Facies Anatomy of a Sand-Rich Channelized Turbiditic System: The Eocene Kusuri Formation in the Sinop Basin, North-Central Turkey

  1. Gary Nichols,
  2. Ed Williams and
  3. Chris Paola
  1. Nils E. Janbu1,†,
  2. Wojciek Nemec1,
  3. Ediz Kirman2 and
  4. Volkan özaksoy3

Published Online: 30 MAR 2009

DOI: 10.1002/9781444304411.ch19

Sedimentary Processes, Environments and Basins: A Tribute to Peter Friend

Sedimentary Processes, Environments and Basins: A Tribute to Peter Friend

How to Cite

Janbu, N. E., Nemec, W., Kirman, E. and özaksoy, V. (2007) Facies Anatomy of a Sand-Rich Channelized Turbiditic System: The Eocene Kusuri Formation in the Sinop Basin, North-Central Turkey, 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.ch19

Author Information

  1. 1

    Department of Earth Science, University of Bergen, 5007 Bergen, Norway

  2. 2

    Department of Geological Engineering, University of Ankara, 06100 Ankara, Turkey

  3. 3

    General Directorate of Mineral Research and Exploration (MTA), 06520 Ankara, Turkey

  1. Statoil Research Centre, Rotvoll, 7005 Trondheim, Norway

Publication History

  1. Published Online: 30 MAR 2009
  2. Published Print: 7 DEC 2007

Book Series:

  1. Special Publication Number 38 of the International Association of Sedimentologists

Book Series Editors:

  1. Ian Jarvis

Series Editor Information

  1. School of Earth Sciences & Geography, Centre for Earth & Environmental Science Research, Kingston University, Penrhyn Road, Kingston upon Thames KT1 2EE, UK

ISBN Information

Print ISBN: 9781405179225

Online ISBN: 9781444304411

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Keywords:

  • facies anatomy of sand-rich channelized turbiditic system - Eocene Kusuri formation in Sinop Basin;
  • basin-floor turbiditic system in Eocene foredeep basin;
  • lower to middle Eocene Kusuri formation in Sinop Basin - succession of siliciclastic turbidites;
  • Pontide and Tauride orogenic belts of Anatolia;
  • pre-Eocene development;
  • coeval Eocene succession in Boyabat Basin referred to as Cemalettin formation;
  • Kusuri formation;
  • sedimentary facies - basic ‘building blocks’ of sedimentary succession

Summary

This study focuses on a basin-floor turbiditic system in an Eocene foredeep basin, using facies analysis supplemented with micropalaeontological and ichnological data. Sediment dispersal processes are interpreted from sedimentary facies, and the morphogenesis, spatial relationships and stratigraphic distribution of facies associations are used to reconstruct the behaviour and morphodynamic evolution of the turbiditic system. The case study sheds more light on the development of submarine channels and related patterns of overbank sedimentation in narrow foreland basins, and contributes to a better understanding of the geological history of the Central Pontides.

The lower to middle Eocene Kusuri Formation in the Sinop Basin, north-central Anatolia, is a succession of siliciclastic turbidites ∼ 1200 m thick, well-exposed on the Turkish Black Sea coast. The deposition occurred in a west-trending foredeep trough of the Central Pontides, ∼ 30 km wide and > 150 km long, and involved a deep-water axial dispersal system supplied with coarse sediment by a fluvio-deltaic feeder draining the emerged adjacent foreland of the Eastern Pontides. Sedimentary facies include hemipelagic ‘background’ mudstones, thin muddy turbidites and ‘classic’ Bouma-type turbidites, a wide range of non-classic turbidites attributed to low- and high-density sustained currents, and gravelly debrisflow deposits. These facies form four major associations:

1 mudstones interspersed with thin turbidite sheets;

2 broad depositional lobes with thickening-upward bedding trends;

3 poorly defined wide palaeochannels, solitary sinuous palaeochannels and multistorey palaeochannel complexes;

4 packages of thin overbank turbidites with tabular, wedge-shaped or sigmoidal bedding.

The first assemblage forms the lowermost and uppermost part of the Kusuri Formation, whereas the others occur in its middle main part. The poorly defined palaeochannels are 20–25 m thick, typically overlie the depositional lobes and are themselves overlain by the sinuous palaeochannels, 20–30 m thick and ≤ 400–500 m wide, which suggests that the former channels tended to evolve into the latter. The sinuous channels show lateral accretion (point bars) indicating meander-bend expansion combined with a marked downstream translation, and their depth/width aspect ratios are much lower than those of many modern submarine channels. The multistorey complexes of sinuous palaeochannels are 100–160 m thick and estimated to be ≤ 3–5 km wide. The vertical stacking of multistorey channels is attributed to the growth of syndepositional blind-thrust anticlines on the basin floor. The overbank facies assemblages indicate basin-wide flows (tabular bed packages), small and highly depletive spill-over flows forming minor levées (wedge-shaped bed packages), and overbank flows deflected by local topography (sigmoidal packages of laterally plastered turbidites).

The narrowness of the basin, the rate of sediment supply (turbidity current discharges) and the temporal topographic confinement provided by syndepositional seafloor deformation are considered to have been the main factors controlling the behaviour and morphodynamic evolution of the turbiditic system. The basin was subject to orogenic compression, with the pulses of tectonic contraction causing both seafloor deformation and an increased sediment supply. As the Sinop foredeep was eventually converted by thrusting into a wedge-top (‘piggyback’) basin, the fluvial feeder was diverted away from the latter and contributed to a rapid shallowing and deltaic system advance in the adjacent Boyabat Basin. Both basins were gradually inverted by compressional tectonics in late Eocene to early Miocene time, during the climax and final stages of the Tauride orogeny to the south.