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East Harpswell Group

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Published: 01 September 2010
DOI: 10.1130/2010.1206(10)
... Ordovician to Early Silurian rocks of the East Harpswell Group; Silurian to Early Devonian rocks of the Central Maine Basin; and highly tectonized enigmatic rocks of the Rye complex of uncertain age. Stratigraphic reassessment and new U/Pb zircon ages support a model of east-directed Middle Ordovician...
Journal Article
Published: 01 December 2023
Canadian Journal of Earth Sciences (2024) 61 (2): 205–222.
...Sophia A. Johnson; David P. West, Jr.; Emily M. Peterman The Yarmouth Island Formation of the East Harpswell Group (EHG) is an assemblage of metamorphosed volcanic and sedimentary rocks exposed in Casco Bay, Maine. Although previously interpreted to have been deposited ca. 445 Ma, two new U–Pb...
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U–Pb detrital zircon probability density plot from the Sebascodegan Formation of the East Harpswell Group and the Cape Elizabeth Formation of the Casco Bay Group (from Cartwright et al. 2019).
Published: 01 December 2023
Fig. 8. U–Pb detrital zircon probability density plot from the Sebascodegan Formation of the East Harpswell Group and the Cape Elizabeth Formation of the Casco Bay Group (from Cartwright et al. 2019 ).
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Stratigraphic correlation chart for rocks in the Casco Bay area, coastal Maine, and selected correlative rocks in eastern Massachusetts (Nashoba terrane) and eastern Maine (Miramichi terrane). (1) Merrimack Group: Hepburn et al. (2021) use a combination of detrital zircon ages and cross cutting plutons to provide a depositional age range of 434–420 Ma for Merrimack Group rocks. (2) Vassalboro Group: the Waterville Fm. contains Middle Silurian (Wenlockian) graptolites (Osberg 1988). Based on detrital zircon studies, Ludman et al. (2018) and Cartwright et al. (2019) provide a maximum depositional age of 422 ± 20 Ma for Vassalboro Group rocks in south-central Maine—consistent with the Waterville Fm. fossil age. (3) East Harpswell Group: an unpublished U–Pb zircon age of 445 ± 2 Ma from metavolcanic rocks in the Yarmouth Island Fm. is reported in Hussey and Berry (2002). However, this age is superseded by two U–Pb zircon ages from metavolcanic rocks in the Yarmouth Island Fm. (this study) that indicate a prolonged period of magmatism between ca. 469 and 474 Ma (see text). Detrital zircon ages from the Sebascodegan Fm. (this study) provide a maximum deposition age of 472 ± 11 Ma (see text). (4) Falmouth–Brunswick Group: U–Pb zircons ages of 472 ± 7 Ma from the Nehumkeag Pond Fm. and 471 ± 6 Ma from the Mt. Ararat Fm. are interpreted by Hussey et al. (2010) to represent the timing of volcanism in the Falmouth–Brunswick Group. (5) Casco Bay Group: a U–Pb zircon age of 465 ± 4 Ma from the Cushing Fm. is interpreted by Hussey et al. (2010) to represent the timing of volcanism. A U–Pb zircon age of 469 ± 3 Ma from the Spring Point Fm. is interpreted by Tucker et al. (2001) to represent the timing of volcanism. (6) Miramichi belt in Maine: Ludman et al. (2021) report U–Pb zircon ages of 471 ± 4 and 467 ± 4 Ma from the Olamon Stream Fm. and interpret these to represent eruptive ages. (7) Nashoba Belt in eastern Massachusetts: based on U–Pb detrital zircon ages and the timing of cross-cutting plutons, Walsh et al. (2021) and Hepburn et al. (2021) independently interpret deposition of the Nashoba Fm. protoliths to have occurred between 485 and 435 Ma.
Published: 01 December 2023
depositional age of 422 ± 20 Ma for Vassalboro Group rocks in south-central Maine—consistent with the Waterville Fm. fossil age. (3) East Harpswell Group: an unpublished U–Pb zircon age of 445 ± 2 Ma from metavolcanic rocks in the Yarmouth Island Fm. is reported in Hussey and Berry (2002) . However, this age
Journal Article
Published: 01 January 2015
European Journal of Mineralogy (2015) 27 (1): 19–29.
... a representative inclusion fabric for the garnets from samples WB137 and WB142. Sample HN05-18 is a metapelite from the Jewell Formation, a pelitic unit of the Casco Bay Group at Harpswell Neck, Maine, USA. The mineral assemblage is biotite + chlorite + garnet + muscovite + quartz + plagioclase + ilmenite...
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Journal Article
Journal: Geology
Published: 01 July 2003
Geology (2003) 31 (7): 649–652.
... Casco Bay Group, and (4) the Late Ordovician–Early Silurian East Harpswell Group. All of the stratified rocks in the area of Figure 1 were metamorphosed to amphibolite facies conditions during the middle to late Paleozoic. (See Hussey [1988 ] and Hussey and Berry [2002 ] for details of the geology...
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Journal Article
Published: 01 March 2009
Journal of the Geological Society (2009) 166 (2): 201–204.
... to evaluate the tectonic setting is the Neoproterozoic Moine Supergroup of the Scottish Caledonides (Fig. 1 ). The Moine rocks and probably correlatives east of the Great Glen Fault were affected by mid-amphibolite-facies ’Knoydartian' metamorphism and intruded by syntectonic pegmatites at c . 790–840 Ma...
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Journal Article
Journal: Lithosphere
Publisher: GSW
Published: 01 December 2014
Lithosphere (2014) 6 (6): 409–418.
... Society of America 2014 * [email protected] Figure 1. (A) Sketch of the Variscan belt with location of the Órdenes complex. (B) Map of the Órdenes complex with indication of the main units and groups of units and the location of cross sections. MP—medium pressure; HP-HT—high-pressure–high...
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Journal Article
Published: 01 February 2005
The Canadian Mineralogist (2005) 43 (1): 157–182.
... and Molare synclines, and developed the main penetrative foliation, which strikes east–west and dips steeply north. The third phase produced a weak crenulation cleavage and small-scale folds whose axial planes strike southeast and dip shallowly to the northeast, with fold axes plunging shallowly to the east...
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Journal Article
Journal: AAPG Bulletin
Published: 15 June 2019
AAPG Bulletin (2019) 103 (6): 1321–1350.
... of Maine to the west and by the Yarmouth arch and LaHave platform to the east ( Poppe and Poag, 1993 ). The New England seamounts extend southeastward from the continental slope to the deep ocean floor. The Yarmouth arch is a complex horst trending southward that curves and plunges southwesterly beneath...
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Journal Article
Published: 01 August 2017
Reviews in Mineralogy and Geochemistry (2017) 83 (1): 55–102.
... of mineral phases and by inter- and intragranular diffusion of the chemical components ( Fig. 1b ). The driving forces for diffusion are the chemical potential gradients that are established between minerals such as the reactants and products of a metamorphic reaction or between different groups of minerals...
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Journal Article
Published: 01 August 2017
Reviews in Mineralogy and Geochemistry (2017) 83 (1): 469–533.
... of these calibrations was compared by Wu and Cheng (2006) , but taken as a group the GASP calibrations have become probably the most widely used chemical geobarometer for metamorphic rocks, due in part to the large range of P–T conditions over which garnet and plagioclase can both co-exist with a suitable buffering...
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