Emplacement of the North Mountain basalts of the 200 Ma CAMP event: evidence from the magnetic fabric

Richard E. Ernst1, Jelle Zeilinga de Boer2, Peter Ludwig2 , Taras Gapotchenko2

1 Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario Canada KlA OE8, (rernst@gsc.nrcan.gc.ca)
2 Department of Earth and Environmental Sciences, Wesleyan University, Middletown, CT 06459-0139, USA (jdeboer@wesleyan.edu)

Abstract

The relationship between flood basalts and feeder dykes is investigated through an anisotropy of magnetic susceptibility (AMS) study of CAMP event (200 Ma) magmatism in the Fundy basin of southeastern Canada.  Over a 200 km strike length, the North Mountain basalts exhibit a consistent N-NE emplacement direction flow pattern (based on the orientation of maximum AMS axes).  Less definitively, the data suggest that the lower lavas (including the Grand Manaan basalts) have a NE-SW flow axis, while the middle and upper flow units have a more N-S flow axis.  The Swallowtail dyke of Grand Manan Island exhibits sub-vertical flow based on AMS data.  Its presumed extension along the axial zone of the Fundy basin is the possible feeder for as least some of the North Mountain flows.