摘要
在系统总结前人对植物钙质根管定义及形成机制的基础上,采用形态学方法对阿拉善沙漠26组不同形态的植物钙质根管进行了分类,初步统一了我国植物钙质根管的定义及其分类;通过统计阿拉善沙漠不同类型植物钙质根管在全新世的数量分布,探讨了其分布特征可能蕴含的古环境意义。结果表明,植物钙质根管是陆生植物形成的次生碳酸盐结壳,包括钙质根套、绕根结核、根模具、根导管和根状结核五种类型。其中钙质根套和绕根结核的形成受到植物生长及其根围微生物活动的影响,而根模具、根导管和根状结核的形成则不受上述作用的影响。据此将阿拉善沙漠植物钙质根管分为钙质根套和绕根结核两种类型。这两类植物钙质根管在不同时期的相对数量百分比能够指示植物钙质根管形成时期有效湿度的高低,绕根结核数量百分比较高能够指示较高的有效湿度,而钙质根套数量百分比较高则指示了较低的有效湿度。因此,从植物钙质根管中能够提取丰富的古环境信号,并将其运用于沙漠地区的古环境研究中。
The definition and classification ol calcareous root tubes which have been used in different studies are still unified. However, it remains uncertain that whether different definitions of calcareous root tubes indicated the same morphology or not. At the same time, there were disagreements over the formation mechanism and paleoenvironment significance of calcareous root tubes. Some research results suggested that the formation of calcareous root tubes in this area indicated relatively humid climate conditions, while others argued that they were formed by recrystallization of calcium carbonate required the presence of underground water. In this study, 26 calcareous root tubes samples collect-ed from the Alashan Desert are classified using morphological method, which was based on previous studies about the definition and formation mechanism of calcareous root tubes. Then the paleoenvironment significance for different types of calcareous root tubes was discussed. The results showed that calcareous root tubes were products of terricolous plants and were formed by encrustation of plant roots by secondary carbonates, including five subclasses, namely calcareous sheath, rhizocretion, root mould, root tubule, and root cast. Calcareous sheath and root tubule have hollow tubes in morphology, and then rhizocretion and root cast have structure of double layer cemented by calcium carbonate or solid construction filled with coarse gravel or sediment. Root mould is simply tubular voids left after roots decayed. Accord-ing to whether the formation process is under the influence of plant growth and rhizosphere microorganism activity or not, the formation process can be divided into two patterns. Calcareous sheath and rhizocretion were formed by the in-fluence of plant growth and rhizosphere microorganism activity, while the formation of root mould, root tubule, and root cast were not influenced by them. Thus, the classification of the above five subclasses can be distinguished by morphology character clearly. Results from n-alka
出处
《沉积学报》
CAS
CSCD
北大核心
2017年第1期75-84,共10页
Acta Sedimentologica Sinica
基金
国家自然科学基金项目(41301217)
美国国家地理项目(GEFC34-15)~~
关键词
阿拉善高原
植物钙质根管
钙质根套
绕根结核
次生碳酸盐
沙漠
Alashan Plateau
calcareous root tubes
calcareous sheath
rhizocretion
secondary carbonate
desert
