TY - CONF T1 - Latest Paleozoic through Mesozoic faults in north-central Massachusetts and their correlations with New Hampshire T2 - Geological Society of America - Northeastern section Y1 - 2016 A1 - Kopera J.P. A1 - Roden-Tice, M.K. A1 - Robert P Wintsch KW - #Bibliography KW - #StaffPubs KW - AFT KW - apatite KW - apatite fission track KW - brittle KW - Campbel Hill KW - Clinton Newbury KW - Cretaceous KW - extension KW - fault KW - fault zone KW - fault zones KW - faults KW - fission track KW - Fitchburg KW - Fitchburg Plutons KW - Flint Hill KW - I-290 KW - Johnny Appleseed KW - Jurassic KW - merrimack KW - mesozoic KW - Nashua Trough KW - Normal Faults KW - Oakdale formation KW - Permian KW - Pinnacle KW - Rt 2 KW - Sterling KW - Stodge Meadow Pond KW - Triassic KW - Wachusett KW - Wekepeke KW - Worcester Formation AB -

Several faults in south-central New Hampshire can be extended into Massachusetts (MA) as a result of detailed mapping in both states since publication of the MA state bedrock geologic map in 1983. Many of these faults delineate and/or cut Devonian metamorphic isograds in the Silurian Merrimack Belt in northern MA, and juxtapose chlorite-grade rocks in the Nashua sub-belt (NSB) between lithologically similar middle- to upper amphibolite-facies rocks on either side.

Recent mapping in the NSB, combined with previous studies, suggest it may represent a graben initially formed during latest Paleozoic transtension contemporaneous with formation of the Narragansett Basin in southeastern MA and RI. Mylonites along the Silver Hill-Wekepeke Fault (Robinson, 1981), bounding the western edge of the NSB, show east-side-down normal motion and west-side down normal motion along the Clinton-Newbury Fault Zone (CNFZ; Goldstein, 1994) which bounds the NSB’s southeastern margin. A possible extension of the Flint Hill fault system (NH) forms the eastern edge of the NSB offsetting the CNFZ with normal west-side down motion near Ayer, MA. Late brittle normal faults in the NSB are abundant. Late, low-T˚, west-side-down shear zones in the Nashoba Terrane and similar rocks to the south may also be related to down-dropping of the NSB.

AFT ages were collected across north-central MA to constrain its late uplift history. A ~127 Ma AFT age in the NSB is discontinuous with AFT ages in the belts adjoining it, with ~182-144 Ma ages west across the Wekepeke fault and ~160-167 Ma east across the CNFZ. To the west, the brittle southern extension of the Pinnacle Fault in NH (Stodge Meadow Pond fault of Peterson, 1984) follows the western edge of the Fitchburg plutons in MA while a well-exposed west-side down brittle normal fault system, possibly the southward extension of the Campbell Hill Fault (NH), is developed along their eastern edge. AFT ages of ~144-136 Ma immediately west of the Pinnacle Fault in MA are discontinuous with ~117-115 Ma ages immediately to the east within the Fitchburg plutons. A single ~106 Ma age in the plutons west of the Campbell Hill Fault in MA is discontinuous with ~128-123 Ma ages to the east of it. The discontinuities amongst AFT ages across these faults suggest that they may have been active through the Cretaceous.

 

 

JF - Geological Society of America - Northeastern section PB - Geological Society of America CY - Albany, NY UR - https://gsa.confex.com/gsa/2016NE/webprogram/Paper272576.html ER - TY - MAP T1 - Bedrock geologic map of the Ayer 7.5’ quadrangle, Worcester and Middlesex Counties, Massachusetts Y1 - 0 A1 - Kopera J.P. KW - Ayer KW - ayer granite KW - Ayer Granodiorite KW - Ayer Quadrangle KW - Berwick KW - Campbell Hill Fault KW - chelmsford granite KW - Clinton Newbury Fault KW - Devens KW - Harvard Conglomerate KW - merrimack KW - Oakdale formation KW - pin hill KW - Shepley's Hill KW - Shirley Fault KW - tadmuck brook schist KW - Worcester Formation AB -

Editing and review are still underway.  This map should be available in winter 2015/2016

JF - Open File Report PB - Massachusetts Geological Survey U2 -

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ER - TY - MAP T1 - Bedrock geologic map of the Ayer 7.5’ quadrangle, Worcester and Middlesex Counties, Massachusetts (2015) Y1 - 0 A1 - Joseph P Kopera KW - Ayer KW - ayer granite KW - Ayer Granodiorite KW - Ayer Quadrangle KW - Berwick KW - Campbell Hill Fault KW - chelmsford granite KW - Clinton Newbury Fault KW - Devens KW - Harvard Conglomerate KW - merrimack KW - Oakdale formation KW - pin hill KW - Shepley's Hill KW - Shirley Fault KW - tadmuck brook schist KW - Worcester Formation AB -

Editing and review are still underway.  This map should be available in winter 2015/2016

JF - Open File Report PB - Massachusetts Geological Survey U2 -

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ER - TY - MAP T1 - Digital conversion of Peck, J.H., 1975, Preliminary bedrock geologic map of the Clinton quadrangle, Worcester County, Mass., U.S. Geological Survey Open File Report 75-658 Y1 - 2012 A1 - Peck, J.A. ED - Joseph P Kopera KW - #BedrockMap KW - #MGSPub KW - andalusite KW - ayer granite KW - Berlin KW - Bolton KW - Boylston KW - Clinton KW - Clinton-Newbury Fault KW - Devens KW - Harvard KW - Lancaster KW - Leominster KW - nashoba KW - Oakdale Quartzite KW - Peck KW - phyllite KW - quartzite KW - Reuben's Hill Formation KW - Sterling KW - tadmuck brook schist KW - Tower Hill quartzite KW - Wekepeke Fault KW - Worcester Formation AB - This map is an interim product and will be superseded by an updated bedrock map of the quadrangle in 2016. This map is a digital version of USGS OFR 75-658: http://pubs.er.usgs.gov/publication/ofr75658 There are some cartographic errors in creating a digital version: A Jurassic diabase dike along the western edge of the quadrangle is not shown in the digital version. These errors are being corrected. JF - Digital Conversion PB - Massachusetts Geological Survey U2 - 1:24000 ER - TY - MAP T1 - Preliminary bedrock geologic map of the Ayer quadrangle, Massachusetts Y1 - 2006 A1 - Joseph P Kopera KW - #BedrockMaps KW - #MGSPub KW - arsenic KW - Ayer KW - ayer granite KW - Berwick formation KW - Boxborough KW - chelmsford granite KW - Clinton-Newbury Fault KW - Devens KW - Fort Devens KW - Groton KW - Harvard KW - Jahns KW - LITTLETON KW - Merrimack Terrane KW - mylonite KW - nashoba KW - Nashua Trough KW - Oakdale formation KW - Shepley's Hill Landfill KW - Shirley KW - tadmuck brook schist KW - Worcester Formation AB -

This preliminary version of the Bedrock Map of the Ayer Quadrangle (Kopera, 2006) has been removed pending the release of an updated version in the near future. The above version should be considered outdated. If you would like a copy of this map, please contact Joseph Kopera at jkopera[at]geo[dot]geo[dot] umass[dot]edu

JF - Open-File Report PB - Massachusetts Geological Survey UR - http://www.geo.umass.edu/stategeologist/ U2 -

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ER - TY - MAP T1 - Preliminary bedrock geologic Map of the Webster quadrangle, Massachusetts Y1 - 2009 A1 - Patrick J Barosh KW - #BedrockMaps KW - #MGSPub KW - ayer granite KW - Charlton KW - Dudley KW - Eastford granite KW - Nashua Trough KW - Oakdale Quartzite KW - Oxford KW - Paxton Formation KW - Paxton Group KW - Plainville KW - Plainville Formation KW - Southbridge KW - Webster KW - Worcester Formation JF - Open-File Report PB - Massachusetts Geological Survey U2 -

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