ADVANCES IN RADIOCARBON DATING RESEARCHES IN THE LOESS-PALEOSOL SEQUENCES
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摘要: 14C年龄的可靠性在于测年物质的可靠。木质样品被认为是最可靠的测年物质,但在黄土序列中不易发现。最常用的测年物质是有机质,其含量低于2%,并受到农业施肥和现代植物根系渗透的影响,造成14C年龄偏年轻,本实验室采用新的前处理法能有效地分离年轻污染物。在稳定沉积的古土壤中,孢粉可作为可靠的测年物质。黄土中的蜗牛吸收了不同放射性比度的14C,如果用于测年能影响年龄的准确性,通常挑选蜗牛文石进行测年。加速器质谱测年技术的运用使得黄土序列14C年代研究更快捷、更灵敏,但研究重点仍集中在可靠测年物质的选择和提取方法上。Abstract: The reliability of radiocarbon dating depends on the reliability of dating material. The wood material is considered most reliable for dating,but it isn't easy to get in the loess-paleosol sequence.Commonly dated material is organic matter, with the amount less than 2% in the sequence and affected by modern plant rootlets and agriculture,making younger 14C ages of all the organic materials but our laboratory can efficiently isolate young organic matter by adopting new pretreatment method. Our study shows that pollen may be a better material for dating paleosol in the condition that pollen was deposited simultaneously with sediment in the stable sedimentary environment.From a loess profile sequence dating terrestrial shells that may absorb different 14C concentrations from around environment will result in dates with low precision, and thus the shells with aragonite are generally chosen for dating. Combining the reliable dating material based on correct pretreatment with AMS method, we can acquire high resolution and reliable dating.
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Keywords:
- loess /
- dating /
- wood material /
- pollen /
- shell aragonite
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