Paleoenvironmental and tectonic controls of sedimentation in coal-forming basins of southeastern New England

Abstract

An erosional hiatus over almost the entire area between Pennsylvania and western New Brunswick suggests that the region was mountainous from the Middle Devonian Acadian orogeny through Pennsylvanian time. Of seven basins or deposits of southeastera New England, the ages of three (Narragansett, Norfolk, and Worcester) are florally determined as Westphalian B (Middle Pennsylvanian) to Stephanian B or C (Late Pennsylvanian); three lack flora but are of inferred Carboniferous age (North Scituate, Woonsocket, and Pin Hill), and one is of possibly Carboniferous age (Sturbridge). The first three are characterized by flora suggesting a tropical or subtropical climate and by alluvial fan facies deposited in an intermontane basin. Four of these basins or deposits lie in the Avalon Terrane, three just west of the Nashoba Terrane, but none has been recognized in the intermediate Nashoba Terrane. These basin deposits can be correlated with similar deposits in Atlantic Canada.Tectonic effects of the Alleghanian orogeny are many and diverse, resulting in important tectonic controls on the formation and evolution of the coal basins. Grabens surrounded by uplands were formed by extension or strike-slip fault-related extension and were filled with Carboniferous sediments during the earliest Alleghanian orogenic episode. These sediments along with the basement complex, were multiply deformed during Permo-Carboniferous Alleghanian orogenic episodes, which involved folding, thrust faulting, plutonism, regional metamorphism, and strike-slip faulting. Metamorphism throughout the outcrop areas ranges from anchizone to K-spar zone in the Narragansett Basin; anchizone to possibly lower greenschist in the Norfolk Basin; and below the almandine zone in the "Worcester Coal Mine" deposit. Important effects of the tectonism are the widespread anthracitization and tectonic thickening of the lowsulfur and high-ash coals. on July 26, 2015 specialpapers.gsapubs.org Downloaded from Skehan, Rast, and Mosher PI-Masslite Quarry, Plainville; and J-Mackeral Cove, Jamestown, Rhode Island; between lower Paleozoic igneous rocks and Pennsylvanian sedimentary rocks at BH. The contact of basal Sachuest Arkose (formerly called Pondville Formation, Quinn, 1971) is probably a fault at S-Sachuest Point, the type locality, but an unconformity is exposed at T-Tiverton. Other named localities on Figure 2 or in the text are as follows: At-Attleboro; C-Canton; Cr-Cranston; E-Easton; F-Foxboro; Se-Seekonk, Massachusetts; B-Barrington; Br-Bristol; N-Newport; Pa-Pawtucket; P-Portsmouth; So-Somerset; VF-Valley Falls; SH-Stook Hill, Rhode Island; ME-Wamsutta volcanic outlier in Medway, Massachusetts.

Tectonostratigraphic relationships and coalification trends in the Narragansett and Norfolk Basins, New England

“…The few megaflora found in the Wamsutta Formation indicate similar to slightly older ages (reviewed in Murray et al, 1981;Skehan et al, 1986;Lyons, 1984; and references therein). Megafloral age patterns, plus less-thancompelling stratigraphic arguments, hold that the northern Narragansett basin is thicker and represents a longer interval of deposition than the southern Narragansett basin (see Mosher, 1983).…”

“…Sediments in the Narragansett and Norfolk basins are interpreted to have been deposited on wet alluvial fans formed along uplifted and tectonically active basin margins (Severson, 1981;Severson and Boothroyd, 1981;Mosher, 1983;Cazier, 1987) that formed as either extensional grabens or pull-apart basins (Mosher, 1983;Skehan et al, 1986). Mosher and Rast (1984) and Rast (1989) address possible correlations of the southeastern New England Carboniferous basins with those of Maritime Canada.…”

“…Detailed descriptions of the sedimentology, discussions of depositional environments, and comprehensive bibliographies of earlier work can be found in the following: Quinn (1971); ; Murray et al (1981); Mosher (1983); Skehan et al (1986); Zen et al (1983); and Hermes et al (1994); and references therein.…”

“…Floral locality abbreviations are: At-Attleboro; B-Barrington; Br-Bristol; C-Canton; E-Easton; F-Foxboro; JJamestown; M-Mansfield; N-Newport; P-Portsmouth; Pa-Pawtucket; Pl-Plainville; Se-Seekonk, Perrins Crossing; SPI-South Plainville; VF-Valley Falls. Adapted from Skehan et al, 1986. contains bimodal, mildly alkalic rhyolite and basalt flows Maria and Hermes, 2001) that are typical of volcanism associated with extensional tectonics. Zircons collected from rhyolite interstratified with volcaniclastic rocks of the Wamsutta Formation yield concordant ages of 370 Ma, and represent the first direct evidence of rocks older than Pennsylvanian within the Narragansett basin (Thompson and Hermes, 2003).…”

“…The Rhode Island Formation comprises the bulk of the Narragansett basin, and (as elaborated in the next section) contains megaflora that range in age from Westphalian A or B to Stephanian B (Lyons, 1984;Skehan et al, 1986;Wagner and Lyons, 1997;Pfefferkorn, 1999), establishing the timing of deposition as $310-290 Ma. The few megaflora found in the Wamsutta Formation indicate similar to slightly older ages (reviewed in Murray et al, 1981;Skehan et al, 1986;Lyons, 1984; and references therein).…”