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通过有机碳同位素(δ~(13)C_(crg)),磁化率和粒度的测定和分析,结合光释光年龄标定,对新疆巴里坤湖区滨湖相沉积物14ka B.P.以来δ~(13)C_(crg)值变化的影响因素及其反映的气候特征进行了研究。结果表明:在巴里坤湖区植被类型主要以C_3植被为主,干湿变化是导致δ~(13)C_(crg)值波动的主要因素,在末次冰消期至早全新世阶段(14.0~8.4ka B.P.),巴里坤湖区周围冰川尚未融化,剖面δ~(13)C_(crg)值最为偏正,在-22‰到-21‰之间变化,暗示剖面处在干-旱的气候条件下;进入全新世后,随着巴里坤山冰川的融化,湖区湿度增加,同位素值持续偏负,达到23.5‰,同时中值粒径和磁化率同步降低;在中全新世阶段(7.2~5.0ka B.P.)出现高湖面,同位素值达到-24‰左右,为剖面同位素值最低阶段;中晚全新世阶段(5.0~1.5ka B.P.)δ~(13)C_(crg)值开始逐渐偏正,表明气候开始变干;1.5ka B.P.至今的δ~(13)C_(crg)值则是在-24‰~-23‰间频繁波动,反映了该时段气候的不稳定性。
Through the determination and analysis of the magnetic carbon isotope (δ ~ (13) C_ (crg)), magnetic susceptibility and particle size, combined with the photoluminescence age calibration, the δ ~ (13) values of the lacustrine facies sediments in the Barkol Lake area of Xinjiang since 14ka BP, The influencing factors of C_ (crg) value changes and the climatic characteristics are also studied. The results showed that the main vegetation types in Barkol Lake were mainly C 3 vegetation, and the main factors that caused the fluctuation of δ 13 C crg values were the dry-wet changes. From the last ice age to the Early Holocene (14.0 ~ 8.4 ka BP). The glaciers around the Barkhun Lake area have not yet melted. The δ13Crg value of the section is the most positive and varies between -22 ‰ and -21 ‰, suggesting that the section is under dry-drought conditions After the Holocene, with the melting of the Balikuen glacier, the wetness of the lake area increased and the isotope value continued to be negative, reaching 23.5 ‰. Meanwhile, the median diameter and magnetic susceptibility decreased synchronously. During the middle Holocene (7.2 ~ 5.0 ka BP) appeared on the high lake, and the isotopic value reached -24 ‰, which was the lowest stage of isotopic value of the profile. The value of δ ~ (13) C_ (cr) began to become more positive in the mid-late Holocene (5.0 ~ 1.5ka BP) Began to dry out. The δ ~ (13) C crg value of 1.5ka BP fluctuated frequently from -24 ‰ to -23 ‰, which reflected the instability of climate during this period.