Continental margin of the eastern United States

Abstract

The continental margin of eastern North America has been studied as part of the North American Continent-Ocean Transect Program by synthesizing existing data along six corridors, each at least 100 km wide, between Newfoundland and Georgia that extend from the Phanerozoic craton to the oceanic crust. The term Phanerozoic craton is used here for a cratonal area that has not undergone significant deformation since the beginning of Phanerozoic time. One of these corridors is in Canada (Dl; Haworth and others, 1985), and two additional Canadian transects (D2 and D3; Keen and Haworth, 1985a, 1985b) cross the present continental margin, but do not extend westward to the craton. Herein I analyze the evolution of the eastern continental margin as depicted by the five corridors or transects, El through E5, prepared or in preparation for the United States. The five transects in eastern United States are outlined in Figure 1 and are as follows. E1, Adirondacks to Georges Bank (Thompson and others, 1993). The corridor length is 1000 km. E2, New York Appalachian basin to the Baltimore Canyon trough (Drake and others, unpublished). The corridor length is 860 km. E3, Pittsburgh to Baltimore Canyon trough (Glover, 1989; Glover and others, unpublished). The corridor length is approximately 850 km. E4, Central Kentucky to the Carolina trough (Rankin and others, 1991). The corridor length is 1100 km. E5, Cumberland Plateau to Blake Plateau (Hatcher and others, 1994). The corridor length is approximately 1280 km. Because of the time constraints, E2 and E3 will not

Anisotropy Versus Heterogeneity in Continental Solid Earth Electromagnetic Studies: Fundamental Response Characteristics and Implications for Physicochemical State

“…Static levels in the apparent resistivity were estimated from Sq variations. and one in the early-middle Paleozoic (Taconic), with final collision and plutonism in the Late Paleozoic (Alleghanian) (Hatcher, 1989;van Schmus et al, 1993;Rankin, 1994;Hibbard et al, 2002). Tectonic setting and problems, MT data collection, and basic response trends were discussed by Wannamaker et al (1996), and a 2D isotropic inversion model using just the sparser long period soundings was derived by Ogawa et al (1996).…”

Shear velocity structure and azimuthal anisotropy beneath eastern North America from Rayleigh wave inversion

“…ago, perhaps combined with melting related to the Monteregian plume. However, because water tends to partition into melt, hotspot magmatism or melting related to the Jurassic opening of the Atlantic Ocean [ Rankin , 1994] would tend to remove water from the shallow mantle. Alternatively, Levin et al [2000] and Park and Levin [2002] suggested that the slow velocities represent iron‐rich asthenosphere that replaced delaminated lithosphere beneath the Appalachians and then subsequently became part of the lithosphere through cooling and dehydration.…”

“…Our area of interest contains several different lithospheric provinces: the Grenville Province, the Appalachian Orogen, and the western edge of the Atlantic passive margin [ Rankin , 1994]. It manifests a rich variation in surface geology with crustal rocks dating from the Proterozoic Grenvillian orogeny (1.1 Ga), the Phanerozoic Appalachian orogeny, Triassic and Jurassic rifting, and Cretaceous plutonism in the Monteregian Hills and New England [ Hatcher , 1989; Hoffman , 1989; Rankin , 1994]. …”

Insights into the Acadian orogeny, New England Appalachians: a provenance study of the Carrabassett and Kittery formations, Maine

“…For these reasons, some workers think that Avalonia did not arrive in southern New England until the Alleghanian orogeny (Zartman and Naylor 1984;Wintsch and Sutter 1986;Mosher et al 1993;Wintsch et al 1993;Rankin 1994;Walsh et al 2007) and may have been emplaced along strike-slip faults in the Late Paleozoic (Robinson et al 1998). Alternatively, Wintsch et al (1992) suggested that the portion of Avalonia that collided during the Acadian was subsequently thrust further under the allochthonous rocks of the Central Maine Basin, Merrimack Trough, and Putnam-Nashoba terrane during the Alleghanian orogeny and is no longer exposed to provide evidence of Avalonian involvement with the Acadian event.…”

“…More studies have been conducted of and more has been written about the Acadian orogeny than any other New England orogenic event (e.g., Osberg et al 1989;Roy and Skehan 1993;Rankin 1994;Bradley et al 2000;Eusden et al 2000;Tucker et al 2001 and references therein). In spite of this volume of work, the fundamental problem of what caused the New England part of the Acadian orogeny remains.…”