Definition - What does Imbrication mean?

Imbrication is a primary depositional fabric of clasts which are arranged in a way such that they overlap one another in a consistent fashion, rather like a run of toppled dominoes. Imbrication is observed in conglomerates and some volcano remains of clastic deposits. The shape and orientation of Imbrication clasts are generally ellipsoid with long axis, intermediate axis and short axis.

Petropedia explains Imbrication

Imbrication is related to geology and sedimentary rocks. Depending on the shape of imbrication, there are two types of imbrication:

  • A-axis Imbrication – For such type of imbrication, the long axis of the clasts are oriented parallel to the flow direction. This fabric is typical of conglomerates at the base of turbidite beds but is also occasionally observed in alluvial fan deposits reworked by flash floods.
  • AB plane imbrication – For such type of imbrication, the long axes of the clasts are oriented perpendicular to the flow direction and the imbrication is of the flattened AB plane, with the intermediate axes in the flow direction. This fabric is characteristic of clasts carried as bed load.
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