Two-dimensional geostatistical modeling and prediction of the fracture system in the Albala Granitic Pluton, SW Iberian Massif, Spain

We use a fracture index distribution method of geostatistical modelling and prediction to characterize quantitatively the fracture system in two-dimen sions (2D) in the Mina Ratones area, located in the Albala Granitic Pluton (SW Iberian Massif). The fracture index (FI) is a quantitative estimate of the fracture density in discrete domains. To validate the results of geosta tistical modeling a detailed structural map of the area was also made on a scale of 1:1000. The resulting grids, expressed as pixel-maps, describe the continuous value of the FI in 2D for the whole Mina Ratones area. Based on the modelled distribution of the FI and their correlation with mapped faul ts, we distinguish two structural domains in the studied area: elongated ba nds of fracture zones with high FI values and romboidal blocks located betw een them with low FI values. The separation between both domains is gradual . Though a threshold value of the FI that separate both structural domains is not clearly defined, the fracture zones generally present FI > 1 and the individualized blocks FI < 0.50. As a consequence, the obtained grid of th e FI permits the quantitative structural classification of the granitic mas sif in 2D and understanding fault zone architecture in the Mina Ratones are a. (C) 2001 Elsevier Science Ltd. All rights reserved.