TY - JOUR
T1 - Large-scale natural fracture network patterns
T2 - Insights from automated mapping in the Lilstock (Bristol Channel) limestone outcrops
AU - Prabhakaran, Rahul
AU - Urai, J. L.
AU - Bertotti, G.
AU - Weismüller, C.
AU - Smeulders, D.M.J.
PY - 2021
Y1 - 2021
N2 - The Lilstock outcrop in the southern Bristol Channel provides exceptional exposures of several limestone beds displaying stratabound fracture networks, providing the opportunity to create a very large, complete, and ground-truthed fracture model. Here we present the result of automated fracture extraction of high-resolution photogrammetric images (0.9 cm/pixel) of the full outcrop, obtained using an unmanned aerial vehicle, to obtain a spatially extensive, full-resolution map of the complete fracture network with nearly 350,000 ground-truthed fractures. We developed graph-based functions to resolve some common issues that arise in automatic fracture tracing such as incomplete traces, incorrect topology, artificial fragmentation, and linking of fracture segments to generate geologically significant trace interpretations. The fracture networks corresponding to different regions within the outcrop are compared using several network metrics and the results indicate both inter- and intra-network (layer to layer) structural variabilities. The dataset is a valuable benchmark in the study of large-scale natural fracture networks and its extension to stochastic network generation in geomodelling. The dataset also highlights the intrinsic spatial variation in natural fracture networks that can occur even in weakly-deformed rocks over relatively short length scales of tens of metres.
AB - The Lilstock outcrop in the southern Bristol Channel provides exceptional exposures of several limestone beds displaying stratabound fracture networks, providing the opportunity to create a very large, complete, and ground-truthed fracture model. Here we present the result of automated fracture extraction of high-resolution photogrammetric images (0.9 cm/pixel) of the full outcrop, obtained using an unmanned aerial vehicle, to obtain a spatially extensive, full-resolution map of the complete fracture network with nearly 350,000 ground-truthed fractures. We developed graph-based functions to resolve some common issues that arise in automatic fracture tracing such as incomplete traces, incorrect topology, artificial fragmentation, and linking of fracture segments to generate geologically significant trace interpretations. The fracture networks corresponding to different regions within the outcrop are compared using several network metrics and the results indicate both inter- and intra-network (layer to layer) structural variabilities. The dataset is a valuable benchmark in the study of large-scale natural fracture networks and its extension to stochastic network generation in geomodelling. The dataset also highlights the intrinsic spatial variation in natural fracture networks that can occur even in weakly-deformed rocks over relatively short length scales of tens of metres.
KW - Carbonates
KW - Discrete fracture networks
KW - Fractured pavements
KW - Graph theory
KW - Natural fracture networks
KW - Spatial graphs
UR - http://www.scopus.com/inward/record.url?scp=85109133066&partnerID=8YFLogxK
U2 - 10.1016/j.jsg.2021.104405
DO - 10.1016/j.jsg.2021.104405
M3 - Article
AN - SCOPUS:85109133066
SN - 0191-8141
VL - 150
JO - Journal of Structural Geology
JF - Journal of Structural Geology
M1 - 104405
ER -