Deformation in portions of the distal continental margin to ancestral North America: An example from the westernmost internal zone, central and southern Appalachian Orogen, Virginia

Tectonics ◽  
1989 ◽  
Vol 8 (3) ◽  
pp. 535-554 ◽  
Author(s):  
Judith G. Patterson
Keyword(s):  
North America ◽  
Continental Margin ◽  
Southern Appalachian ◽  
Internal Zone ◽  
Appalachian Orogen

scholarly journals Two new species of Bimastos (Oligochaeta, Lumbricidae) from the Southern Appalachian Mountains, North America

Zootaxa ◽  
2021 ◽  
Vol 5052 (3) ◽  
pp. 395-405
Author(s):  
ROBERTO CARRERA-MARTÍNEZ ◽  
DANIEL JONES ◽  
SEAN D. SCHOVILLE ◽  
BRUCE A. SNYDER ◽  
MAC A. JR. CALLAHAM
Keyword(s):  
New Species ◽  
Body Size ◽  
North America ◽  
Appalachian Mountains ◽  
Molecular Data ◽  
Southern Appalachian Mountains ◽  
Southern Appalachian ◽  
Two New Species ◽  
Morphological And Molecular Data ◽  
Posterior Position

Two new species of Bimastos Moore are described based on morphological and molecular data. Bimastos nanae n. sp. resembles B. lawrenceae Fender, B. zeteki (Smith and Gittins) and B. welchi (Smith). Bimastos nanae n. sp. differs from these species in the position of the clitellum, size and number and position of thickened septa. Bimastos magnum n. sp. is similar to B. schwerti Csuzdi & Chang and B. palustris Moore in having a fully annular clitellum and male pores on huge porophores. Bimastos magnum n. sp. differs from both species by having a more posterior position of the clitellum (in xxiv-xxxiii, xxxiv) and larger body size. With the description of these new species, the number of Bimastos species is raised to 14.  

40Ar/39Ar incremental-release ages of hornblende and biotite from Grenville basement rocks within the Indian Head Range complex, southwest Newfoundland: their bearing on Late Proterozoic – Early Paleozoic thermal history

1978 ◽  
Vol 15 (8) ◽  
pp. 1374-1379 ◽  
Author(s):  
R. D. Dallmeyer
Keyword(s):  
North America ◽  
Continental Margin ◽  
Thermal History ◽  
Structural Unit ◽  
Elevated Temperatures ◽  
Early Paleozoic ◽  
Present Position ◽  
Thermal Peak ◽  
Basement Rocks ◽  
The Times

Hornblende and biotite from autochthonous basement rocks within the Indian Head Range complex of southwest, insular Newfoundland record undisturbed 40Ar/39Ar release spectra with average total-gas ages of 880 Ma (hornblende) and 825 Ma (biotite). These gas-retention ages date the times when this segment of the western Appalachian basement terrane cooled below hornblende and biotite argon retention temperatures (~500 °C and ~300 °C respectively) following culmination of the ~ 1150–1100 Ma Grenville metamorphism. Although these results indicate that elevated temperatures were maintained for a prolonged period following the Grenville thermal peak, once initiated, cooling must have been relatively rapid because hornblende and biotite record generally similar total-gas dates.The undisturbed release spectra of minerals within the Indian Head Range complex indicate that this segment of the western Appalachian basement terrane was not affected by Paleozoic metamorphism. This is consistent with recent tectonic models that indicate that the overlying Humber Arm allochthon was emplaced into its present position as a cold, already assembled structural unit. Lack of Paleozoic metamorphism within the Indian Head basement rocks is also compatible with suggestions that the obduction site of the Bay of Islands ophiolite lay considerably east of the Early Paleozoic continental margin of North America.

Population Aggregation and the Emergence of Circular Villages in Southwest Virginia

2018 ◽  
pp. 140-159 ◽  
Author(s):  
Richard W. Jefferies
Keyword(s):  
Spatial Distribution ◽  
North America ◽  
Late Woodland ◽  
Eastern North America ◽  
Late Prehistoric ◽  
Archaeological Evidence ◽  
Settlement Structure ◽  
Southern Appalachian ◽  
Late Prehistoric Period ◽  
Population Aggregation

Archaeological evidence from throughout much of eastern North America documents a transition from small, scattered settlements to nucleated, often circular, villages during the Late Woodland/Late Prehistoric period (ca. A.D. 1000-1600). In southwestern Virginia's Appalachian Highlands, this transition is marked by the appearance of large circular palisaded villages associated with what Howard MacCord called the Intermontane Culture. This paper investigates the origin, structure, and spatial distribution of Late Woodland circular villages across the southern Appalachian landscape and compares their emergence to similar trends in settlement structure and organization witnessed in other parts of the Appalachian Highlands and beyond.

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.

A speculative reconstruction of the Middle Paleozoic Continental Margin of southwestern North America

Tectonics ◽  
1992 ◽  
Vol 11 (2) ◽  
pp. 405-419 ◽  
Author(s):  
Calvin H. Stevens ◽  
Paul Stone ◽  
Ronald W. Kistler
Keyword(s):  
North America ◽  
Continental Margin ◽  
Middle Paleozoic
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