贵州中寒武世凯里生物群的生活环境及古生态系统

Living environment and palaeoecosystem of the Middle Cambrian Kaili Biota in Guizhou Province

以原地埋藏为主的中寒武世凯里生物群生活环境为远离古陆、盐分正常、透光性良好和含氧量充分的热带海洋;沉积环境为波浪基准面与风暴基准面之间、软性泥质基底、水体相对平静的正常浅海,深度在100 m以内,可能为一系列岛屿所组成的海湾边缘相。依据生物的主要生活和活动空间,可将凯里生物群分为水体上层群落、水体下层群落、底栖表生群落和底栖内生群落。这些生物群落依赖食物链将生态系统中的生物结成一个整体,其群落特征随海平面的变化而有所变化。热带频繁的风暴流或洋流等为生活于海湾边缘的凯里生物群的生长和繁殖提供了大量的营养物质和矿物质,同时由此产生的快速沉积事件是生物遗体得以较为完整保存的重要原因之一。

The Middle Cambrian Kaili Biota which were buried mainly in situ, lived in the tropical sea far away from the oldland with a normal salinity, good light transmission, oxygen-rich and low energy. The sedimentary environment of the Kaili Formation was a shallow sea between the fair-weather wave base and storm wave base, being less than 100 m in depth, with a quiet-water and muddy soft sea floor. It was a gulf margin facies which was made up of a series of islands away from the continent. The Kaili Biota, according to their living and moving spaces, can be divided into four biocommunities： surface water, bottom water, epibenthic and endobenthic communities. The characters of these communities can change with the changes of sea-level. Depending on the food chain, all organisms of the Kaili Biota congregated into an ecosystem. The tropical storm-currents or ocean-currents provide a large number of nutriments and minerals for the Kaili Biota, and the abrupt deposition event induced by the currents is an important factor to make this biota be preserved well.