利用荧光光谱仪、等离子发射光谱,测定关中盆地卤阳湖区沉积物(0~280 cm)元素含量变化,在光释光定年与R型聚类分析基础上,探讨3万年来该区26种元素的地球化学行为特征及环境意义。结果表明:卤阳湖沉积物元素大致可分4类:第1类Si、Zr、Hf、Na,指示4.6ka B.P.后湖泊萎缩,外源沉积减少;第2类Ga、U、Sr,指示4.6ka B.P.和2.0ka B.P.前后的湖区干旱气候;第3类Cu、Hg、Mn、Mg,指示4.6 ka B.P.后湖水咸度的增加;第4类Ti、Sb、Pb、V、Th、Co、Fe、Bi、Cs、Zn、Ni、Rb、Ga、K、Al,这15种元素指示湖水咸度与周边人为活动的增加。元素变化特征说明,卤阳湖在33~10.4 ka B.P.之间,沉积环境稳定,全新世前期(10.4~4.6ka B.P.)湖水变淡,4.6ka B.P.后,外源沉积减少,湖水咸度升高,在2.0ka B.P.前后,湖泊干旱造成大量盐分生成,之后,虽气候转湿,但人为活动增加使湖泊快速走向衰亡。
英文摘要:
The characteristics of 26 geochemical elements and their environmental implications in Luyang Lake sediments(0~280 cm)for the last 30,000 years in Guanzhong basin were discussed based on the element contents determinated by fluorescence spectrometer and plasma emission spectrometry,the OSL dating results and the Rtype cluster analysis.Results showed the geochemical elements in Luyang Lake sediments could be divided into four categories:The first include Si,Zr,Hf,Na,indicating the decreased exogenetic clastics and the lake shrink after 4.6ka B.P.,the second included Ga,U,Sr,indicating the arid climate at 4.6ka B.P.and 2.0ka B.P.,the third included Cu,Hg,Mn,Mg,indicating the increasing lake salty since 4.6ka B.P.,the fourth contained 15 elements,Ti,Sb,Pb,V,Th,Co,Fe,Bi,Cs,Zn,Ni,Rb, Ga,K,Al,indicating the increasing lake salinity and the human activities around the lake.Different behaviors of geochemical elements in Luyang Lake indicated the sedimentary environment in Luyang Lake was stable between 33ka B.P.and 10.4 ka B.P.,then the lake salinity decreased in the early Holocene(10.4~4.6ka B.P.)while increased after 4.6ka B.P.accompanying with the reduced exogenetic clastics.The drying process at 2.0ka B.P.caused a lot of salt formation,then the climate turned relatively wet,however, the increasing human activities accelerated the lake disappearance.