Quantifying diagenetic and stratigraphic controls on fracture intensity in platform carbonates: An example from the Sierra Madre Oriental, northeast Mexico

Normalized fracture intensity measured along 1D scanlines was used to compare fracture intensity for different sedimentary facies, stratigraphic position, bed thickness and degree of dolomitization in carbonate beds of the Cupido and Tamaulipas formations, northeast Mexico. We calculated the fracture intensity for individual beds, for single and combined fracture sets, and the statistical significance of relationships using bivariate weighted regressions and multivariate methods. Results suggest that the degree of dolomitization is positively correlated with fracture intensity and has the strongest correlation, followed by the position of the bed in the stratigraphic cycle and the mud content. Dolomite content, normalized position in the parasequence, environment of deposition, and mud content show a significant degree of correlation among themselves and should be considered dependent variables for statistical purposes. Geological observations suggest that dolomite precipitation and fracturing occurred, at least in part, synchronously in these rocks. A fracture-intensity distribution model integrating sequence-stratigraphic and diagenetic history is proposed for the Cupido and Tamaulipas formations with potential use in similar carbonate successions. Our analysis does not support the classic bed-thickness fracture-spacing relationship. (C) 2010 Elsevier Ltd. All rights reserved.