Taxonomy and paleoecology of Lower Silurian radiolaria from Rookery Creek, Cornwallis Island, Canadian Arctic.

摘要

A new radiolarian fauna has been extracted from the Sheinwoodian perneri-opimus graptolite zone in the Canadian Arctic. The fauna is dominated by Haplotaeniatumidae and Palaeoscenidiidae (15% and 40%) and new genus Franklinia (25%). Entactiniidae comprises a moderate component (9%) at the base of the section but rapidly decrease in abundance. Inaniguttids and Secuicollacta make up a minor but persistent component (6% and 3%). Five new genera and ten new species were discovered. The new genera are Inanisilva, n. gen., Franklinia, n. gen., Involutaentactinia, n. gen., Perforentactinia, n. gen. and Patulaentactinia, n. gen. The new species presented are Inanisilva aethra, n. sp., Gyrosphaera cavea , n. sp., Labyrinthosphaera lancia, n. sp., Haplotaeniatum vertigospongium, n. sp., Involutaentactinia eccentra, n. sp., Involutaentactinia cupressa, n. sp., Perforentactinia excepta, n. sp., Patulaentactinia ostentata, n. sp., Franklinia tricae, n. sp., and Franklinia dipulvisphaera, n. sp. This fauna falls within the existing preliminary Long Spined Inaniguttid Zone 3 of Noble and Aitchison, but due to the low abundance of Inaniguttidae and Rotasphaeridae, and high abundance of Haplotaeniatumidae, this fauna most closely resembles the underlying Long Spined Inaniguttid Zone 2. Revisions to the existing biostratigraphy are proposed; the Long Spined Inaniguttid Zone 2 extends through the perneri-opimus Zone encompassing this fauna, and the base of the Long Spined Inaniguttid Zone 3 is redefined and moved to the base of the Homerian. Palaeoscenidiid abundance fluctuations within the section are correlative to delta 13Corganic values within this section. This observation is supported quantitatively by detrended correspondence analysis and Spearman's rank correlation. This correlation is hypothesized to indicate paleoenvironmental control.