Major Proterozoic basement features of the eastern midcontinent of North America revealed by recent COCORP profiling

The Grenville orogenic cycle of southern Laurentia: Unraveling sutures, rifts, and shear zones as potential piercing points for Amazonia

“…Normal displacement across the Ramapo fault during the late Grenville orogeny was also noted by Costa and Gates (1993) and Gates and Costa (1998) in the New Jersey Highlands. Along much of the western part of the Grenville orogen, west-dipping reflectors appear to be widespread, as noted in seismic lines across Ohio (Pratt et al, 1989) and eastern Tennessee (Hopkins, 1995). These reflectors terminate downward or merge with the Grenville front tectonic zone and are consistent with late Grenville or post-Grenville extension and listric normal faulting that soles into that basal shear zone as depicted farther north along Lithoprobe lines across the exposed Grenville province.…”

“…Thus, the extension is (Krogh, 1984). Blue arrows show extension along the Carthage-Colton shear zone (CCSZ) (Johnson et al, 2004) and Robertson Lake shear zone (RLSZ) (e.g., Streepey et al, 2002Streepey et al, , 2004, along the Ramapo fault in New Jersey (e.g., Costa and Gates, 1993;Gates and Costa, 2006), and inferred from seismic lines across both Ohio (Pratt et al, 1989), and eastern Tennessee (Hopkins, 1995). BG -biotite gneiss (Tollo et al, 2006); AMS -Archer Mountain Suite (e.g., Hughes et al, 2004;unpublished preliminary age: B.V. Miller and M.J. Bartholomew); LA -Labrieville Anorthosite (e.g., Owens and Dymek, 1992;Owens et al, 1994); LAMLac Michel Complex Erdmer, 1990, 1986;Heaman et al, 2002); AMCG -anorthosite-mangerite-charnockite-granite suite; LM -Lovingston massif (Bartholomew and Lewis, 1984); MA -Montpelier Anorthosite (Owens and Samson, 2004;Aleinikoff et al, 1996); MEG -Mount Eve granite (Gorring et al, 2004); PM -Pedlar massif (Bartholomew and Lewis, 1984); RA and RMP -Roseland Anorthosite and Roses Mill pluton (e.g., Herz and Force, 1987; unpublished preliminary ages: B.V. Miller and M.J. Bartholomew); Oaxaquia metamorphism (m) (e.g., Cameron et al, 2004;Keppie et al, 2003Keppie et al, , 2004 widespread and associated with the rapid rise of hot, metamorphic cores (e.g., the Adirondacks) -again analogous to the Basin and Range province and associated metamorphic core-complexes.…”

Mesoproterozoic-trans-Laurentian magmatism: A synthesis of continent-wide age distributions, new SIMS U–Pb ages, zircon saturation temperatures, and Hf and Nd isotopic compositions

“…Several of these, such as seismic refraction surveys (e.g., Pratt et al, 1989) or electromagnetic surveys, provided local or linear control, but only two methods provided broad, comprehensive coverage over wide areas: regional gravity anomaly maps and regional aeromagnetic anomaly maps. Perhaps surprisingly, some inferred major crustal province boundaries, notably the Yavapai-Mazatzal boundary in the mid-continent and the southeastern edge of the Paleoproterozoic basement (Nd line) cannot be recognized unequivocally in either the aeromagnetic or gravity data, even in the latest iterations of such maps.…”

Natural and Induced Seismicity in the Lake Erie-Lake Ontario Region: Reactivation of Ancient Faults with Little Neotectonic Displacement

“…comm.) and reflection profiles (Pratt et a/., 1989) have so far failed to detect vertical separation of stratigraphy in the = 2 km thick platform cover rocks that may be associated with a fault along the lineament. A vertical separation of only a few tens of meters may go undetected and horizontal offsets cannot be resolved at all by these methods.…”