新疆焉耆盆地博湖拗陷早侏罗世大孢子及孢形体化石

EARLY JURASSIC MEGASPORES AND PALYNOMORPHS FROM THE BOHU DEPRESSION, YANQI BASIN, XINJIANG NW CHINA

新疆焉耆盆地的下侏罗统自下而上分为八道湾组和三工河组 ,产孢形体和大孢子化石。孢形体有 5种 :K uqaia quadrata L i,K.concentrica L i,K.radiata L i,K.yangii sp.nov.和 K.yanqiensissp.nov.,大量分布于八道湾组和三工河组。大孢子 N athorstisporites yanqiensis sp.nov.,H ughesisporites gibbosus(Reinhardt etFricke) Kannegieser只见于八道湾组 ,而 Paxillitriletes phyllicus(Murray) Hall et Nicolson,Bacutriletes corynac-tis(Harris) Marcinkiewicz和 Erlansonisporites sparassis(Murray) Potonié仅在三工河组有少量分布 ,对盆地内探区地层的划分和对比有指示意义。大孢子和孢形体化石证据表明 :焉耆盆地的八道湾组和三工河组可与准噶尔盆地的八道湾组和三工河组及塔里木盆地的阿合组和阳霞组分别对比 ,时代同属早侏罗世。描述 3新种 :N athorstisporites yanqiensissp.nov.,K uqaia yangii sp.nov.和 K uqaia yanqiensissp.nov.和 1新联合种 Kuqa-ia cucuma(Yang et Sun) comb.nov.

The Yanqi Basin situated in Xinjiang Uygur Autonomous Region, NW China comprises southwards the Heqing Depression, and the Yanqi Uplift and the Bohu Depression. The Jurassic series developed in the Bohu Depression is of the terrestrial clastic sediments with coal beds and divided into the Lower Jurassic Badaowan and Sangonghe Formations and Middle Jurassic Xishanyao Formation. Totaly 733 Lower Jurassic cutting samples collected from 9 wells within the Bohu Depression (Fig.1) are macerated and 358 of them yield megaspores and palynomorphs (Fig.2 and Tables 1—8). Palynomorph Kuqaia, which was recorded from the Lower Jurassic of western Hubei Province (Yang and Sun, 1987), the Tarim (Li,1993) and Junggar (Wang,2000) Basins in Xinjiang Uygur Autonomous Region, has been found commonly through the whole Lower Jurassic sequence in the Bohu Depression. Five species under the genus, nammely K. quadrata Li, K. concentrica Li, K. radiata Li, K. yangii sp. nov. and K. yanqiensis sp. nov., are herein identified. The megaspore compositions of the Badaowan and Sangonghe Formations are different. Nathorstisporites yanqiensis sp. nov. and Hughesisporites gibbosus (Reinhardt et Fricke) Kannegieser occur commonly in the Badaowan Formation only while Paxillitriletes phyllicus (Murray) Hall et Nicolson, Bacutriletes corynactis (Harris) Marcinkiewicz and Erlansonisporites sparassis (Murray) Potonié appear sparsely and restrictively in the Sangonghe Formation. They may be taken as index species for the formations respectively and bear importance of regional stratigraphical division and correlation in the prospecting practice. Three new species and one new combination are described as follows.