摘要
1796 2钻孔沉积物提供了南沙海区 3万年来古气候、古环境变化的高分辨沉积记录。通过对 314个柱状样沉积物进行有机分析 ,提取了相关的古环境信息 ,揭示出南沙海区末次冰期的古海洋环境及古气候是不稳定的 ,水生生物来源的生物标志物沉积通量在冰期出现了较大的波动 ,H3时出现了海洋生产力增大事件 ;陆源指标如高碳类脂物的沉积通量 ,既反映了陆源物对南沙海区海洋沉积的贡献 ,又揭示了造成末次冰期南沙海区陆源物质增高的古气候事件。高碳正烷烃、长链脂肪醇、长链脂肪酸的单体化合物碳同位素 δ1 3C值 :- 34.2‰～ - 2 8.6‰、- 35 .8‰～ - 2 6 .6‰、- 31.8‰～ - 2 7.1‰都显示其陆源 C3植物输入的特征 ,末次冰期的普遍的干旱化在这一地区并不存在。这些化合物的堆积速率在 H3都出现了极大值 ,反映出在南海海平面降低 ,巽它陆架出露背景下这一时期丰富的季风降雨导致河流洪水泛滥 ,从而引起南沙海区输入的陆源营养元素增多 ,海洋表层生产力增高。
The palaeoenvironmental change of Nansha area, South China Sea since last 30 ka has been inferred using the biomarker and carbon isotopic composition in 314 samples from core 17962. The paleoproductivities of microalgae indicate the paleoceanographic and paleoclimatic instablity in Nansha area during the last glacial. Terrigenous proxies, for examples, higher molecular weight lipids and terrestrial organic carbon show that terrestrial input in Nansha area is higher in the last glacial than in the Holocene. The specific stable carbon isotope of terrigenous long-chain compounds, the n-alkanes δ 13C=-28.6‰～-34.2‰), the n-alkanoic acids δ 13C =-27.1‰～-31.8‰), and the n-alkanols δ 13C=-26.6‰～-35.8‰) indicate the derivation of higher plants of C 3, implying that the surrounding area of southern South China Sea was not dry during the last glacial. The maxima in microalgae productivity and the accumulation rates of terrigenous long-chain compounds at H3 demonstrate that the enhancement of marine productivity is caused by an increased terrigenous nutrient supply from the Sunda Shelf. This interpretation coincides with the low sea level and river flood due to the abundant monsoon precipitation in southern South China Sea in the last glacial.
出处
《沉积学报》
CAS
CSCD
北大核心
2003年第2期211-218,共8页
Acta Sedimentologica Sinica
基金
国家杰出青年基金 (批准号 :4945 3 0 0 4)资助。
