Advances in Earth Science ›› 2012, Vol. 27 ›› Issue (8): 815-827. doi: 10.11867/j.issn.1001-8166.2012.08.0815

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Reviews on Fluid Properties and Sedimentary Characteristics of Debris Flows and Turbidity Currents

Gao Hongcan 1,Zheng Rongcai 2,Wei Qinlian 3,Chen Faliang 1,Chen Jun 1,Zhu Dengfeng 1,Liu Yun 1   

  1. 1. Geophysical Research Institute of Zhongyuan Oilfield Company, SINOPEC, Puyang〓457001, China;
    2.State Key Laboratory of Oil and Gas Reservoir Geology and Exploration,Chengdu University of Technology,Chengdu〓610059, China;
    3.School of Petroleum Resources,Xi’an Petroleum University,Xi’an〓710065,China)[JZ)]
  • Received:2011-12-02 Revised:2012-05-27 Online:2012-08-10 Published:2012-08-10

Gao Hongcan,Zheng Rongcai,Wei Qinlian,Chen Faliang,Chen Jun,Zhu Dengfeng,Liu Yun. Reviews on Fluid Properties and Sedimentary Characteristics of Debris Flows and Turbidity Currents[J]. Advances in Earth Science, 2012, 27(8): 815-827.

Influenced by the sedimentary models of turbidity currents and the turbidite mind set, the concepts of turbidity currents and turbidites have been expanded gradually since 1970s. Specially, Some deposition of debris flows and bottom flows are considered as turbidites by the introduction of the term “highdensity turbidity currents” and the incorrect comparison of subaerial rive currents and subaqueous turbidity currents. Turbidity currents and debris flows, especially sandy debris flows, have been rerecognized with application of modern observation facilities and detailed description of conventional cores. Turbidity currents are sedimentgravity flows with Newtonian rheology and turbulent state in which sediment is supported by fluid turbulence. Debris flows are sedimentgravity flows with plastic rheology and laminar state in which sediment is mainly  supported by matrix strength and frictional strength (caused by interlocking of grains and clasts). The normal grading is the main sedimentary rhythm of turbidites. The basal contacts of turbidites are invariably sharp or erosive, and the top contacts are gradational. Generally, the sedimentary rhythm of debris flows consist of the rigid raft with massive bedding in the upper part and the laminar flow zone with planar clast fabrics in the lower part.  When debris flows undergo only partial transformation by assimilation of ambient fluids (i.e., the diluteion effect), strongly coherent debris flows can transform into moderately coherent and weakly coherent debris flows, and its depositions from the bottom to the top are characterized by inverse to normal grading with complications (such as floating quartzose granules, mudstone clasts and so on), which distinguish from the turbidites with simple normal grading. Both basal and top contacts of debris flows are sharp. Depositional models of turbidity currents are simple baseofslope models with smooth basin floors, whereas the debris flows are complex slope models.

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