Author: wrchurch
Company: UWO

CONTRIBUTION OF THE
DEPARTMENT OF GEOLOGY
UNIVERSITY OF WESTERN ONTARIO
LONDON, CANADA        no. 140-b
Crustal Evolution of the Western Margin of the Newfoundland Appalachians
W.R. Church and R.K. Stevens
University of Western Ontario,
London, Ontario.
*** Reprinted from;
Program of the 1968 Annual Meetings of the Geological Society of America,
Mexico City, Mexico, p. 53-54.

The "Taconic" (Caradoc) klippen of Western Newfoundland are composite thrust sheets.  Thick ophiolite units structurally overlie allochthonous Cambro-Ordovician clastic sediments which include Arenig flysch with fragments of serpentine and grains of chromite.  The foreland or miogeosyncline on which the klippen lie is bounded to the east by the Cabot fault zone which marks the transition from crust of Canadian Shield type to that of Appalachian type.  East of the fault occurs a vertical belt of rock, composed of a thick apparently unrepeated succession of high-grade meta-morphic rock separated by a screen of ultramafic rock from an easterly younging ophiolitic sequence.  Sediments associated with the ophiolites contain clasts of volcanic rock, grains of chromite, and material from the nearby Burlington granodiorite.  The allochthonous ophiolites of Western Newfoundland may have been derived from a similar although perhaps slightly older sequence.  However,no source exists for the lower units of allochthonous sedimentary rock, which represent a facies at least 30 miles wide intermediate between that of the eugeosyncline and the miogeo-syncline.  The segment of crust on which the allochthonous sediments were laid down seems to have been lost along the line of the Cabot fault zone; perhaps as a result of downward movements (Verschluckung) in association with thrusting and rotation during the Acadian orogeny.