Mineral Resources On-Line Spatial Data
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|Geologic age||Lower Jurassic|
|Original map label||Jdb|
|Comments||Part of Mesozoic Basins (Jurassic and Triassic Rocks); Sedimentary and Volcanic Rocks of Deerfield and Northfield Basins. Secondary unit description per MA003 as reported in USGS Geologic Names lexicon (ref. MA024): The Deerfield Diabase is here redefined as Deerfield Basalt of the Newark Supergroup to reflect its extrusive origin, shown by pillows and pillow breccias at the base, and by vesicular pahoehoe flows at the top. The Triassic-Jurassic boundary is arbitrarily drawn at the base of the Deerfield in clastic rocks of the Sugarloaf Formation (Robinson and Luttrell, 1985).|
|Primary rock type||tholeiite|
|Secondary rock type|
|Other rock types|
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow, pillows)Well-jointed quartz tholeiite, locally vesicular and locally pillowed near base.
Unpublished Digital Geologic Map of Massachusetts received from Rudi Hon at Boston College in 1998.
Zen, E-An (ed.), Goldsmith, R. (comp.), Ratcliffe, N.M. (comp.), Robinson, P. (comp.), Stanley, R.S. (comp.), Hatch, N.L., Jr., Shride, A.F., Weed, E.G.A., Wones, D.R., 1983, Bedrock Geologic Map of Massachusetts: U.S. Geological Survey, Reston, VA, scale 1: 250,000.
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