Original paper

Emplacement mechanisms of the Siaufrudalur pluton, Southeast Iceland, inferred from its three-dimensional shape

Burchardt, Steffi; Tanne, David C.; Krumbholz, Michael

Abstract

The excellent exposures of the roof and walls of the Slaufrudalur Pluton, Southeast Iceland, made it possible to map its shape with high-resolution GPS. Based on the GPS mapping and field observations, we reconstructed the three-dimensional shape of the pluton using Gocad and 3DMove. The reconstructedpluton shape is characterizedby steep walls and a relatively flat roof at map- scale. This shape and the internal compositional layering indicate that the pluton was probably emplaced by cauldron subsidence along subvertical faults. The roof contact of the pluton exploits the original layering of the flood basalts. At outcrop-scale, however, the roof was modified by magmatic stoping resulting in a step-like pattern. Hence, the reconstruction of the three-dimensional shape of the Slaufrudalurpluton combinedwith field observationsprovided valuable informationabout its mechanisms of emplacement.