Impact of climate change on the magnetic mineral assemblage in marine sediments from Izu rear arc, NW Pacific Ocean, over the last 1 Myr
Impact of climate change on the magnetic mineral assemblage in marine sediments from Izu rear arc, NW Pacific Ocean, over the last 1 Myr
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DOI：
10.1016/j.palaeo.2017.05.016
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发表时间：
2017-08-15
影响因子：
3
通讯作者：
Bauersachs, Thorsten
中科院分区：
文献类型：
--
作者：
Kars, Myriam;Musgrave, Robert J.;Bauersachs, Thorsten
对国际海洋发现计划350考察站U1437上更新世海洋沉积物进行了岩石磁学研究，以突出东亚季风体制影响下西北太平洋的古环境变化。进行了剩磁分析、磁滞特性、一阶反转曲线和低温磁性测量，沿着电子显微镜观察。结果表明，粗粒（钛）磁铁矿是磁性矿物组合中的主要磁性相。时间序列分析支持这一组合调制的全球气候变化在过去的1 Myr。在间冰期阶段，磁性矿物更丰富，主要是陆源（可能来自中国大陆）和火山（伊豆弧前，日本）起源的粗粒（钛）磁铁矿。在冰期，磁性矿物含量较低，可能反映了（Ti）-磁铁矿的部分溶解，磁性矿物组合由陆源粗粒（Ti）-磁铁矿和较高的磁化率组成，可能是亚洲大陆冬季风增强的结果，风成颗粒较细（可能是赤铁矿）。磁性矿物组合反映了火山和全球气候信号的叠加。散装有机地球化学分析的总有机碳以及氮和硫的含量证实了气候特征的沉积物的组成与更多的含氧水体存在于冰期。对大量样品的额外X射线荧光测量表明，沉积物颗粒的近端和远端来源不同。(C)2017爱思唯尔B. V.保留所有权利。
A rock magnetic study was conducted on upper Pleistocene marine sediments from International Ocean Discovery Program Expedition 350 Site U1437 in order to highlight the paleoenvironmental changes in the NW Pacific Ocean influenced by the East Asian monsoon regime. Remanent magnetization analyses, hysteresis properties, first-order reversal curves and low temperature magnetic measurements were carried out, along with electron microscope observations. The results indicate that coarse-grained (titano)-magnetite is the dominant magnetic phase in the magnetic mineral assemblage. Time-series analysis supports that this assemblage is modulated by global climate changes over the last 1 Myr. During the interglacial stages, magnetic minerals are more abundant; and are dominated by coarse-grained (titano)-magnetite of both terrigenous (likely from mainland China) and volcanic (Izu arc front, Japan) origin. During the glacial stages, the magnetic mineral content is lower, probably reflecting partial dissolution of (Ti)-magnetite, and the magnetic assemblage is composed of terrigenous coarse-grained (titano)-magnetite and of higher coercivity, presumably finer eolian particles (likely hematite) as a result of the enhancement of the winter monsoon in continental Asia. The magnetic mineral assemblage reflects a superimposition of volcanic and global climate signals. Bulk organic-geochemical analyses for total and organic carbon as well as nitrogen and sulfur contents confirm a climatic signature in the composition of the sediments with more oxygenated water masses being present during glacial periods. Additional X-ray fluorescence measurements on bulk samples indicate various origins of the sediment particles with both proximal and distal sources. (C) 2017 Elsevier B.V. All rights reserved.