ORGANIC-WALLED MICROFOSSILS FROM THE EDIACARAN-CAMBRIAN GLOBAL BOUNDARY STRATOTYPE SECTION, CHAPEL ISLAND AND RANDOM FORMATIONS, NEWFOUNDLAND, CANADA

New data for organic-walled microfossils from coastal sections of the Chapel Island and Random formations on the Burin Peninsula, southeastern Newfoundland, add substantial detail to the limited previous information in this region concerning the distribution of these biostratigraphically important fossils for the Ediacaran-Cambrian transition and the early Cambrian. Filamentous sheaths and leiosphaerids occur throughout the examined interval of the Chapel Island and Random formations. This assemblage dominates the Ediacaran-Cambrian transition interval of upper member 1 to lower member 2A of the Chapel Island Formation. Also present are probable Cochleatina and problematic forms of uncertain identification, including a single specimen of an acritarch with rigid processes. The first specimens of Granomarginata prima approximate the base of the Rusophycus avalonensis Ichnozone in member 2A. The first abundant process-bearing acritarchs were encountered in the mid-portion of the Random Formation, comprising Asteridium tornatum, A. lanatum, and Comasphaeridium agglutinatum. A more diverse assemblage of acritarchs appears near the top of the Random Formation, including Fimbriaglomerella membranacea, Skiagia ornata, S. orbicularis, Comasphaeridium mollicum, and C. brachyspinosum. The association from near the top of the Random Formation indicates the Skiagia-Fimbriaglomerella Zone of Baltica, which has been taken to approximate, or somewhat precede, the first global appearance of trilobites. Acritarchs from the mid-portion of the Random Formation indicate the Asteridium-Comasphaeridium Zone, which on Baltica has been suggested to have a first appearance that approximates the base of the Cambrian. In the present study Granomarginata, which has generally been considered elsewhere to first appear in the Cambrian, has a first appearance much closer to the base Cambrian GSSP than do Asteridium or Comasphaeridium, and strata of the Treptichnus pedum Ichnozone are devoid of any “Cambrian” acritarchs. This study further shows that in Newfoundland the first appearance of Watsonella crosbyi, a candidate fossil for the base of Cambrian Stage 2, is within the range of Granomarginata, but below the first appearances of Asteridium and Comasphaeridium.