Thermal contraction crack polygons in Nunavik (northern Quebec): Distribution and development of polygonal patterned ground

We evaluated the spatial distribution and morphological variability of thermal contraction crack polygon (TCCP) networks across Nunavik, a 440,000-km2 region northern Québec that spans northward transition from discontinuous to continuous permafrost. A population 4,567 TCCP sites was sampled analyzed 80,737 georeferenced high-resolution aerial photographs 264,504 km2 ESRI satellite basemaps. For each site, six parameters were inventoried compiled into database: (a) network geometric arrangement; (b) intersection angles; (c) number subdivisions nested polygons (referred as generations development); (d) dominant morphology; (e) surficial geology; (f) vegetation cover. Statistical analyses tabulated data revealed strong association between Holocene glacial, glacio-fluvial, fluvial, marine, organic landforms different intersections angles in networks, providing insight how processes cracking function manifest geomorphically varied permafrost landscapes. Orthogonal (intersection angle 90°) dominate on flat terrains where thermo-mechanical stresses are probably spatially homogeneous. Hexagonal (angles 120°) poorly structured tend form topography generates heterogeneous heat flow patterns ground, resulting irregular patterns.