JURASSIC PALYNOFLORAL PROVINCES OF TARIM BASIN

Jurassic strata are widely distributed in Tarim Basin and rich in fossil spores and pollen grains. According to the present data, two Jurassic palynofloras occupy the South Tarim and the North Tarim palynofloral provinces. For each palynoflora an assemblage sequence is proposed and described. The southern flora is composed of five assemblages (in ascending order): 1. Cyathidites-Classopollis Assemblage; 2. Disacciatrileti-Cyathidites-Classopollis-Quadraeculina Assemblage; 3. Disacciatrileti-Cyathidites-Classopollis-Neoraistrackia Assemblage; 4. Disacciatrileti-Cyathidites-Classopollis Assemblage; and 5. Cyathidites-Classopollis-Disacciatrileti Assemblage. The northern flora includes assemblages: 1. Disacciatrileti-Cyathidites Assemblage; 2. Cyathidites-Cibotiumspora-Disacciatrileti Assemblage; 3. Cyathidites-Neoraistrickia-Disacciatrileti Assemblage; and 4. Cyathidites-Classopollis Assemblage. There are clear differences in the Jurassic palynological floras between South Tarim and North Tarim provinces. A preliminary study shows that the sporopollen fossils from South Tarim are close to those of South China, the sporopollen assemblages from the North Tarim are similar to those of North China. According to Vakhrameev (1988), South China Jurassic Floral Province is an important part of the East Asia Province in the Europe-China Region. The flora of North China falls into the Siberia Region. Thus, the boundary between the South and North Tarim provinces should be shifted northward to central Tarim, extending in northwest-southeast direction. The above boundary separated the Tarim Sporopollen Province into two different sporopollen subprovinces, namely the South Tarim Palynofloras province and North Tarim Palynofloras province (Fig.1).