Determination of strain from stretched belemnites

Belemnites are valuable strain markers and can be used to determine the elongation that has been suffered by the matrix in which they are situated. Experiments simulating the development of stretched belemnites have been performed to verify their deformation history. The analysis of the experimental results is used in the interpretation of field examples collected from Leytron, Valais, Switzerland. The amount of strain suffered by Leytron belemnites has been evaluated using the “least square” method and the result has been compared with that obtained by the “average elongation” method. The relationship between the final orientation of the whole specimen (θ′_b) and that of the fragments (θ′_f) demonstrates that the Leytron belemnites have suffered an irrotational type of deformation.