Kinematic and structural development of the Cßankiri Basin (Central Anatolia, Turkey)

29 Pages·2003·3.51 MB·English

Tectonophysics364(2003)85–113
www.elsevier.com/locate/tecto
Kinematic and structural development of the C(cid:1)ankiri Basin
(Central Anatolia, Turkey): a paleostress inversion study
Nuretdin Kaymakcia,*, Stanley H. Whiteb, Paul M. Vandijkc
aGeologicalEngineeringDepartment,FacultyofEngineering,MiddleEastTechnicalUniversity,06531-Ankara,Turkey
bFacultyofEarthSciences,UtrechtUniversity,Budapestlaan4,3508Utrecht,TheNetherlands
cITCHengelosestr99,P.O.Box6,7500AAEnschede,TheNetherlands
Received13November2002;accepted23January2003
Abstract
Three different deformation phases have been recognized in the southern part of the C(cid:1)ankırı Basin from (1) the major
structuresand(2)throughusingpaleostressinversiontechniquesforfaultslipdata.Thedeformationphasesrecognizedfromthe
paleostressdataarecorrelatedwiththoserecognizedfromthemajorstructuresanddatedaccordingly.Thefirstphaseoccurred
in the Late Paleocene to pre-Burdigalian and is characterized by an oblique r and NNE–SSW to NE–SW trending
2
subhorizontalr andWNW–ESEtoNW–SEtrendingr patternswhichindicatetranscurrentdeformationassociatedwitha
1 3
combinationofthrustingandstrikeslipfaulting(transpression)possiblyduetoindentationoftheKır(cid:1)sehirBlocktotheSakarya
Continent. The second phase occurred from the Burdigalian to the Serravallian and is characterized by a subvertical r and
1
obliquer andr ,whichindicateobliqueextensionassociatedwithnormalfaultingpossiblyduetoapost-orogeniccollapse.
2 3
Thethirddeformationphaseischaracterizedbyaverticalr whiletheotherstresseswerehorizontal,whichindicateregional
2
transcurrenttectonics,whichiscorrelatedwiththecurrenttranscurrenttectonicscontrolledbytheNorthAnatolianFaultZone.
D2003Elsevier ScienceB.V.All rights reserved.
Keywords:Paleostressinversion;C(cid:1)ankırı;Kinematics;Transcurrent;Turkey
1. Introduction al., 1981; Angelier, 1979, 1984, 1994; Petit and
Laville, 1985; Means, 1987; Reches, 1987; Krantz,
Paleostress inversion methods provide an estima- 1988; Lisle, 1987; Doblas, 1998). The faults in three
tion of the orientation of the principal stress axes dimensionmayconformtotheColoumbcriterion,but
using fault slip data sets. The direction of slip is due to anisotropy and inherited planes of weakness,
inferred from the fault slip data, which are assumed faults may develop at angles to principal stress direc-
to record the direction of maximum shear stress on a tions other than those predicted for isotropic media
fault surface (Carey and Brunier, 1974; Etchecopar et (WojtalandPershing,1991).Wallace(1951)andBott
(1959) suggested that slip on pre-existing surfaces
occurs parallel to the maximum resolved shear stress.
After the pioneering paleostress inversion technique
* Correspondingauthor.
ofCarey and Brunier (1974), anumber ofpaleostress
E-mail addresses: [email protected] (N. Kaymakci),
[email protected](S.H.White),[email protected](P.M.Vandijk). techniques have been developed. They have been
0040-1951/03/$-seefrontmatterD2003ElsevierScienceB.V.Allrightsreserved.
doi:10.1016/S0040-1951(03)00043-X
86 N.Kaymakcietal./Tectonophysics364(2003)85–113
N.Kaymakcietal./Tectonophysics364(2003)85–113 87
applied to fault slip data for a variety of tectonic Themajorstructuresdefiningthewestern,northern
contextwithconsistentresults.Thankstothissuccess, andeasternmargin ofthe C(cid:1)ankırı Basin are compres-
paleostress inversion procedures are becoming a rou- sional(Kaymakci,2000;Kaymakcietal.,2000).They
tineanalyticaltechniqueinstructuralgeology(Pollard defineadistinctiveV-shapetotheC(cid:1)ankırıBasin(Figs.
et al., 1993). 1and2).Alongthesefaults,anophioliticme´langeand
Thepurposesof thisstudy aretoapply paleostress associated Late Cretaceous volcano-sedimentary suc-
inversiontechniquestounravelthepaleostresshistory cessionshavebeenthrustoverthebasinfill(Akyunrek
of the southern part of the C(cid:1)ankırı Basin, including et al., 1984; Dellalog˘lu et al., 1992; Tunysunz and
the Kır(cid:1)sehir Block (basement), and to constrain the Dellalog˘lu, 1992; Onzc(cid:1)elik, 1994; Koc(cid:1)yig˘it et al.,
timing of each deformation phase. We relate the 1995; Kaymakci et al., 1998, 2000). To the south,
results to the major structures that were active during thegranitoidsoftheKır(cid:1)sehirBlockdelimitthesouth-
each deformation phase. This is a complement to ern margin of the basin and constitute the basement
another study carried out in the northern part of the (Dellalog˘luetal.,1992;TunysunzandDellalog˘lu,1992;
C(cid:1)ankırı Basin. Therefore, the numbering of subareas Kaymakci,2000).
and the analytical and numerical procedures follow The other major structures that affected the
those outlined indetail inKaymakci etal.(2000) and C(cid:1)ankırı Basin are NE–SW trending strike-slip faults
briefly described in Section 3. (see Figs. 1c and 2), namely, the Kızılırmak Fault
Zone (KFZ), Yag˘basa Fara(cid:1)slı Fault Zone (YFFZ),
Sivritepe Fault Zone (STFZ) and the Ezinepazarı-
2. Regional setting Sungurlu Fault Zone (ESFZ), all of which splay off
the NAFZ. They cross the basin and displace the
The C(cid:1)ankırı Basin lies adjacent to the I˙zmir– basin fill, the rim, and the basement. The south-
Ankara–Erzincan Suture Zone along which the central part of the basin is dominated by generally
Sakarya continent (Pontides) and the Kır(cid:1)sehir Block NNW–SSE- to NE–SW-oriented normal faults (Fig.
(Taurides) (Fig. 1) are thought to have collided and 2). The southern area is dominated by the ESFZ, one
amalgamated (S(cid:1)engonr and Yılmaz, 1981; Tunysunz of the major splays of the NAFZ (Fig. 1d) that partly
and Dellalog˘lu, 1992). Besides being affected by ruptured during the Erzincan Earthquake (Mw. 7.9,
collisional processes, the C(cid:1)ankırı Basin was sub- 26 December 1939).
jected to further deformation in the post-Late Mio- The fill of the C(cid:1)ankırı Basin is more than 4 km
cene as part of the Anatolian wedge caught between thick and accumulated during five different cycles of
the transcurrent motions on the North and East sedimentation (Fig. 3). The cycles are discussed in
Anatolian Faults (Fig. 1). This has resulted in a detail in Kaymakci (2000) and only a summary is
number of northwards convex dextral strike-slip given here. The oldest cycle comprises the Late
faults, which bifurcate from the North Anatolian Cretaceous volcanoclastics and regressive shallow
Fault Zone (NAFZ) (Barka and Hancock, 1984; marine units, and the Paleocene mixed environment
S(cid:1)engonr et al., 1985; Kaymakci and Ko(cid:1)cyig˘it, 1995). red clastics and carbonates (Onzc(cid:1)elik, 1994; Kay-
The Kızılırmak and Sungurlu Fault Zones are the makci, 2000). The second cycle is a Paleocene to
two major splays of the NAFZ in this area, which Oligocene regressive flysch to molasse sequence
partly controlled the Late Miocene evolution of the overlain by a widespread thin (<100 m) nummulitic
C(cid:1)ankırı Basin (Fig. 2). limestone,MiddleEoceneinage,thatpassesintovery
Fig.1.(a)InsetmapshowingthegeologicaloutlineoftheEasternMediterraneanarea(modifiedafterGonrunretal.,1984;S(cid:1)engonretal.,1984).
EAAC: East Anatolian Accretionary Complex. (b) Active tectonic outline of Turkey and surrounding regions (modified after Barka and
Hancock,1984;S(cid:1)engonretal.,1985;Ko(cid:1)cyig˘it,1989;Onz(cid:1)celik,1994;KaymakciandKo(cid:1)cyig˘it,1995).C(cid:1)B:C(cid:1)ankırıBasin,DFZ:DeadSeaFault
Zone,EAFZ:EastAnatolianFaultZone,NAFZ:NorthAnatolianFaultZone.LargeblackarrowsarethemovementdirectionsofArabianplate
and Aegean–Anatolian Block. (c) Detailed tectono-stratigraphical map of the central Anatolia. Box shows the location of the study area.
Concentriccirclesaremajortowns.
8
8
N
.
K
a
y
m
a
k
c
i
e
t
a
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/
T
e
c
to
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ic
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(2
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)
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Fig.2.GeologicalmapoftheC(cid:1)ankırıBasin.Thenumbersandtheboxesindicatethelocationsofthesubareas.
N.Kaymakcietal./Tectonophysics364(2003)85–113 89
Fig.3.Generalizedtectono-stratigraphiccolumnfortheunitsexposedinandaroundtheC(cid:1)ankırıBasin.MNzonesareafterKaymakcietal.
(2001b).
90 N.Kaymakcietal./Tectonophysics364(2003)85–113
thick (up to 2000 m) Late Eocene to Oligocene re-computed and re-analyzed using the software
continental red clastics intercalated with and overlain developed by Hardcastle and Hills (1991) for the
by the Oligocene evaporites. The third cycle is rep- automatic separation of stress tensors associated with
resented by fluvio-lacustrine clastics deposited in the thedifferentdeformationphasesasindicatedfromthe
Early to Middle Miocene. The fourth cycle is repre- field observations. Concordant data were then taken
sented by the units that were deposited in Late as indicating that the computed stress tensor is likely
Miocenefluvio-lacustrineconditions.Theyfrequently correct.Theinitialspuriousdatawerere-computedby
alternatewithevaporites.ThePlio-Quaternaryalluvial the Hardcastle and Hills (1991) method and if again
fan deposits and recent alluvium locally overlie all of spurious they were not used in the final construction
these units (Fig. 3) and form the fifth cycle. of the stress tensors. If concordant (both in direct
inversion method and automated separation process)
theywereincludedandre-analyzed.Itshouldbekept
3. Methodology in mind that automatic separation was used only to
verify the results obtained from Angelier’s method.
InthesouthernpartoftheC(cid:1)ankiriBasin,morethan By this way results were cross-checked.
280 fault-slip data from 32 sites have been collected. In order to determine the mean stress tensor con-
The relative ordering of fault motions and related figuration for a given movement phase in each sub-
deformation was established from overprinting and area, all the data from each site and each phase were
cross-cutting relationships. The age constraints were grouped and the above procedure repeated. After the
appliedthroughthecarefuldocumentationandanalysis mean stress orientations were determined, all of the
of the fault structures in each of the stratigraphical raw data was re-processed and the results were com-
horizon. To avoid problems due to relative block and pared with those obtained using the direct inversion
faultplaneinteractions(seePollardetal.,1993;Twiss method. Because the minimum number of slickenline
andUnruh,1998)andtokeepstructuralhomogeneity, data required to construct a stress tensor is 4 in the
sampling sites were kept to less than 50 m diameter direct inversion method (Angelier, 1979), the data of
(Hancock, 1985). Areas larger than this were subdi- sites containing less than this number was used only
vided into subsites and analyzed independently. In in the construction of mean stress tensor for the
addition, the faults with less than 1-m displacement subarea within which it was located.
wereusedintheanalysisbecausetheyshouldaccom- Afterthestresstensorsforeachsetateachsitehad
modate small strain associated with parallel principal been determined, they were correlated between sites.
strainandstressaxes(Hardcastle,1989). By combining the stratigraphic information and the
Relative age of each movement phase was deter- relative order of the different sets, the stress tensors
mined independently for each fault and carefully were arranged into ordered deformation phases.
correlated with data from other subareas to form a In both the direct inversion and the Hardcastle–
regionalsubset,whichisthenprocessedfollowingthe Hills methods, 15j was chosen as the maximum
algorithmproposedinKaymakcietal.(2000).During angular deviation acceptable for the computation of a
the analyses, the data from each site were carefully given stress tensor. Faults with greater angular devia-
examined and correlated to the site within a subarea. tions,afterre-groupingsandre-calculations,werecon-
The slip data, which have the same order of occur- sideredtobespuriousanddeleted.Tenpercent(10%)
rence, could be grouped together for preliminary ofthewholedatasetfallsintothiscategory.
stress inversion processing (Kaymakci et al., 2000).
For computational processing of the data, Angelier’s
method was used (see Angelier, 1984, 1994, for an 4. Field observations and results
overview of the stress inversion procedure).
After preliminary processing, faults having more The southern part of the C(cid:1)ankırı Basin is subdi-
than 15j misfit angle were considered spurious, vided into three subareas (Fig. 2) based on marked
separated from the data set and treated separately. differencesintheunderlyinglithologies,andtypeand
After removal of spurious data, the stress tensor was trends of the structures.
N.Kaymakcietal./Tectonophysics364(2003)85–113 91
4.1. Subarea 1 4.1.1. Faults
ThemainfaultsobservedinthisareaaretheBedes-
Subarea 1 lies in the southwestern part of the ten Faults (BTF-1, BTF-2, and BTF-3), Malıbog˘azı
C(cid:1)ankırı Basin where the basement and the rim come TrustFaults(MTF),Kazmaca–HamzalıReverseFault
closertoeachotherthanatanyotherpartofthebasin (KHRF), Sivritepe Fault (STF), Kıl(cid:1)cak Thrust Fault
(Fig.4).TheyareseparatedfromeachotherbytheLate (KLTF), Kayadibi Fault (KDF), Babas–Ekincibayırı
CretaceoustoPaleoceneandLatePaleocenetoMiddle Fault(BETF)andHıdır(cid:1)seyhThrustFault(HITF)(Fig.
Eocene units. The main structures in the subarea are 4).Mostofthesefaults delimitthewesternrimofthe
faultsandfolds(Fig.4). basinandaredextrallydisplaced bythesubstrandsof
Fig.4.Geologicalmapandsamplelocationsforsubarea1(seeFig.3fortheagesofthestratigraphicalunits).
92 N.Kaymakcietal./Tectonophysics364(2003)85–113
the Yag˘basan–Fara(cid:1)slı (YFFZ) and Sivritepe Fault ange (NAOM) are intensely deformed and sheared.
Zones (STFZ). The structural characteristics and pos- No reliable slickenlines were observed. Along the
sibleagerangesofthesefaultsareoutlinedinFig.5. fault BTF-3, the NAOM tectonically overlies the
Along the faults BTF-1 and -2, various constit- Late Cretaceous to Paleocene Dizilita(cid:1)slar Formation
uent units of the North Anatolian Ophiolitic Me´l- (Fig. 4). The Dizilita(cid:1)slar Formation, in turn, has
Fig.5.Figureillustratingthestructuralandkinematiccharacteristics,possibleagerangesofthefaultsandthefoldsdevelopedinsubarea1.
BTF: Bedesten Faults, MTF: Malıbog˘azı Fault, KHRF: Kazmaca–Hamzalı Fault, KLTF: Kıl(cid:1)cak Thrust Fault, STF: Sivritepe Fault, KDF:
KayadibiFault,BETF:Babas–TermeyeniceFault,YFFZ:Yag˘basan–Fara(cid:1)slıFaultZone,STFZ:SivritepeFaultZone,KFS:KırıkkaleFaultset.
N.Kaymakcietal./Tectonophysics364(2003)85–113 93
been thrusted over the Early to Middle Eocene being due to the coupling of thrusting and deposition
Karabal(cid:1)cık and Yoncalı Formations along the fault of the Incik Formation in the post-Middle Eocene to
BTF-4. Along the fault BTF-5 the NAOM tectoni- pre-Oligocene (Kaymakci, 2000). The characteristics
cally overlies the Early to Middle Eocene Mahmat- of these folds are summarized in Fig. 5.
lar Formation in the southwesternmost part of the
basin. This relationship is important for determining 4.1.3. Paleostress inversion
the amount of E–W tectonic transport of the rim. Inordertounderstandthekinematichistoryofthis
The Mahmatlar Formation is derived mainly from subarea, 91 out of 105 fault slip data have been
the Kır(cid:1)sehir Block and lies adjacent to it (Kay- analyzedfrom17sites(Fig.6).Theremaining14data
makci, 2000). It is separated from the rim of the were spurious. Therefore, they were not used in the
C(cid:1)ankırı Basin by the Late Cretaceous to Paleocene construction of stress tensors. With the exception of
Dizilita(cid:1)slar Formation and from the Early to Middle sites 109 and 89 where the data was collected from
Eocene units (Yoncalı and Karabal(cid:1)cık Formations). Aquitanian (MN 1–2) Kılc(cid:1)ak Formation and the
Therefore, the cumulative vertical offset of this fault NAOM,respectively,alltheotherdatawerecollected
is larger than the total thickness of these units, fromPaleocenetoEoceneunits.Thedetailsofthedata
which is more than 2 km. In the north, along the from each site aregiven inTable1.
fault BTF-6, the NAOM is thrusted over the Early At seven sites, two different sets of overprinting
to Middle Eocene Karabalc(cid:1)ık Formation. It is slickenlines and slickenfibres developed in the dilata-
unconformably overlain by the latest-Early Miocene tional jogs and three different fault movements were
to Middle Miocene (MN ?4–6) C(cid:1)andır Formation observed in the field (Table 1). In ordering of move-
where it is displaced by a NW–SE trending normal ment sets and deformation phases, the procedure
fault (location e in Fig. 4) indicating post-Middle discussed in Kaymakci et al. (2000) was followed as
Eocene and pre-latest-Early Miocene to Middle mentioned before.
Miocene activity of this thrust fault. Phase 1: This phase is recognized at only six sites
The Kıl(cid:1)cak Thrust Fault (KLTF) is the youngest (Fig.6aandTable2).Theorientationofthehorizontal
well-constrained thrust fault observed in the C(cid:1)ankırı principal stress is relatively consistent between sites
Basin.AlongtheKLTF,theNAOMandtheYayla(cid:1)cayy´ and it is oriented ENE–WSW to NNE–SSW. Except
Formation have been thrusted over the Aquitanian for sites 109 and 131-2 in which r is vertical, in all
3
(MN 1–2) Kıl(cid:1)cak Formation. other sites r and r are oblique (see Table 2).
2 3
The Yag˘basan–Fara(cid:1)slı and Sivritepe Fault Zones The orientations of the subarea based mean
have displaced the rim, the basin fill, including the regional stresses are as follows r =023jN/01j,
1
LateMioceneunits,andthebasement(Fig.4)indicat- r =116jN/64j, r =293jN/26 (Fig. 7 and Table 2).
2 3
ing the syn- to post-Late Miocene activity. The youngest unit which has been deformed in this
phase is the MN-1 Kılc(cid:1)ak Formation. Therefore,
4.1.2. Folds deformation phase 1 postdates the deposition of the
The folds (f1–f9) developed in this subarea are Kıl(cid:1)cak Formation in theAquitanian (MN 1–2 in MN
oriented mainly in a N–S to NNW–SSE direction zones,Fig.3).Theapproximatelysubverticalorienta-
except f2, which has a curved trace and becomes tion of r and oblique orientation of r indicate
2 3
parallel to the SFZ in the north (Fig. 4). The folds f1 transcurrent deformation in the deformation phase 1.
and f3 trend parallel to the fault BTF-4, which leads Phase 2: This phase was recognized at two sites
foracommontectonicorigin.Thefolds(f5–9)inthe (Fig. 6). In both sites r is subvertical and r is
1 3
north of the YFFZ are subparallel to the BTF-6 and subhorizontalandr issubhorizontal(Fig.6andTable
2
trendNNW–SSEtoN–S.Inaddition,thefoldsf8–f9 2).Theorientationsofthemeanregionalstressesareas
are overridden by the BTF-6 indicating their sequen- follows: r = 303jN/67j, r = 075jN/16j,
1 2
tialdevelopment.Thefoldsf4andf55areoverturned r =170jN/17 (Fig. 7 and Table 2). The subvertical
3
synclines developed within the Incik Formation and orientation of r and approximately subhorizontal
1
associatedwithprogressiveunconformitieswithinthe orientation of the other principal stress indicate a
Incik Formation. This relation was interpreted as dominantlyextensionaldeformation.
94 N.Kaymakcietal./Tectonophysics364(2003)85–113
Fig.6.Plotsoffaultsplanes,slickenlines,andstressorientationsforeachsiteinsubarea1(lowerhemisphere,equalareaprojection).