T146 Presentaciones de Geociencias en Español II: Una Nueva Experiencia en una Reunión de la Sociedad Geológica Americana (GSA)//Spanish Presentations about Geosciences in the America II: A new GSA Experience

Monday, 23 September 2024
1:30 PM - 5:30 PM
304C

DEFORMATION HISTORY AND FAULT REACTIVATION IN SOUTHERN MEXICO IN LIGHT OF CALCITE CEMENTS DATING AND SYSTEMATIC FRACTURE ANALYSIS

Paper number: T146-5
Program: Technical Sessions
Time: 2:40 PM – 2:55 PM

Authors

Abstract

Calcite vein cements are very sensitive markers of the deformation, and have become great indicators of the tectonic history of the rocks. In addition, modern fracture analysis, using fracture maps, adds important information about the amount, the arrangement, and the connectivity of the fractures. The relationship between fracture reactivation and some metrics (box-dimension, correlation dimension, mass-dimension, intensity and connectivity) is fundamental to understanding the fluid flow process in the reactivated fault zones.

We focused our study on middle Permian limestone layers (Paso Hondo Fm.), which were deposited on an isoclinal platform in southernmost Mexico, and later deformed by shortening in the latest Permian to the Early Triassic during the consolidation of Pangea, forming NW-SE oriented folds, to which extensional faults (NW-SE and NE-SW oriented) were superimposed in the Early Jurassic-Early Cretaceous, and then NW-SE oriented faults overlaid.

Our results suggest that the values of box-dimension (2.3-2.8), correlation dimension (2.4-2.6), and mass-dimension (2.5-3) are related to fracture clusters. The analysis of fracture size distribution shows that the small fractures (fracture length between 0.2 to 5 centimeters) dominate the mesoscopic scale compared with the large fractures (fracture length between 6 to 20 centimeters). The fracture connectivity is dominated by the I and X node types, and has values below the critical threshold connectivity suggested in other works (C=2). The fracture intensity has a positive relationship with the box dimension, correlation dimension, and fracture connectivity. On the other hand, the mass-dimension decreases with an increase in the fracture intensity, suggesting that the fracture intensity controls the degree of clustering. Finally, our results show that fracture reactivation is an important mechanism because it decreases connectivity despite multiple overlapping fracture events and promotes the formation of fracture clusters.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-405110

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