摘要：

济阳坳陷车镇凹陷古近系沙河街组发现的Macaronichnus segregatis(分离通心粉管迹)是一种直到微弯曲形状的层内进食潜穴，个体较小，不分枝，长一般7～8 mm，直径1～3 mm，与前人发现的化石在个体大小上存在着差异。它主要出现于四类环境：①三角洲平原河道间低地，②三角洲、扇三角洲前缘远端砂坝和浊积扇的中扇到外扇，③潮湿气候条件下的浅湖，④周期性干旱气候条件下的滨浅湖。不同沉积环境中产出的Msegregatis都分布于粉砂质泥岩中。通过分析各沉积环境的水动力条件和水体化学性质以及Msegregatis的形成过程，可得出以下结论：①Msegregatis出现的水动力条件中等，水体能量过高或过低，都不适宜其生成；②Msegregatis出现的水体化学性质介于贫氧与富氧之间；③Msegregatis是在沉积物沉积后还未固结时由食沉积物生物活动造成的，衬壁的出现反映了软基底性质。

Abstract:

Macaronichnus segregatis in the Shahejie Formation of Paleogene in Chezhen Sag of Jiyang Depression is an intrastratal and irregularly meandering burrow structureIt is 7～8 mm in length and 1～3 mm in diameter，which is different in size from the same genus formerly discoveredThe ichnotaxon is commonly distinguished from several sedimentary environments：①places between channels of delta plain; ②delta，fan delta front bar and middle to outer fan of turbidite fan; ③shallow lake under humid climate；and ④shore to shallow lake sediments under periodically arid climateThey are generally found in silty mudstone deposited in different environmentsBased on the analyzed results of the hydrodynamic conditions,the chemical characters in different sedimentary environments and the forming process of Macaronichnus segregatis，some conclusions can be drawn as following: ① Msegregatis occurs in moderate water energy environments，and rather high or low water energy is not suitable for its existence；② The burrowmaker of Msegregatis lives among the upper dysoxic zone；③ Msegregatis is produced by depositfeeder before the substrate becomes firm，implied by the presence of linings surrounding the trace fossils