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	北极新奥尔松全新世冰碛物物理化学特征及环境意义
其他题名	PHYSICAL AND CHEMICAL CHARACTERISTICS OF HOLOCENE MORAINES FROM NY-ALESUND,ARCTIC AND THEIR ENVIRONMENTAL IMPLICATIONS
	张子洋 1; 闫明 2; 刘连文 1; 孟先强 1; 何同 1; 季峻峰 1
来源期刊	第四纪研究
ISSN	1001-7410
出版年	2017
卷号	37 期号:2 页码:293-306
中文摘要	冰碛物是全球的一个主要粉尘源,联系着全球气候、大气气溶胶、海洋元素和生产力的变化。过去对粉尘,特别是沙漠、黄土的研究主要集中在中纬度地区,但对来自高纬度的冰川粉尘研究较少。为了解现代高纬度冰缘环境下冰川作用、搬运作用和化学风化对冰碛物的物理化学性质的影响,本文以北极新奥尔松Austre Lovenbreen冰川(简称A冰川,下同)深度小于5cm的冰碛物(包括小冰期冰碛物和冰沼土)≤2mm组分为对象,测定了小冰期(Little Ice Age,简称LIA)冰碛物和冰沼土的粒径、磁化率以及元素组成。研究表明:1)A冰川冰碛物粒径组成以砂级为主(>63mum)、粉砂级次之(2~63mum)、粘粒最少(<2mum)。A冰川冰碛物大部分呈双峰或多峰特征,LIA冰碛物典型双峰峰值为10~30mum和100~200mum;冰沼土为30~60mum和300~450mum。近岸LIA冰碛物和冰沼土相对冰川末端LIA冰碛物具有较粗的平均粒径及较高的正偏度,表明其在沉积之后受搬运作用影响损失了细组分。2)A冰川冰碛物磁化率介于5.510~(-8)~11.410~(-8)m~3/kg之间,平均值为7.7*10~(-8)m~3/kg。LIA冰碛物磁化率与总铁含量呈正相关,主要受母岩和搬运作用制约,未受成壤作用影响。3)A冰川冰沼土与LIA冰碛物相比,富Si,但贫Al、Fe、K、Ca、Mg等元素;LIA冰碛物平均化学组成与洛川黄土和上部大陆地壳(Upper Continental Crust,简称UCC)非常接近。A冰川冰碛物CIA平均值为58.57,反映冰缘环境较弱的化学风化条件。 A冰川冰碛物CIA值集中分布在UCC至黄土的平均化学组成风化趋势线上,证明了黄土粉尘起源于由一系列的冰川和高山作用产生的沉积物的可能性。分析结果表明,在弱风化的冰缘环境下,CIA值能从整体上反映LIA冰碛物和冰沼土的化学风化差异,但对沉积年龄小的LIA冰碛物而言,搬运作用引起的粒度组成差异和相应的不同矿物类型和含量的改变或是CIA值变化的主要原因。
英文摘要	Moraines are main sources of global dusts, which link to global climate, atmospheric aerosol, the oceanic elemental cycles and productivity of the ocean. There has been a focus on the studies of contemporary dust sources (especially the desert and loess) at middle latitudes, but these have been little study of modern high-latitude dust sources, which come primarily from glacial sources. For understanding influence of glaciation, transportation and chemical weathering to physical and chemical property of moraines in modern periglacial environment, here, we investigate the grain size, magnetic susceptibility and chemical elements of moraines (grain size ≤ 2mm) from Austre Lovenbreen glacier, Ny - Alesund, Arctic. 32 moraines have been sampled on the ground surface at the depth of no more than 5cm in front of Austre Lovenbreen glacier, which covers 5.69km~2 with its terminus at an elevation of 100m. These samples can be divided into two parts, 28 LIA (Little Ice Age) moraines (sedimentation age ≤ 100 years) and 4 tundra soil samples (sedimentation age 8762 years). The results display that: (1) Among the grain sizes of glacial moraines, sand (>63mum) occupies first place, silt (2~63mum) comes second and clay (<2mum) is the least. For most moraines, grain size distribution of them generally show bimodal or multimodal spectrum, and the spectrum peaks of LIA moraines and tundra soils appear at 10 ~30mum,100 ~200 mum and 30 ~60mum,300~450mum respectively. Nearshore LIA moraines and tundra soils have more coarse average grain sizes and higher positive skewness than LIA moraines near the terminus of Austre Lovenbreen glacier, indicating that fine component (≤63mum) of them was lost distinctly because of transportation. (2) The magnetic susceptibility of moraines ranges from 5.5* 10~(-8)m~3/kg to 11.410~(-8)m~3/kg with the average of 7.710~(-8)m~3/kg. It can be found that the magnetic susceptibility of moraines is positively correlated with total iron content, depends on parent material and has an effect by transportation and size sorting. The pedogenesis is weak in periglacial environment. (3) Compared with LIA moraines, tundra soils accumulate Si and deplete Al,Fe,K, Ca and Mg elements. The average chemical compositions of LIA moraines are very similar pattern with Luochuan loess and Clark values of UCC (Upper Continental Crust). The average of CIA (Chemical Index of Alteration) values is 58.57,which indicates the low weathering intensity in periglacial environment. The moraines’ values plotted on a trend between UCC and Luochuan loess in triangle chart of CIA, thus, provides an implication that the loess dust could come from moraines which are the glaciogenic dust sources. Based on the observations, we suggest that the CIA values can generally tell the difference of weathering intensity between of LIA moraines and tundra soils in periglacial environment. For LIA moraines that were deposited with relatively short time,the CIA values could mainly be changed by the grain size sorting and corresponding changes of different mineral types and contents in sediment transportation.
中文关键词	北极 ; 新奥尔松 ; Austre Lovenbreen冰川 ; 冰碛物 ; 粉尘 ; 元素 ; 粒径 ; 磁化率
英文关键词	Arctic Ny-Alesund Austre Lovenbreen glacier, moraine, dust, element, grain size, magnetic susceptibility
语种	中文
国家	中国
收录类别	CSCD
WOS类目	GEOLOGY
WOS研究方向	Geology
CSCD记录号	CSCD:5944977
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/235832
作者单位	1.南京大学, 表生地球化学教育部重点实验室, 南京, 江苏 210023, 中国; 2.中国极地研究中心, 上海 200136, 中国
推荐引用方式 GB/T 7714	张子洋,闫明,刘连文,等. 北极新奥尔松全新世冰碛物物理化学特征及环境意义[J],2017,37(2):293-306.
APA	张子洋,闫明,刘连文,孟先强,何同,&季峻峰.(2017).北极新奥尔松全新世冰碛物物理化学特征及环境意义.第四纪研究,37(2),293-306.
MLA	张子洋,et al."北极新奥尔松全新世冰碛物物理化学特征及环境意义".第四纪研究 37.2(2017):293-306.