Tectonic Controls on Stratigraphic Evolution of the Adana Basin, Turkey
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Journal of the Geological Society, London, Vol. 152, 1995, pp. 873-882, 13 figs., 2 tables. Printed in Northern Ireland Tectonic controls on stratigraphic evolution of the Adana Basin, Turkey G.D. WILLIAMS’, U CANUNLUGENC’, G. KELLING’ & C. DEMIRKOL2 ’Geology Department, Keele University, Keele, Staffordshire, ST.5 5BG, UK 2 Geology Department, Cukurova University, 01330 Adana, Turkey Abstraet: The Neogene Adana Basin of SE Turkey was initiated after thrust emplacement of the Tauride Belt to the north of the basin. Seismic reflection profiles across the southern part of the Adana Basin provide information on structural and stratigraphic evolution of the basin. Based on seismiccharacter and theidentification ofunconformities, three megasequences and two mega sequence boundaries are identified. Thefirst megasequence is partly coincident with an early Miocene rifting event and it comprises reefs that have grown on fault footwall crests with fore and back-reef sediments in intervening lows. Subsequent rapid flexurally induced subsidence generated an under- filled basin whichwas then passivelyfilled by turbiditicsediments (megasequence 2) showing aggradational character on seismic profiles. Further extensional faulting and coupled sinistral wrench faulting took place after the deposition of megasequence 2. Erosional truncation of its upper part is followed by the deposition of continental and shallow marine sediments of megasequence 3 which shows localized progradational sequences characteristic of shallow water deposition. Further minor extensional faulting took place after the deposition of megasequence 3. Keywords: Adana Turkey, structural geology, stratigraphy. The structuralevolution of SE Turkey has been described in sediments represent seismic ‘basement’ with little resolvable terms of the interaction of several major wrench faults in the stratigraphy beneath this level. The interpretation of seismic Kharaman Mara? triple junction (Sengor 1980; Robertson & reflection profiles linked to field observations of structure Dixon 1984; Sengor et al. 1985). These major faults are the and stratigraphy in theAdana Basin hasproved to bea N-S-trending Dead Sea fault zone separating Africa from powerful tool in understanding basin forming mechanisms Arabia,the NE-SW-trending Bitlis suture which divides and in establishing an outline of basin evolution. This paper Arabia from Eurasia and the eastern part of the Hellenic is anattempt to integrate the tectonicevolution of the trenchwhere Africa is subducting beneath Eurasia. The Adana Basin with the filling of the basin in Neogene times. Adana Basin is locatedentirely onthe Anatolian Plate whose southerly boundary is marked by the Bitlis Suture which appearsto continue to the SW intothe Misis Traditional stratigraphic treatment Structural High (Fig. 1) (Sengor & Yllmaz 1981; Dewey et The traditional stratigraphy has involved subdivision of the al. 1986). basin fill into formations on the basis of lithostratigraphic The Adana Basin is bounded by the Ecemis Fault Zone and biostratigraphiccorrelations (Kirk 1935; Blumenthal to the west, the Misi? Structural High to the east and the 1941; Ternek 1957; Abdiisselamogou 1959; Schmidt 1961). overthrust Tauride Orogenic Belt to the north (Fig. 1). The More recent palaeontological and sedimentological research main Adana Basin was initiated afterthe late Eocene to has been carried out by Goriir (1979,1982), YalGin & Goriir Oligocene thrust emplacement of an ophiolitic complex and (1984) and Yeti? & Demirkol (1986). Todate, little associated melange in the Taurides to the north of the area. emphasis has been placed on the possible diachroneity of Awidespread, early Miocene phase of rapidsubsidence formations nor on the nature of formation (or sequence) probably in a foreland basin setting (Kelling et al. 1987) and boundaries (but see Goriir 1992). A full stratigraphic accompanied by extensionalfaulting gave rise to marine column for the Adana Basin is given in Table 1. invasion followed by gradual passive infilling and shoaling of The KarsantiFormation was depositedin a separate the basin during mid to late Miocene times. Late Miocene intermontane basin tothe northwest of the main Adana deformation occurred in the Misis Structural High and this Basin. It unconformably overlies Tauride ophiolitic rocks producedan area in thesouth of the basin of extensive which were eroded and derived into the Karsanti Formation erosion marked by shallow angular unconformity followed sediments which comprise alluvial fan, fluvial, lagoonal and by the deposition of Tortonian and Messinian continental lacustrinedeposits (UnliigenG & Demirkol 1991). These deposits. sediments were deformed by a compressional event of late Seismic reflection profiles across the southern part of the Oligocene age in the NE of theAdana Basin andare Adana Basin (Fig. 2) and selected well logs have been made unconformably overlain by succeeding sequences. The available by theTurkish Petroleum Company (TPAO). Gildirli Formation is restricted to the northern part of the Because of thegeneral southerly dip of the Neogene Adana Basin and comprises a thick sequence of sediments, sequences observed at outcrop in the north of the fluvio-lacustrine sediments. In the NW of the Adana Basin a basin are present atdepth in the seismic profiles. The conformable passage of the Gildirli Formation into younger seismic profiles are unmigrated, and early Miocene reefal sequences is seen. 873 Downloaded from http://pubs.geoscienceworld.org/jgs/article-pdf/152/5/873/4890413/gsjgs.152.5.0873.pdf by guest on 02 October 2021 a74 WILLIAMS G. D. ET AL. 37 36 Fig. 1. Location map of the Adana Basin in SE Turkey: major faults are indicated (+, upthrown and -,dow- nthrown side). D.S.F.Z., Dead Sea fault zone; E.A.F.Z., east Anatolian fault zone. Field investigationshave shown thatthe Karaisali (TWTT). The seismic lines have been tied by well data Formation is predominantlya carbonate reefalsequence where possible. Miocenereefal sediments of the Karaisali (Goriir 1977, 1979, 1985) thatappears to be mainly Formation form a bright positive reflection event and this is developed on isolated highs. Thereare flanking fore-reef effectively seismic basement beneath which the sections are and shallow marine sequences surrounding the reefal bodies. largely seismically transparent (Figs 3 & 4). TheAdana This formation passes laterally intothe Kaplankaya Basin stratigraphy may be subdivided intothree megase- Formation which marks the first input of marine clastics into quencesbased on internal seismic character and megase- the basin. The Cingoz and GiivenG Formations represent a quence boundary relationships. The megasequences broadly sequence of turbiditic sediments that show a shallowing of relate to traditional stratigraphy as shown in Table 2. the basin through time. Turbidites are point-sourced to the Megasequence 1 is a bright reflection event representing north and northwest and exhibit southerly and southeasterly Lower Miocene reefal deposits which appear to have formed palaeocurrents (Giirbiiz 1993). preferentially on the crests of major extensional fault blocks The Pliocene Kuzgun Formation overlies the GiivenG (Fig. 4). Megasequence 2 comprises parallel continuous Formation with slight angular unconformity. Field exposures reflectors indicative of turbiditic sediments. There is no show that at this boundary there is locally a marked facies evidence of expansion or growth of sequences in extensional change from outer marine shelf to continental fluvio-deltaic fault hanging walls (Figs 5 & 6) and therefore this is deposits (Unliigenq 1993). interpreted to represent sediment that has passively infilled a deep basin. There is some evidence for local onlap at the base of megasequence 2 on to megasequence 1 (Fig. 5) a Seismic sequence stratigraphy: Adana Basin relationship also observed in the field within the Adana Morethan 300 km of onshore seismic reflection data Basin (as in the Karaisali region; Goriir 1977). Marked supplied by TPAO (Fig. 2) havebeen interpreted in an erosionaltruncation at the top of megasequence 2 occurs attempt to understand the stratigraphy and structure of the beneath the 213 megasequence boundary (Fig. 5). Megase- Adana Basin. The seismic is of 1986 to 1988 vintage, is quence 3 shows local evidence for onlap at its base (Fig. 6). unmigrated and was shotto 4s two way traveltime It is shown seismically as largely parallel reflectors that dip Downloaded from http://pubs.geoscienceworld.org/jgs/article-pdf/152/5/873/4890413/gsjgs.152.5.0873.pdf by guest on 02 October 2021 STRATIGRAPHICEVOLUTION ADANATHE OFBASIN, TURKEY 875 Fig. 2. Map to show the extent of seismic coverage in the Adana Basin (individual lines identified by three-figure numbers). broadlysouthwards. Some progradational sequences, pos- and displacement of the bright reflector of megasequence 1 sibly representingdeltaic deposits, are present atthe (Figs 3, 5 & 6). The megasequence 2/3boundary is southern part of line 307 (Fig. 3). displaced by the same extensional faults, but only a minor amount of displacement is present (Figs 5 & 6). At the south Structural geology: seismic lines of the seismic line shown Fig.in a 3 suite of southward-downthrowingextensional faults is present in Megasequences 1 and 2 are cut by numerousextensional megasequence 3. Relativelycontinuous reflection events faults asshown by truncated reflectors (megasequence2) deep in the profiles beneath megasequence 3 dip northwards Table 1. Traditional stratigraphic