Magnetostratigraphic results from impact crater Lake El'gygytgyn, northeastern Siberia: a 300 kyr long high-resolution terrestrial palaeoclimatic record from the Arctic
Magnetostratigraphic results from impact crater Lake El'gygytgyn, northeastern Siberia: a 300 kyr long high-resolution terrestrial palaeoclimatic record from the Arctic
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DOI：
10.1046/j.1365-246x.2002.01625.x
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发表时间：
2002-07
影响因子：
2.8
通讯作者：
N. Nowaczyk;P. Minyuk;M. Melles;J. Brigham‐Grette;O. Glushkova;M. Nolan;A. Lozhkin;T. Stetsenko-
中科院分区：
文献类型：
--
作者：
N. Nowaczyk;P. Minyuk;M. Melles;J. Brigham‐Grette;O. Glushkova;M. Nolan;A. Lozhkin;T. Stetsenko-
从位于西伯利亚东北部楚科特卡半岛晚白垩世火成岩形成的3.6 Ma陨石坑中的El‘gytgyn湖中发现了12.7m长的沉积记录，对其古磁性和岩石磁性进行了分析。连续的高分辨率(1毫米)磁化率测量产生了一系列明显的低和高。通过磁化率的低温和高温运行、磁滞参数的测定以及IRM采集实验对岩石磁性的分析表明，PSD(拟单区)磁铁矿在高磁化率区间占主导地位，而在有机质的强化沉积时期，由于与缺氧湖水和/或孔隙水条件有关的选择性磁铁矿溶解，赤铁矿在低磁化率区间占主导地位。然而，在这里，磁性仍然由磁铁矿主导。5个加速器质谱学年龄(14C)、8个红外激发发光年龄(IRSL)和初步的孢粉数据表明，磁铁矿含量的变化反映了末次∼300ka的气候变化，具有代表冷(暖)气候的低(高)敏感性。这种模式是由有机质和/或磁性矿物的沉积、保存或分解的复杂系统造成的，反过来又可以与全球气候档案详细相关，例如分别来自格陵兰冰芯和海洋沉积物的氧同位素记录。因此，从El‘gytgyn湖恢复的沉积序列代表了目前在北极可获得的最长的连续陆地气候记录。
SUMMARY A 12.7 m long sedimentary record recovered from Lake El’gygytgyn, located in a meteorite impact crater created 3.6 Ma in Late Cretaceous igneous rocks on Chukotka Peninsula, northeast Siberia, has been analysed for its palaeo- and rock-magnetic properties. Continuous high resolution (1 mm) measurements of magnetic susceptibility yielded successions of pronounced lows and highs. Analyses of the rock-magnetic properties by low and high temperature runs of magnetic susceptibility, determination of hysteresis parameters as well as IRM acquisition experiments, yielded a dominance of PSD (pseudo-single domain) magnetite in intervals of high magnetic susceptibility, whereas, due to selective magnetite dissolution associated with anoxic Lake water and/or pore water conditions during times of enhanced deposition of organic matter, haematite dominates within low susceptibility intervals in terms of mass percentage. Here however, magnetic properties are still dominated by magnetite. Five AMS (accelerator mass spectromentry) 14 C ages, eight IRSL (infrared stimulated luminescense) ages together with preliminary pollen data suggest that variations in magnetite content reflect climatic variability of the last ∼300 ka with low (high) susceptibilities representing cold (warm) climates. This pattern, caused by a complex system of deposition, preservation or decomposition of organic matter and/or magnetic minerals, in turn can be correlated in detail to global climate archives such as the oxygen isotope records from Greenland ice cores and marine sediments, respectively. Thus, the sedimentary sequence recovered from Lake El’gygytgyn represents the longest continuous terrestrial climate record now available from the Arctic.