Magnetic signature of environmental change reflected by Pleistocene lacustrine sediments from the Nihewan Basin, North China
Magnetic signature of environmental change reflected by Pleistocene lacustrine sediments from the Nihewan Basin, North China
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华北泥河湾盆地更新世湖泊沉积物反映的环境变化的磁特征
DOI：
10.1016/j.palaeo.2007.12.006
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发表时间：
2008-04
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影响因子：
--
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中科院分区：
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--
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对泥河湾盆地徐家窑旧石器时代遗址更新世湖相沉积物进行了矿物磁学研究。磁信号以高矫顽力（赤铁矿）矿物为主，间冰期受低矫顽力磁铁矿-磁铁矿组合调制。磁性S−0.3 t参数的高振幅记录与复合海洋氧同位素记录一致，表明气候调节了磁性成分。徐家窑遗址位于中国黄土高原（CLP）的北郊，既没有受到明显的风成作用，也没有受到与CLP作用相当的成土过程的影响。矿物磁学分析表明，磁铁矿和赤铁矿的变化主要是由碎屑通量控制的，而不是由磁性矿物的自生产生控制的。本文认为徐家窑磁信号的波动并非源于冰期/间冰期风成通量组成的变化或间冰期小风成通量的变化，而可能是由径流相关过程主导的，在间冰期，一些具有较强磁信号的风化/土化黄土和土壤被侵蚀并输送到流域，导致磁信号增强。从Brunhes/Matuyama边界到古土壤S1（ca.）的连续沉积推断。（129 ka）给出了徐家窑旧石器遗址沉积物的年龄约500 ka，表明用U-Th法测定的旧石器器物和哺乳动物骨骼的异源起源约为100 ka。
A mineral magnetic study has been conducted on Pleistocene lacustrine sediments from the Xujiayao Paleolithic site within the Nihewan Basin, North China. The magnetic signal is characterized by a dominance of high-coercivity (hematite) minerals that is modulated by low-coercivity magnetite–maghemite assemblages during interglacials. A high-amplitude record of the composition dependent magnetic S−0.3 T-parameter varies in accord with composite marine oxygen isotope records, suggesting climate modulation of magnetic composition. The Xujiayao site is situated at the northern outskirts of the Chinese Loess Plateau (CLP) and has neither received significant eolian input nor been exposed to pedogenic processes comparable to those acting on CLP. Mineral magnetic analyses suggest that variations in both magnetite and hematite are primarily controlled by detrital fluxes rather than by authigenic production of magnetic minerals. Here we propose that the fluctuations of magnetic signals at Xujiayao are not derived from varying compositions of eolian flux with glacial/interglacial periods or minute eolian influx during interglacials, but is likely dominated by runoff-related processes, by which some weathered/pedogenized loess and soils with stronger magnetic signals have been eroded and transported to the catchment during interglacials resulting in magnetic enhancement. The inferred continuous deposition from the Brunhes/Matuyama boundary to the paleosol S1(ca. 129 ka) gives the age of ca. 500 ka for the sediments carrying the Xujiayao Paleolithic site, suggesting an allogenic origin of the Paleolithic artifacts and mammalian bones dated by U–Th method to ca. 100 ka.
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影响因子：
4
作者：
B. Zolitschka;J. Negendank
通讯作者：
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影响因子：
64.8
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影响因子：
5.3
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通讯作者：
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影响因子：
2.8
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通讯作者：
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