摘要
对岱海西南部湖滨地区（40°32．127′N，112°37．802′E）钻取的一根长79．16m的高取芯率（98．8％）沉积岩芯（DH06A）进行了高分辨率的湖泊沉积物磁学性质测量。对U型槽法和常规散样方法得到的磁化率和非磁滞剩余磁化强度测量结果进行了系统的比较。U型槽法得到的低场体积磁化率（κlf）变化范围为1．09×10^-5-283．00×10^-5SI，常规散样法得到的κlf变化范围是2．23×10^-5～319．37×10^-5SI；U型槽法得到的非磁滞剩余磁化强度（ARM）的变化范围为0～33．33×10^-3A／m，常规散样法得到的ARM值变化范围是0～1070×10^-3A／m。尽管两种方法获得的κlf和ARM在数值上存在差别，其随深度的变化却显示出相同的趋势，Spearman相关系数分别达0．873和0．834，表明两种方法具有很好的相关性和可比性。对高分辨率的湖泊长岩芯磁学研究而言，U型槽法较常规散样法具有可靠、高效、便捷的特点，是一种具有广泛应用前景的磁性测量方法。磁化率对比研究表明，用常规散样法获得的质量频率磁化率（χfd）能够更为敏感地揭示次一级的高频波动特征，而百分比频率磁化率（χfd％）主要集中在1％～5％范围内，其变化趋势与其他磁化率参数变化趋势有明显差异，其原因尚需进一步研究。
High-resolution magnetic measurement on lake sediments from arid and semi-arid regions is an important means of characterizing paleoenvironmental changes. Previous research has shown that the Daihai Lake, an inland graben-type basin in Inner Mongolia, China, contains rich information about the evolution of paleomonsoons. Here we present results of high-resolution magnetic measurements of the lake sediments from a 79.16m core（ DH06A ）, drilled at the southeast littoral area of the Daihai Lake（40°32. 127′N, 112°37.802′E）. We compared the magnetic susceptibility and anhysteretic remanent magnetization （ ARM ） that are obtained by both U-channel and discrete sample methods. Low-frequency magnetic susceptibility （χfd） from detailed U-channel measurements varies in the range of 1.09×10^-5 to 283.00×10^-5SI ,in contrast to 2.23×10^-5～319.37×10^-5SI SI for the conventional measurement on discrete cubic samples. The ARM value measured by U-channel and discrete sample methods ranges from 0 to 33.33×10^-3A/m and from 0 to 1070×10^-3A/m, respectively. Although the κlf and ARM obtained with these two methods differ in values, the similar trends of variations against depth and the high Spearman coefficients （0. 873 and 0. 834, respectively） suggest that these two methods are well correlated and comparable in general. For high-resolution long-core magnetic measurements, the U-channel method is a reliable,rapid, and efficient alternative to its discrete sample counterpart. Our comparative study on DH06A core magnetic susceptibility suggests that the mass-specific frequency-dependent susceptibility （χfd）is capable of sensitively depicting sub-order high frequency variations. In contrast, the percentage frequency-dependent susceptibility （χfd%） primarily falls in the range between 1% - 5%. Its trend differs significantly from other magnetic susceptibility parameters, the reason of which remains ambiguous and require further work.
出处
《第四纪研究》
CAS
CSCD
北大核心
2007年第6期983-988,共6页
Quaternary Sciences
基金
国家自然科学基金项目(批准号:90411017和49925307)资助
关键词
岱海
U型槽
磁化率
ARM
湖泊沉积物
Daihai Lake, U-channel, magnetic susceptibility parameters, ARM, lake sediments
