Multiscale Spatial Patterns in Giant Dike Swarms Identified through
Objective Feature Extraction
Abstract
Dike swarms are ubiquitous on terrestrial planets and represent the
frozen remnants of magma transport networks. However, spatial
complexity, protracted emplacement history, and uneven surface exposure
typically make it difficult to quantify patterns in dike swarms on
different scales. In this study, we address this challenge using the
Hough Transform to objectively link dissected dike segments and analyze
multiscale spatial structure in dike swarms. We apply this method to
swarms of three scales: the Spanish Peaks, USA; the Columbia River Flood
Basalt Group (CRBG), USA; the Deccan Traps Flood Basalts, India. First,
we cluster dike segments in Hough Transform space, recognizing prevalent
linearly aligned structures that represent single dikes or dike packets,
with lengths up to $10-30x$ the mapped mean segment length. Second, we
identify colinear and radial dike segment mesoscale structures within
each data set, using the Hough Transform to segment swarms into
constituent spatial patterns. We show that for both the CRBG and Deccan
Traps, a single radial swarm does not well characterize the data.
Instead, multiple and sometimes overlapping mesoscale linear and radial
features are prevalent. This suggests a time-evolving transport network
where structural inheritance of dike pathways over an extended time is
likely common, but large-scale reorganizations of the plumbing system
that imply state shifts in crustal stresses or mantle melt supply also
occur. We expect that the Hough Transform may find useful applications
in a variety of geologic settings where many quasi-linear features, at
any scale, are superimposed spatially.