1983 Articles

Paleomagnetism of the Lower Devonian Traveler Felsite and the Acadian orogeny in the New England Appalachians

Spariosu, Dann J.; Kent, Dennis V.

A suite of felsic extrusive rocks from the Lower Devonian Traveler Felsite, northcentral Maine (46.1°N lat., 68.9°W long.) was collected for paleomagnetic study: 28 samples from 5 sites in the (lower) Pogy member, 56 samples from 10 sites in the (upper) Black Cat member, and 13 samples from 10 cobbles in the basal conglomerate of the overlying Trout Valley Formation. Characteristic magnetizations based on AF demagnetization analyses and supported by thermal studies give a formation mean direction, after simple correction for bedding tilt, of D = 25.2°, I = -20.2°, α₉₅ = 10.6° for 13 sites in the Traveler Felsite. The occurrence of normal and reversed magnetozones under stratigraphic control and the antiparallel directions of the polarity units following the tilt correction indicate an acquisition of remanence near the time of formation of the rock units. The mean direction corresponds to a (south) paleopole position of 29°S lat., 262°E long. (δp, δm = 6°, 11°) for the Traveler Felsite. This pole position is in close agreement with poles from two other rock units of similar age from the same lithostratigraphic belt in the northern Appalachians. The mean of these three poles is distinct from Late Silurian and Middle Devonian poles from cratonic North America (Laurentia) and from Early Devonian results from the Acadia displaced terrane, suggesting that this area constituted a separate tectonic unit during the Early Devonian. We propose a tectonic model in which a "Traveler terrane" is rotated 20° to 30° while converging with Laurentia and undergoing deformation during the Early to Middle Devonian Acadian orogeny.