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Neoacadian Phase

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Series: Geological Society, London, Special Publications
Published: 01 January 2009
DOI: 10.1144/SP327.13
EISBN: 9781862395756
...-dominated pulses are explained as products of slab-breakoff rather than contemporaneous slab subduction. The four phases of orogenesis associated with accretion of these microcontinents are known as the Taconic, Salinic, Acadian and Neoacadian orogenies, respectively. The Ordovician Taconic orogeny...
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Journal Article
Journal: Geology
Published: 22 April 2021
Geology (2021) 49 (8): 946–951.
...Ian W. Hillenbrand; Michael L. Williams Abstract The Acadian and Neoacadian orogenies are widely recognized, yet poorly understood, tectono-thermal events in the New England Appalachian Mountains (USA). We quantified two phases of Paleozoic crustal thickening using geochemical proxies. Acadian (425...
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Series: GSA Memoirs
Published: 23 January 2023
DOI: 10.1130/2022.1220(26)
EISBN: 9780813782201
... orogenic front. Orogenesis continued in the Late Devonian to Carboniferous Neoacadian orogeny. This phase was also associated with amphibolite-facies metamorphism and intrusion of I- and S-type granitoids. Widespread crustal melting and 50–60 km crustal thicknesses may have favored the development...
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Series: GSA Memoirs
Published: 11 September 2017
DOI: 10.1130/2017.1213(10)
EISBN: 9780813782133
... are: (I) a Middle to Late Ordovician Taconic core (462–448 Ma); (II) a mixed domain of polymetamorphism (Taconic, Neoacadian, and Alleghanian); (III) a Devonian to middle Mississippian Acadian-Neoacadian core (395–340 Ma), and middle to late Mississippian early phase of the Alleghanian (335–322 Ma...
Series: GSA Field Guide
Published: 01 January 2012
DOI: 10.1130/2012.0029(11)
EISBN: 9780813756295
... England and migrated southward in time. Once thought to be the fourth tectophase of the Acadian orogeny, this event is now called the Neoacadian orogeny. Active deformational loading during the event initially produced the Sunbury black-shale basin, whereas subsequent relaxational phases produced...
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Journal Article
Published: 01 October 2015
American Mineralogist (2015) 100 (10): 2254–2271.
... crop out in the southern end of the Central Maine Terrane and thus are a part of the Acadian/Neoacadian Orogen. The typical mineral assemblage is garnet + sillimanite + K-feldspar + plagioclase + quartz + cordierite + biotite ± spinel. The sillimanite is commonly pseudomorphous after kyanite...
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Series: GSA Field Guide
Published: 24 September 2021
DOI: 10.1130/2021.0061(07)
EISBN: 9780813756615
... isochemical phase diagram sections and garnet Sm-Nd ages. P-T-t paths and garnet Sm-Nd ages for migmatitic garnet sillimanite schist document high-grade 460–411 Ma metamorphism extending south from Winding Stair Gap to Standing Indian in the Blue Ridge of North Carolina. In the Alabama Blue Ridge, Wedowee...
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Series: GSA Memoirs
Published: 01 January 2004
DOI: 10.1130/0-8137-1197-5.525
... in the core near the southwest end. The coarse augen gneiss phase constitutes a larger proportion of the Toxaway Gneiss toward the northeast. Field evidence indicates that the augen phase intruded the banded Toxaway lithology; U/Pb isotopic ages of these lithologies, however, are statistically...
Journal Article
Published: 01 November 2018
American Mineralogist (2018) 103 (11): 1851–1868.
...Duncan S. Keller; Jay J. Ague Abstract We quantify the metamorphic pressure-temperature ( P-T ) conditions for a newly discovered silica-undersaturated high-pressure granulite (HPG) from the Central Maine Terrane (CMT) in northeastern Connecticut, U.S.A. The rocks lie within the Acadian-Neoacadian...
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Journal Article
Published: 01 September 2018
The Journal of Geology (2018) 126 (5): 511–530.
... experienced extensional magmatism resulting from oblique convergence of Meguma accreting to Laurentia during the Neoacadian Orogeny. A transtensional zone along dextral transcurrent faults allowed the formation of the Maritimes Basin of Nova Scotia and New Brunswick and the eruption of the 373 ± 4 Ma Fisset...
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Journal Article
Journal: Lithosphere
Publisher: GSW
Published: 01 December 2009
Lithosphere (2009) 1 (6): 337–342.
... at ca. 390 Ma and was associated with widespread migmatization. A third metamorphic event (M3) occurred during the ca. 378–371 Ma time interval and was possibly associated with the Neoacadian orogeny. Intermittent monazite growth during the 360–305 Ma interval suggests that the main phase...
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Journal Article
Journal: Geology
Published: 01 October 2016
Geology (2016) 44 (10): 871–874.
... ). In contrast, the U-Pb apatite and rutile age data more fully characterize the full duration of Appalachian orogenesis, particularly the Neoacadian and Alleghanian tectonic phases ( Fig. 2 ). The insensitivity of the U-Pb detrital zircon system to magma-poor Neoacadian and Alleghanian orogenesis...
Journal Article
Journal: Lithosphere
Publisher: GSW
Published: 14 August 2019
Lithosphere (2019) 11 (5): 722–749.
... Neoacadian deformation in the eastern Blue Ridge of Alabama. Garnet Sm-Nd geochronology, pressure-temperature ( P - T ) phase diagram sections (pseudosections), and thermobarometry were applied to the host metasedimentary rocks that were metamorphosed during this period. The southernmost exposures...
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Journal Article
Published: 11 April 2022
Journal of Sedimentary Research (2022) 92 (3): 304–319.
... Ordovician Taconic and Middle Devonian Acadian ages with two discrete modes at 463 and 369 Ma, and the latter dominated by Late Ordovician Taconic, Middle Devonian Acadian, and Late Devonian Neoacadian ages with discrete modes at 445, 397, 360, and 351 Ma. The new data suggest that early Pennsylvanian...
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Journal Article
Journal: Geosphere
Published: 05 January 2023
Geosphere (2023) 19 (1): 19–46.
... of the southern Appalachian Acadian-Neoacadian deformational and metamorphic core. The granite occurs as disconnected concordant to semi-concordant plutons in migmatitic, sillimanite zone rocks of the Brindle Creek thrust sheet. Locally garnet-bearing, the Walker Top Granite contains blocky alkali feldspar...
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Journal Article
Published: 21 September 2015
Canadian Journal of Earth Sciences (2015) 52 (10): 921–937.
... to the contact, the Alleghanian cleavage (S 2 ) is parallel to the contact in both units, with S 0 in the White Rock Formation metavolcanic rocks and Halifax slate parallel to and discordant to the contact. The geometry of deformed Neoacadian minor folds, quartz fringes on sulphide grains, and micro...
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Journal Article
Journal: Geosphere
Published: 02 November 2021
Geosphere (2021) 17 (6): 1840–1860.
... and Ridge. Both the Cambrian Chilhowee Group and Pennsylvanian Pottsville Formation exhibit (U-Th)/He dates ranging from 507 to 263 Ma with a Mississippian subset (353–329 Ma, n = 4), which indicates rapid cooling and inferred exhumation during Late Devonian–Early Mississippian Neoacadian tectonism. We...
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Journal Article
Journal: GSA Bulletin
Published: 16 May 2017
GSA Bulletin (2017) 129 (9-10): 1195–1208.
...–Mississippian and refer to this tectonic phase as the Neoacadian ( Hatcher, 1987 ; Hatcher et al., 2007 ). Others consider the Acadian orogeny to be largely absent in this region aside from local magmatism and metamorphism ( Hibbard, 2000 ). In either case, metamorphism documented for this Acadian-Neoacadian...
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Journal Article
Published: 01 July 2016
The Canadian Mineralogist (2016) 54 (4): 945–969.
... to Mississippian Neoacadian orogeny and the Pennsylvanian to Permian Alleghanian orogeny. Thus the New England LCT pegmatites were emplaced during the latter stages of the assembly of Pangea. 40 Ar/ 39 Ar muscovite ages from 11 LCT and one NYF pegmatites range from ca . 339 to ca . 243 Ma and are interpreted...
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Journal Article
Published: 11 November 2014
Geological Magazine (2015) 152 (5): 767–787.
... ductile deformation in white mica-bearing rocks. Deformation-induced recrystallization of white mica and associated phases will generally lead to complete Sr-isotopic re-equilibration and resetting of ages (Inger & Cliff, 1994 ; Müller et al. 1999 ). Such resetting...
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