erosion in our age calculation.
Sarıkaya et al. [2015a, 2015b] identied
and dated the same geomorphic surfaces
(QAF-1 and QFT-1) along with two alluvial
fan surfaces along the Emli River (QAF-2
and QAF-3 in Figure 3). Their study used
36
Cl dating of surcial samples (cobbles
and boulders) and a 2.6 m depth prole
in the QFT-1 surface. Their depth prole
revealed an inherited component of
49.6 × 10
4
atoms
36
Cl g
1
, and this inheri-
tance correction was also applied to
their QAF-1 age. Their ages were scaled
using the model of Desilets and Zreda
[2003], which we found to produce ages
1 to 3% younger than our preferred
time-dependent scaling methods from
Lifton et al. [2014].
The three cobbles (TIIC-02a, TIIC-02b,
and TIIC-02d) from the QAF-1 surface
(Figures 3 and 5) show a strong cluster,
with ages of 100 ± 10, 93 ± 9.5, and 94.1 ± 9.6 ka (Table 2; 1σtotal external uncertainty). The surface has a
weighted average age of 97.5 ± 10 ka. When corrected for 7 mm ka
1
erosion rate (Figure 7), our data give
a weighted average age of 105 ± 15ka with a 4.4% coefcient of variation (Table 2). The 7 mm ka
1
erosion
rate increases the mean age calculated for the QAF-1 by 7.7% from the zero erosion age. However, the
coefcient of variation about the mean ages of the individual cobbles from the QAF-1 surface (4.4%) is less than
the total precision of each age (>10% 1σ). This suggests that the inherited
36
Cl concentration is either very low
or very consistent, as it is unlikely that three cobbles would yield such similar ages if inheritance was signicant.
We favor the former, simpler interpretation because for a low inheritance catchment erosion rate must be
relatively high; a high erosion rate is consistent with the observation that catchments and valleys in Aladağlar
Range were glaciated during late Pleisotocene-Holocene time [Zreda et al., 2011]. However, we also make
a correction for inheritance using in recently published data from Sarıkaya et al. [2015b] that are included
in Table 2. When corrected for erosion, the 7 mm ka
1
surface age decreases to 98.6 ± 13 ka (or ~6%).
The four cobble samples (TIIC-06b, TIIC-06c, TIIC-06e, and TIIC-06f) analyzed from the QFT-1 surface
(Figures 3 and 5) yielded younger ages than the QAF surface: 48.2 ± 5.5, 44.6 ± 4.3, 42 ± 4.3, and
44.8 ± 4.4 ka (1σtotal uncertainty) corrected for 7 mm ka
1
of erosion, yielding a weighted average ages
of 44.5 ± 4.6 ka (43.0 ± 4.4 ka with zero erosion). Like t he QAF-1 surface, the ages have a low coefcient
of variation about their mean (5.0%).When corrected for erosion, the 7 mm ka
1
surface age decreases to
40.3 ± 4.0 ka (or ~9%).
When the different data sets are treated the same way (Desilets and Zredas [2003] scaling, corrected for
inheritance; 7 mm ka
1
) our su rfaces have average ages of 95.8 ± 12 ka (QA F-1) and 39.7 ± 16 ka (QFT-1)
compared with ages of the 104.2 ± 16.5 ka (QAF-1) and 64.5 ± 5.6 ka (QFT -1) reported from Sarıkaya et al.
[2015b]. We proceed in slip-rate calculations with our exposure ages of 105 ± 15 (QAF-1) and 44.5 ± 4.6 ka
(QFT-1), based on our own production rates using the scaling method of Lifton et al. [2014] and an erosion rate
of 7 mm ka
1
(Table 2).
4.2. Site 2: Dundarlı-Erciyes Fault
The Dundarlı-Erciyes fault trends N25°E north of the Ecemişcorridor and probably continues beneath the
southern Erciyes basin (Figure 2). The fault has acted as a conduit for numerous dacitic lava domes but is
buried beneath the peak of the Erciyes stratovolcano (Figure 8). At least 75 monogenetic volcanic vents
Figure 7.
36
Cl ages for cobblesamples from the QAF-1 and QFT-1 surfaces.
The black squares are ages corrected for erosion, and the orange squares
are uncorrected for erosion. The horizontal black lines indicate the
weighted mean age for each surface with grey boxes indicating the
surface uncertainty. Time intervals between the two surfaces were used
to calculate Demirkazik-Sulucaova fault slip rates.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 12
are distributed on the volcano anks. Twelve of these are basaltic cinder cones and 63 are lava domes, mostly
rhyolitic and dacitic in composition. Alignments of monogenetic vents radiate out from the central peak,
particularly to the west. On the SW ank of the volcano a series of volumetrically small dacitic-rhyodacitic lava
domes are tightly aligned (Figure 8). The alignment has deected the course of a younger dacite ow,
erupted from Dikkartin Dağ(Figure 8), dated to 0.115 ± 0.02Ma [Ercan et al., 1994].
In the absence of fault surface ruptures through the southern Erciyes basin and the Erciyes volcanic complex,
we use the alignment of volcanic vents to infer syneruptive stresses along this buried portion of the CAFZ.
Figure 8. (a) Geologic map of the Erciyes stratovolcano on 50 m contour intervals and a shaded relief map, modied from
Şen et al. [2003]. Samples and age data from this study and for Dikkartin Dağ(DD) from Ercan et al. [1994]. (b) Vent to vent
azimuths for vents within 2.86 km.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 13
When we consider anomalously close vents (d(X σ)/2 or 2.86 km), a dominant azimuth direction of
25 to 35° points to an anomalous high-frequency cluster on the SW ank, where the Dundarlı-Erciyes fault
is expected to cross through the stratovolcano. Fifteen individual volcanic vents are aligned above the
projection of the Dundarlı-Erciyes fault. Homogeneous lithology, spatter ramparts parallel to the alignment
and tight vent-to-vent spacing of between 200 and 500 m indicate that the eruptions were controlled by a
fracture with low conning pressure or an extensional fault [Corazzato and Tibaldi, 2006; Paulsen and
Wilson, 2010]. The alignment azimuth of N32°E indicates extension in a WNW-ESE direction along the NNE
trending fault [Nakamura, 1977; Paulsen and Wilson, 2010]. Two samples from the aligned dacite domes
(Figure 9b) were collected for
40
Ar/
39
Ar dating. They are grey porphyritic dacites with 13 mm quartz, feldspar,
and hornblende phenocrysts.
40
Ar/
39
Ar dating of the groundmass yielded ages of 210 ± 18 ka (Erciyes Dag (ED)
1301) and 580 ± 130 ka (ED 1303) (Figure 9c). As geomorphic markers, these domes record no strike-slip
offset since emplacement.
4.3. Site 3: Erkilet and Gesi Faults
North of the Erciyes stratovolcano the CAFZ continues to bound the Erciyes basin (Figure 10a) and offset
at-lying volcanics of the Central Anatolian volcanic province. Relief from the oor of the Erciyes depression
to the surrounding plateaus is 400 to 500 m.
Figure 9. (a) SW view from the ED VOL 1301 sample location looking down the vent alignment at ED VOL 1303.
(b) Satellite Image of the rifted vent alignment and sample locations. Copyright Digital Globe. (c)
40
Ar/
39
Ar results for
Erciyes volcanic samples.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 14
The Gesi fault makes up the northeast margin of the Erciyes basin, trending N30°E for 3035 km through the
towns of Talas and Gesi (Figure 10a). It juxtaposes the Valibaba Tepe Ignimbrite in its hanging wall against
older pyroclastics in its footwall. The trace of the fault is generally linear, with one major left step linked
by a NNE-SSW trending pure normal fault. At multiple locations, syndepositional faulting is seen in the
Plinian deposits underlying the Valibaba Tepe Ignimbrite (Figure 11), which shows that activity along the
Gesi fault began before emplacement of the Valibaba Tepe Ignimbrite, which yielded an
40
Ar/
39
Ar date of
2.73 ± 0.08 Ma on plagioclase phenocrysts (n= 10) (T11V02; Figure 12c). The Gesi fault terminates at its south-
ern end beneath the Ali Dağvolcanic dome, an endogenic lava dome of andesitic composition. The Gesi fault
plane acted as a conduit for its emplacement. The lava dome does not exhibit any vertical or horizontal offset.
Itscoolingageis1.0±0.3Ma,determinedfrom
40
Ar/
39
Ar dating of amphibole phenocrysts (11TR-08; Figure 12b),
thus providing a minimum age for the end of activity along the Gesi fault. Our topographic surveys show that
cumulative displacement on the Gesi fault reaches 230m near Talas in the SW and decreases along strike
to 130m near Gesi in the northeast. Near the town of Gesi (Figure 11c), the exposed main fault scarp has been
produced by a steep 80° west dipping fault, trending N25°E. Displacement vectors (Figure 13c) show sinistral-
normal strain, with a rake of 45° to the fault plane, suggesting a small component of left-lateral motion along
the Gesi fault. N-S trending antithetic normal faults (Figure 11c) dipping 60° toward the east are abundant
and produce a horst-and-graben structure just east of the main strand.
The Erkilet fault bounds the Erciyes basin to the northwest; it extends over 3540 km in a N45°E direction from
SW of Erkilet to the Tuzla Gölü (Figures 2 and 10). The fault juxtaposes a at-lying lacustrine carbonate unit
and underlying horizontal basalt ow in the hanging wall with a thick volcaniclastic sequence in the footwall,
made up of weakly deformed tuffs and pumice deposits. A basalt ow, with a groundmass dated to 2.22 ± 0.25 Ma
Figure 10. (a) Geologic map of the northern Erciyes basin. The yellow stars denote
40
Ar/
39
Ar geochronology samples. Modied from Kayseri sheet, MTA [2002];
(b) cross section.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 15
(ERK VOL-1307: Figure 12a), is exposed
on both sides of the main fault and is
downthrown >40 m to the basin oor
in a step-like morphotectonic pattern
where relay ramps connect up to four
separate normal faults (Figure 11a). The
basalt conformably overlies horizontally
stratied volcaniclastics and is truncated
by the main Erkilet fault strand. There
is no indication that the basalt ow
cascaded down an already developing
fault scarp; therefore, we interpret it to
record onset of Erkilet fault activity.
Fault slip indicators (Figure 13c) point to
mostly N-S and NW-SE directed exten-
sion, oblique to the trace of the fault
plane, but no signicant left-lateral offset
is observed in the faulted volcanics.
North of Kayseri, horst-and-graben
structures (Figure 11b) are well exposed
in the basin center. The Valibaba Tepe
Ignimbrite and underlying pyroclastics
record syndepositional faulting and
are vertically displaced up to 10 m.
Steep normal faults bounding the
central basin structure strike N40°E and
W35°S in the west and east, respectively
(Figure 11b). The geometry of the fault
planes suggests that the structure opens
to the south and pinches to the north.
Strain markers on major and minor
faults are almost pure dip slip and indi-
cate NW-SE extension (Figure 13c).
Vertical displacements across theErkilet
and Gesi faults were measured with
GPS proles (Figure 10b). For the Gesi
fault vertical offset is constrained to 220m, as measured by the offset of the Valibaba Tepe Ignimbrite on both
sides of the fault. The Erkilet fault records a minimum vertical offset of 310m, as the downthrown basalt is
exposed in the hanging wall of only the rst few step faults and is buried in the hanging wall beneath the
Quaternary basin ll. Coupled with geochronological constraints for initiation of major activity on each fault
(Erkilet: maximum interval of 2.22 ± 0.25 to present; Gesi: maximum interval of 2.73 ± 0.08 Ma to 1.0 ± 0.3 Ma)
we are able to estimate minimum vertical displacement rates of ~0.100.18 mm a
1
on each fault and horizontal
extension rates of less than 0.1 mm a
1
. These rates are minimums based on the average fault dip observed
in the northern Erciyes basin, 68 ± 7° (n=45). Considering that these two faults account for only 0.060.17 mm a
1
of extension across the basin, and modern, GPS-derived rates range up to 2 mm a
1
[Aktuğet al., 2013],
additional extension is likely accommodated by buried, antithetic, and/or listric fault geometries at depth.
An alternative scenario is recent acceleration of fault slip rate within the Erciyes basin.
5. Discussion
5.1. Quaternary Activity of the CAFZ
Original interpretations of the CAFZ by Koçyiğit and Beyhan [1998] argued for the presence of a major
intracontinental shear zone crossing the entire Anatolian plate, developed in the Pliocene-Quaternary to
Figure 11. Field photos from the northern Erciyes basin, see Figure 10 for
photo locations. (a) Downthrown basalt and step-like faulting pattern
along the Erkilet fault. (b) Graben structures in the central Erciyes basin.
(c) Main fault scarp and antithetic faults along the Gesi fault.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 16
accommodate the northward motion of the Arabian plate. Those authors proposed that the CAFZ developed
a total neotectonic offset of up to 24 km and has an active slip rate of 3 mma
1
. We question much of the
evidence they proposed for the left-lateral nature and the continuity of the CAFZ.
The strongest evidence for an active component of sinistral displacement on the CAFZ comes from the
Demirkazık-Sulucaova fault in the Ecemişcorridor. Displacement of the QAF-1 surface accumulated after
the abandonment of the surface and before the formation of the QFT-1 surface, an interval of 52 ± 12 ka
for the zero erosion case and 61 ± 14 ka for the 7 mm ka
1
erosion case. Combining this time interval with
sinistral offsets ranging from 69 ± 5 m to 254 ± 3 m a range of minimum slip rates can be estimated. We agree
with the interpretation of Sarıkaya et al. [2015b] that the ~250 m Fenk stream bend is a result of stream
deection around a rising topographic barrier and not a reliable marker of fault offset. However, we challenge
their proposed piercing point that yield table 68 ± 2 m offset of the QAF-1 terrace riser north of the Yaluk
stream (Figure 3b). No comparable offset of this feature was observed in the eld or from satellite imagery.
Additionally, terrace risers on the north side are displaced into the stream path and are therefore subject
to reworking by erosion. We therefore consider the offset observed at the Marti River (Figure 5d) to be
Figure 12.
40
Ar/
39
Ar age (weighted plateau) derived from step heating of samples in the northern Erciyes basin. See Figure 10
for sample locations. T11V02 is an age probability diagram of single-crystal laser fusion of 10 individual plagioclase phenocrysts.
The relatively large error associated with 11TR08 reects the smaller analytical signal sizes associated with these
potassium-poor grains.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 17
the most reliable. In this location, following displacement the terrace riser located downstream of the fault
trace was sheltered from incision and has therefore evolved through diffusional processes to a gentler slope
compared to the same riser located upstream of the fault. As a result the offset corner has been only slightly
truncated by erosion. Our mapping suggests that left-lateral slip on datable geomorphic surfaces totals only
69 ± 5 m, which yields a minimum strike-slip rate of 1.1 ± 0.4 mm a
1
(erosion corrected) to 1.2 ± 0.4 mm a
1
(erosion and inheritance corrected) over the period. This is lower than the previous estimates (3mm a
1
[Koçyiğit and Beyhan, 1998]). Using the maximum offset of 254 ± 3 m yields a minimum strike-slip rate
Figure 13. (a) Syndepositional faulting below the Valibaba Tepe Ignimbrite (2.73 ±0.08 Ma) along the Gesi fault (left) and (b) central Erciyes basin. (c) Stereonets
plotting fault planes and slip indicators from six sites in the northern Erciyes basin, see the map in Figure 10 for locations.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 18
of 4.2 ± 1.2 mm a
1
(erosion corrected)
to 4.4 ± 1.3 mm a
1
(erosion and inheri-
tance corrected) over the period. For
reasons mentioned above, we do not
believe this offset amount and result-
ing slip rate to be accurate.
Although its slip rate remains difcult
to constrain, the Demirkazık-Sulucaova
fault has clearly not been active since
abandonment of the QFT-1 surface
at 44.5±4.6ka. In contrast, the west
facing, range-front normal Cevizlıkfault
(Figure 3) records most of the recent
activity in the Ecemişcorridor, with
meter-scale scarps observed in young
colluvium and a cumulative vertical
offset of at least several hundred
meters at the range front. These obser-
vations are consistent with Aktuğet al.s
[2013] geodetic slip rates of less than
slip 1 mm a
1
(sinistral) and 2 mm a
1
(extensional) [Aktuğet al., 2013]. We
conclude that while the Ecemişfault
zone records left-lateral displacement
during the late Quaternary, this
is secondary to predominantly E-W
extension, coeval with multiphase
uplift of the Central Taurides (Figure 2)
from 8 Ma to present [Schildgen et al.,
2012, 2014].
Evidence for a link between faults in
the Ecemişcorridor and the Erciyes
basin is tenuous. We interpret dacitic
lava domes emplaced along the Dundarlı-Erciyes fault to record syneruptive extensional stress between
580 ± 130 and 210 ± 180 ka, with no sinistral component during that period or since dome emplacement.
This nding refutes the attempt of Jaffey et al. [2004] to link late-Quaternary strike-slip activity between
the Ecemişand Dundarlı-Erciyes faults. Therefore, the most recent phase of late-Pleistocene strike-slip
faulting described in the Ecemişcorridor is not kinematically linked to faulting farther north along the
Erciyes fault. We also argue for an earlier onset of opening of the Erciyes basin than earlier studies
[Koçyiğit and Beyhan, 1998; Koçyiğit and Erol, 2001; Dirik, 2001], which have speculated that it began after
deposition of the youngest regionally extensive ignimbrite layer, the 2.73 ± 0.08 Ma Valibaba Tepe
Ignimbrite, that is found on both margins of the basin. However, we observe that conformable pyroclastic
rocks below the Valibaba Tepe Ignimbrite are syndepositionally deformed, suggesting earlier an earlier
initiation of faulting. Ignimbrites are density currents that locally thicken in valleys and topographic lows
but are capable of draping landscapes with minimal relief [Branney and Kokelaar, 2002] and therefore could
have owed up the margins of an already opening proto-Erciyes basin. Our study suggests dominantly
extensional deformation in the northern Erciyes basin, with minimal evidence for sinistral displacement.
Our measurements of faults in the northern Erciyes basin consistently display dominantly dip-slip kinematic
indicators. This is consistent with a regional GPS strain analysis [Aktuğet al., 2013], which highlighted a zone
of WNW-ESE extension in the Erciyes basin (Figure 14). We disagree with the use of polygenetic volcanoes
along the border of the basin as piercing points [Toprak, 1998], which were used to estimate strike-slip offset
and basin extension at 28 and 45 km, respectively (Xto Yin Figure 2). Late Pliocene pyroclastics and the
Valibaba Tepe Ignimbrite are preserved throughout the central basin, meaning that the width of the basin
Figure 14. (a) Proposed model for Quaternary activity of the CAFZ, including
regional deformation rates from this study and compiled from literature. Tecer
fault [Akyuz et al., 2013] and Malatya Ovacik fault zone (MOFZ) [Zabci et al.,
2014]. Plate vectors North Anatolian fault and East Anatolian fault from
Reilinger et al. [2006]. Earthquakes from USGS earthquake catalogue [Jenkins
et al., 2013]. Strain indicators from Aktuğet al. [2013]. (b) Proposed block
model for the neotectonic framework of Central and Eastern Anatolia. The
small circular arrows are small clockwise rotations which would accommodate
a block model.
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 19
is not a valid estimation of expansion or extension. Piercing points from the basin margins are therefore
invalid as both a strike-slip and normal strain markers. Further, although Koçyiğit and Beyhan [1998] argue
for dominantly left-lateral displacement along the Gesi fault, citing 2.2 km of left-lateral offset of the
Yüzbaşı stream (Figure 10), we were unable to nd any trace of a fault in the vicinity of this bend in the eld,
and we nd no other gorges or smaller rivers which show similar offset. We attribute the bend instead to
stochastic drainage variation.
We question the continuity and importance of the CAFZ beyond our study area as well. Faults in the far
south-western part of the proposed CAFZ, including the Namrun fault and the offshore Cyprus-Anamur fault
(Figure 1 [Koçyiğit and Beyhan, 1998]), make up over 300 km of the proposed 700 km fault zone. These strands
are proposed to extend from the south of the Ecemişcorridor, connecting the fault zone to the Cyprus trench.
Recent seismic reection studies [Aksu et al., 2014], however, show that these structures likely belong to the
Kozan fault zone (Figure 2). The Kozan fault zone is a 300 km long, 1520 km wide transtensional sinistral
fault zone that splays from the triple junction between the East Anatolian fault and the Dead Sea fault zone
and extends offshore near Adana, where it separates the Tauride Mountains to the north and the Cilicia
and Adana basins to the south (Figure 2). Aksu et al. [2014] propose latest Messinian-Recent slip rates of
4.37.5 mm a
1
based on offset of sediment lobes imaged from seismic proles. These rates are much higher
than slip rates we have measured along the CAFZ. Their results, along with a high density of earthquakes,
suggest that the Kozan fault zone is a more signicant left-lateral structure and has accommodated partitioned
strain that had previously been attributed to the CAFZ.
The northeast part of the CAFZ, from Erkilet to the North Anatolian fault, appears more continuous and seismically
active. A small cluster of eight M4.0 to 5.1 earthquakes have been recorded in the northern part of the Erciyes
basin since 1985 (USGS [Jenkins et al., 2013]), roughly delimiting the trace of Erkilet fault (Figure 14a) and
suggest that it is still active. All of these events were located at depths of less than 10km. The focal mechanisms
of these faults were not available. Akyuz et al. [2013] compiled data for 11 earthquakes between M3.0 and M5.0
since 1960 that occurred on the Deliler and Teer faults of the NE part of the CAFZ. Six of these events were
recorded at depths of less than 5km. In the southern Erciyes basin and the Ecemişfault zone, active seismicity
does not delimit the CAFZ further to the south, where only sporadic events have been recorded.
In summary, skepticism about the continuity, left-lateral nature, Quaternary offset, and activity along the CAFZ
is justied [Westaway, 1999; Westaway et al., 2002]. Our results document Quaternary faulting with spatial
connectivity, (i.e., the strong linear trend shared by the Ecemiş-Erciyes and Gesi faults), but we nd no direct
evidence of coeval motion along the length of the CAFZ, and everywhere they are measured, we nd that faults
are slipping slowly and often have become dormant or inactive. Finally, we nd total neotectonic offset to be
much less than the 24 to 28km estimates from previous studies [Koçyiğit and Beyhan,1998;Toprak, 1998].
5.2. Evolution of the CAFZ
Koçyiğit and Beyhan [1998] originally proposed that slip along the CAFZ began in the Ecemişcorridor and
propagated to the northeast and southwest, eventually linking into a throughgoing structure that accommodated
signicant strike-slip displacement across the entire Anatolian plate (Figure 2). We propose a new model for the
evolution of the CAFZ, in which two paleotectonic structures, the Ecemişcorridor in the southwest and the
Inner Tauride suture zone in the northeast, were reactivated independently. These structures were then bridged
together by a zone of active extension to produce the modern CAFZ.
In our proposed scenario, the NE part of the CAFZ developed into a broad NE-SW trending, sinistral strike-slip
fault zone, including the Kızılırmak, Gemerek-Şarkışla, Deliler, and Tecer faults (Figure 14). They developed
along preexisting weaknesses in the vicinity of the Inner Tauride suture zone as a result of compression
in eastern Anatolia during the late Miocene to Quaternary [Yılmaz and Yılmaz, 2006; Kaymakci et al.,
2010]. Many of these faults remain seismically active, and slip rates of 1 mm a
1
have been proposed for
the Tecer fault [Akyuz et al., 2013]. Additional strain is likely distributed across this broad zone of faults.
To the east, the Malatya-Ovacık fault zone (MOFZ; Figure14a) is of the same orientation and sense of shear
[Kaymakci et al., 2006; Westaway et al., 2008; Zabci et al., 2014]. Both of these structures may represent an
array of en echelon antithetic faults accommodating strain along the North Anatolian fault. We suggest that
internal deformation of the northeastern part of the Anatolian plate is predominantly strike slip and could
be explained by a domino block faulting model with small amounts of clockwise rotation of crustal blocks
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 20
bounded by weakly active strike-slip faults (e.g., CAFZ, Malatya-Ovacık fault zone, and potentially the Sariz
and Gürün faults) (Figure 14b). These small clockwise rotations between these blocks are consistent with an east
to west transition from counterclockwise to clockwise rotations deduced from regional paleomagnetic data
[Piperetal., 2010].
Where the CAFZ bends to the south near the southern end of the Erkilet fault, it intersects a WNW-ESE extensional
domain (Figure 14a) [Aktuğet al., 2013] and normal displacement along the fault increases. This extensional
domain stretches from west of the Delier fault to the southern Erciyes basin (Figure 14). The resulting releasing
bend observed along the Erkilet fault produced a horsetail splay and step-like morphologic patterns, which bend
south and transition to pure normal faulting on the Yeşilhisar fault. Their kinematics is mirrored by the conjugate
Develi fault in the SE margin of the basin, where the fault scarp has relief of >900 m [Koçyiğit and Erol, 2001].
WNW-ESE opening of the basin was coeval with growth of the Erciyes stratovolcano, and the same stress regime
controlled emplacement of monogenetic dome alignment on its SW ank along the Erciyes fault. We propose
that Erciyes fault cuts through the middle of the basin and aligns with the Ecemişfault; extensional faulting is
consistent with mountain front normal faulting in the Ecemişcorridor, where large vertical offset is observed
at the mountain front near the Cevizlik fault. Normal faulting is accompanied by transtensional strike slip along
the Demirkazık-Sulucaova fault. This WNW-ESE extensional stress eld is likely related to the westward extrusion
of Anatolia, primarily driven by the Western Anatolian extensional province. Given their orientation (NE to ENE)
and the overall westward pull of Anatolia, small amounts of sinistral motion and larger amounts of horizontal
extension are expected along these structures. Ongoing counterclockwise rotation of Central Anatolia toward
the Hellenic trench has oriented this part of the CAFZ closer to N-S orientation. We propose that extensional
faulting in the central and southern parts of the CAFZ accommodates the increasing E-W velocity gradient across
the region (Figure 14b). A Pliocene-Quaternary changeover to NE-SW extensional along the Tuz Gölü fault zone
has been attributed to the inuence of the Western Anatolian extensional province [Özsayin et al., 2013], and the
results of this study support the suggestion that further extend this extensional inuence as far east as the CAFZ
[Aktuğet al., 2013].
With low sliprate and little evidence for majorstrike-slip offset during the Quaternary, the modern CAFZ cannot
be characterized as a tectonic escape structure, such as the North Anatolian fault or East Anatolian fault.
We prefer to characterize the modern CAFZ as a weakly active fault with nonuniform slip rates and spatially
and kinematically linked zones of heterogeneous deformation in Central Anatolia.Second-order strike-slip fault
systems within the Anatolian plate, such as the CAFZ and the Malatya-Ovacık fault zone, are likely shallow upper
crustal structures that divide east and central Anatolia into smaller tectonic blocks that move relative to one
another while also moving west with respect to Eurasia (Figure 14b). This interpretation is based on the shallow
seismicity along the CAFZ and supported by low sliprates presented in this study as well the similarly low rates
inferred along the Tecerfault (~1mm/yr [Akyuz et al., 2013]) and the Malatya-Ovacık fault zone (1.61.9 mm a
1
[Zabci et al., 2014]). The variability in recent kinematics observed along the central part of the CAFZ (~350km) can
be explained by its propagation through rapidly transitioning N-S and E-W stress patterns (stress permutations),
which are well dened within the Anatolian plate [Aktuğet al., 2013].
6. Conclusions
We have created new Quaternary fault maps and constrained kinematics and slip rates on important faults in
the southern and central parts of the CAFZ. When compiled with additional neotectonic data (GPS, seismicity,
and paleoseismology) the main conclusions of this study are as follows. Geomorphically derived slip rates
on the Ecemişfault zone of 1.1 ± 0.4 mm a
1
(erosion corrected) or 1.2 ± 0.4 mm a
1
(erosion and inheritance
corrected) are lower than original estimates. These are comparable with other slip rate estimates of weakly
active internal strike-slip faults of the Anatolian plate (Malatya-Ovacık fault zone 1.61.9 mm a
1
[Zabci
et al., 2014] and Teçer fault 1 mm a
1
[Akyuz et al., 2013]) and are more an order of magnitude smaller than
major plate bounding strike-slip faults (North Anatolian fault and East Anatolian fault). The most recent
episodes of faulting in the Ecemişcorridor are not kinematically linked with faulting in the Erciyes basin.
Most of the faulting in the Erciyes basin occurred between 2.73 ± 0.08 Ma (T11V02; Figure 12c) and
1.0 ± 0.3Ma (11TR-08; Figure 12b), dominated by horizontal extension in a WNW-ESE direction. The combined
effects of a strike-slip-releasing bend and extrusion-related crustal extension produced the modern basin
topography. Previous attempts to estimate total left-lateral offset along the CAFZ from restoration of an
Tectonics 10.1002/2015TC003864
HIGGINS ET AL. SIGNIFICANCE OF THE CAFZ REVISITED 21
Erciyes pull-apartbasin [Koçyiğit and Beyhan,1998;Toprak, 1998; Koçyiğit and Erol, 2001] are much too
large. Our alternative model for opening of the Erciyes basin by predominantly WNW-ESE extension is
supported by kinematic, geomorphological, and geodetic data and suggests that the inuence of the
Western Anatolian extensional province on deformation patterns in Central Anatolia is greater than previously
thought. Any strain partitioned from the Eastern Anatolian compressional province is mostly restricted to
the NE part of the CAFZ.
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Acknowledgments
This research was funded by NSF grant
EAR-1109762, Continental Dynamics:
Central Anatolian Tectonicsto Jane
Willenbring (University of Pennsylvania)
and an NSERC Discovery grant to
Schoenbohm (University of Toronto).
The authors are grateful to Mustafa
Bozkurt for logistical and eld assistance.
Editon Nathan Niemi (University of
Michigan) and anonymous reviewer
provided excellent feedback that
signicantly improved the manuscript.
Any use of trade, product, or rm names
is for descriptive purposes only and does
not imply endorsement by the U.S.
Government.
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found in the supporting information or
by contacting the corresponding author
(mark.higgins@mail.utoronto.ca). Satellite
imagery is copyright DigitalGlobe,
Inc. and provided through the Polar
Geospatial Center (University of
Minnesota - Twin Cities).
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... Erciyes, the neighboring Koç Dag complex is noteworthy as the source of the ca. 2.73 Ma (Friedrichs et al., 2021;Higgins et al., 2015) Valibaba Tepe Ignimbrite, one of the youngest large-volume eruptions (∼40 km 3 dense-rock equivalent; Şen et al., 2003) within the Neogene-Quaternary CAVP. ...
... Hasan and up to ca. 800 ka for Mt. Erciyes, for the latter with preceding peaks at ca. 2-3 Ma, corresponding to the age of the Valibaba Tepe Ignimbrite (Fig. B.6; Friedrichs et al., 2021Friedrichs et al., , 2020cHiggins et al., 2015). ...
... Erciyes on major strike-slip faults within the trans-tensional tectonic regime of the Anatolian Block (Fig. 1) suggest coupled seismic and tectonic activity (e.g., Dilek and Sandvol, 2009), but faulting is an unlikely eruption trigger for Late Pleistocene-Holocene eruptions: at Mt. Hasan, a lava flow dated at ca. 41 ka overflowed the Tuz Gölü Fault without detectable morphological offset despite several subsequent eruptions (Friedrichs et al., 2020a), and dacitic lava domes of Mt. Erciyes indicate no offset of the edifice-cutting branch of the Ecemi¸s Fault since the Middle Pleistocene (Higgins et al., 2015). Another external trigger for enhanced volcanism could be climatic forcing through glacial retreat and lithospheric unloading (Cooper et al., 2018, and references therein), and a tephra gap between ca. 30 and ca. ...
Article
Contrasting Late Pleistocene–Holocene eruptive behavior observed for Mt. Hasan and Mt. Erciyes, two neighboring stratovolcanic complexes in Central Anatolia, Turkey, poses general questions on the size and nature of magma systems underlying active volcanoes. Here, we complement U–Th–Pb zircon rim and interior crystallization ages for >1000 crystals from these volcanoes with trace element analyses on the same spots to unravel their magmatic histories. Thermochemical modeling of zircon crystallization is applied to quantify contrasting magma recharge and storage regimes. Both Mt. Hasan and Mt. Erciyes are characterized by protracted magmatic and volcanic activity since the Middle Pleistocene that is evident from individual crystals and crystal populations. However, zircon records contrasting thermochemical evolutions for both systems: Mt. Hasan with a history of recurrent eruptions throughout the Late Pleistocene exhibits comparatively narrow ranges of Ti-in-zircon crystallization temperatures and differentiation indices such as Zr/Hf ratios as well as Eu anomalies (Eu/Eu*) over the last ca. 300 ka. On the contrary, these parameters fluctuate over broader ranges for Mt. Erciyes, where relatively primitive zircon interiors nucleated during two major eruptive activity phases at ca. 105–85 and ca. 9 ka, whereas zircon rims evolved to more differentiated compositions during the protracted eruptive lull in between. The contrasting zircon record is interpreted to mirror a protracted thermochemical steady-state of the Mt. Hasan magma system, but fluctuating conditions in Mt. Erciyes due to recharge rate variations. Zircon ages are modeled with integrated magma recharge rates of ∼1–0.5 km³/ka for Mt. Hasan, but only ∼0.1 km³/ka for Mt. Erciyes, indicating “warm” magma storage under eruptible conditions for Mt. Hasan, but “cold” magma storage below the rheological lockup temperature for Mt. Erciyes. The smaller volume of the Mt. Erciyes subsurface plumbing system contrasts with its larger edifice volume, suggesting that the volcano has reached a waning stage where episodically intensified magma recharge can trigger violent eruptions. The early Holocene resurgence of Mt. Erciyes may be in response to glacial unloading, whereas the peak-stage Mt. Hasan system may be less responsive to changes in magma recharge due to thermal buffering by a voluminous magma reservoir.
... The Quaternary volcanism in cluster-1 is mostly represented by the Erciyes stratovolcano stage consisting of two eruptive cycles that form numerous scoria cones and lava domes with a maar (Şen, the southwestern flank) is N32 E based on the spatial analysis, indicating a WNW-ESE extension along the NNE trending Dündarlı-Erciyes fault (Higgins et al., 2015) (Fig. 1B). ...
... Cluster-1 is the only exceptional case among the other clusters with its almost circular field shape and the radial vent patterns along the flanks of Erciyes stratovolcano (Şen et al., 2003) (Tables 5 and 6, and Fig. 7). The dominant azimuthal trend of the spatial vent distribution in cluster-1 is in the N7 E direction, consistent with the local tectonic stress (e.g., Toprak, 1998;Higgins et al., 2015). On the other hand, the trends in other clusters are generally sub-parallel, except cluster-2 that has a trend (N115 ) almost normal to the main extensional direction. ...
... Additionally, the vent and local fault alignments in clusters 3 and 5 are almost perpendicular to the local extension axes (Fig. 7). The radial vent pattern, on the other hand, was solely observed in cluster-1 with the main trend of N17-38 E (Fig. 7) as also inferred in the literature (Toprak, 1998;Şen et al., 2003;Higgins et al., 2015). The extension-sub-parallel trend of vent alignments in this cluster (N17-38 E) as inferred in the literature (Toprak, 1998;Şen et al., 2003;Higgins et al., 2015) can be related to the local rotations of extension direction which is evident by the southward bending of the eastern border fault (i.e., lazy S to the rhomboidal pull-apart basin, Dirik, 2001;Fig. ...
Article
The interaction and competition between magmatic and tectonic processes mostly control the spatial distribution and morphology of monogenetic volcanoes. The Central Anatolian Volcanic Province, situated in a strike-slip environment, provides a remarkable opportunity to understand this relationship. We defined six monogenetic clusters and analyzed 540 Quaternary monogenetic volcanoes in terms of morphological and spatial characteristics. There is no distinct correlation among the morphological parameters of scoria cones or lava domes, possibly owing to the various factors and the sporadic nature of magmatic activity in the region. Our detailed multivariate statistical and vent alignment analyses together with several implications in the literature reveal that the CAVP is a tectonically-controlled intraplate volcanic field, which is mostly driven by regional deformations. The presence of both clustered and non-clustered vent distributions and the petrological characteristics of the volcanic within the region indicates that the dikes are derived directly by the pre-existing melt-bearing heterogeneous mantle (i.e., Eğrikuyu monogenetic field) or the independent and short-lived shallow or deep crustal magma reservoirs (i.e., Nevşehir-Acıgöl volcanic field). The local changes in the stress regimes and crustal lithology result in variations of field shape, spatial vent distribution, and vent alignments throughout the region. The triggering mechanisms for the initiation of the Quaternary volcanism in the region can be the lithospheric-scale Central Anatolian fault zone, here considered as an immature rift zone where Erciyes volcanic field is developed and behaves as a possible magmatic transfer zone. Tuz Gölü fault zone as a western border of the so-called rift basin in the region is mostly responsible for the crustal propagation of magma, and the kinematic changes along this fault zone (i.e., strike-slip to normal) mostly shaped the spatial vent distributions and alignments of the clusters in its close proximity (e.g., Hasandağ-Keçiboyduran volcanic field).
... This possibly favors the assimilation and fractional crystallization processes, and results in the formation of less voluminous basaltic volcanism in the region. In addition, the emplacement of studied monogenetic complexes along the probable parallel dike intrusions is also in line with the significant role of tectonism in the widespread Quaternary volcanism in the CAVP (Toprak and Göncüoğlu, 1993;Toprak, 1998;Higgins et al., 2015;Uslular et al., 2021). As for the recent discussions on the lithology of mantle source in the CAVP suggesting a pyroxenite inheritance (Gall et al., 2021;Gençoğlu-Korkmaz et al., 2021), we could not provide any contribution with our findings on the mafic İcik maar due to its slightly evolved composition. ...
Article
Full-text available
Recent experiments have largely reshaped our knowledge of maar volcanism. A new evolutionary model promoting the role of explosion depth and vent migration during the formation of maars has provided an alternative approach to previous models. Despite a few attempts to test this model with real cases, there is still a need for field-based studies exploring the depositional characteristics of maars to better understand the factors affecting the model constraints. More investigations on less known felsic maars are required to elucidate the possible differences from their more common mafic counterparts. Here, we explore compositionally distinct monogenetic clusters within the Acıgöl caldera (NW of Central Anatolian Volcanic Province, CAVP), with four felsic maars (İnallı, Kalecitepe, Acıgöl, and Korudağ) and one mafic maar (İcik). Our field observations reveal a successive formation between rhyolitic maars and adjacent lava domes. The mugearitic İcik coalescent maar and the adjacent scoria cone are synchronously formed, which is disclosed by the intercalation of the maar and scoria cone deposits. The geochemistry of the maar juveniles suggests a parental basaltic magma source that has been possibly differentiated by varying degrees of fractional crystallization. Our findings identify the main factors in maar formation (i.e., optimum scaled depth-OSD, water-magma interaction, and basement lithology). We also determine some differences between the felsic and mafic maars in the region, such as higher juvenile content, less amount of sedimentary structure, and a clear transition from phreatomagmatic to magmatic explosions through the end of stratigraphy. All these reflect the complexity of maars, mainly formed by different depths of explosions that occurred in the shallowest few hundred meters rather than a systematic incremental decrease of the eruption locus. Further geophysical and geochronological studies will complete our proposed evolutionary model for the youngest monogenetic activity in the Acıgöl caldera that would also warrant volcanic hazard assessment due to the presence of low-velocity anomalies, shallow Curie depths, and prevalent geothermal activity.
... Rights reserved. Based on the transformation of Miocene strike-slip faults into normal faults in the Pliocene-Quaternary, it was argued that the CVP basins were subjected to an extensional or a trans-tensional tectonic regime (e.g., Özsayın and Dirik 2007;Higgins et al. 2015). Thus, it can be concluded that the Quaternary volcanoes in the region erupted in horst-graben/ half-graben systems associated with pull-apart basins in an intra-continental setting. ...
Article
Full-text available
Voluminous moderate- to high-magnesian [Mg# = molar Mg/(Mg + Fe²⁺) = 44–64] andesitic and dacitic rocks with high silica (mostly 61–66 wt%) adakitic affinity (Y = 13–22, Yb = 1.3–2.1, Sr/Y = 18–44, La/Yb = 10–25) and common mafic magmatic enclaves (MMEs) are first reported in the Keçiboyduran stratovolcano (KSV) from the Cappadocia volcanic province (CVP), Central Anatolia, Turkey. We present comprehensive whole-rock geochemistry and Sr–Nd–Pb isotope data, mineral chemical compositions and ⁴⁰Ar–³⁹Ar ages for KSV samples. Based on the volcanostratigraphy and ⁴⁰Ar–³⁹Ar dating results, two successive eruption ages of 2.2–1.6 Ma (stage I: amphibole-rich) and 1.6–1.2 Ma (stage II: pyroxene-rich) were established for the KSV, corresponding to the Gelasian and Calabrian stages of Early Pleistocene, respectively. Textural and geochemical evidence indicates that the KSV magnesian andesites–dacites are products of a hybrid magma formed by mixing between mantle-derived mafic and crust-derived felsic magmas with further fractionation and minor contamination during magma storage and ascent. Our new data, combined with previous geological and geophysical results suggest that parental magnesian mafic melts of the KSV rocks originated from a heterogenous mantle source generated through the metasomatism of mantle wedge material by subducted sediment-derived melts, and then partially melted through asthenospheric upwelling in response to slab break-off. The mafic magma underplated the overlying lower crust, resulting in its partial melting to generate crustal felsic magma. Both magmas mixed at lower crustal levels creating MME-rich hybrid magmas. Subsequently, the hybrid magmas were emplaced at different depths of the crust (c. 4–11 and 11–15 km for the stage I and II, respectively), where they crystallized at moderate temperatures (c. 1180–840 °C) and under relatively high oxygen fugacity (LogƒO2 = − 11.4 to − 9.2), water-rich (H2Omelt = 5.6–3.6 wt%) and polybaric (~ 1.2 to 5.1 kbars) conditions, and underwent fractionation of primarily amphibole ± pyroxene causing adakitic affinity. We propose a new petrogenetic model for the early Quaternary magnesian/adakitic andesites/dacites of the CVP in a post-subduction tectonic setting. Our results provide robust evidence for slab break-off of the eastern Cyprus oceanic lithosphere and put further constraints on the tectonic evolution of the eastern Mediterranean collision zone during the Early Quaternary.
... Further to the northeast, segments of the Ecemiş-Deliler Fault (EDF) create the Erciyes pull-apart basin (Dirik and Göncüoğlu, 1996;Koçyiğit and Beyhan, 1998) and a segment passing from the summit of Erciyes volcano Higgins et al., 2015) seems to behave as a cross basin fault ( Figure 6; Appendix A, B, and C). The Ecemiş-Deliler Fault (EDF) has an ENE-WSW direction between Gemerek and Ulaş where Tuzla Gölü and Altınyayla Plain are two pull-apart structures ( Figure 6). ...
Article
Full-text available
Recent detailed examination of the internal deformation of the Turkish-Iranian Plateau in the hinterland of Bitlis-Zagros Suture Zone, which is related to the collision of the Arabian and Eurasian plates, indicates multiple intersection points between the right- and left-lateral strike-slip structures explained by an inevitably broad left-lateral strike-slip shear zone, the Anatolian Diagonal. The faults bounding and internally deforming the Anatolian Diagonal were closely examined by using high-resolution satellite images, focal mechanism solutions of the earthquakes, and published seismic reflection data in the offshore areas. The Anatolian Diagonal is a NE-SW trending left-lateral shear zone having a 170 km width between the Central Anatolian and the East Anatolian fault zones and an 850 km length between Erzincan and the Cyprus Arc. It has at least four intersection points with the right-lateral North Anatolian Fault Zone and the Southeast Anatolian-Zagros Fault Zone. As the offshore continuation of the Ecemiş-Deliler Fault of the Anatolian Diagonal, the Biruni Fault reaches the Cyprus Arc and Piri Reis (Mediterranean) Ridge Front west of Cyprus. This structure creates a restraining stepover with the left-lateral Antalya-Kekova Fault Zone and causes NW-SE trending thrusts of the Florence Rise and Antalya Thrust in the Antalya Basin. There is another restraining stepover between the Antalya-Kekova Fault Zone and the Pliny-Strabo Fault Zone, where the thrust-controlled northern margin of Rhodes basin developed. In this neotectonic framework, there is no need for the existence of the highly-debated left-lateral Fethiye-Burdur Fault Zone as an onshore continuation of the Pliny and Strabo faults. In fact, the westerly motion of the Anatolian plate is accommodated by the left-lateral Anatolian Diagonal Shear Zone, Antalya-Kekova Fault Zone and Pliny-Strabo Fault Zone together with the right-lateral North Anatolian Fault Zone. Keywords: Anatolian Diagonal, East Anatolian Fault Zone, Neotectonics, Eastern Mediterranean, Cyprus
... mm m.y. -1 [Özsayın et al., 2013], Central Anatolian fault zone: 0.36-1.1 mm yr -1 [Higgins et al., 2015;Sarıkaya et al., 2015]), but they are sufficiently fast to affect erosion and sedimentation rates across the Central Anatolian Plateau, and therefore influence the evolution of its drainage. ...
Article
Full-text available
Continental sedimentation was widespread across the Central Anatolian Plateau in Miocene–Pliocene time, during the early stages of plateau uplift. Today, however, most sediment produced on the plateau is dispersed by a well-integrated drainage and released into surrounding marine depocenters. Residual long-term (106–107 yr) sediment storage on the plateau is now restricted to a few closed catchments. Lacustrine sedimentation was widespread in the Miocene–Pliocene depocenters. Today, it is also restricted to the residual closed catchments. The present-day association of closed catchments, long-term sediment storage, and lacustrine sedimentation suggests that the Miocene–Pliocene sedimentation also occurred in closed catchments. The termination of sedimentation across the plateau would therefore mark the opening of these closed catchments, their integration, and the formation of the present-day drainage. By combining newly dated volcanic markers with previously dated sedimentary sequences, we show that this drainage integration occurred remarkably rapidly, within 1.5 m.y., at the turn of the Pliocene. The evolution of stream incision documented by these markers and newly obtained 10Be erosion rates allow us to discriminate the respective con­tributions of three potential processes to drainage integration, namely, the capture of closed catch­ments by rivers draining the outer slopes of the plateau, the overflow of closed lakes, and the avul­sion of closed catchments. Along the southern plateau margin, rivers draining the southern slope of the Central Anatolian Plateau expanded into the plateau interior; however, only a small amount of drainage integration was achieved by this process. Instead, avulsion and/or overflow between closed catchments achieved most of the integration, and these top-down processes left a distinctive sedi­mentary signal in the form of terminal lacustrine limestone sequences. In the absence of substantial regional climate wetting during the early Pliocene, we propose that two major tectonic events triggered drainage inte­gration, separately or in tandem: the uplift of the Central Anatolian Plateau and the tectonic com­pletion of the Anatolian microplate. Higher surface uplift of the eastern Central Anatolian Plateau relative to the western Central Anatolian Plateau promoted more positive water balances in the eastern catchments, higher water discharge, and larger sediment fluxes. Overflow/avulsion in some of the eastern catchments triggered a chain of avulsions and/or overflows, sparking sweeping integration across the plateau. Around 5 Ma, the inception of the full escape of the Anatolian microplate led to the disruption of the plateau surface by normal and strike-slip faults. Fault scarps partitioned large catchments fed by widely averaged sediment and water influxes into smaller catchments with more contrasted water balances and sediment fluxes. The evolution of the Central Anatolian Plateau shows that top-down processes of integration can outcompete erosion of outer plateau slopes to reintegrate plateau interior drainages, and this is overlooked in current models, in which drainage evolution is dominated by bottom-up integration. Top-down integration has the advantage that it can be driven by more subtle changes in climatic and tectonic boundary conditions than bottom-up integration.
... mm m.y. -1 [Özsayın et al., 2013], Central Anatolian fault zone: 0.36-1.1 mm y -1 [Higgins et al., 2015;Sarıkaya et al., 2015]), but they are sufficiently fast to affect erosion and sedimentation rates across the Central Anatolian Plateau, and therefore influence the evolution of its drainage. ...
Article
Full-text available
Continental sediment was widespread across the Central Anatolian Plateau in Miocene–Pliocene time, during the early stages of plateau uplift. Today, however, most sediment produced on the plateau is dispersed by a well-integrated drainage and released into surrounding marine depocenters. Residual long-term (106–107 yr) sediment storage on the plateau is now restricted to a few closed catchments. Lacustrine sedimentation was widespread in the Miocene–Pliocene depocenters. Today, it is also restricted to the residual closed catchments. The present-day association among closed catchments, long-term sediment storage, and lacustrine sedimentation suggests that the Miocene–Pliocene sedimentation also occurred in closed catchments. The termination of sedimentation across the plateau would therefore mark the opening of these closed catchments, their integration, and the formation of the present-day drainage. By combining newly dated volcanic markers with previously dated sedimentary sequences, we show that this drainage integration occurred remarkably rapidly, within 1.5 m.y., at the turn of the Pliocene. The evolution of stream incision documented by these markers and newly obtained 10Be erosion rates allow us to discriminate the respective contributions of three potential processes of drainage integration, namely, the capture of the closed catchments by rivers draining the outer slopes of the plateau, the overflow of closed lakes, and the avulsion of closed catchments. Along the southern plateau margin, rivers draining the southern slope of the Central Anatolian Plateau expanded into the plateau interior; however, only a small amount of drainage integration was achieved by this process. Instead, avulsion and/or overflow between closed catchments achieved most of the integration, and these top-down processes left a distinctive sedimentary signal in the form of terminal lacustrine limestone sequences. In the absence of substantial regional climate wetting during the early Pliocene, we propose that two major tectonic events triggered drainage integration, separately or in tandem: the uplift of the Central Anatolian Plateau and the tectonic completion of the Anatolian microplate. Higher surface uplift of the eastern Central Anatolian Plateau relative to the western Central Anatolian Plateau promoted more positive water balances in the eastern catchments, higher water discharge, and larger sediment fluxes. Overflow/avulsion in some of the eastern catchments triggered a chain of avulsions and/or overflows, sparking sweeping integration across the plateau. Around 5 Ma, the inception of the full escape of the Anatolian microplate led to the disruption of the plateau surface by normal and strike-slip faults. Fault scarps partitioned large catchments fed by widely averaged sediment and water influxes into smaller catchments with more contrasted water balances and sediment fluxes. The evolution of the Central Anatolian Plateau shows that top-down processes of integration can outcompete the erosion of outer plateau slopes to reintegrate plateau interior drainages, and this may be overlooked in the currently dominant models of bottom-up integration. Top-down integration can also be driven by more subtle changes in climatic and tectonic boundary conditions.
Article
The Plio-Quaternary post-collisional volcanism in the Karapınar area is represented by two occurrences: (1) Karacadağ Volcanic Complex (KCVC) and (2) Karapınar Volcanic Field (KPVF). The investigated volcanic units are the southwestern part of the Neogene to Quaternary Cappadocia Volcanic Province (CVP) in Central Anatolia. The CVP generally displays calc-alkaline affinity in the Late Miocene to Pliocene rocks, but both calc-alkaline and sodic alkaline affinity in the Plio-Quaternary rocks, all of which have an orogenic geochemical signature. Such a volcanic activity contradicts the Western and Eastern Anatolian volcanism characterized by anorogenic OIB-like sodic alkaline volcanic rocks postdating early orogenic calc-alkaline ones. We hypothesize that such temporal and geochemical variations in the investigated rocks result from crustal contamination and present major and trace element chemistry and Sr-Nd–Pb–O isotope geochemistry, coupled with 40Ar/39Ar geochronology data to restrict the genesis and evolution of the rocks. The Neogene Karacadağ volcanic rocks are represented by lava flows, domes and their pyroclastic equivalents constituting a stratovolcano, and dated by new 40Ar/39Ar ages of 5.65 to 5.43 Ma. They are mainly composed of andesitic, rarely basaltic, dacitic and trachytic rocks and have a calc–alkaline character. Constituting a monogenetic volcanic field, the Quaternary Karapınar volcanic rocks are typically formed by cinder cones, maars and associated lavas, including xenoliths and xenocrysts plucked from the Karacadağ rocks. They comprise basaltic to andesitic rocks with a transitional affinity, from sodic alkaline to calc-alkaline. Both the Karacadağ and Karapınar volcanic rocks display incompatible trace element patterns a characteristic of orogenic volcanic rocks. The Sr, Nd, and Pb isotopic systematics of both units show a relatively narrow range, but their δ18O values are markedly different. The Karacadag volcanic rocks have δ18O values ranging from 7.5 to 8.9 ‰, resembling those of subduction-related basalts, but the Karapınar volcanics have δ18O ratios between 5.7 and 6.5 ‰ corresponding to OIB-like rocks. Additionally, δ18O values and 87Sr/86Sr ratios correlate positively with SiO2 in the rocks, indicating that contamination played an important role during differentiation processes. All the data obtained suggest that the Karacadağ basaltic rocks stemmed from a subduction-modified lithospheric mantle source. On the other hand, the origin of the Karapınar basaltic rocks can be explained in terms of OIB-like melts contaminated with the Karacadağ volcanic rocks to gain an orogenic geochemical signature, which may be an alternative model for the origin of the CVP sodic alkali basalts.
Article
A dense grid of high-resolution multichannel seismic reflection profiles are used to delineate the stratigraphic and structural architecture of the Anamur–Kormakiti zone which separates the Outer Cilicia Basin from the eastern Antalya Basin. The data showed that the uppermost Messinian–Quaternary structural framework of the region is characterized by two arcuate south-convex sinistral strike-slip fault zones in the northeast and east which converge to form a ∼70–80 km wide NW–SE trending zone, consisting of two internally-parallel dextral strike-slip fault zones in the northwest and west. A narrow NNW–SSE trending zone occupied by similarly trending positive flower structures across the Anamur–Kormakiti zone suggests that this region is probably a rotational stepover between two oppositely moving strike-slip fault zones. The regionally extensive strike-slip fault zones are largely developed during the Pliocene–Quaternary along the southern fringes of the Taurus Mountains in response to the westward escape of the Aegean–Anatolian Microplate following the collision and suturing of the Arabian Plate to the Eurasian Plate during the end of Miocene–Early Pliocene.
Chapter
The major zone of continent-continent collision on Earth today is along the Alpine Himalayan Chain, which is home to the Pyrenees, European Alps, Turkish-Iranian Plateau, Himalaya and the Tibetan Plateau. Continent-continent collision also occurs in the Southern Alps of New Zealand and has produced a number of ancient orogens, including the Appalachians, Urals and Caledonides. The extensive, long-lived deformation, and particularly the crustal thickening, and therefore weakening, associated with continental collisions results in unique tectonic geomorphology. The debate around tectonic-climate interactions is centered in many collisional orogens. Another important topic in understanding the tectonic geomorphology of continent-continent collision zones is whether or not flux, topographic, thermal or exhumational steady state can be achieved, and how each can be recognized; related topic of the relative controls of tectonics and climate on range width and asymmetry is also significant. Tectonic geomorphology has also been used to identify the lateral transport of crust, either through brittle deformation along strike-slip faults, or through ductile lower crustal flow. Drainage reorganization is a particularly powerful tool for inferring uplift patterns, and how uplifted regions are sustained in the face of erosion. Geomorphologic studies also yield insight into lithospheric foundering. Finally, tectonic geomorphology can help explain the persistence of topography over long-dead orogens.
Conference Paper
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Continental plate boundaries are often displayed as broadly deforming regions by parallel or sub-parallel fault systems. Understanding the behavior and interactions of the individual faults provide invaluable data not only to figure out the role of each fault sets in accommodation of the relative plate motion, but also to reveal the seismic potential of the region. Contradictory to the diffused deformation zones, the strain is mainly localized along the North Anatolian (NAF) and the East Anatolian (EAF) faults at the boundaries of the Anatolian Block. However, recent geodetic studies show considerable magnitude of strain accumulation higher than the previous expectations along the Malatya-Ovacık Fault (MOF), which is located parallel or sub-parallel with a changing distance from 40 km to 100 km to the EAF. Elastic block model slip-rates change from 1.2 to 1.8 mm/a, which are exceeded with almost factor of 7 to 8 by the modeled velocities of the EAF (∼10 mm/a). Understanding both the quantitative slip partitioning and the temporal behavior of these two fault zones at the eastern boundary of the Anatolian block will provide very important data not only for this particular region, but also for plate boundaries where the deformation are broadly distributed. In order to find answer for some of the questions raised above, we started to study the northeastern section, the Ovacık Segment, of the MOF, where faulting is clearly observed along well-preserved fault scarps, pressure ridges, and, offset alluvial fans and inset terraces. In order to reconstruct the chronology of the fan and inset terrace surfaces we collected samples for cosmogenic 36 Cl dating at the Köseler site (Ovacık, Tunceli). In addition, we performed rtk-GPS survey for precise offset measurements of the terrace risers. Our preliminary analyses show that at the eastern banks, the boundary between the Alluvial fan and the inner channel is displaced for 30±5 m. In addition to that, we also measured 19±3 m sinistral offset on the terrace riser, bounding the upper alluvial fan and the lower inset terrace treads at the western banks. Preliminary 36 Cl results from upper and lower treads yielded exposure ages of ca. 16 and 12 ka, respectively. Based on these, we calculated two independent geologic slip rates, 1.9 and 1.6 mm/a, which represent close but higher values than the block model based geodetic velocities. Our results from this study play an important role both in understanding of the temporal relationship of the MOF and the EAF and the seismic risk assessment of the region.
Chapter
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The Niǧde Massif, south-central Turkey, experienced two complete cycles of burial and exhumation during orogenesis and is, therefore, an excellent example of yo-yo tectonics. We propose that burial and exhumation of the metamorphic basement and, in the second cycle, the basement and its sedimentary cover rocks, were driven largely by transpression and transtension in an intracontinental strike-slip zone. The eastern margin of the massif, where it is adjacent and subparallel to the sinistral Central Anatolian fault zone, is comprised of Upper Cretaceous basement that was the source of, and is unconformably overlain by, early Tertiary sedimentary rocks. The contact between the Tertiary rocks and basement is an unconformity that is locally sheared and characterized by a low-angle oblique-normal shear system with cataclasite in the basement and brittle-ductile shear zones in the sedimentary rocks. These relationships, documented by geo/thermochronology to encompass 80 million years, define the timing and magnitude of the yo-yo process: burial and heating of Mesozoic sedimentary rocks during Late Cretaceous transpression to form the high- grade metamorphic basement (peak metamorphism at 85-91 Ma); Late Cretaceous (ca. 80-60 Ma) unroofing by transtension and erosion, with early Tertiary deposition of massif-derived clastic material at the edge of a marine basin along the Central Anatolian fault zone; reburial of basement and cover rocks involving folding, shearing, and greenschist facies metamorphism of the sedimentary cover in late Eocene through early Miocene time (ca. 50-20 Ma); and final exhumation in the middle Miocene (17-9 Ma) along strike-slip and normal faults.
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Alluvial fans within the paraglacial Ecemiş River drainages on the Aladağlar Mountains in south central Turkey were studied using geomorphological, sedimentological, and chlorine-36 terrestrial cosmogenic nuclide (TCN) surface exposure dating methods to examine the timing of alluvial fan abandonment/incision, and to understand the role of climatic and tectonic processes in the region. These alluvial fan complexes are among the best-preserved succession of alluvial fans in Turkey and they were offset by the major strike-slip Ecemiş Fault of the Central Anatolian Fault Zone. The alluvial fans are mostly composed of well-lithified limestone cobbles (5 to 25 cm in size), and comprise crudely stratified thick beds with a total thickness reaching up to about 80 m. TCN surface exposure dating indicates that the oldest alluvial fan surface (Yalak Fan) was likely formed and subsequently abandoned latest by 136.0 ± 23.4 ka ago, largely on the transition of the Penultimate Glaciation (Marine Isotope Stage 6, MIS 6) to the Last Interglacial (MIS 5) (i.e. Termination II). The second set of alluvial fan (Emli Fan) was possibly developed during the Last Interglacial (MIS 5), and incised twice by between roughly 97.0 ± 13.8 and 81.2 ± 13.2 ka ago. A younger alluvial fan deposit placed on relatively older erosional terraces of the Emli Fan suggests that it may have been produced during the Last Glacial Cycle (MIS 2). These events are similar to findings from other fluvial and lacustrine deposits throughout central Anatolia. The incision times of the Ecemiş alluvial fan surfaces largely coincide with major climatic shifts from the cooler glacial periods to warmer interglacial/interstadial conditions. This indicates that alluvial fans were produced by outwash sedi-ments of paleoglaciers during cooler conditions, and, later, when glaciers started to retreat due to a major warming event, the excess water released from the glaciers incised the pre-existing fan surfaces. An alluvial fan in the study area was also cut by the Ecemiş Fault, highlighting the influence of tectonics on fan development. It was offset vertically 35 ± 3 m since at least 97.0 ± 13.8 ka, which suggests a 0.36 ± 0.06 mm a −1 vertical slip-rate of the fault.
Chapter
Strike slip on various scales and on faults of diverse orientations is one of the most prominent modes of deformation in continental convergence zones. Extreme heterogeneity and low shear strength of continental rocks are responsible for creating complex 'escape routes' from nodes of constriction along irregular collision fronts toward free faces formed by subduction zones. The origin of this process is poorly understood. The 2 main models ascribe tectonic escape to buoyancy forces resulting from differences in crustal thickness generated by collision and to forces applied to the boundaries of the escaping wedges. Escape tectonics also creates a complicated geological signature, whose recognition in fossil examples may be difficult. We examine the Neogene to present tectonic escape-dominated evolution of Turkey both to test the models devised to account for tectonic escape and to develop criteria by which fossil escape systems may be recognized.-from Authors
Chapter
While recognition and measurement of strain markers in active tectonic settings have improved over the past half century, our capacity to establish rates and timing of neotectonic processes lagged due to difficulties in dating the deformed landforms. The development and refinement of geochronology strategies based on the interpretation of terrestrial in situ produced cosmogenic nuclides (TCN) have provided a means to directly date fault surfaces and estimate rupture frequency, date or bracket the timing of deformation events, and demonstrate more clearly than ever the relationships between sediment fluxes and tectonic processes. With an effective range of decades to 107 years, theTCNmethod bridges the gap between geodetic time scales and chronologies of longer time scale processes associated with orogen-scale crustal dynamics. This chapter provides a summary of current TCN approaches for assessing the erosion and exposure history of surfaces and sediments in tectonically active regions.
Article
Central Anatolia plays a key role to connect the theories about the subduction of African Plate along Hellenic and Cyprian Arcs and the collision of Arabia indenter along Bitlis-Zagros Thrust Zone. Taking place between the North Anatolian and East Anatolian mega shear zones, the neotectonics of seismically less active Central Anatolia is often regarded as tectonic escape or extrusion tectonics. Although, available GPS studies dating back to early 1990s reported coherent rotation, they were mostly focused on the seismically more active and more populated Western Anatolia and lack sufficient spatial resolution in quantifying second-order structures such as Tuz Gölü Fault Zone, Central Anatolia Fault Zone which comprises Ecemiş Fault and Erciyes Fault, Ezinepazarı Fault and their related basins and associated processes. Besides, the new dense GPS velocity field of Central Anatolia exhibits systematic local patterns of internal deformation which is inconsistent with either coherent rotation or translation. The velocity gradients computed along the rotation profiles of Central Anatolia show nearly westward and smooth increments which cannot be explained through a simple rotation/transport of Central Anatolia Basin. Moreover, estimating and removing an Euler rigid-body rotation rate which is computed from the sites lying in the middle part of Central Anatolia absorbs the velocity discrepancies between the Eastern and Western part of Central Anatolia down to a few millimetres and leaves out systematic residuals. Upon completion of Turkish National Fundamental GPS Network (TNFGN) in 1999, early revision surveys were carried out in Marmara region because of the 1999 Marmara earthquakes. Additional observations were carried out in Central Anatolia, resulting in a velocity field of unprecedented spatial density with average inter-station distance of 30–50 km.We computed the horizontal velocity field with respect to a not-net rotation frame, to Eurasia, and to a computed Anatolia Euler Pole. Two distinct models of Anatolia neotectonics, microplate and continuum deformation were tested through the rigid-body Euler rotations, block modelling and strain analysis. The results show that the decomposition of the Eurasia-fixed velocity field into the rigid rotations and the residuals reveals systematic residuals up to 5 mm/yr with respect to a computed best-fit Euler Pole located at 31.6820N ± 0.05, 31.6130E ± 0.02 and with a rotation rate of 1.3800/Myr ± 0.01. The relative velocities computed along rotation paths exhibit westward increasing linear gradients of 0.7–1.3 mm per 100 km depending on the latitude which is mechanically inconsistent with the assumptions of a coherent transport or a rigid rotation due to an extrusion in the east. Moreover, the strain analysis results show E-W extension rates up to 100 nanostrain/yr along approximately N-S striking faults within the region from the west of Karliova to Isparta Angle, which is another indication of the partitioned extensional strain across the Central Anatolia. On the other hand, the compressional strains were also obtained near the eastern branch of Isparta Angle, Tuz Gölü and southern Anatolia. In this study, we provide new quantitative results about the fact that the deformation in Central Anatolia is not uniform and possibly driven by the extension through slab pull and/or suction in west-southwest and the compression in the south rather than a simple coherent rotation and/or translation/transport of Anatolia driven by an extrusion process in the east. We also propose that the tectonics of Central Anatolia comprises a dominant tensional driving force along Hellenic Arc in the southwest and a restraining belt along Cyprian Arc in the south.