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运城盆地11 kaBP以来气候环境变迁与湖面波动 总被引:7,自引:0,他引:7
通过黄土区湖泊沉积研究来恢复古气候、古环境,是对黄土区古气候、古环境研究的补充和检验。通过山西运城盆地硝地湖泊沉积物的多环境代用指标分析,结合史料记载,探讨了该地区11kaBP以来古气候演化和湖面波动的历史。结果表明,该地区存在YD(Younger Dryas)事件,进入全新世后气候有显著的趋势,最高湿润度发生在7.88-5.15和5kaBP后,气候逐渐变干,湖面波动与气候波动相关,全新世早期湖面开始上升,湖泊扩张,5kaBP后湖泊萎缩,盐类结晶析出。 相似文献
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太湖14000年以来古环境演变的湖泊记录 总被引:5,自引:0,他引:5
本文根据东西太湖短柱岩芯的沉积物的物理、化学、生物指标的综合分析,讨论了该区距今14ka来的古气候变化过程,结果表明14.3-13.3kaBP,太湖水位低,环境指标甚至表现为暴露特征,反映了气候干旱:13.3-12.4kaBP,为偏暖湿的过渡阶段;该孔柱270-280cm (11.5kaBP左右)各类指标均明显反映冷干特征,可能是YoungerDrays事件的记录,与我国东部其它地区有可比性;约10.9-10kaBP,这一时期是整个研究时段内一个较显著的温暖期。表现为还原沉积环境和水位相对较深;约10-7.2kaBP为冷暖交替的过渡带;7.2-5.737kaBP为暖湿气候;5.05kaBP多项分析指标发生突变,反映物源发生显著变化,可能存在沉积间断;表层沉积物则呈现现代环境的特征,西太湖藻类生长茂盛,偏氧化的沉积环境。目前湖泊生产力较高,富营养化程度高,表现为藻型湖泊特征;东太湖有机质来源以东太湖中生长较为茂盛的维管水生植物为主,目前湖泊生产力较低,富营养化程度低,表现为典型的草型湖泊特征。 相似文献
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湖泊沉积物的磁化率、频率磁化率及其古气候意义—以青海湖、岱海近代沉积为例 总被引:28,自引:9,他引:28
湖泊沉积物的磁性参数是古气候、古环境的重要代用指标。通过对青海湖QI5孔和岱海DH32孔短岩心的磁化率、频率磁化率的研究,并与地球化学参数等其它资料对比,探讨了以上两个湖区历史时期古气候变化规律;论证了用磁化率、频率磁化率作为古气候、古环境指标的可靠性和敏感性;并对其变化机制进行了初步探讨。 相似文献
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根据洱海湖泊沉积物有机碳稳定同位素、元素、磁化率记录,近8ka来西南季风区洱海古气候演化可以分为9个阶段,气候变化以暖干-冷湿交替为主,暖干气候阶段西太平洋副热带高压控制西南地区的频率增加,夏季印度季风路径偏向西亚、中亚和青藏高原西部,包括洱海在内在云南高原气候暖干明显;冷湿气候阶段,副热带高压偏弱向东撤退,印度季风路径移向中国西南地区,降水增加,造成气候冷湿.湖泊沉积物记录的洱海流域人类耕作农业历史最早出现在5ka BP左右. 相似文献
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湖泊沉积物的磁化率、频率磁化率及其古气候意义—以青海湖、岱海近代沉积为例 总被引:15,自引:3,他引:12
湖泊沉积物的磁性参数是古气候、古环境的重要代用指标。通过对青海湖QI_5孔和岱海DH_(32)孔短岩心的磁化率、频率磁化率的研究,并与地球化学参数等其它资料对比,探讨了以上两个湖区历史时期古气候变化规律;论证了用磁化率、频率磁化率作为古气候、古环境指标的可靠性和敏感性;并对其变化机制进行了初步探讨。 相似文献
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Two sediment cores, one 396 cm long from west Taihu Lake, another 246 cm long from east Taihu Lake, are interpreted from the analysis of their magnetic susceptibility, total organic carbon, total nitrogen, total pigments, organic carbon isotope, hydrogen index, saturated hydrocarbons, 14C dating and surficial sediment conditions. The west Taihu Lake core is the longest one studied in this lake so far, and has provided us the most complete environmental and climatic information for this lake. The results from the west Taihu lake core indicate that Taihu Lake has undergone the following stages:from ca.14 300 to 13 300 aB.P. Taihu Lake was in low lake-level, and there existed exposed features from the proxies reflecting arid paleoclimate. From ca.13 300 to 12 400 aB.P. an arid transitional stages occurred with a slightly warmer and wetter climate. From ca. 12 400 to 10 900 aB.P. a period of large climatic fluctuation occurred and from 10900-10 000 aB.P. a warm period developed with deep water and strongly reducing sediments. During ca.10 000-7 200aB.P., a cool transitional period alternating with a warm climate occurred. It was warm and wet during 7 200-5 700aB.P.; some proxies changed violently in 5 050aB.P., reflecting obvious changes in material source and a probable interruption of sedimentation. The east Taihu Lake history from ca. 6 550 to 6 450 aBP, the climate was cold and dry, and gradually turned warm and wet in ca. 6 450-6 050 aBP. It was warm and wet in ca. 6 050-5 800 aBP and had a cold tendency in 5 800-ca. 5 000 aBP. An abrupt change occurred at ca. 5 000 aBP, and the lake sediment in the uppmost part was disturbed by wave action indicating shallow water conditions. 相似文献