Determination of 2D strain from a fragmented single ammonoid

摘要: Planispiral ammonoids are used for strain analysis, as the pre-strain shapes of their shells thought to be approximated by logarithmic spirals. Comparison pre- and observed post-strain spirals determines strain. We show in this short note that Rf/ϕ analysis is applicable ammonoids, where interspaces a shell markers. Unlike previous methods assumed spiral, present technique can use fragmented shells, provided they have at least half windings clear limbs. A ellipse its 95% confidence limit were determined hyperbolic vector mean method from ellipses fitted fragmented, deformed ammonite Kitakami Massif, Northeast Japan, worked problem technique.