下珠江三角洲平原生物遗迹特征及对古环境的指示

Characteristics of the biogenic traces in the Lower Pearl River Delta Plain and their implication to paleoenvironment

  • 摘要: 下珠江三角洲平原受河流和海洋共同影响,生物种类繁多且对环境响应灵敏,在一定程度上反映了沉积环境特征。通过使用三维重构技术,对研究区内不同微环境中的生物遗迹组成进行了精细研究,对沉积环境中的盐度、粒度、浑浊度、TOC等因素进行了分析。结果如下:① 研究区内造迹生物有甲壳类动物螃蟹、环节动物沙蚕、双壳类动物河蚬、弹涂鱼以及鸟类等,其中甲壳类螃蟹和环节动物沙蚕为主要造迹生物。② 研究区内主要生物遗迹有双壳类动物河蚬的进食迹、居住迹,甲壳类动物螃蟹的居住迹和爬行迹,环节动物沙蚕的居住迹,弹涂鱼的居住迹和爬行迹等,垂向潜穴主要呈I型、L型、Y型和U型。③ 研究区内潜穴形态与ArenicolitesCylindrichnusDiplocraterionOphiomorphaPalaeophycusSkolithos等遗迹化石进行了类比分析,并与Skolithos遗迹相存在相似之处。研究了下珠江三角洲平原生物遗迹组成及分布特征,绘制了生物及遗迹分布图,确定了下珠江三角洲平原的遗迹学特征,为下三角洲古遗迹学和古沉积环境提供了现代实证。

     

    Abstract: Affected by both rivers and oceans, the Lower Pearl River Delta Plain has a wide variety of organisms and is sensitive to the environment, which reflects the characteristics of the sedimentary environment to some certain extent. By using three-dimensional reconstruction technology, the composition of biological traces in different microenvironments was studied n detail. The physic-chemical factors such as salinity, particle size, turbidity, and TOC in the biogenic traces were analyzed in the study area. Results are as follows. (1) The tracemakers in the study area included crustacean crabs, annelid Perinereis, bivalve river clams Corbicula fluminea, mudskippers Periophthalmus, and birds. Among them, the crabs and Perinereis were the main tracemakers. (2) The main biological traces in the study area included feeding and dwelling traces of Perinereis, dwelling and crawling traces of crabs, dwelling traces of Corbicula fluminea, dwelling and crawling traces of Periophthalmus, etc. The vertical burrows are mainly in I-, L-, Y- and U-shapes. (3) The burrow morphology in the study area was compared with the ichnofossils of Arenicolites, Cylindrichnus, Diplocraterion, Ophiomorpha, Palaeophycus, and Skolithos. They are analog with Skolithos ichnofacies. Meanwhile, the composition and distribution of the biogenic traces in the study areas were studied, and the distribution maps were analyzed. This study provided modern evidence for the sedimentological study in the Lower Pearl River Delta and implication to the identification of the ichnology and paleoenvironment in the ancient lower delta plain.

     

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