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Insight Into Provenance and Variability of Atmospheric Dust in Antarctic Ice Cores During the Late Pleistocene From Magnetic Measurements
Frontiers in Earth Science ( IF 2.0 ) Pub Date : 2020-06-09 , DOI: 10.3389/feart.2020.00258
Luca Lanci , Barbara Delmonte , Maria Cristina Salvatore , Carlo Baroni

We measured saturation isothermal remanent magnetization (SIRM), coercivity of remanence (Hcr), and insoluble dust mass concentration (IDC) of 49 ice samples from Vostok and EPICA Dome-C ice cores (Antarctica) as a measure of magnetic properties of the aerosol dust trapped in the ice. Samples range in age from marine isotopic stage (MIS) 7 to 19 in EPICA Dome-C ice core and from MIS 1 to 11 in Vostok ice core. Data from ice samples were compared with 86 samples from possible source areas (PSA) from East Antarctica, including 11 samples from South America and New Zealand. Previous results from MIS 1 to MIS 6 found that magnetic properties of aerosol dust could be divided in two distinct groups characterized by high-Hcr and low-SIRMdust for glacial samples, and low-Hcr and high-SIRMdust, for interglacial samples. The new data from older ice samples highlighted several discrepancies from this expectation with significant differences between Vostok and Dome-C sites. Magnetic properties of Antarctic PSA sample show a large variability, however, PSA samples from Victoria Land and few other, have magnetic properties compatible with that of the glacial dust, or more precisely with samples characterized by high dust flux. The new data from Pleistocene ice and from PSA samples confirm South American and Antarctic provenance of the largest atmospheric dust load typical of glacial stages. On the other hand, we did not found any PSA sample with properties compatible with the highly magnetic samples (mostly from interglacial stages), which are characterized by low IDC. These samples from the oldest and deepest part of the cores revealed a more complex picture than previously outlined from the analysis of MIS 1–6, and show unusual magnetic properties which can be tentatively attributed to post-depositional alteration occurring into the ice.



中文翻译:

磁场测量对晚更新世南极冰芯大气尘源和变化的认识

我们测量了来自Vostok和EPICA Dome-C冰芯(南极洲)的49个冰样品的饱和等温剩余磁化强度(SIRM),剩磁矫顽力(H cr)和不溶性粉尘质量浓度(IDC),作为测量其磁性能的量度。气溶胶粉尘被困在冰中。在EPICA Dome-C冰芯中,样品的年龄范围从海洋同位素阶段(MIS)7至19,在Vostok冰芯中,样品的年龄范围从MIS 1至11。将冰样品的数据与南极东部可能来源地区(PSA)的86个样品进行了比较,其中包括南美和新西兰的11个样品。MIS 1到MIS 6的先前结果发现,气溶胶粉尘的磁性可以分为两个不同的组,其特征是高H cr和低SIRM粉尘用于冰川样品,低H cr和高SIRM灰尘,用于冰间样品。来自较旧冰样的新数据突出显示了这一预期的一些差异,其中Vostok和Dome-C站点之间存在显着差异。南极PSA样品的磁性能表现出很大的变异性,但是,来自Victoria Land和其他少数几个州的PSA样品的磁性能与冰川粉尘的磁性能兼容,或更确切地说,与高粉尘通量的样品具有良好的磁性能。来自更新世的冰和PSA样本的新数据证实了南美和南极地区冰期典型的最大大气尘埃负荷。另一方面,我们没有发现具有与高磁性样品(主要来自冰期)兼容的特性的PSA样品,这些样品的特征在于IDC低。

更新日期:2020-06-30
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