末次盛冰期和全新世大暖期湖光岩玛珥湖沉积记录的正构烷烃和单体稳定碳同位素分布特征及其古植被意义  

VARIATIONS OF n-ALKANES AND COMPOUND-SPECIFIC CARBON ISOTOPES IN SEDIMENT FROM HUGUANGYAN MAAR LAKE DURING THE LAST GLACIAL MAXIMUM AND HOLOCENE OPTIMUM:IMPLICATIONS FOR PALEOVEGETATION

作　　者：匡欢传[1,2] 周浩达[2] 胡建芳[2] 杨小强[3] 彭平安[2] 杨浩[1] 

机构地区：[1]南京师范大学地理科学学院,江苏省环境演变与生态建设重点实验室,南京210023 [2]中国科学院广州地球化学研究所有机地球化学国家重点实验室,广州510640 [3]中山大学地球科学系,广州510275

出　　处：《第四纪研究》2013年第6期1222-1233,共12页Quaternary Sciences

基　　金：中国科学院战略性先导科技专项项目(批准号:XDA05120103);国家自然科学基金项目(批准号:41072264和40930106)共同资助

摘　　要：通过对湖光岩玛珥湖钻孔沉积物中正构烷烃的分析以及高碳数正构烷烃单体化合物稳定碳同位素(δ^(13)C)的测定,重点探讨末次盛冰期和全新世大暖期湖光岩玛珥湖古植被状况及相关的古气候特点。结果显示:沉积物中正构烷烃整体呈现以高碳数为主的组成特征,在nC_(25)~nC_(33)范围内存在显著的奇碳优势。高碳数正构烷烃的分布特征表明在末次盛冰期湖光岩地区以草本植物为主,气候相对冷而干燥;全新世大暖期,木本植物减少,草本植物相对增多,气温较高且湿润,有利于草本植物发育。长链正构烷烃的δ^(13)C值揭示在21.1~5.5kaB.P.间,湖光岩地区陆地植被为C_3/C_4植物混合格局,但总体上以C_3植物为主。末次盛冰期,气候干旱,整体上以C_4植被为主;全新世大暖期,湖光岩地区陆地植被以C_3植物占主导,当时的气候温暖湿润,有利于C_3植物发育。Huguangyan Maar Lake （21 °09＇N, 110 ° 17＇E ） is located in the Leizhou Peninsula, South China. The natural vegetation of the Huguangyan area is tropical semi-evergreen seasonal rainforest. In order to investigate the paleovegetation in Huguangyan during the Last Glacial Maximum （LGM）and the Holocene Optimum, a sediment core （21 °08＇43.01＂N, 110°16°48.62＂E） with length ca. 22m was obtained during a drilling in 2011 from the lake, using a high-precision piston coring. The lithology is relatively uniform. The lithogogy is black mud, light black mud, gray black mud, dark gray black mud, gray mud, black mud and black volcanic tuff from the top of the core to the end. After drilling, core sediments were stored at 4℃ before sub-sampling. The chronology was established according to the 14C-AMS data of hand-picked terrestrial leaves from the core sediments, extending back to about 52kaB. P. The present study launches a full-scale investigation from 4. 1m to 8.8m of the core which covers approximately from 21. 1kaB. P. to 5.5kaB. P. Fifty samples were collected with lcm resolution to obtain a representative organic record of the present study profile. The molecular biomarkers including n-alkanes and n-alcohols were identified from the core sediments from the Huguangyan Maar Lake. The distribution of n-alkanes was mainly discussed in this paper. The compositions of n-alkanes are mainly consisted of long-chain n-alkanes, which is total amount of 7.1 - 34.5μg/g, it account for 39.4% to 63.2% of the n-alkanes. The individual concentration of nC27 ,nC29 and nC3~ ,as well as nC33 is 0.91μg/g to 5.81.zg/g,1.7μg/g to 9.71μg/g,2.91.zg/g to 11.01μg/g and 1.71μg/g to 12.9μg/g, respectively. The n-alkanes exhibit strong odd-over-even predominance between nC25 and nC33, suggesting that the n-alkanes in the lake sediments were mainly derived from terrestrial higher plants. The average chain length （ACL）of n-alkanes increased and the ratios of n-alkanes （C27 ＋C29 ）/2C31 decreased during the

关 键 词：湖光岩玛珥湖 正构烷烃 碳同位素 古植被 

分 类 号：P593[天文地球—地球化学] P941.78[天文地球—地质学]