Early Paleozoic development of the Maine–Quebec Boundary Mountains region
Abstract: Pre-Silurian bedrock units played key roles in the early Paleozoic history of the Maine–Quebec Appalachians. These units represent peri-Laurentian material whose collision with the craton deformed the Neoproteozoic passive margin and initiated the Appalachian mountain-building cycle. We pr...
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Text |
| Language: | English |
| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.552.9774 http://www.geology.um.maine.edu/user/scott_johnson/papers/gerbiEtAl2006b_cjes.pdf |
| Summary: | Abstract: Pre-Silurian bedrock units played key roles in the early Paleozoic history of the Maine–Quebec Appalachians. These units represent peri-Laurentian material whose collision with the craton deformed the Neoproteozoic passive margin and initiated the Appalachian mountain-building cycle. We present new field, petrological, geochronological, and geochemical data to support the following interpretations related to these units. (1) The Boil Mountain Complex and Jim Pond Formation do not represent part of a coherent ophiolite. (2) Gabbro and tonalite of the Boil Mountain Complex intruded the Chain Lakes massif at ca. 477 Ma. (3) The Skinner pluton, an arc-related granodiorite, intruded the Chain Lakes massif at ca. 472 Ma. (4) The Attean pluton, with a reconfirmed age of ca. 443 Ma, is unrelated to Early Ordovician orogenesis. (5) The most likely timing for the juxtaposition of the Jim Pond Formation and the Boil Mountain Complex was during regional Devonian deformation. These interpretations suggest that the Boundary Mountains were once part of a series of arcs extending at least from central New England through Newfoundland. Résumé: Les unités pré-siluriennes du substratum rocheux ont joué un rôle décisif dans l’histoire des Appalaches du Québec et du Maine au début du Paléozoïque. Ces unités constituent le matériau péri-laurentien dont la collision avec le craton a déformé la marge passive néoprotérozoïque et enclenché le cycle orogénique des Appalaches. Nous présentons ici de nouvelles données de terrain, des données pétrologiques, géochronologiques et géochimiques qui étayent les interprétations suivantes au sujet de ces unités. (1) Le complexe de Boil Mountain et a Formation de Jim Pond ne font |
|---|