Re-study Of The Early Jurassic Schitukhe Flora From South Primorye Of Russia And Its Comparisons With Some Coeval Floras From China And Japan

The Early Jurassic flora from the Lower Jurassic Schitukhe Formation of South Primorye, Far Eastern Russia is re-studied in some detail for the first time. The plant-bearing strata are sandwiched by marine beds, which documented the Early Jurassic age. The Schitukhe flora consists of over42species of26genera, dominated by the ferns (e.g. Marattiopsis, Phlebopteris, Clathropteris, Hausmannia, Cladophlebis), cycadophytes (including bennettitales and cycadales, e.g. Pterophyllum, Ctenis, Nilssonia, Taeniopteris) and conifers (e.g. Cycadocarpidium, Podozamites), with some of ginkgoales and czekanowskiales, and a few seed-ferns (Sagenopteris). Meanwhile, there are very few Coniopteris and some horsetails (e.g. Neocalamites) in the composition. All the floral characters show a typical Early Jurassic flora.This thesis has also studied the comparisons of the Schitukhe flora with its coeval floras from the adjacent regions including China and Japan for the first time. The study demonstrates that the Schitukhe flora has some similarities with the Early Jurassic floras from the Shansonggang and Yihe Formations of Jilin, Beipiao Formation of Liaoning, and the lower-middle Guanyintan Formation of Hunan in China, in which it appears to be more similar to the Yihe flora of Jilin in floral composition and characters. Regarding the comparisons to the Japanese Early Jurassic floras, the Schitukhe flora is some similar to the Kuruma-type floras represented by the Early Jurassic floras of the Kuruma Group and Iwamuro Formation from the Central Japan though there are still some differences in composition and floral characters, such as in having Cycadocarpidium, while no Ptilophyllum, etc.Based on the floral and stratigraphic characters, the author discussed that the Schitukhe flora might be growing under the warm and humid climates and located in subtopic-warm temperate zone. And, the age of the Schitukhe flora might be some earlier Early Jurassic.