Paleomagnetism and magnetic mineralogy of the Nahant gabbro and tonalite, eastern Massachusetts.
Article
Weisse, PA, Haggerty, SE, Brown, LL. (1985). Paleomagnetism and magnetic mineralogy of the Nahant gabbro and tonalite, eastern Massachusetts.
. 22(10), 1425-1435. 10.1139/e85-149
Weisse, PA, Haggerty, SE, Brown, LL. (1985). Paleomagnetism and magnetic mineralogy of the Nahant gabbro and tonalite, eastern Massachusetts.
. 22(10), 1425-1435. 10.1139/e85-149
Palaeomagnetic analyses of the Nahant gabbro and an associated tonalite from E Massachusetts reveal five separate populations of palaeomagnetic directions. Detailed petrographic data indicate that these five populations correspond with five styles of magnetic mineral alteration; a mean alteration index was calculated for each site. There is an apparent relationship between magnetite alteration and normalized intensity at a given demagnetization level, with normalized intensity decreasing as magnetite alteration increases. This relationship illustrates the interdependence between palaeomagnetic properties and magnetic minerals. Mineral alteration is probably associated with periods of magnetic overprinting. The Nahant gabbro poles are interpreted as representing either a deuteric or metasomatic chemical remanent magnetization (CRM). The tonalite pole is interpreted as a deuteric CRM. The gabbro and tonalite poles are similar to a number of poles from Ordovician to Devonian intrusives in the Acadia terrain, including St. Stephen and St. George plutons.-J.M.H.
