渤海南岸LZ908孔海陆交互相地层气候代用指标及沉积环境研究

发布时间：2018-02-28 05:16

本文关键词： 渤海南岸有孔虫组合沉积环境气候代用指标　出处：《中国科学院研究生院（海洋研究所）》2014年博士论文　论文类型：学位论文

【摘要】：第四纪冰期-间冰期交替的气候变化造成了全球海平面的波动，在海岸带地区表现为海陆交互相沉积。海岸带地区沉积物记录了沉积环境变化的丰富信息。通过研究海陆交互相沉积物来探讨沉积环境演化，重建区域环境变化历史，对于认识海陆相互作用以及预测未来环境演变具有重要意义。本文研究的LZ908孔位于渤海莱州湾南岸，在建立相对可靠的年龄框架的基础上，结合沉积物有孔虫特征研究了渤海南部地区海侵、海退的古海洋环境变化；对沉积物的颜色反射率各参数变化进行主成分分析，根据结果讨论影响海陆交互相沉积物颜色变化的主要因子；对沉积物粒度、颜色反射率、磁化率及孢粉这些指标进行分析，探讨各指标的环境指示意义、周期性变化及可能的影响因素。将各指标反映的气候变化与全球气候变化或海平面变化进行对比，得到莱州湾地区的区域性气候变化特征。得到的初步结论如下： 1.通过对渤海莱州湾南岸LZ908孔的研究，识别了LZ908孔的有孔虫组合特征，结合AMS14C和光释光测年结果，对比渤海地区其它钻孔资料，，对晚第四纪的环境变化过程进行了重建，认为三次大规模海侵开始于MIS7，MIS5和全新世，另外在MIS6的中期也发生了一次小规模的海侵。LZ908孔在MIS3阶段存在海侵地层，但是有孔虫特征显示这一时期的温度低于MIS5阶段。 2.通过将LZ908孔的亮度与碳酸钙含量进行对比，发现L*值与CaCO3含量曲线的变化非常一致，在海陆交互相沉积物中，将L*值作为碳酸盐的替代指标是可行的。采用方差极大旋转法对样品颜色反射率的一阶导数进行了因子分析，通过将因子的载荷曲线与已知沉积物组分的一阶导数曲线进行对比，得到因子1与沉积物中有机物含量相关，因子2与沉积物中的粘土矿物含量关系较大，因子3与沉积物中针铁矿相关。 3.通过对沉积物粒度的主成分分析，发现LZ908孔32μm的细粒部分的含量与65oN夏季太阳辐射的变化和神农架三宝洞石笋的δ18O值的变化十分相似，表明LZ908钻孔沉积物32μm的细粒部分的含量可以作为指示东亚季风强度的一个很好的指标。通过将磁化率和孢粉数据相结合，结果表明磁化率是一个良好的气候指标，高磁化率指示暖湿气候，低磁化率反映干冷气候。将LZ908孔的磁化率曲线与深海氧同位素曲线进行对比，磁化率高值对应氧同位素低值，为间冰期环境，磁化率低值对应氧同位素高值，为冰期环境。亮度值和CaCO3含量较高的层位大致为海平面较高的时期，指示温暖湿润的环境；相反地，亮度值和CaCO3含量较低的层位表明气候寒冷干燥，大多为海平面较低的时期。在LZ908钻孔的沉积序列中，红度值a*值的变化主要反映了沉积环境的氧化还原状态，冰期时期为低海平面时期的河漫滩环境，沉积环境为氧化环境，高价铁的氧化物和氢氧化物增加，沉积物颜色为红褐色或黄褐色，a*值也较大。间冰期的浅海或滨海环境，沉积环境为还原环境，高价铁的氧化物和氢氧化物转化为低价铁的氧化物和氢氧化物，沉积物颜色为深灰色、灰褐色或棕绿色，a*值也较小。 4.通过对LZ908钻孔沉积物的粒度、磁化率和红度值a*值时间序列的频谱分析，得到250ka以来，渤海莱州湾南岸海陆交互相沉积物粒度、磁化率和红度值分别记录了轨道岁差、倾斜度和偏心率的周期特征。
[Abstract]:The Quaternary glacial interglacial alternation of climate change caused by global sea-level fluctuations, with area in the coast of paralic zone sediment deposition. Rich information recorded the changes of sedimentary environment of the coast. Through the study of paralic sediments to explore the evolution of the sedimentary environment, the reconstruction of regional environment change history, for the understanding of the interaction between sea and land and to predict the future environmental change has important significance. This paper studies the LZ908 hole is located on the South Bank of Bohai Bay in Laizhou, based on the framework of age is relatively reliable, the transgressive region of southern Bohai with sediments foraminiferal characteristics, ancient marine environment change regression; the parameters change on sediment color reflectance by principal component analysis and discussion the main factors affecting paralic sediments change color according to the results of grain size, color reflectance, Analysis of magnetic susceptibility and pollen of these indicators, the index of environmental significance, cyclical changes and possible influence. Comparing the climate change and global climate change and sea level changes in the indicators reflect the regional climate, from Laizhou Bay area and the characteristics of the preliminary conclusions are as follows:
1. through the study of Bohai Laizhou Bay LZ908 hole, characteristics of foraminiferal assemblages to identify the LZ908 hole, the combination of AMS14C and OSL dating results, in contrast to the Bohai area other drilling data, the late Quaternary environmental change on the process of reconstruction, that the three transgression started at MIS7 and MIS5 and also in the Holocene. Middle MIS6 also occurred in a small hole are transgressive.LZ908 transgressive formations in the stage of MIS3, but this time the foraminifera characteristics show that the temperature is lower than MIS5.
2. through the LZ908 hole brightness and the content of calcium carbonate were compared, it was found that L* value is consistent with the change of CaCO3 content curve, in paralic sediments, the L* value as an alternative index of carbonate is feasible. Using the varimax rotation method of sample color reflectance first derivative by factor analysis, through comparing the first derivative curve load curve factor with known sediment composition, organic matter content by factor 1 and relative content of clay minerals in sediments, the relationship between factor 2 and sediment in the larger, factor 3 and goethite in sediments.
3. through the principal component analysis of sediment grain size, change Delta 18O variation of LZ908 hole 32 m fine part of 65oN and the content of solar radiation in summer and Shennongjia Sanbao Cave Stalagmite value is very similar to that of sediments of core LZ908 32 m fine part of the content can be a good index as an indicator of East Asia the intensity of monsoon. By combining the magnetic susceptibility and pollen data, results show that the magnetic susceptibility is a good climate index, high magnetic susceptibility indicates low susceptibility to reflect the warm and humid climate, dry and cold climate. The magnetization of the LZ908 hole rate curve was compared with the deep-sea oxygen isotope curve, high magnetic susceptibility values correspond to low oxygen isotope values for, inter glacial environment, low magnetic susceptibility values corresponding to oxygen isotope value for the glacial environment. The lightness and high content of CaCO3 layer is roughly the period with higher sea levels, indicating the warm and humid environment; on the contrary And the lightness and low CaCO3 content layers show that the climate is cold and dry, mostly for the lower sea level period. In the sedimentary sequence of LZ908 drilling, the red value a* value changes mainly reflect the sedimentary environment of the oxidation reduction state, glacial period for low sea level period floodplain environment, sedimentary environment as the oxidation environment, oxides and hydroxides of Fe increases, sediment color is red brown or brown, a* value is also larger. Binhai interglacial or shallow water environment, sedimentary environment is reductive, ferric oxide and hydroxide into low iron oxides and hydroxides, the sediment color is dark gray, brown or brown green, the a* value is smaller.
4. the granularity of LZ908 cores, magnetic susceptibility and red value spectrum analysis of a* time series, 250kA, Bohai Laizhou Bay paralic sediment grain size, magnetic susceptibility and redness were recorded in orbital precession cycle characteristics of inclination and eccentricity.

【学位授予单位】：中国科学院研究生院（海洋研究所）
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P736.21

【参考文献】