氨基酸分析结果与第四纪气候旋回

样品采自陕西洛川、新疆新源坎苏黄土-古土壤系列和新疆柴窝堡盆地CK-(?)钻孔湖相沉积物。氨基酸分析结果与氧同位素记录进行对比,发现古土壤及湖相沉积层位的氨基酸总量偏高并与氧同位素的奇数阶段相对应,反映较为温暖湿润的气候环境;反之,在黄土和洪积或冲洪积层位的氨基酸总量偏低并与氧同位素的偶数阶段相对应,反映相对干冷的气候环境。说明氨基酸总量在垂直剖面的变化,在一定程度上有间接指示古气候的意义。

QUATERNARY CLIMATE CYCLES AND AMINO ACIDS DATA

Organic geochemistry of amino acids has been investigated in an attempt to explore thechanges of environment since the Quaternary.As a recorder of climate fluctuation,the va-riation of total amount of amino acids in the sediments collected from Luochuan section inShaanxi Province,loess section of Xingyuankanshu and CK-l core of Chaiwopu basin in Xin-jiang Autonomous Region has been discussed.There are fourteen paleosols developed and interbedded beds of paleosol with loess inLuochuan section.By comparison of fluctuation in total amount of amino acids and oxygenisotope recordings in the loess-paleosol series,it has been found that the amino acids amountof paleosols in the beds of S₂—S₉ are in correspondence with odd stages of oxygen isotope,i.e.7—23,corresponding to warm interglacial periods in climate.It is also found that theamount of amino acids in L₂—L₉ loess beds are in correspondence with 6—22 even stages of oxy-gen isotope.The variation of amino acids amount with climate is also found to be in cor-respondence with variation of other indirect climate indicators and they are complementary toeach other.The amino acids amount,percentages of organic carbon and OEP value of n-alkane have been measured for samples of CK-l core in the Chaiwopu basin.Variations of the abovethree measures tend to be the same,i.e.four high values of them are found to be for the lacu-strine sediments,but the low values are for the pluvio-alluvial sediments.The odd stages ofoxygen isotope are in correspondence with lacustrine strata and the peaks in the curves ofamino acids amount,organic carbon percentages and n-alkane OEP,indicating warm and hu-mid climate during the period of lacustrine deposition.On the contrary,the even stages ofoxygen isotope are in correspondence with the pluvio-alluvial strata and values of the curvesof the above three measures,indicating relative arid and cool climate during the period ofpluvio-alluvial deposition.The periodic variation of the above measures have reflected thatthere had been four remarkable climatic alteration between cool-arid and warm-humid.