Examples of intrusive acid dykes in E. Tasmania

Observations of the relationship between linear or planar features on either side of dykes usually form the basis of a field determination of their mode of emplacement, although it is known that sections oblique to planar features may lead to conflicting results. In Eastern Tasmania only rarely are examples encountered where dyke wall-rock units are of use. However, dyke wall irregularities are common and a comparison of opposite walls have shown the dykes to be intrusive. Disproportionate offsets of corresponding wall irregularities due to connecting cross-dykes are general, which results in intrusive bodies resembling those of a replacement origin.