新疆巴楚地区中上奥陶统生物礁群落古生态学

Paleoecology of Middle-Upper Ordovician Reefal Community in Bachu,Xinjiang,Northwestern China

新疆巴楚东部地区良里塔格山出露有中奥陶统达瑞威尔阶一间房组和上奥陶统中部凯迪阶良里塔格组的生物礁。一间房组礁的厚度为数米到十多米,以棘屑滩为礁基,主要造礁生物为托盘类,形成典型的骨架岩,托盘类中央腔形成的原生孔隙发育,基质为灰泥,纹层状、皮壳状的藻类缠结包裹托盘类生长,可定为皮壳状藻-托盘类密群落。良里塔格组的礁体主要由分枝状绿藻形成骨架岩,基质为灰泥,原有的原生或次生孔隙现被亮晶方解石充填;该组下部一些直径约1m的小型礁由丰富的分枝状绿藻和少量乳孔藻构成,为分枝状绿藻密群落。良里塔格组上部较大的礁体(直径10～30m)由分枝状绿藻和一种未知的球状生物(可能也是绿藻)构成,可称为"球状藻"-分枝状绿藻密群落。

At the Lianglitage Mountrain in the eastern Bachu area, Xinjiang, outcrops the Lianglitage reefs （Yijianfang Formation） of Middle Ordovician and Kaidi reefs （mid Lianglitage Formation） of Upper Ordovican. The former, about a few meters to a few tens meters in thickness, has echinoderm banks reefframe builders, which consists of receptaculitids and formed typical framestone. Primary porosities widely developed at the centre of receptaculitids, with lime mud as matrix. Lamniar or crustiform algae growing around receptaculitids can be defined as crustform algae-receptaculitids community. The reef-builders in the small mounds of Lianglitage Group comprise mainly branched dasycladales, with some large spherical dasycladales as secondary builders. Primary or secondary porosities were filled with sparry calcite. Small reef units usually less than 1 min diameter consists of abundant dasycladales and minor Epimastopora, forming so called the branched dasycladales community. But the bigger reef （with a diameter ranging from 10 to 30 m） of Upper Lianglitage Group often consists fo branched dasycladales and a unknown small spherical organism （probably dasycladale）, constituting a so called spherical algae a kind of branched dasycladale community.