东北地区五大连池湖相沉积物正构烷烃和单体碳同位素特征及其古植被意义  

CHEMICAL AND COMPOUND-SPECIFIC CARBON ISOTOPIC CHARACTERISTICS OF n-ALKANES IN THE QINGSHI LACUSTRINE SEDIMENTS, WUDALIANCHI, NORTHEAST CHINA, AND THEIR PALEOVEGETATION SIGNIFICANCES

作　　者：汪亘[1,2] 王永莉[1] 孟培[1,2] 王自翔[1,2] 孙则朋 杨辉[1] 巩俊成[1] 张虹[1] 吴应琴[1] 

机构地区：[1]甘肃省油气资源研究重点实验室(中国科学院地质与地球物理研究所油气资源研究中心)/中国科学院油气资源研究重点实验室,兰州730000 [2]中国科学院大学,北京100049

出　　处：《第四纪研究》2015年第4期890-900,共11页Quaternary Sciences

基　　金：中国科学院战略性先导科技专项项目（批准号：XDA05120204和XDB03020405）、国家自然科学基金面上项目（41172169,41272147和40672123）、“西部之光”联合学者项目、甘肃省重点实验室专项项目（批准号：1309RTSA041）和教育部科学技术研究重大项目（批准号：311010）共同资助

摘　　要：对中国东北地区小兴安岭与松嫩平原过渡带五大连池青石钻孔湖相沉积物进行了有机地球化学分析,检测出丰富的正构烷烃生物标志化合物.本文主要讨论了正构烷烃的分布及其单体碳同位素组成特征.正构烷烃具有前峰型和双峰型两种分布特征,表明其有机质为混合来源,包括低等菌藻类生物和陆生高等植物输入.正构烷烃的分布特征表明,自35.2ka B.P.以来,nC27/nC31和ACL指标共同记录了东北地区小兴安岭与松嫩平原过渡带的植被以草本为主.对C27、C29和C31长链正构烷烃进行了单体碳同位素测定,并利用二元模式估算了C3和C4植物相对生物量,结果表明,自35.2ka B.P.以来,研究区的植被以C3植物为主.期间在典型冷暖气候事件中,受温度变化的影响,C3/C4植物的相对生物量有明显的变化,在全新世大暖期（6.0ka B.P.）,受温度升高影响,C3植物的生物量显著减少,C4植物的生物量则明显增加;而在两次典型冷气候事件（中全新世降温事件8.2ka B.P.和新仙女木事件12.9ka B.P.）时期,受温度降低影响,C3植物的生物量有增加的趋势,C4植物的生物量则相对呈减少的趋势;在末次冰盛期21.0ka B.P.时,受明显低温特征的影响,C3植物生物量高达80.0％,这可能是当时低温的气候特征抑制了C4植物的生长.研究结果对探索我国东北地区C3/C4植物分布格局,并为评估未来气候演化对该地区植被格局和农业生产的影响提供科学依据.Wudalianchi is located in the transition zone of the Lesser Khingan Range and Songnen Plain, Heilongjiang Province, Northeast China. In order to investigate the paleovegetation in Wudalianchi during the typical warm and cool weather events, a 300cm-long core called Qingshi Core （48°37＇8.66″N, 126°7＇25.9″E） was obtained during a drill in 2012. The lithology is relatively uniform. The lithology is mainly lacustrine clay. After drilling, core sediments were stored at δ13C before sub-sampling. The chronology was established according to the AMS-~4C data of the sediments, extending back to about 35.2ka B.P. 29 samples were collected to obtain a representative organic record of the present study profile. The molecular biomarkers including n-alkanes were identified from the sediments of Qingshi Core. The distribution of n-alkanes and composition of δ13C values were mainly discussed in this paper. According to the two distribution patterns of n-alkanes, the n-alkanes exhibited mixed sources, both the import of the algae and fungi and the terrestrial higher plants. The distribution of n-alkanes indicated that from 35.2ka B.P. to the present, the vegetation types in the study area are mainly grasses from the indexes of nC27/nC31 and ACL25-31. In addition, the compound-specific carbon isotopic composition was determined for C27, C29 and C31 n-alkanes in the core, ranging from -27.3‰-33.6,-28.8‰--34.3‰ and -29.5‰--34.3‰, respectively. Relative contribution of C3 and C4 plants was estimated by using a binary model, indicating that from 35.2ka B.P., C3 plants was dominated in the study area. The relative biomass of C3/C4 plants varied obviously in the typical warm and cool weather events influenced by the temperature. While during the Holocene Megathermal （ 6.0ka B.P.）, controlled by the high temperature, the biomass of C4 plants increased （from 18.6% to 43.1% ） while that of C3 plants decreased （from 81.4% to 56.9%）. After the typical events of cold weather （the cooling event of the M

关 键 词：湖相沉积物 正构烷烃 单体碳同位素 古植被意义 五大连池 东北地区 

分 类 号：P941.78[天文地球—自然地理学] P593