长江口及邻近海域现代生物扰动构造定量表征及影响因素

生物扰动构造是表征海底环境状态的重要指标，是古沉积环境重建的主要依据，且它影响沉积物早期成岩作用以及物质的再分配，成为百年尺度沉积记录解读的干扰因素。本文基于长江口及其邻近海域的21个站位的沉积物岩心，利用高分辨X射线计算机断层扫描技术，通过matlab的数据处理，定性和定量表征了该区生物扰动构造，分析了影响生物扰动构造的主要因素。研究表明：长江口及邻近海域生物扰动构造较为发育，从功能上划分为生物扩散构造、运输构造、交换构造和廓道扩散构造4种类型，运输构造和廓道扩散构造常见；生物扰动构造在岩心中分布形式多样，包括指数衰减型、波动衰减型、均匀分布型、脉冲分布型等垂向分布形式；扰动深度深浅不一，多数在20 cm以内，但也有超过40 cm者；生物扰动构造空间上不均一，长江口及内陆架较发育，扰动构造体积在0～13 972 mm³之间，而苏北沿岸、中陆架则较少，扰动构造体积在351～3 212 mm³之间，从岸向外生物扰动构造有减少趋势。生物扰动构造发育程度主要受底质类型、沉积速率制约，黏土质粉砂以及适宜的沉积速率（0.52～1.34 cm/a）有利于生物扰动构造发育和保存。

Quantitative characterization and influencing factors of modern bioturbation structure in the Changjiang River Estuary and its adjacent areas

The bioturbation structure is an important indicator of the state of the seabed environment and the main basis for the reconstruction of the paleosedimentary environment; moreover, it affects the early diagenesis of sediments and the redistribution of materials, and becomes the interference factor for the interpretation of the 100-year scale sedimentary records. In this article, sediment cores from 21 stations in the Changjiang River Estuary and its adjacent areas were characterized qualitatively and quantitatively by using high-resolution X-ray computed tomography technology, and the main factors affecting the bioturbation structures were analyzed. The result shows that the bioturbation structures in the Changjiang River Estuary and its adjacent areas are relatively developed, which can be divided into four types: biodiffusor structures, conveyor structures, regenerator structures and gallery-diffusor structures. Conveyor structures and gallery-diffusor structures are common. The bioturbation structure is distributed in various forms in the core, including exponential attenuation type, wave attenuation type, uniform distribution type, pulse distribution type and other vertical distribution forms. The depth of disturbance varies, most of which are within 20 cm, but some are more than 40 cm. The bioturbation structures are spatially uneven. The Changjiang River Estuary and the inner shelf are relatively developed, with a disturbance inventory of 0–13 972 mm3, while the northern Jiangsu coast and the middle continental shelf are less, with a disturbance inventory of 351–3 212 mm3. The bioturbation structures from the coast to the outside have a decreasing trend. The development degree of bioturbation structure is mainly restricted by the type of bottom material and sedimentation rate. Clay silt and suitable sedimentation rate (0.52–1.34 cm/a) are conducive to the development and preservation of bioturbation structures.