南海北部晚第四纪颗石藻生产力变化及其影响因素

通过对南海北部MD05-2904岩心进行有机地球化学分析,以长链不饱和烯酮作为颗石藻生产力的替代性指标,讨论颗石藻生产力的变化及其影响因素。结果显示,260ka以来,颗石藻生产力有着明显的冰期/间冰期变化:冰期高,间冰期低;冰阶高,间冰阶低;在轨道尺度上岁差周期明显,反映出太阳辐射、东亚季风对颗石藻生产力在长期尺度上起调控作用;而由于特殊的地理位置,河流输送的营养盐对本区海洋初级生产力的影响可能也较大;与前人研究结果一致,同时认为,在地质历史上沉积速率变化大的区域,对生物标记物的含量和堆积速率的对比讨论,更有利于反映生产力的变化。

LATE QUATERNARY COCCOLITH PRODUCTIVITY IN THE NORTHERN SOUTH CHINA SEA

We present hereby the C37 long chain alkenones record from the Core MD 05-2904 located in the northern South China Sea.The C37 alkenones was applied to assess the haptophytes productivity variations.The content and Mass Accumulation Rates(MARs) of the C37 alkenones indicate that during the last 260 ka,the productivity of the haptophytes has generally followed a glacial/ interglacial pattern with high values in glacials,and low values in interglacials.And three high productivity intervals are identified in MIS 2,4 and MIS 6.There were precession signals in both records.All these display a close link between East Asian winter monsoon and paleo-productivity,and on the orbital scale,marine productivity was controlled by insolation and monsoon variations,mainly through nutrients mechanism.And for the northern SCS,sea level changes and river transportation may also play an important role.These results are consistent with other reports.We also notice that,with consideration of both contents and MARs of biomarker,we can better decipher biomarker record,especially for those areas with big fluctuations in sedimentation rates.