02173nas a2200169 4500008004100000245009300041210006900134300001200203490000700215520165300222653002601875653001301901100001601914700002001930700001401950856003901964 2008 eng d00aFaunas and Cambrian Volcanism on the Avalonian Marginal Platform, Southern New Brunswick0 aFaunas and Cambrian Volcanism on the Avalonian Marginal Platform a884-9050 v823 a

The Cambrian inlier at Beaver Harbour, southern New Brunswick, is now confidently referred to the marginal platform of the late Proterozoic–Early Paleozoic Avalon microcontinent. The sub-trilobitic Lower Cambrian Chapel Island and Random Formations are unconformably overlain by the mafic volcanic-dominated Wade's Lane Formation (new). Late Early Cambrian trilobites and small shelly taxa in the lowest Wade's Lane demonstrate a long Random–Wade's Lane hiatus (middle Terreneuvian–early Branchian). Latest Early–middle Middle Cambrian pyroclastic volcanism produced a volcanic edifice at Beaver Harbour that is one of three known volcanic centers that extended 550 km along the northwest margin of Avalon. Middle Middle Cambrian sea-level rise, probably in the Paradoxides eteminicus Chron, mantled the extinct volcanics with gray-green mudstone and limestone of the Fossil Brook Member. Black, dysoxic mudstone of the upper Manuels River Formation (upper Middle Cambrian, P. davidis Zone) is the youngest Cambrian unit in the Beaver Harbour inlier. Lapworthella cornu (Wiman, 1903) emend., a senior synonym of the genotype L. nigra (Cobbold, 1921), Hyolithellus sinuosus Cobbold, 1921, and probably Acrothyra sera Matthew, 1902a, range through the ca. 8 m.y. of the trilobite-bearing upper Lower Cambrian, and H. sinuosus and A. sera persist into the middle Middle Cambrian. Lapworthella cornu and H. sinuosus replaced the tropical taxa L. schodackensis (Lochman, 1956) and H. micans Billings, 1872, in cool-water Avalon.

10aAvalon microcontinent10aCambrian1 aLanding, E.1 aJohnson, S., C.1 aGeyer, G. uhttp://dx.doi.org/10.1666/07-007.1