四川龙门山地区下泥盆统平驿铺组的遗迹化石

ICHNOCOENOSIS OF THE LOWER DEVONIAN PINGYIPU FORMATION , LONGMEN MOUNTAIN , SICHUAN

四川龙门山甘溪剖面下泥盆统平驿铺组的滨浅海相地层中赋存无脊椎动物遗迹化石,可识别出居住迹、停息迹、觅食迹3大类,鉴定为11属,包括Arenicolites,Chondrites,Cylindrichnus,Diplocraterion,Palaeophycus,Planolites,Phycodes,Rhizocorallium,Rusophycus,Skolithos和Thalassinoides。根据遗迹化石特征及其沉积环境,可识别出5个遗迹组合:1)Planolites-Palaeophycus遗迹组合,主要由觅食迹组成,指示低能的砂质近滨环境;2)Rusophycus-Phycodes遗迹组合,主要是觅食迹和停息迹,形成于低能的近滨环境;3)Chondrites-Palaeophycus遗迹组合,主要是居住迹和觅食迹,反映了贫氧低能的近滨下部环境;4)Skolithos-Cylindrichnus遗迹组合,主要由居住迹组成,形成于高能的前滨环境;5)Skolithos-Diplocraterion遗迹组合,主要为居住迹和觅食迹组合,反映了低能、食物丰富的近滨上部环境。

The littoral-neritic sediments of Lower Devo- nian Pingyipu Formation in the Ganxi Section are enriched with ichnocoenosis, which consists of at least 11 ichnogenera of Arenicolites, Chondrites, Cylindrichnus, Diplocraterion, Palaeophycus, Planolites, Phycodes, Rhizocorallium, Rusophycus, Skolithos, Thalassinoides. The ichnocoenoses represent types of domichnia, fodiniehnia and cubichnia. Five ichnocoenoses under different sedi- mentary environments have been recognized as follows： 1） Planolites-Palaeophycus ichnocoenosis mainly consists of fodinichnia from a lower-energy zone of nearshore ; 2）Rusophycus-Phycodes ichnocoenosis mainly consists of fodinichnia and cubich- nia generated in lower-energy zone of nearshore; 3） Chondrites-Palaeophycus ichnocoenosis mainly consists of domichnia and fodinichnia as indicator of the lower-energy and suboxic conditions of lower nearshore; 4） Skolithos-Cylindrichnus ichnoco- enosis is characterized by dwelling burrows from higher-energy foreshore ; 5） Skolithos-Diplocraterion ichnocoenosis, including dwelling and feeding burrows formed in lower-energy zones of upper nearshore enriched with food.