Using spatial relationships between individual plutons and faults to suppor
t genetic correlations between faulting and magmatism is meaningless since
even random magmatic or tectonic processes will result in some plutons adja
cent to faults. Our initial analyses of populations of faults and Carbonife
rous plutons in the Armorican Massif, France and faults and Alleghanian plu
tons in the southern Appalachians, USA indicate that plutons have broad dis
tributions with respect to faults but with a tendency for plutons to occur
away from faults. Maxima of integrated pluton areas occur at 1/4 (Appalachi
ans) and 1/2 (Armorican) of the distance between the average fault spacing
in these orogens. Although there is a great need for statistical evaluation
s of relationships between populations of igneous bodies and structures in
a wide variety of settings and crustal depths, our initial studies suggest
that faults do not preferentially channel magma during ascent or emplacemen
t and that these are relatively unfocused processes within orogenic belts.
(C) 1999 Elsevier Science Ltd. All rights reserved.