Features of the tertiary volcanism around sea of Marmara T. Ercan, Ahmet Türkecan, Herve Guillou, M. Satir, D. Sevin, F. Saroglu To cite this version: T. Ercan, Ahmet Türkecan, Herve Guillou, M. Satir, D. Sevin, et al.. Features of the tertiary volcanism around sea of Marmara. Bulletin of The Mineral Research and Exploration, 1998, 120, pp.97-118. hal-03323404 HAL Id: hal-03323404 https://hal.archives-ouvertes.fr/hal-03323404 Submitted on 21 Aug 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. 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See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/264851168 FEATURES OF THE TERTIARY VOLCANISM AROUND SEA OF MARMARA Article · January 1998 CITATIONS READS 8 107 6 authors, including: Ahmet Türkecan Hervé Guillou General Directorate of Mineral Research and Exploration of Turkey Laboratoire des Sciences du Climat et l'Environnement 49 PUBLICATIONS 673 CITATIONS 345 PUBLICATIONS 7,955 CITATIONS SEE PROFILE SEE PROFILE Fuat Şaroğlu Jeolojik Mirası Koruma Derneği (JEMİRKO) 75 PUBLICATIONS 5,254 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Updating of Active Fault Map of Turkey and its Database View project Eruptive history and magma chemistry evolution through time View project All content following this page was uploaded by Hervé Guillou on 18 December 2014. The user has requested enhancement of the downloaded file. Mineral Res. Expl. Bull., 120, 97-118, 1998 FEATURES OF THE TERTIARY VOLCANISM AROUND SEA OF MARMARA Tuncay ERCAN*; Ahmet TÜRKECAN*; Herve GUILLOU"; Muharrem SATIR*"; Dilek SEVİN*** and Fuat SAROĞLU***** ABSTRACT.- In the region around the sea of Marmara, limited by the boundaries of the 1:500 000 scale Istanbul Quadrangle, the volcanism starting in Upper Cretaceous and intermittently continuing through the end of Upper Miocene has been differentiated into five different stages, namely Upper Cretaceous, Eocene, Oligocene, Lower-Middle Miocene and Upper Miocene, and the volcanic outcrops situated in the region have been dated. Together with the detailed petrographic studies, nine samples from different areas and stages have been dated by K/Ar method, resulting in that the oldest and the youngest lava is of 74.3 ± 1.0 million years old (Upper Cretaceous) and 8.9±0.2 years old (Upper Miocene), respectively. Of these, belonging to the first four stages are mostly calcalkaline (some of the Eocene aged samples are tholeiitic) and are of basalt, basaltic andesite, trachyandesite, andesite, dacite, rhyolite type, whereas that of belonging to the fifth stage are alkaline and of basanite, basalt and trachybasalt types. The pyroclastics of various size and the tuffs of the first four volcanism stages crop out in a wide area. The Upper Cretaceous volcanics have completely formed beneath the sea. On the other hand, some of Eocene volcanics have formed beneath the sea which are seen intercalated with sediments while the others have formed on land. The lavas of Oligocene, Lower-Middle Miocene and Upper Miocene age have formed on land and are observed to be intercalated with lacustrine sediments, in places. Of the lavas stranded along the Black sea coast, the Upper Cretaceous aged ones have formed in a group of island arc volcanics and have been produced in a subduction zone and the Eocene, Oligocene and Lower-Middle Miocene aged ones have formed in an environment of compression during and after the collision and have been produced from a material of crust and mantle mixture. It is proposed that the Upper Miocene aged alcaline basaltic volcanics have formed in an environment of extension by the uplift of mantle after the change of tectonic regime in Middle Miocene. INTRODUCTION THE FEATURES OF THE TERTIARY VOLCANISM In the area around sea of (Marmara region, an in- The Tertiary volcanics around the sea of Marmara, tense volcanism has been effective starting from. Upper limited by the boundaries of the 1:500000 scale Istan- Cretaceous to the beginning of Pliocene displaying va- bul Quadrangle, and the Upper Cretaceous volcanics rious stages and forming widespread lavas and pyroc- cropping out along the Black sea coast have all toget- lastics having different petrographic and geochemical her been studied and differentiated into five different features. Although there have been many geological groups: studies in the region, there are no special and suffici- ent studies to reveal the Tertiary volcanism, the regi- Upper Cretaceous volcanics onal extension of the volcanic rocks, their ages, sta- ges, petrochemical features and genetic explanations. Upper Cretaceous volcanics in the study area are This study intends to shed light on these questions to- situated in the north, along the Black sea coast in vici- gether with their relations with the adjacent sedimen- nity of Istanbul and in Igneada, close to Bulgarian-Tur- tary rocks and their datings. For this reason, samples kish State Boundary (Fig. 1). They generally are obser- from the Upper Cretaceous, Eocene, Oligocene, Lo- ved to intercalate with the sedimentary rocks of the sa- wer-Middle Miocene and Upper Miocene were taken me age. Upper Cretaceous aged sedimentary and vol- and dated by K/Ar method. canic rocks are widespread in the east of Istanbul, aro- 98 Tuncay ERCAN; Ahmet TÜRKECAN; Herve GUILLOU; Muharrem SATIR; Dilek SEVİN and Fuat ŞAROĞLU VOLCANISM AROUND SEA OF MARMARA 99 und Şile. Flysch type sediments, comprising an alter- rocks have completely formed during Upper Cretace- nation of conglomerate, sandstone, siltstone, marl, ous (Santonian - Campanian - Maastrichtian). claystone and limestone, bear various kinds of pyroc- lastics and lava flows in rather lesser amounts. These In the study area, the Upper Cretaceous volcanism are spilitic basalts, basalts, andesites, basaltic andesi- having small outcrops towards west (Akartuna 1953; tes, trachyandesites, dacites rhyolitic lavas, agglome- Erentöz,1953) is observed again in vicinity of lğneada. rates and tuffs, displaying typical submarine volca- These are basalts, basaltic andesites, spilitic basalts, nism. The most widespread of these is highly altered andesites, rhyodacites and rhyolitic lavas, tuffs and an- andesitic lava which contains plagioclase, rather less desites and are intercalated with Upper Cretaceous hornblende, biotite, augite and opaque minerals. The marine sediments. Pillow lavas are locally observed. argillization observed in these rocks is of large scale They are mostly andesites and basaltic andesites. An- and significant in industrial point of view. Besides, seri- desites are called "pyroxene andesites" since the citization, chloritization, carbonatization and zeolitizati- samples displaying porphyritic texture includes plagi- on are observed. Andesitic lavas are of porphyritic, oclase and pyroxene crystals. The plagioclases (ande- hyaloporphyritic, partly pylotaxitic texture. Plagioclase sine and oligoclase), crystallized as macro and microp- phenocrysts are hypidiomorph in places and its types henocrystals in hypidiomorph form, are generally seri- such as albite showing polysynthetic twinning and zo- citized, chloritized and epidotized. Some display glo- nal structure, andesine, oligoclase and labrador were meroporphyritic texture. Pyroxenes (clinopyroxene-au- determined (Yeniyol and Ercan, 1989/1990). Augites gite) form assemblages of glomeroporphyritic texture are partly idiomorphic and have uralitized and epidoti- as in xenomorph crystals. Some change into chlorite zed in places. Generally biotites have undergone mag- pseudomorphs including carbonates and carbonatiza- matic corrosion. In dacites and rare rhyolites, additi- tion. The matrix has intersertal texture and is formed by onal to the minerals listed above quartz crystals in va- the interfingering plagioclase microliths and the altered rious amounts can be seen. In trachyandesitic lavas pyroxene granules, chlorite and intercitial silica filling sanidine crystals are clearly visible. Spilitic lavas are in the space between. In the matrix, locally, concentric lesser amounts than intermediate lavas. Spilites comp- carbonatization, silicification and epidotization is obser- rise albite, augite and opaque minerals. Serpentinizati- ved. The andesitic lavas which are close to basalts in on, chloritization and carbonatization are seen in pla- texture, have been called as pyroxene andesite or ba- ces. Basaltic lavas display porphyritic, pylotaxitic, hya- saltic andesite in andesite-basalt transition. Tuffs are in loporphyritic and vitrophyric textures. They comprise many places have the appearance of lavas and are mainly of plagioclase and augite microliths together with plagioclase, augite, opaque mineral and olivine called as lapilli tuff and crystal tuff. Lapilli tuffs have a phenocrystals in a matrix of volcanic glass. Plagiocla- silicified, epidotized and prehritized matrix including ses display polysynthetic twinning and zonal structure volcanic rock fragments of andesitic nature and pyro- and are of andesine and labradorite type. Augites