Pegmatites of the Middletown area, Connecticut

Stugard, Frederick

doi:10.3133/ofr55177

Cited by 8 publications

(3 citation statements)

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“…The Middletown-Portland district, along both sides of the Connecticut River, has produced a small amount of aquamarine from crystals embedded in pegmatite (Stugard 1958). Aquamarine is also known from such pegmatites as the Case prospect and the Strickland-Cramer, Hale, Sawmill, White Rock, and Simpson quarries.…”

Section: Connecticutmentioning

confidence: 99%

Aquamarine in the United States

Jacobson

1993

Rocks & Minerals

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Section: Connecticutmentioning

confidence: 99%

Aquamarine in the United States

Jacobson

1993

Rocks & Minerals

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“…This fault, which is known locally as the Great Fault, separates the area of crystalline rocks from the area of Triassic rocks in north-central Connecticut. The position of the Triassic border fault shown on plate 1, is adapted from Aitken (1955), Collins (1954), Herz (1955), andStugard (1958). The deposition was interrupted by periods of igneous activity during which three distinct flows of basaltic lava poured out upon the surface of the sediments.…”

Section: Pre-pleistocene Historymentioning

confidence: 99%

“…The rocks are not shown on plate 1, except as isolated outcrops. The distribution of individual units of crystalline rocks is shown on the detailed maps of Stugard (1958), Herz (1955), Aitken (1955), and Collins (1954).…”

Section: Genebal Chabacter and Extentmentioning

confidence: 99%

Ground-water resources of north-central Connecticut

Cushman¹

1964

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Location and general features of the area...______________________ 3 Purpose of the investigation____________________________________ 4 Methods of study and scope of investigation ______________________ 5 Previous groundwater and geologic investigations _________________ 6 Acknowledgments. __________________________________________ 8 Well-numbering system ________________________________________ 10 Topography ______________________________________________________ Streams-_______________________________________________________ 12 Climate-_________________________________________________________ 14 Physiographic development_________________________________________ 16 Pre-Pleistocene history.________________________________________ 17 Pleistocene glaciation__________________________________________ 18 Post-Pleistocene history ______________________________________ Geology.__ _ ____________________________________________________ Descriptions and water-bearing properties of the geologic formations. Consolidated rocks_______________________________________ 22 Crystalline rocks of pre-Triassic age____________________ General character and extent______________________ Water-bearing properties ___________________________ Yields of wells. __ ______________________ Sedimentary rocks of Triassic age______________________ General character and extent___________________ Water-bearing properties___-___-__-___-__-______ 31 Factors causing areal variation in yield_____________ Igneous rocks of Triassic age__________________________ General character and extent_____________________ Water-bearing properties.________________________ Well construction________________________________ Unconsolidated deposits____________________________________ Ground-moraine deposits_________________________-___-_ General character and extent______________________ Water-bearing properties____-____________-_______ Ice-contact deposits__________________________________ General character and extent___________________ Water-bearing properties____-_-____-__-__-_-46 Ice-contact deposits in Glastonbury, Manchester, and Vernon_________________________________________ Ice-contact deposits in South Windsor and East Wind-sor_____________________________ Ice-contact deposits in Ellington and Somers______-49 in IV CONTENTS Geology Continued Descriptions and water-bearing properties of the geologic formations Continued Unconsolidated deposits Continued Page Outwash-plain, valley-train, and undifferentiated outwash deposits..- .-______________________________________ General character and extent______________________ Water-bearing properties___________________________ Buried outwash deposits in the preglacial channel of the Connecticut River_____-_-_-_-_-_-_-_-_-_-___-___-General character and extent______________________ Water-bearing properties___________________________ Glaciolacustrine and associated delta deposits_____________ General character and extent of the glaciolacustrine deposits______________________________________ Water-bearing properties of the glac...

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Alpha-decay damage in minerals of the pyrochlore group

1988

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Abstract. X-ray diffraction analysis and transmission electron microscopy have been used to study the effects of alpha-decay damage in pyrochlore group minerals, characterized by the general formula A1 ,~BzO6(O,OH,F)I -n'pH20.As defined by the XRD intensity ratio I/Io, both the saturation dose (for which I/Io =0.1-0.0) and the dose which signifies the initial loss of crystallinity (for which I/Io = 1.0-0.8) increase as a function of geologic age. The increase is attributed to annealing of isolated alpha-recoil tracks back to the original crystalline structure. The tracks have calculated mean lives, za, on the order of 108 years. In contrast, minerals which remain crystalline (e.g., uraninite, UO2) despite doses of up to 1018 alpha-events/mg have mean alpha-recoil track lives ~ 104 years (Eyal and Fleischer 1985).After correcting the calculated dose for annealing of alpha-recoil damage, I/Io is observed to decrease exponentially to zero over the dose range 0.02-1.0 x 1016 alphaevents/rag. The relationship between I/Io and "corrected" dose was used to calculate an average alpha-recoil track diameter of 4.6 nm, in which < 2600 atoms are displaced. XRD line broadening due to strain dominates the first half of the crystalline-to-metamict transition, reaching a maximum of 0.003, then decreasing to < 0.001. Line broadening due to decreasing crystallite size dominates the latter half of the transition. Estimated crystallite dimensions decrease from 450 nm to < 15 nm prior to reaching the fully metamict state. With increasing dose HRTEM images of microlites from the Harding pegmatite sequentially exhibit: 1) mottled diffraction contrast, 2) isolated 1-5 nm aperiodic areas, 3) coexisting aperiodic and crystalline areas, 4) relict" islands" of crystalline material in an aperiodic matrix, and 5) complete loss of lattice fringe periodicity. With no consideration given to alpha-recoil track fading, the transition covers a dose range of 0.04-1.7x 1017 alpha-events/mg. Using a value of za=108 years, this dose range is corrected down to 0.02-1.2 x 10 ~6 alpha-events/mg.The metamict state is characterized by a range of M-M and M-O distances which give rise to bands of diffuse scattering centered at 0.30 nm and 0.18 nm, respectively, in x-ray and electron diffraction patterns. Random image contrast shown by HRTEM is consistent with a random network type structure, an interpretation supported by EX-AFS/XANES studies (Greegor et al. 1985a(Greegor et al. , b, 1987. The structure of metamict pyrochlore consists of an aperiodic framework of corner-sharing B--O polyhedra. Compared to the crystalline precursor, the metamict state displays a reduced M-O coordination number and mean bond length, increased distortion of the B-site, and a slight increase in the average M-M distance.

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Pegmatites of the Middletown area, Connecticut

Cited by 8 publications

References 0 publications

Aquamarine in the United States

Aquamarine in the United States

Ground-water resources of north-central Connecticut

Alpha-decay damage in minerals of the pyrochlore group

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