Power-law vein-thickness distributions and positive feedback in vein growth

The thicknesses of veins of a single generation from the Kodiak accretionary complex show a power-law distribution with an exponent of D = 1.33. This value indicates that a significant portion of the vein-related extension is accommodated by the thinnest veins. Thick vein segments are typically confined to southeast-dipping brittle-ductile shear zones. Model simulations of vein-thickness distributions show that a constant growth model results in a negative-exponential distribution and that it is neceesary to assume size-proportional growth to produce a power-law distribution. Textures and power-law thickness distributions for the Kodiak veins are thus consistent with an increasing time-averaged growth rate as vein thickness increased, comprising a positive feedback. -Authors