陆地生态系统演替过程中的磁性矿物响应——以粤西小良水土保持观测站为例  

MAGNETIC MINERAL RESPONSE TO THE SUCCESSION OF ECOSYSTEM——XIAOLIANG SOIL AND WATER CONSERVATION STATION,GUANGDONG PROVINCE AS A SAMPLE

作　　者：杨小强[1] 周文娟[1] 阳杰[1] 

机构地区：[1]中山大学地球科学系

出　　处：《第四纪研究》2007年第6期1121-1128,共8页Quaternary Sciences

基　　金：广东省自然科学基金项目(批准号:031602);国家自然科学基金重点项目(批准号:40331009)资助

摘　　要：位于广东茂名的小良水土观测站因同时保持了人类活动破坏生态后的光板地区域和在光板地上人工恢复生态的区域,而成为联合国"人与生物圈"考察点和"中国科学院水土保持实验推广站"。文章通过对源于同一花岗岩的风化壳生态恢复剖面MX-1和光板地剖面MX-2进行系统的环境磁学研究,揭示出两个剖面磁性矿物类型有显著差别。MX-1剖面亚铁磁性矿物,如磁赤铁矿、磁铁矿控制了剖面的磁性特征,它们浓度与粒度的变化很好的指示了风化壳的结构;MX-1剖面磁性矿物粒度的变化反映了成土作用强度对磁性矿物形成的控制作用;MX-1剖面的磁组构特征也反映了风化壳发育过程中不同层位体积变化与矿物形成的情况。MX-2剖面的磁性矿物则以反铁磁性矿物,如赤铁矿、针铁矿为主。两剖面磁性矿物类型的差别,显示在湿热气候条件下,生物风化作用与化学风化作用的共同参与,对磁性矿物的转变具有明显的促进作用。Xiaoliang Soil and Water Conservation Station, the observation station of human and biosphere of the United Nation and the popularizing station of soil ＆ water conservation of CAS located at the Maoming City of Guangdong Province of South China, preserves two kinds of area on the weathering crust of the same granite： the bare ground with its ecosystem destroyed by human activities, and the artificially ecosystem-resumed area on original bare ground. Profiles MX-1 （ca. 5.35m in depth）and MX-2 （ca. 2.65m in depth）were excavated on the ecosystemresumed area and the bare ground respectively to study the response of magnetic characteristics to the succession of ecosystem. The results show that magnetic minerals from two profiles are different in type and grain size. The magnetic properties of MX-1 are dominated by ferromagnetic, such as maghemite and magnetite. Their variations of concentration and grain-size can denote the structure of weathering crust, e. g., the grain-size of magnetic minerals can reflect the intensity of soil-forming. The fabric of susceptibility of MX-1 also suggests the volumetric changes and the forming of minerals in weathering process in different layers. Different from MX-1, the canted antiferromagnetic minerals, such as hematite and goethite, play an important role in the contribution to magnetic properties in MX-2 profile, and its anisotropy of susceptibility inherited mainly from the parent rock. The difference of magnetic minerals in two profiles confirms that the combined effort of bio-weathering and chemical weathering can obviously enhance the transition of magnetic minerals under humid and torrid climate.

关 键 词：小良观测站 磁性矿物 生态系统 环境磁学 

分 类 号：P318.4[天文地球—固体地球物理学]