Lithosphere Plate-Continental Margin Tectonics and the Evolution of the Appalachian Orogen

1970 ◽  
Vol 81 (4) ◽  
pp. 1031 ◽  
Author(s):  
JOHN M. BIRD ◽  
JOHN F. DEWEY
Keyword(s):  
Continental Margin ◽  
Appalachian Orogen ◽  
Lithosphere Plate

Appalachian Orogen in Canada

1979 ◽  
Vol 16 (3) ◽  
pp. 792-807 ◽  
Author(s):  
Harold Williams
Keyword(s):  
Continental Margin ◽  
Eastern North America ◽  
Early Paleozoic ◽  
The West ◽  
Late Precambrian ◽  
Northwest Africa ◽  
Iapetus Ocean ◽  
History Of ◽  
Appalachian Orogen ◽  
Andean Type

The Appalachian Orogen is divided into five broad zones based on stratigraphic and structural contrasts between Cambrian–Ordovician and older rocks. From west to east, these are the Humber, Dunnage, Gander, Avalon, and Meguma Zones.The westerly three zones fit present models for the development of the orogen through the generation and destruction of a late Precambrian – Early Paleozoic Iapetus Ocean. Thus, the Humber Zone records the development and destruction on an Atlantic-type continental margin, i.e., the ancient continental margin of Eastern North America that lay to the west of Iapetus; the Dunnage Zone represents vestiges of Iapetus with island arc sequences and mélanges built upon oceanic crust; and the Gander Zone records the development and destruction of a continental margin, at least in places of Andean type, that lay to the east of Iapetus.The Precambrian development of the Avalon Zone relates either to rifting and the initiation of Iapetus or to subduction and a cycle that preceded the opening of Iapetus. During the Cambrian Period, the Avalon Zone was a stable platform or marine shelf.Cambrian–Ordovician rocks of the Meguma Zone represent either a remnant of the continental embankment of ancient Northwest Africa or the marine fill of a graben developed within the Avalon Zone.Silurian and younger rocks of the Appalachian Orogen are mixed marine and terrestrial deposits that are unrelated to the earlier Paleozoic zonation of the system. Silurian and later development of the orogen is viewed as the history of deposition and deformation in successor basins that formed across the already destroyed margins and oceanic tract of Iapetus.

Peritidal origin of the Lower Ordovician Upton Group, southern Quebec Appalachians

1992 ◽  
Vol 29 (5) ◽  
pp. 1106-1118 ◽  
Author(s):  
Denis Lavoie
Keyword(s):  
Continental Margin ◽  
Lower Cambrian ◽  
Outer Shelf ◽  
Lower Ordovician ◽  
External Domain ◽  
Appalachian Orogen ◽  
Shallow Subtidal ◽  
Volcanic Succession ◽  
Mixed Carbonate

The Lower Ordovician Upton Group is part of the Cambrian–Ordovician external domain of the Appalachian Orogen of southern Quebec. It is a mixed carbonate–siliciclastic–volcanic succession occurring within flyschoid sediment of the Lower Cambrian Granby Nappe. The bulk of the Upton Group is a grey, massive, recrystallized limestone of probable peritidal and shallow subtidal origin. Associated siliciclastic lithofacies are typical of peritidal and outer-shelf settings. The proposed peritidal paleoenvironmental model differs from previous interpretations and indicates that it is unlikely that the Upton Group is a slab derived from the Ordovician continental margin which has slid into the Granby Nappe.

Tectonic setting of Avalonian volcanic and Plutonic rocks in the Caledonian Highlands, southern New Brunswick, Canada

1996 ◽  
Vol 33 (2) ◽  
pp. 156-168 ◽  
Author(s):  
S. M. Barr ◽  
C. E. White
Keyword(s):  
New Brunswick ◽  
Subduction Zone ◽  
Continental Margin ◽  
Tectonic Setting ◽  
Sedimentary Rocks ◽  
Igneous Activity ◽  
Appalachian Orogen ◽  
Group Form ◽  
Plutonic Rocks ◽  
Clastic Sedimentary

The Caledonian Highlands of southern New Brunswick consist of Late Proterozoic to Cambrian rocks generally considered typical of the Avalon terrane of the northern Appalachian Orogen. Mainly tuffaceous volcanic and sedimentary rocks of the Broad River Group and cogenetic dioritic to granitic plutons with ages ca. 620 Ma form most of the eastern Caledonian Highlands. They have petrological features indicative of origin in a continental margin subduction zone. Significantly younger ca. 560–550 Ma dacitic to rhyolitic lapilli tuffs and flows, laminated tuffaceous siltstone, basaltic and rhyolitic flows, and clastic sedimentary rocks of the Coldbrook Group form most of the western highlands, and occur locally throughout the highlands. The mainly tuffaceous lower part of the group has been intruded by gabbroic and syenogranitic plutons that are interpreted to be cogenetic with basaltic and rhyolitic flows in the upper part of the group. This voluminous subaerial magmatism may have formed during postorogenic extension in the earlier ca. 620 Ma subduction zone complex represented by the Broad River Group and associated plutons. This tectono-magmatic model differs from other interpretations that related most of the igneous units to ca. 630–600 Ma subduction, and did not recognize the importance of ca. 560–550 Ma magmatism. The ca 620 Ma subduction-related volcanic and plutonic rocks of the Caledonian Highlands are comparable to units in other parts of the Avalon terrane, but voluminous ca. 560–550 Ma igneous activity like that represented by the Coldbrook Group and related plutons has not been documented yet in other Avalonian areas.

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