Hydrology, geochemistry and Sr isotopes in solids and solutes of the meltwater from Mittivakkat Gletscher, SE Greenland
Hydrology, geochemistry and Sr isotopes in solids and solutes of the meltwater from Mittivakkat Gletscher, SE Greenland
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格陵兰东南部米蒂瓦卡特冰川融水固体和溶质中的水文、地球化学和锶同位素
DOI：
10.2166/nh.2004.0028
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发表时间：
2004
影响因子：
2.7
通讯作者：
B. Hasholt
中科院分区：
文献类型：
--
作者：
B. Hagedorn;B. Hasholt
本研究通过直接比较冰川径流中颗粒物和溶解物的含量，探讨了冰川侵蚀过程中元素分馏和Sr同位素系统学。排放测量沿着化学和锶同位素调查在格陵兰东南部Ammassalik O的Mittivakkat Gletscher（冰川）进行。主要的基岩类型是镁铁质成分的安马萨利克侵入杂岩（AIC）和酸性成分的石榴石-花岗岩片麻岩（GGG）。机械剥蚀率（1毫米-1）反映在主要流出的范围内的温带山谷冰川在挪威。化学剥蚀速率（32 t km-2 a-1）和硅酸盐风化作用引起的CO2下降速率（72 0 ~ 10 0 kgC km-2 a-1）低于全球平均值和斯瓦尔巴特群岛高北极冰川的相应测量值。基岩的化学和Sr同位素组成的对比，使Sr同位素比值的一个强有力的工具，确定来源地区的固体和溶解负荷。与悬浮颗粒物（SPM）相比，水中的高Ca/K比表明Ca矿物的溶解更快。相比之下，在GGG基岩，黑云母和钾长石是丰富的，Sr同位素比值溶质高于SPM，支持87 Sr从钾矿物晶格的优先释放。
This study was initiated to investigate elemental fractionation and Sr isotope systematics associated with glacial erosion by direct comparison of particulate and dissolved load in glacial runoff. Discharge measurements along with chemical and Sr isotope investigations were carried out at the Mittivakkat Gletscher (Glacier), Ammassalik O, Southeast Greenland. Major bedrock types are the Ammassalik Intrusive Complex (AIC) of mafic composition and garnet-granite gneiss (GGG) of acidic composition. Mechanical denudation rates (1 mma -1 ) reflected in the major outflow are in the range of temperate valley glaciers in Norway. Chemical denudation rates (32 t km -2 a -1 ) and estimated rates of CO 2 drawdown by silicate weathering (720-100kgC km -2 a -1 ) are low compared to global mean and match values measured for High Arctic glaciers on Svalbard. The contrast in chemical and Sr isotope composition of bedrock makes Sr isotope ratios a powerful tool for determining source areas of solid and dissolved load. High Ca/K ratios in water compared to suspended particulate matter (SPM) indicate faster dissolution of Ca minerals. By contrast, in GGG bedrock, where biotite and K-feldspar are abundant, Sr isotope ratios in solutes are higher than in SPM, supporting preferential release of 87 Sr from a K-mineral lattice.