NEOGENE STRATIGRAPHY AND PALEOGEOGRAPHIC EVOLUTION OF THE KARABURUN AREA, İZMİR, WESTERN TURKEY

Abstract

The western margin of the Foça Depression (FD) is located in the NE of the KaraburunPeninsula. Terrestrial Neogene sediments in the study area which partly representing thewestern margin of the FD and the mafic volcanics have NW-SE directions towards ‹zmirbay and are separated from the basement rocks by synthetic normal faults. During theMiocene deposition the basin’s boundaries became structurally narrower and two mainsedimentary successions have been defined namely the Karaburun group and the Eflenderegroup which have been separated with angular unconformity in regional scale. TheKaraburun group is represented with dominantly lacustrine deposition in Early-MiddleMiocene period that includes Haseki and Hisarcık formations and Karaburun volcanics.The Lower Miocene Haseki formation is represented by the Salman member developed inthe alluvial fan environment and lacustrine deposits of algal-biostromal Yenilimanlimestone and micritic limestone dominated Aktepe member. NW trending basin marginfaults which formed a boundary between Karaburun high and the FD and caused theeffective second stages of mafic volcanism did not interrupt the lacustrine deposition at thebeggining of the Early Miocene. But it caused relative deepening of the basin, changeddepositional conditions and lacustrine sedimentation continued with the Hisarcıkformation. The activity shaping the FD from the western part and partly coinciding withthe Early Miocene basin margin faults has been documented with the unconformityshowing no time gap between Haseki and Hisarcık Formations. Hacıhüseyintepe memberhas unconformity with the lavas that represent the second stage of Karaburun volcanicsand laterally passes into the Karaba¤ları member. The Karaba¤ları member consists ofgreen coloured lacustrine shoreface sediments which lie on the Aktepe succession withsublacustrine paraconformity. De¤irmentepe limestone transitionally lies on the top and itis the last member of the Karaburun group. Eflendere group lies on the Hisarcık formationwith regional scale angular uncoformity and presents the Late Miocene-early EarlyPliocene(?) sedimentation grading from alluvial fan deposits of the Saip formation tolacustrine Çukurcak limestone. Calc-alkaline Karaburun volcanism which is representedwith potassium rich andesitic products has three stages that laterally connected with theEarly Miocene-early Middle Miocene deposition The first two stages have dual faciesnamely, pyroclastics at the base and lavas on the top. The first stage products are laterallydiscontinuous reference level that is separating Yeniliman limestone and Aktepe member.Second stage products are in/on the Aktepe member. The third stage lava flows are datedas K/Ar 16.0±1.3 Ma age which is thought to be located at the bottom of the De¤irmentepelimestone that is the last member of the Karaburun group.1988; Çakmako¤lu ve Bilgin, 2006) tektonikyerleflimi ile Erken Miyosen havza oluflumu arasındageçen süre boyunca bölgenin deformasyona u¤radı¤ıve aflındı¤ı kabul edilmektedir. ‹nceleme alanında,Çakmako¤lu ve Bilgin (2006)’in tanımladı¤ıDikenda¤ı formasyonuCamibo¤azı formasyonu (Ladiniyen), Güvercinlikformasyonu (Resiyen-Karniyen) ve ‹zmir fliflinden(Geç Kretase-Erken Tersiyer) oluflan temel kayaları