Depositional Models for Fine-Grained Sediment in the Western Hellenic Trench, Eastern Mediterranean

  1. Dorrik A. V. Stow
  1. Daniel Jean Stanley1 and
  2. Andrés Maldonado2

Published Online: 29 APR 2009

DOI: 10.1002/9781444304473.ch41

Deep-Water Turbidite Systems

Deep-Water Turbidite Systems

How to Cite

Stanley, D. J. and Maldonado, A. (1991) Depositional Models for Fine-Grained Sediment in the Western Hellenic Trench, Eastern Mediterranean, in Deep-Water Turbidite Systems (ed D. A. V. Stow), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304473.ch41

Editor Information

  1. Department of Geology, University of Southampton, UK

Author Information

  1. 1

    Division of Sedimentology, Smithsonian Institution, Washing ton, D.C. 20560, USA

  2. 2

    CSIC, Egipciac as 9, Barcelona-1, Spain

Publication History

  1. Published Online: 29 APR 2009
  2. Published Print: 11 NOV 1991

ISBN Information

Print ISBN: 9780632032624

Online ISBN: 9781444304473



  • western Hellenic Arc;
  • Turbiditic and hemipelagic muds;
  • trench slope and trench basin;
  • hemipelagic mud;
  • slump, displaying deformed stratification


Sediment in tectonically active, topographically restricted settings of the western Hellenic Arc, eastern Mediterranean, consists primarily of clayey silt and silty clay. Failure of metastable sediment temporarily stored on relatively steep slopes is triggered by earthquake tremors and eustatic oscillations. Redeposition of these materials by gravitative transport has resulted in markedly different lithofacies from site to site. Most piston cores include three Late Quaternary stratigraphic units that can be correlated with sections in other parts of the eastern Mediterranean; numerous radiocarbon-age determinations enhance the correlation.

Seven fine-grained sediment types are identified in cores from eight distinct depositional environments. Some muds are closely related to specific environments (slump and debris flow deposits on slope and high-relief environments), or to time (well laminated mud during the latest Pleistocene–mid-Holocene), or to both (uniform and faintly laminated muds restricted to trench basins). Turbiditic and hemipelagic muds are common throughout the study area. Mud distribution patterns correlate closely with calculated sedimentation rates.

We propose two depositional models for these sediments. The first emphasizes downslope transformations resulting in progressively reduced flow concentration during transport: from slump and debris flow[RIGHTWARDS ARROW]turbidity current[RIGHTWARDS ARROW]low density turbidity current or turbid layer mechanisms. The distal end-member deposits settling from low concentration flows are thick, rapidly emplaced, fine-grained uniform muds closely associated with faintly laminated muds. These were ponded in flat trench basin-plains. Planktonic and terrigenous fractions in the turbiditic, finely laminated and uniform muds record mixing of materials of gravitative and suspension origin during redeposition. This sequence prevails under conditions of minimal stratification of water masses, as characterized by the present Mediterranean.

In the second model developed for conditions of well-developed water mass stratification, well laminated rather than uniform mud prevails as the end product of low concentration flows. These very finely laminated and graded muds record particle-by-particle settling from detached turbid layers concentrated along density interfaces; they include material from turbid layers complemented by the normal ‘rain’ of pelagic material. Stratification barriers resulted in region-wide distribution of such deposits, in both slope and trench environments.