The Belchertown quartz monzodiorite pluton, West-central Massachusetts; a syntectonic Acadian intrusion

Ashwal, Lewis D.; Leo, Gerhard W.; Robinson, Paula; Zartman, Robert E.; Hall, Duncan

doi:10.2475/ajs.279.8.936

Cited by 20 publications

(7 citation statements)

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“…Reassessment of the petrologic data for the Beaver Brook locality leads to estimates of time-integrated metamorphic fluid flux of 10 6 cm 3 /cm 2 (Ferry & Dipple, 1991). The Belchertown pluton in west-central Massachusetts intruded along the axis of the Bronson Hill anticlinorium as an anhydrous pyroxene quartz monzodiorite but was almost completely altered by an influx of aqueous fluid during regional metamorphism to a pyroxene-free hornblende-biotite-epidote gneiss (Ashwal et al, 1979). Numerous metamorphic 'hot spots' were reported by Chamberlain & Rumble (1988 along or near the axis of the Central New Hampshire anticlinorium (Eusden, 1988;J.…”

Section: Other Possible Regional Metamorphic Hydrothermal Systems In mentioning

confidence: 98%

Regional Metamorphism of the Waits River Formation, Eastern Vermont: Delineation of a New Type of Giant Metamorphic Hydrothermal System

Ferry

1992

Journal of Petrology

131

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Metamorphic isograds and time-integrated fluid fluxes were mapped over the ~ 1500 km 2 exposure of the Waits River Formation, eastern Vermont, south of latitude 44°30'N. Isograds based on the appearance of oligoclase, biotite, and amphibole in metacarbonate rocks define elongated metamorphic highs centered on the axes of two large antiforms. The highest-grade isograd based on the appearance of diopside is closely associated spatially with synmetamorphic granitic plutons. Pressure, calculated from mineral equilibria, was fairly uniform in the area, 7± 1-5 kb; calculated temperature increases from ~480°C at the lowest grades in the area to ~575°C in the diopside zone. Calculated X CC)2 of equilibrium metamorphic fluid increases from <0O3 at the lowest grades to ~0-2 in the amphibole zone and decreases to ~ 0-07 in the diopside zone. Time-integrated fluid fluxes increase with increasing metamorphic grade, with the following mean values for each metamorphic zone (in cm 3 /cm 2): ankerite-oligoclase zone, 1 x 10 4 ; biotite zone, 7 x 10*; amphibole zone, 2 x 10 5 ; diopside zone, 7 x 10'. The mapped pattern of time-integrated fluxes delineates two large deep-seated (~25-km depth) regional metamorphic hydrothermal systems, each centered on one of the major antiforms. Fluid flowed subhorizontally perpendicular to the axis of the antiforms from their low-temperature flanks to their hot axial regions and drove prograde decarbonation reactions as they went. Along the axes of the antiforms fluid flow was further focused around synmetamorphic granitic intrusions. In the hot axial region fluid changed direction and flowed subvertically out of the metamorphic terrane, precipitating quartz veins. Estimates of the total recharge, based on progress of prograde decarbonation reactions, nearly match estimates of the total discharge, based on measured quartz vein abundance, (2-10) x 10 12 cm 3 fluid per cm system measured parallel to the axes of the antiforms. Within the axial regions fluids had lower X COl and rocks record greater time-integrated fluxes close to the intrusions than at positions more than ~ 5 km from them. The differences in both fluid composition and time-integrated flux can be explained by mixing close to the intrusions of regional metamorphic fluids of XQQ^O-I with fluids from another source with X COl~0 in the approximate volume ratio of 1:2.

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Section: Other Possible Regional Metamorphic Hydrothermal Systems In mentioning

confidence: 98%

Regional Metamorphism of the Waits River Formation, Eastern Vermont: Delineation of a New Type of Giant Metamorphic Hydrothermal System

Ferry

1992

Journal of Petrology

131

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“…The posttectonic Concord Granite gives an age of 359 + 11 Ma (Lyons & Livingston 1979). The core of the Belchertown pluton was unaffected by the ensuing metamorphism and yields a zircon age of 380 +_ 5 Ma, and hornblende from the hydrated gneissic outer parts of the pluton give K-Ar cooling ages of 361 + 6 Ma (Ashwal et al 1979). 1).…”

Section: Background and Settingmentioning

confidence: 98%

Acadian metamorphism in central massachusetts and south-western New Hampshire: evidence for contrasting P-T trajectories

Schumacher

Robinson

1989

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Early work by numerous investigators (Robinson 1963, Tracy et al. 1976, Robinson et al. 1982, 1986a provides a structural and metamorphic framework for the Acadian metamorphic high in central Massachusetts within which changes in phase composition and assemblage in the rocks can be correlated. Six metamorphic zones have been distinguished (Tracy et al. 1976, Robinson et al. 1982, reflecting prograde (T) metamorphic conditions in graphite-bearing pelitic rocks (Fig. 1) that range from the amphibolite through to the lower granulite facies. The T and P estimates are based mainly on A. B. Thompson's (1976) pioneering work in quantifying T and P using biotite-garnet Fe/Mg exchange and the garnet-cordierite-sillimanitequartz assemblage, respectively. Background and setting

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“…These rocks were apparently at too high a structural level to feel the effects of the younger metamorphisms. The northern boundary of the zone of 360 Ma metamorphic monazite ages in western New Hampshire is not well known and is the subject of ongoing research by Tucker and Robinson. Falling within the time gap between the older Acadian and Neo-Acadian metamorphisms was the peculiar 380±5 Ma Belchertown Quartz Monzodiorite intrusion (Ashwal et al 1979), with its relict contact aureole, and geochemically and temporally similar dikes and sills at widely distributed locations (Fig. 7).…”

Section: Discovery Of Neo-acadian Metamorphismmentioning

confidence: 99%

“…Locally Silurian Clough Quartzite rests unconformably above the Fourmile. East-directed recumbent folds involving the top contact of the Fourmile and Lower Devonian strata appear to be truncated on the map by the 380±5 Ma Belchertown intrusion (Ashwal et al 1979), thus placing these folds as Early to Middle Devonian.…”

Section: The Pelham Gneiss Domementioning

confidence: 99%

Paleozoic orogens in New England, USA

Robinson

Tucker²,

Bradley

et al. 1998

GFF

154

131

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The Belchertown quartz monzodiorite pluton, West-central Massachusetts; a syntectonic Acadian intrusion

Cited by 20 publications

References 0 publications

Regional Metamorphism of the Waits River Formation, Eastern Vermont: Delineation of a New Type of Giant Metamorphic Hydrothermal System

Regional Metamorphism of the Waits River Formation, Eastern Vermont: Delineation of a New Type of Giant Metamorphic Hydrothermal System

Acadian metamorphism in central massachusetts and south-western New Hampshire: evidence for contrasting P-T trajectories

Paleozoic orogens in New England, USA

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