过去5万年来珠江流域火历史的南海沉积记录  

FIRE HISTORY IN PEARL RIVER BASIN SINCE 50 kaBP:SEDIMENT RECORDS FROM THE SOUTH CHINA SEA

作　　者：裴文强[1,2] 万世明[1] 谭扬[3] 瞿成利[3] 殷学博[1] 李安春[1] 

机构地区：[1]中国科学院海洋研究所中国科学院海洋地质与环境重点实验室,青岛266071 [2]中国科学院大学,北京100049 [3]中国科学院烟台海岸带研究所,烟台264003

出　　处：《海洋地质与第四纪地质》2017年第3期47-57,共11页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金项目(41576034);亚洲大陆边缘"源-汇"过程与陆海相互作用项目(GASI-GEOGE-03)

摘　　要：黑碳作为燃烧产生的一种独特颗粒态含碳物质,广泛存在于土壤、沉积物、大气乃至极地冰雪中,因其物理化学性质高度稳定而常被用来恢复其源区火的历史。南海西北部陆架K6-2孔岩心沉积物的黏土矿物和常微量元素组成分析表明,其细粒级陆源组分主要来自珠江,推测由广东沿岸流携带而来,从而岩心黑碳含量可以用来重建珠江流域火的演化历史。结果表明:(1)约47~27kaBP,该时期火活动较频繁,但约35kaBP之后有降低趋势;(2)约13~6kaBP:火活动逐渐增多,尤其在11~6kaBP火活动十分频繁;(3)约6~4kaBP,火活动强度整体较之前减弱。与温度、降水等气候指标对比发现,末次冰期以来珠江流域火活动强度明显受气候控制,即在温暖时期火发生较频繁,反之则较弱。进一步分析认为,升温是促进该地区火发生的主要因素,而降水的增多则可能对火起抑制作用。所以,在全球变暖背景下,推测珠江流域火活动将会趋于频繁。而自4kaBP以来,人类活动(毁林开荒、刀耕火种、冶炼金属、战争等)的加强可能是导致珠江流域火灾频发的主因。Black carbon（BC）, a special kind of charted materials, is the product of incomplete combustion, which can be found in soils, sediments, atmosphere and ice cores. Due to its physical and chemical inertness, BC is often used as a proxy for wildfires reconstruction. Here we present a combined analysis of clay minerals, major and trace elements, black carbon content and isotopes of sediments from core K6-2 on the inner continental shelf of the northwestern South China Sea in order to constrain the sediment source and further reconstruct the fire history of South China. Clay mineral assemblages and trace elements composition suggest that the fine-grained silicate fractions of the sediment are mainly derived from Pearl River by the Guangdong offshore current. Therefore, BC of core K6-2 can be used to reconstruct fire history around the Pearl River Basin. From this study, we draw the following conclusions. （1） 47-27 kaBP. fire activi- ties were relatively high, but showed a decrease trend since 35 kaBP. （2）13-6 kaBP. fire activities were almost the highest except for some particular phases. （3） 6-4 kaBP., fire activities weakened than before. In general, there were more fires when climate was warmer and wetter, and less fires when climate became colder and drier,suggesting the dominant control of climate on fire dynamics since 50 kaBP. Further study indicates that an increase in temperature can always promote fires while an increase in precipitation may reduce fires. So fire activities around the region may be more frequent with global warming. However, intensified human activities such as deforestation for farmland, slash-and-burn cultivation, metal smelting and wars may play important roles in increasing fire activities since 4 kaBP.

关 键 词：物源 黑碳 珠江流域 火历史 末次冰期 南海 

分 类 号：P534.63[天文地球—第四纪地质学]