Late Cretaceous to Early Eocene Sedimentation in the Sinop–Boyabat Basin, North-Central Turkey: A Deep-Water Turbiditic System Evolving into Littoral Carbonate Platform
- Gary Nichols,
- Ed Williams and
- Chris Paola
Published Online: 30 MAR 2009
Copyright © 2007 International Association of Sedimentologists
Sedimentary Processes, Environments and Basins: A Tribute to Peter Friend
How to Cite
Leren, B. L. S., Janbu, N. E., Nemec, W., Kirman, E. and Ilgar, A. (2007) Late Cretaceous to Early Eocene Sedimentation in the Sinop–Boyabat Basin, North-Central Turkey: A Deep-Water Turbiditic System Evolving into Littoral Carbonate Platform, in Sedimentary Processes, Environments and Basins: A Tribute to Peter Friend (eds G. Nichols, E. Williams and C. Paola), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304411.ch18
- Published Online: 30 MAR 2009
- Published Print: 7 DEC 2007
Book Series Editors:
- Ian Jarvis
Series Editor Information
School of Earth Sciences & Geography, Centre for Earth & Environmental Science Research, Kingston University, Penrhyn Road, Kingston upon Thames KT1 2EE, UK
Print ISBN: 9781405179225
Online ISBN: 9781444304411
- late Cretaceous to early Eocene sedimentation in Sinop–Boyabat Basin, north-central Turkey;
- Sinop–Boyabat Basin - southeast-trending elongate basin in Central Pontides;
- Sinop–Boyabat Basin of north-central Anatolia, Turkey;
- deep-water turbiditic system evolving into littoral platform;
- collisional Pontide orogeny;
- dynamic stratigraphy of Sinop–Boyabat Basin;
- sedimentary facies associations;
- rapid subsidence and sea-level rise
The Sinop–Boyabat Basin is a southeast-trending elongate basin in the Central Pontides, northern Anatolia, filled with a succession of Lower Cretaceous to middle Eocene deposits, nearly 7 km thick. The basin evolved from a backarc rift related to the Western Black Sea crustal extension into a retroarc foreland basin of the Central Pontides, and was eventually inverted by tectonic compression in the late Eocene. The present sedimentological study, supplemented with petrographical, micropalaeontological and ichnological data, is focused on the Upper Cretaceous to lowest Eocene part of the basin-fill succession, which is ∼ 2 km thick, comprises the Gürsökü, Akveren and Atbaşı formations and corresponds to the basin's transformation from a failed rift into an orogenic foreland. The succession's facies associations reveal a deep-marine turbiditic system that underwent prolonged aggradation and evolved into a wave-dominated littoral carbonate platform, to be drowned again due to a eustatic sea-level rise and rapid tectonic subsidence in late Paleocene time.
The upper Campanian to lower Maastrichtian Gürsökü Formation consists of alternating siliciclastic sandstones, calcareous mudstones and subordinate marlstones. The deposits represent a basin-floor turbiditic system directed towards the east, supplied with epiclastic volcanic detritus and increasingly more abundant bioclastic sediment from the basin's southwestern margin. The bioclastic admixture indicates development of a reefal platform at the basin margin. The northeastern margin was submerged and insignificant as a sediment source. The sheet-like turbidites indicate non-channelized currents of low to high density, and the succession represents transition from the medial to distal part of the system. At least one isolated palaeochannel occurs in the lowermost, thicker bedded part of the succession. The system was supplied with sediment from a storm-dominated littoral ramp perched on the basin margin and was subject to gradual retreat (back-stepping) by onlapping the margin.
The upper Maastrichtian–Paleocene Akveren Formation consists of sheet-like calcarenitic turbidites interbedded with marlstones and calcareous mudstones. Its uppermost part is dominated by tempestites, with wave-worked shoreface calcarenites and a reefal limestone unit at the top. Eastward sediment dispersal persisted, and the basin-floor turbiditic system was supplied with sediment from a distally steepened ramp with bypass chutes. As the turbiditic system aggraded, the ramp became homoclinal and the ignition of turbidity currents declined, giving way to tempestitic sedimentation. The rate of sediment accumulation outpaced the declining subsidence rate, and this imbalance culminated in the rapid shallowing of the basin recorded by the uppermost part of the formation.
The uppermost Paleocene to lowest Eocene Atbaşı Formation recorded a dramatic rise in relative sea level, which could initially be mainly eustatic, with brief normal regressions, but then was greatly accelerated by foreland subsidence due to the crustal loading by Central Pontide thrust sheets. Basal transgressive shoreface and offshore-transition deposits are overlain by deep-water, variegated calcareous mudstones interspersed with thin calcarenitic turbidites. The muddy deposits indicate a sand-starved basin with a very low sedimentation rate and widespread seafloor oxidation.