Microfossils from the Late Precambrian Draken Conglomerate, Ny Friesland, Svalbard

Abstract

An intraformational "flake" conglomerate within the Late Precambrian (700-800 m.y.) Draken Conglomerate of Ny Friesland, Spitsbergen, contains abundant, well preserved microfossils in silicified shards of microbial mats, as well as in associated silicified clasts of non-stromatolitic mud. Sedimentation apparently took place in a lagoonal environment subjected to occasional storms. Within one local area, three distinct microbial mat associations can be recognized, each dominated by a single filamentous cyanobacterial mat builder occurring in densely interwoven patterns oriented parallel to bedding. One mat association often contains an associate mat building filament, and two of the three associations harbor mat-specific stromatolite dwelling blue-greens. Three taxa, all probable cyanobacteria, apparently lived as microbenthos in the non-stromatolitic mud. Approximately a dozen planktonic taxa have been recognized in this microbiota; these occur as randomly scattered individuals and clusters in all three mat associations <i>and</i> in the carbonate mud. The Draken microbiota provides a case study of the ecological heterogeity and microbial distribution within a single late Precambrian environment, and suggests the importance of paleoecology in analyses of Proterozoic evolution and biostratigraphy. Twenty-eight taxa are recognized of which eight are formally described as new: <i>Salome svalbardensis</i> n. gen. et ap., <i>Synodophycus euthemos</i> n. gen. et sp., <i>Sphaerophycus wilsonii</i> n. sp., <i>Eosynechococcus brevis</i> n. sp., <i>Eosynechococcus depressus</i> n. sp., <i>Gloediniopsis mikros</i> n. sp., <i>Myxococcoides cantabrigiensis</i> n. sp., and <i>Myxococcoides ovata</i> n. sp.