Chert Textures

Chert Textures

The Rhynie chert, examined from float blocks, trench and cored material exhibits a wide range of macro-textures (those large enough to be visible in hand specimen) and micro-textures (those clearly visible using optical microscope techniques). Studying both, together with the biota the individual beds contain, can help elucidate the different palaeoenvironments that were present in this hot spring complex at Rhynie 400 million years ago, useful comparisons can be made with modern hydrothermal deposits and settings ( see also the section on The ancient environment and modern analogues ). The following gives a brief summary of the textures observed within the chert beds together with some example images.

Macro-Textures

Five basic textures have been described from the chert beds ( Trewin 1994 ). However, within individual beds, particularly in composite beds of chert, more than one textural type may be present and there are often gradations between the textural types.

Micro-Textures

Apart from the studied large scale morphological features, optical microscope techniques provide a wealth of further information with which, for example, we can deduce the 'way-up' of the beds; and the burial history of the beds (in other words their diagenesis). Textural information can be used to elucidate the palaeoenvironment in which the individual beds were deposited. The following includes examples of micro-textural information that can be used to solve these problems.