Doğu Pontidler (Trabzon, Bayburt, Erzurum ve Artvin) Orta Jura ve Üst Kretase Volkano-Sedimanter İstiflerinin Radyolarya Taksonomisi, Biyostratigrafisi ve Çökel Ortamları

Abstract

ABSTRACT

RADIOLARIAN TAXONOMY, BIOSTRATIGRAPHY AND DEPOSITIONAL ENVIRONMENTS OF THE MIDDLE JURASSIC AND UPPER CRETACEOUS VOLCANO-SEDIMENTARY SEQUENCES IN THE EASTERN PONTIDES (TRABZON, BAYBURT, ERZURUM AND ARTVİN)

Havva SOYCAN Doctor of Philosophy, Department of Geological Engineering Supervisor: Prof. Dr. Uğur Kağan TEKİN February 2017, 465 pages

The biostratigraphy and systematic of radiolarian faunas in the volcano-sedimentary units of the Middle Jurassic and the Late Cretaceous ages around Trabzon, Artvin, Bayburt and Erzurum in the Eastern Pontides (NE Anatolia) have been investigated. The biochronological correlation of radiolarian fauna with planktonic foraminifer fauna of the Late Cretaceous age from the stratigraphic sections measured within this study were revealed. Detailed data related to the lithological features and the setting time constraints of Middle Jurassic and Upper Cretaceous volcano-sedimentary units. Besides that, the depositional environments of the rock units as part of this study were also asserted. In the Middle Jurassic, late Bajocian age from mudstones and cherts in the Hızarlı, Madenler and Çoruh stratigraphic sections of the Berta formation; latest Bajocian–middle Bathonian age from mudstones and cherts in the Hars stratigraphic section of the Kırgülü formation around Artvin; late Bajocian age from tuffs in the Gökçedere, Kop-1 ve Kop-2 stratigraphic sections of the Kelkit formation around Bayburt were obtained based on radiolarian faunas. A total of 189 species belonging to 74 genus from radiolarian faunas in the Middle Jurassic are identified. Three genus are new (Bayburtum, Harsella, Paraminutusolla) and in species, 34 of taxa belonging to 12 genus are determined as new. U.A.Z. 4 (late Bajocian) and U.A.Z. 5-6 (latest Bajocian–middle Bathonian) Unitary Associations Zones belonging to this radiolarian faunas were revealed. Based on paleontological and petrographical data obtained from this study, the volcano-sedimentary units in the northeastern and southern parts of the Eastern Pontides deposited in the marine environment exposed discontinuously active volcanism in the late Bajocian and latest Bajocian–middle Bathonian time intervals. Despite the lithological and stratigraphic differences among the volcano-sedimentary units of the Middle Jurassic age near Artvin and Bayburt in the Eastern Pontides, in the Central Pontides, in the Western Sakarya Zone and in the Transcaucasus, this units have the similarities in terms of the character and the evolution mechanism of volcanism. In the Late Cretaceous, late Coniacian–Santonian and late Santonian ages from bioclastic wackestones and packstones in the Küçükdere-1 ve Küçükdere-2 stratigraphic sections of the Çağlayan formation near Trabzon; early Campanian age from cherts in the Koyuncular stratigraphic section of the Çayırbağ formation around Artvin; early Campanian age from bioclastic wackestones in the Aksu stratigraphic section of the Aksu formation around Erzurum were detected based on radiolarian and planktonic foraminifer faunas 62 species belonging to 31 genus from radiolarian faunas and 49 species belonging to 14 genus from planktonic foraminifer faunas in the Late Cretaceous were established. In addition to this, Alievium gallowayi Zone belonging to radiolarian faunas along with Dicarinella asymetrica and Globotruncanita elevata Zones belonging to planktonic foraminifer faunas were described. Based on this study, bioclastic wackestones and packstones deposited in the toe of slope or the deep sea during the late Coniacian–late Santonian time interval in the Çağlayan formation and in the early Campanian in the Aksu formation. Besides that, the environment of deposition of bio-lithoclastic packstones of the Aksu formation were in the slope, the toe of slope or the deep sea in the early Campanian. The rock units including chert strata of the Çayırbağ formation deposited in the open marine environment in the early Campanian. In the studied sections, basalt and basaltic pyroclastic rocks of late Coniacian–late Santonian age in the Çağlayan formation and asidic pyroclastic rocks of early Campanian age in the Çayırbağ formation reveals to be present the bimodal volcanism in the northern parts of the Eastern Pontides. However, the rock units of early Campanian age in the Aksu formation in the southeastern parts of the Eastern Pontides don’t have the volcanic material. Regionally, also taking into account some previous studies, despite the lithological and stratigraphic differences among the volcano-sedimentary units of the Late Cretaceous age near Trabzon, Artvin ve Erzurum in the Eastern Pontides, in the Central Pontides, in the Western Sakarya Zone, in the eastern parts of Istanbul Zone (Zonguldak Basin) and in the Transcaucasus, this units have similarities to each other in terms of the character and the evolution mechanism of volcanism.