U. Ring, M.T. Brandon, G. Lister and D.S. Willet (Eds.) Exhumation Processes: Normal Faulting, ductile Flow and Erosion. (Geological Society: Special Publication 154), 1999, viii + 378 pp. List Price: £89.00 GSL price: £39.00. ISBN 1-86239-032-0.

Abstract

This Special Publication of the Geological Society followed an International Conference with the same theme. The main aim of the volume according to the editors was to sample ‘frontier research’ on the processes that lead to the exhumation of metamorphic rocks in ancient and modern orogens. The volume contains sixteen papers arranged into three sections. In understanding of exhumation processes, in common with other growth interest areas, the Earth Sciences has generated a raft of often poorly defined terminology. The initial paper by the editors provides, therefore, a useful review of the exhumation problem defining the terms of reference, identifying the tectonic processes, the tectonic settings and criteria that might be diagnostic for specific exhumation processes. The emphasis on the origins and exhumation of ultra-high pressure rocks is clearly of special interest to the editors but their deliberations do distort an otherwise well balanced review. The examples used to illustrate each section are, nevertheless, well chosen and the paper provides an excellent introduction for any student wishing to embark on a study of exhumation processes. The arrangement of the remaining papers into the categories of ‘Subduction-related accretionary wedges’, ‘Collisional belts and intra-continental convergence’ and ‘Lithospheric extension’ seems a little forced and not all are appropriately placed. While the groupings are indicated in the contents page they are not separated in the body of the volume. The first two papers examining exhumation in Subduction-related settings are concerned with Franciscan type HP/LT rocks. Sedlock presents field and structural data to evaluate the mechanisms responsible for the exhumation of the blueschists in western Baja California. Erosion, strike-slip faulting, buoyancy and ductile flow are considered to have played only minor roles while normal faulting is confirmed as the principal exhumation mechanism. In …