Revised stratigraphy of the Cookson Group in eastern Maine and southwestern New Brunswick: an alternate view
DOI:
https://doi.org/10.4138/1719Abstract
Fossil evidence reported by Fyffe and Riva (1990) requires inversion of the stratigraphic succession originally proposed for the St. Croix Terrane (Ludman, 1987). Other suggested revisions, however, are not in accord with structural and sedimentologic data in eastern Maine. Comparison of structural histories indicates that the Pocomoonshine Lake and Digdeguash formations are more appropriately part of the Frederic ton Belt than of the St Croix Terrane as suggested by fyffe and Riva(1990). An alternate view of the stratigraphic and tectonic relationships between the St Croix Terrane and Fredericton Belt includes the following changes: the Pocomoonshine Lake Formation, originally assigned to the St Croix Terrane, is now considered to be the oldest unit of the Fredericton Belt, lying conformably below the Digdeguash Formation; a late Acadian thrust fault is thought to have transported the St Croix Terrane westward over the Fredericton Belt; subsequent high-angle dip-slip and strike-slip faulting have obscured original relationships—these faults now form the boundary between the two terranes in southeastern Maine. RÉSUMÉ Le témoignage apporté par les fossiles qu'ont signaled Fyffe et Riva (1991) nécessite une inversion de la séquence stratigraphique proposée à l'origine pour la Laniere de St Croix (Ludman, 1987). Cependant, les autres révisions, ayant été suggérées sont en contradiction avec les données stiucturales et séclimentologiques en provenance du Maine oriental. La comparaison des antécédents structuraux indique qu'il est plus adéquat d'incorporer les formations de Pocomoonshine Lake et de Digdeguash a la Ceinture de Fredericton qu'à la Lanière de St. Croix comme l'ont suggéré Fyffe et Riva (1991). Une conception de rechange ayant trait aux relations stratigraphiques et tectoniques entre la Laniere de St Croix et la Ceinture de Fredericton englobe les changements suivants: la Formation de Pocomoonshine Lake, rattachée à l'origine à la Lanière de St Croix, est maintenant tenue pour étant la plus vieille unité au sein de la Ceinture de Fredericton, recouverte en concordance par la Formation de Digdeguash; un chevauchement tardi-acadien est envisagé comme ayant transporté la Lanière de St Croix vers l'ouest par-dessus la Ceinture de Fredericton; le jeu subséquent de décrochements et de failles à rejet selon leur pendage, tous fortement inclines, à obscurci les rapports originaux—ces failles constituent maintenant la frontière entre ces deux lanieres dans le sud-est du Maine. [Traduit par le journal]Downloads
Published
How to Cite
Issue
Section
License
All material contained in Atlantic Geology is copyrighted by the journal. Permission to photocopy for internal or personal use or for the internal or personal use of specific clients is granted by Atlantic Geology to libraries and other users registered with the Copyright Clearance Center (CCC), provided that the stated fee per copy is paid directly to the CCC, 21 Congress Street, Salem, Massachusetts 01970 USA. Other requests should be addressed to one of the journal editors, or sent to Atlantic Geology, Box 116, Acadia University, Wolfville, NS, Canada B4P 2R6. Permission to use a single graphic for which Atlantic Geology owns copyright is considered “fair dealing” under the Canadian Copyright Act and “fair use” by the journal, and no other permission need be granted, subject to the image being appropriately cited in all reproductions. The same fair dealing/fair use policy applies to sections of text up to 100 words in length.
