The joint sets on the Lilstock Benches, UK. Observations based on mapping a full resolution UAV-based image

Abstract

Full-resolution UAV-based image of the joint set of the classic Lilstock benches (UK) • Layer-bound joints are fully imaged over an entire large outcrop • Up to eight sets of joints occur in a single limestone layer • Jointing is laterally heterogeneous in the same layer and different between layers • Phases of sealing accompanied the evolution of older joints at Lilstock

Large-scale natural fracture network patterns: Insights from automated mapping in the Lilstock (Bristol Channel) limestone outcrops)

“…Additionally, the studied regions contain sub-regions which were the focus of previous work by Loosveld & Franssen (1992), Rawnsley et al (1998), Engelder & Peacock (2001), Belayneh & Cosgrove (2004), Belayneh (2004, and Gillespie et al (2011). The relationship between joints described in the above-mentioned works is discussed by Passchier et al (2021).…”

“…Passchier et al (2021) utilized the same image dataset as ours and was able to identify eight generations of joints from manually traced fractures that include all regions covered by the previous studies. The criteria used by Passchier et al (2021) to partition individual fractures into jointing generations consisted of combination of length, orientation, and abutting criteria. The results highlighted considerable spatial variability in jointing with some regions containing just 2-3 generations while other areas achieved saturation with the maximum eight sets.…”

“…The validation of manual with respect to automatic mapping indicated closely similar fracture patterns, generating confidence in an endeavour to extend the automatic interpretation to larger regions of the outcrop over multiple layers. Passchier et al (2021) used the same image dataset with similar resolution to identify jointing generations from manual interpretations within Areas 2 and 4.…”

“…We build on the first and second (Passchier et al, 2021) part of this project. The complex shearlet transform method (Reisenhofer et al, 2016;Prabhakaran et al, 2019) is used to automatically extract fracture traces from high resolution photogrammetric data published by .…”

“…covered five regions of 140 sq. m each within the Lilstock pavement while Passchier et al (2021) has mapped the different fracture generations but incompletely. In this work, the automatic tracing is extended to an area that is 20 times larger resulting in a rich dataset that amounts to nearly 350,000 fractures.…”