The orientation and spatial distribution of veins in the Lockport dolostone attest to a fluid circulation system active during the Acadian orogeny in western New York and southern Ontario. Outcrops east of the Clarendon-Linden fault zone are cut by a prominent east-northeast systematic calcite-filled vein set, whereas these systematic veins are absent west of the fault zone, except in two quarries. Systematic veins display distinct characteristics: the mean vein orientation rotates clockwise from 067° in the east to 086° farther west, veins do not propagate into the basal Lockport Group, and calcite vein δ18OPDB values are significantly lighter to the east of the Clarendon- Linden fault zone. Maximum horizontal stress (SH) trend lines drawn parallel to the strike of the systematic veins are incompatible with SH inferred from Alleghanian plateau and other post-Paleozoic structures. However, because east-west SH trend lines are compatible with an Acadian tectonic event in western New England, our interpretation is that systematic veins in the Lockport Group are a cratonward signature of the Acadian orogeny.

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