摘要
通过对湖北省郧西县庹家湾黄土剖面的色度参数分析,并结合磁化率、粒度、铷锶比(Rb/Sr)指标揭示汉江上游地区风成黄土的色度特征及其与气候变化的关系。应用X-rite VS450型分光测色仪对庹家湾黄土剖面色度参数进行了测量。结果表明:庹家湾黄土剖面红度a*的变化与沉积物氧化铁含量呈显著正相关,平均值由高到低依次为S0(6.34)>MS(5.52)>Lt(5.18)>L0(4.98)>L1(4.82)>T1-al2(3.66);亮度L*的变化与氧化铁含量和有机质含量均呈负相关,其中氧化铁含量对L*的影响更大,L*在黄土层出现了峰值;色调角h*在古土壤层呈现低值(68.64°),黄土层呈现高值,a*/b*与h*特征相反,在古土壤呈现高值(0.39),黄土层呈现低值;其中在马兰黄土L1中存在两层弱古土壤层L1-S2、L1-S1,其色度参数特征较L1具有较高的a*值和a*/b*值及较低的L*值和h*。黄度b*指示该区域气候变化有一定的局限性,h*、a*/b*、L*和a*均可作为良好的气候替代指标,a*值和a*/b*值越大指示气候越暖湿,成壤作用越强,L*值和h*越大指示气候越冷干,成壤作用越弱。h*、a*/b*、L*和a*共同记录了该地区晚更新世以来气候经历了晚更新世末期的干冷、全新世早期逐渐回暖、全新世中期的温暖湿润、全新世晚期气候逐渐干冷,在马兰黄土形成时期,气候出现了短暂的温暖湿润期(27.3~21.6ka B.P.)。
Through integrated analysis of the chroma parameters, magnetic susceptibility, grain size and Rb/ Sr ratio of the Tuojiawan loess-paleosol profile in Yunxi County, the correlation between the features of chroma parameters and palaeoclimatic change in the upper reaches of Hanjiang River was revealed. The results showed that： a＊ was strongly positively correlated with the content of iron oxide, and the average value of a＊ was significantly different between loess and paleosol layers, and followed the order of So （6.34） 〉 MS （5.52） 〉 Lt （5.18） 〉 L0 （4.98） 〉 L1 （4.82） 〉 T1- at2 （3.66 ）. L ＊ was negatively correlated with the content of iron oxide and organic matter, with iron oxide having a greater effect on L＊ , which reached the peak in the loess layers, h＊ was the lowest （68.64-）in the paleosol layers, but was high in the loess layers. In contrast, a＂/b＊ was high in the paleosol layers （0.39）, but was low in the loess layers. In Malan Loess, there were two weak paleosol layers, i.e. L1 --Sz and L1 --$1, which showed higher a＊ and a＂/b＊ , but lower L＊ and h＊ than Malan Loess. h＊ , a＊/b , L＊ and a＊ could be used as good indicators of climatic change. A high a＂ and a＊/b＊ , or a low L＂ and h＊ indicated that the climate was warm and wet, and the pedogenesis was strong. In conclusion, h＊ , a＊/b＊ , L＊ and a＊ together recorded the climatic evolution since the late Pleistocene. the climatic was cold and dry during the late Pleistocene, but a short warm and wet period happened in the glacial period （27.3--21.6 ka B. P. ）, then the climatic gradually became warm and humid during the early-mid Holocene. However, cold and dry climate appeared again since the late Holocene in the region.
出处
《水土保持学报》
CSCD
北大核心
2017年第2期151-156,共6页
Journal of Soil and Water Conservation
基金
国家自然科学基金项目(42171108,41371029,41471071)
国家社会科学基金项目(14BZS070)
中央高校基本科研项目(GK201601006)
关键词
色度
黄土剖面
气候重建
庹家湾
chroma
loess-paleosol profile
paleoclimatic reconstruction
Tuojiawan
