Fractal analysis of the evolution of a fracture network in a granite outcrop, SE Korea

Abstract

Kinematical and fractal analyses were conducted on a fracture network in a well-exposed granite outcrop in SE Korea. The objective of this study is to examine the temporal and spatial evolution of the fracture network. From the orientation and abutting relationships of fracture sets, six fracturing events and their relative ages were established, several of which included strike-slip reactivations of earlier formed fractures. These events may be correlated with the Cenozoic to Recent evolution of the Yangsan Fault and surrounding areas. 2-D box counting analyses were performed on maps of the fracture network at the six stages of its evolution. For the earliest event D = 1.11, and represents a clustered development of fractures. Event 2 leads to a large increase of D = 1.51, with subsequent events producing a gradual increase up to 1.55 after the final event. This stabilization of the fractal dimension involved a change from the widespread development of new fractures (event 2) to the greater importance of reactivation of existing fractures, with only localized development of new fractures, usually as tip and linkage damage around pre-existing fractures. Fracture density was greatest for the event 2 fractures and increased only gradually after that. This pattern is similar to that of the fractal dimension and a good linear correlation was found between these two parameters. Although fractal dimensions and density show little change during the late stages of deformation, the fracture connectivity continued to increase due to the formation of local secondary fractures developed during reactivation of earlier formed fractures.

Tectonic interpretation of the connectivity of a multiscale fracture system in limestone

“…The evolution of the percolation parameter implies that a large amount of energy may have been released during the early-stage fracturing (as revealed by the high p at the end of the first formation stage of each pattern), after which tectonic or hydraulic forces could not be elevated to such high levels because they would be dissipated by the shearing and coalescence of the existing large structures [Petit and Mattauer, 1995;Park et al, 2010]. However, relatively small-scale fractures can form during later phases of tectonism [de Joussineau and Aydin, 2007;Park et al, 2010]. A likely universal scaling behavior may exist in a multiscale fracture system [Odling et al, 1999;Marrett et al, 1999;Bour et al, 2002;Du Bernard et al, 2002;Bertrand et al, 2015], whereas inconsistent scaling exponents separated by characteristic lengths can also occur [Ouillon et al, 1996;Hunsdale and Sanderson, 1998 Geophysical Research Letters 10.1002/2015GL067277 may be caused by the different growth mechanisms of jointing and faulting [Pollard and Segall, 1987;de Joussineau and Aydin, 2007], the influence of lithological layering [Ouillon et al, 1996;Hunsdale and Sanderson, 1998;Odling et al, 1999;Putz-Perrier and Sanderson, 2008], and the nature of driving forces (i.e., boundary or body forces) associated with distinct spatial organization of strains [Bonnet et al, 2001;Davy et al, 2010].…”

“…The evolution of the percolation parameter implies that a large amount of energy may have been released during the early‐stage fracturing (as revealed by the high p at the end of the first formation stage of each pattern), after which tectonic or hydraulic forces could not be elevated to such high levels because they would be dissipated by the shearing and coalescence of the existing large structures [ Petit and Mattauer , ; Park et al , ]. However, relatively small‐scale fractures can form during later phases of tectonism [ de Joussineau and Aydin , ; Park et al , ].…”

“…These networks are the results of the superimposition of multiple fracture sets; each of which is associated with distinct orientation and linked to a separate tectonic event. The relative ages of the successively generated fracture sets can therefore be determined according to the sequence of the tectonic events [ Park et al , ]. Figure presents a schematic illustration of the kinematic evolution of the studied fracture system during the tectonic history.…”

Structural Control on the Salmas Geothermal Region, Northwest Iran, from Fractal Analysis and Paleostress Data

“…For example, the relationship between rock grain size and earthquakes, or topography caused by faults and folds are these kind of relationships (Turcotte, 1997). Recently, numerous studies have been published addressing the application of fractal geometry for evaluating fault properties such as fault length, intensity, displacement, aperture, and their distance (Babadagli, 2001;Fagereng, 2011;Kruhl, 2013;Park et al, 2010).…”

“…Also, lineament and fracture spatial orientation are critical because of their effect on the secondary permeability and fluid circulation of geothermal reservoirs. Fractal analysis is an effective tool for quantitative evaluation of the fracture pattern because of its reliability in revealing and detecting the fracture accumulation and distribution (Babadagli, 2001;Park et al, 2010;Fagereng, 2011;Kruhl, 2013;Pérez-Flores et al, 2017).…”