Palynostratigraphy of Ordovician strata, Canning Basin, Western Australia. - Part Two: chitinozoans and biostratigraphy

This second and concluding part of a comprehensive palynological study of the Lower to Middle Ordovician succession of the central-northeastern Canning Basin completes the systematic documentation of the palynomorphs, i.e., chitinozoans, and formulates a palynostratigraphic zonation scheme embracing all three constituent formations of this investigation, viz., the Willara, Goldwyer, and Nita formations. A total of 21 species of chitinozoans (five genera), detailed systematically herein, are identified. Although chitinozoan recovery per sample proved variable, the following species occur fairly persistently in the productive samples: Belonechitina micracantha, Conochitina subcyatha, C. pomoni, C. langei, Calpichitina vindjaga, and Rhizochitina magna. Five, stratigraphically successive suriachitid/ prasinophyte assemblage zones, ranging in age from early Arenig through late Llanvirn, are proposed as follows (ascending order): Athabascaella rossii Assemblage Zone, Compiaubisphara vitzicarum Assemblage Zone, Sacculidium adamsoni Assemblage Zone, Aremocorda minna solaris Assemblage Zone, and Daciydophytis striatographax Assemblage Zone.