诺尔图13A孔记录的1333A.D.以来的古气候环境变化

发布时间：2018-03-26 04:27

本文选题：巴丹吉林沙漠　切入点：诺尔图　出处：《兰州大学》2015年硕士论文

【摘要】：诺尔图湖泊位于巴丹吉林沙漠的东南缘,处于现代东亚夏季风的西北尾闾区,对区域气候环境变化响应敏感,是研究过去气候演化、水文过程与风沙活动历史的理想地点。本文主要利用NET13A钻孔湖泊沉积物的粒度、总有机碳(TOC)、总氮(TN)、C/N值、地球化学元素Si、S、Cl、K、Ca、Sr、Zr/Rb、以及低频磁化率(χlf)等多种环境代用指标分析,同时基于14C年代测定及碳库年龄校准所获得的钻孔年代-深度模式,对诺尔图湖区近700年来的气候变化以及区域的风沙活动历时进行了恢复重建,并与阿拉善高原以及我国其它气候区近千年来的古气候及风沙记录活动进行了对比,得出的初步结论如下：(1)由对诺尔图湖湖泊沉积物进行粒度组分进行分离获得的(C3+C4)粒度组分能够作为反映湖泊水体面积、湖水水位变化的代用指标；元素第一主分量PC1、以及TOC含量可以作为反映区域有效湿度变化的代用指标；TN值指示湖泊初级生产力变化；粒度组分C2、元素第二主分量PC2与低频磁化率(χlf)能够作为指示区域风沙活动强弱的代用资料。(2)对于诺尔图湖所在区域近700年来的气候环境变化可大致划为3个时段,第1阶段(1333-1600A.D.,92-49cm),粒度组分(C3+C4)含量、TOC与TN含量均处于高值、元素第一主分量PC1处于负值,粒度组分C2、元素第二主分量PC2以及低频磁化率(χlf)均为低值,反映这一时段区域气候特征表现为有效湿度较高,湖水水位相对更高,风沙活动较弱,为气候相对冷(凉)湿期；第Ⅱ阶段(1600-1834A.D.,49-12cm),元素第一主分量PC1为正值,粒度组分(C3+C4)、TOC与TN含量均为低值,粒度组分C2、元素第二主分量PC2以及低频磁化率(χlf)整体居于高值,指示出湖区这一时期表现出有效湿度减低,湖泊萎缩、水位降低,风沙活动更为强烈,为气候冷干时期；第Ⅲ阶段(1834-2013A.D.,12-0cm),粒度组分(C3+C4)、TOC与TN含量整体较前一阶段呈缓慢上升趋势,元素第一主分量PC1位于0值附近,粒度组分C2、元素第二主分量PC2以及低频磁化率(χlf)较上一阶段显著减低,表明这一时段区域有效湿度较前一时段有所增加(但不及第1阶段),风沙活动呈逐渐减弱,但在20世纪中期之后,区域气候有往转干方向发展的趋势。(3)与其它古气候记录对比表明,诺尔图13A钻孔重建的近700年来的气候环境变化与空间距离较近的沙漠包气带钻孔(B1钻孔、SW1钻孔与SWDA钻孔)有较好的响应,但在一些时段(如18世纪)也存有明显差异。更大的区域尺度范围内,在年代际-百年尺度上,诺尔图重建的古气候记录与亚洲中部干旱区以及中国中北部地区的古气候演化模式存在明显差异,而与青藏高原东北缘古气候记录有较好的可对比性,表明二者之间的耦合关联效应。与其它区域重建的古风沙活动记录的对比研究表明,诺尔图13A钻孔重建的区域风沙活动与邻近的敦德冰芯记录共同指示出18世纪为风沙(粉尘)活动最强时期,不同于其它记录指示的17世纪为出现最强粉尘活动时期。
[Abstract]:Noel lake located in the southeastern margin of figure Badan Jilin desert, in the northwest of the East Asian summer monsoon marginal area, sensitive to regional climate change, is the study of past climate evolution history, an ideal location for hydrological processes and aeolian activities. This paper mainly use the sediments of Lake NET13A drilling, total organic carbon (TOC), total nitrogen (TN), C/N value, geochemical elements Si, S, Cl, K, Ca, Sr, Zr/Rb, and low frequency magnetic susceptibility (LF) analysis and other environmental proxies, while 14C's drilling and carbon dating age calibration based on the obtained depth model, restored to climate change map of Lake in recent 700 years, Noel and regional sandstorm activity duration, and compared with the Alashan plateau in China as well as other climate zones for nearly a thousand years of ancient climate and aeolian record activities, the conclusions are as follows: (1) by Noel Map of lake sediment particle size fractions were isolated (C3+C4) particle size fractions can reflect the lake water area, the water level changes of the indicator elements; the first principal component of PC1, and the content of TOC can be used as substitute to reflect the regional effective humidity index; TN value indicates the primary productivity of Lake change; grain size group C2, the second principal component elements PC2 and low frequency magnetic susceptibility (x LF) can be used as a proxy data indicating the strength of the wind area. (2) for Noel figure lake is located in the region for the past 700 years climate change could be roughly divided into 3 periods and first stages (1333-1600A.D., 92-49cm), grain size group (C3+C4 the content of TOC and TN), were at a high level, the first principal component of PC1 elements in the negative, particle size fractions C2, PC2 and elements of the second principal component of low frequency magnetic susceptibility (x LF) are low value, reflecting the period of regional climate characteristics Is the effective humidity is high, the water level is relatively high, sandstorm activity is weak, as the climate is relatively cold (cool) wet period; the second stage (1600-1834A.D., 49-12cm), the first principal component element of PC1 is positive, grain size group (C3+C4), TOC and TN contents were low value, grain size component C2 the main elements of the second component PC2 and low frequency magnetic susceptibility (x LF) in the whole high value, indicating the lake during this period showed effective humidity reduced, lowering the water level, Lake shrinking, sand activity is more intense, for a cold and dry climate period; stage III (1834-2013A.D., 12-0cm), grain size group (C3+C4). TOC and TN content were compared with the previous stage showed a slow upward trend, the first principal component of PC1 in the 0 elements of value near the particle size fractions C2, PC2 and elements of the second principal component of low frequency magnetic susceptibility (x LF) was significantly higher than that of the upper stage decreased, indicated that this time regional effective moisture increased over the previous period ( But less than first), stage of Aeolian activity was gradually weakened, but in mid twentieth Century after the regional climate to dry the trend. (3) show that compared with other paleoclimate records, nearly 700 years of climate change and space reconstruction of figure 13A drilling Noel near desert vadose zone drilling (B1 drilling, SW1 drilling and drilling SWDA) has a good response, but in some period of time (as of eighteenth Century) there are also obvious differences. The regional scale bigger range, the interdecadal Centennial scale, there exist obvious differences in climate records in Asia and the Noel map reconstruction in arid region and ancient climate the northern area of the China evolution model, and the northeastern margin of the Tibetan Plateau climate records are well comparable. The effect of the coupling relationship between these two. Compared with other regional reconstruction of palaeo aeolian sands activity records show that Noel figure 13A drill Regional aeolian activities with the adjacent Kong Zhongjian records indicate the Dunde ice core in eighteenth Century for the wind (dust) the most active period, different from other records indicating seventeenth Century appeared the strongest dust activity period.

【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P532

【相似文献】