Early tommotian pre-archaeocyathan reef and associated macroskeletal fossils in olenek uplift section
V.V. Marusin1,2
1Trofimuk Institute of Petroleum Geology and Geophysics of SB RAS, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk,Russia
Keywords: patch reefs, skeletal fossils, Cambrian, Tommotian Stage, Cambrian Explosion
Abstract
Since the origin of the first metazoan reef-builders in the Tommotian, reefs have played an important role in marine ecosystems throughout the Phanerozoic, stimulating ecological diversity, regulating the shoreface hydrodynamic regime, and acting as a locus of skeletal carbonate production. In contrast, pre-archaeocyathan calcimicrobial buildups are comparatively primitive in composition and have barely affected the distribution of benthic organisms in the Nemakit-Daldynian and early Tommotian. This work studies a vast package of biogenic carbonates (Suordakh Member) in the upper Kessyusa Group of the Olenek Uplift and spatiotemporal distribution of associated diverse macroscopic fossils. The Suordakh Member comprises a patch reef, composed of grouped low-relief calcimicrobial buildups surrounded by peloidal and ooidal shoals. The study demonstrates that macroscopic molluscs, anabaritids, hyoliths, and conulariids inhabited granular shoals between the calcimicrobial patch reefs by ~530 Ma, but they neither took part in the reef construction nor inhabited the bioherms.
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