GRIFFITHS, Daniel R., (IO20282@Maine.Maine.edu),
	LUX, Daniel R., (DLUX@Maine.Maine.edu),
		both at Dept of Geological Sciences, 5704 Boardman Hall,
            	University of Maine, Orono, ME W469
	WINTSCH, Robert R., (WlNTSCH@Indiana.edu), Dept. of 	
		Geological Sciences, Indiana University, Bloomington, IN 
		U.S. Geological Survey, M. S. 926, Reston. VA 22902

During the Late Triassic to Early Jurassic over 4 km of strata and 3 
major tholeiitic basalt units of the Newark Super Group were 
deposited in the Hartford Basin in Connecticut and Massachusetts. 
The sediment of the Newark Supergroup consists mainly of coarse-
grained, conglomerate, sandstone, and siltstone. This material was 
deposited mainly in the form of fluvial and alluvial deposits, or fine-
grained lacustrine deposits.
	The immature, coarse-grained nature of the Newark Supergroup 
strata indicates that the deposits are very proximal in nature. Heavy 
mineral studies (Krynine et al., 1950), coupled with paleocurrent and 
petrographic data (Hubert et al., 1992) indicates that most of the 
material in the Hartford Basin was eroded from the metamorphic 
highlands immediately to the west and east of the Hartford Basin.
	The material directly to the east of the Hartford Basin consists 
of a series of tectonic terrains. These terrains were emplaced in the 
Devonian during the Acadian Orogeny, and were later 
metamorphically overprinted and slightly thrusted in the 
Pennsylvanian and Early Permian during the Alleghenian Orogeny 
(Wintsch et al. 1995). The material directly to the west of the basin 
consists of a continuation of the lithotectonic terrains found to the east 
directly adjacent to the basin and the Proto-North American Terrain 
further to the west. Dietsch et al., 1992, published several muscovite 
ages of approximately 355 Ma from the Waterbury Dome directly to 
the west of the Basin. These Early Mississippian ages indicate this 
area was not overprinted by Alleghanian metamorphism.
	Muscovites from 27 samples (4 basement, 23 detrital) collected 
in a narrow hand running east-west across the basin just south of 
Cromwell, Connecticut were dated by the 40Ar39Ar method. 
Basement samples at the "Great Unconformity" (Roaring Brook 
exposure) range between 363 and 371 Ma. The remaining samples are 
all detrital micas and range from 250 Ma in the lower Shuttle Meadow 
formation to 280 Ma at the top of the Portland Arkose. The Late 
Paleozoic age of these detrital muscovites indicates that the source 
areas for the material deposited within the Hartford Basin have 
Permian cooling ages suggesting they were eroded from a terrain 
overprinted by Alleghenian Metamorphism. This suggests a 
predominant source area to the east. In addition muscovite ages 
presented here indicate there is a large discontinuity (83 Ma) between 
the basement rocks beneath the unconformity and the basal 
conglomerate of the New Haven Arkose. This discontinuity precludes 
these basement schists and pegmatites as provenance areas for the 
Newark Supergroup strata of the Hartford Basin.