陕西富平上奥陶统遗迹化石及其环境意义

Trace Fossils and Sedimentary Environments of Upper Ordovician of Fuping in Shaanxi,China

在陕西省富平县上奥陶统赵老峪组发现遗迹化石17属25种（未定种8个）.建立归属于Nereites遗迹相的Lophoctenium-Protopaleodictyon遗迹组合.该组合遗迹以觅食迹占绝对优势,形态以分枝迹为主,分异度较高.此类特征反映出遗迹形成于海水较深且较为宁静的低能环境,推测形成时的海水深度大约在200-1500 m之间,为半深海深海斜坡环境.沉积底质的溶解氧含量相对较高,不是典型的缺氧地层.

At least 17 ichnogeneras and 25 inchnospecies have been found in the Zhaolaoyu formation （Upper Ordovician） of Fuping in Shaanxi, China. It is established that Lopkoctenium- Protopaleodictyon ichnofossil assemblage belongs to Nereites ichnofacie proposed by Seilacher which is predominant in ethology of fodinichnia, shape of ramification and the high differentiation. This assemblage represents quiet lower energy sedimentary environments, once a bathyal-abyssal area at the depths between 200-1 500 m below sea level where turbidity currents could flow. This assemblage indicates the substrate is of relative high dissolved oxygen content instead of being typical oxygen-depleted.