| Abstract: | Dinoflagellate cysts from two Middle-Late Jurassic sections in the Wenquan and Yanshiping regions of the Qiangtang Basin comprise 24 genera and 36 species including one new taxon of the genus Tenua. Based on their stratigraphic distribution, six assemblage zones are recognized in ascending order as follows: 1) Tubotuberella egemenii Zone, probably Callovian, in the mid-upper part of the Xiali Formation; 2) Pareodinia ceratophora Zone, probably Oxfordian, in the lower part of the Suowa Formation; 3) Batiacasphaera floralis Zone, probably Oxfordian, in the middle part of the Suowa Formation; 4) Amphorula metaelliptica Zone, probably Early Kimmeridgian, in the upper part of the Suowa Formation; 5) Alisocysta spp. Zone, probably Early Kimmeridgian, in the base of the Xueshan Formation; 6) Tenua wenquanensis sp. nov. -Dichadogonyaulax schizoblata Zone, probably Late Kimmeridgian-Tithonian, in the lower part of the Xueshan Formation. Based on our analysis the Jurassic-Cretaceous Boundary in the Wenquan section is placed higher than previously. |
