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| 1 | 古环境中沉积物粒度组分分离的数学方法及其应用显示文摘陆相沉积物一般由多个粒度组分叠加组成,根据粒度分布曲线的特征可确定组分数、分布类型以及设定粒度分布函数,用设定的分布函数对实测粒度数据拟合可计算出函数的各参数,并获得各组分的百分比和分布函数,从而从数字特征上分离各组分。对流水和风成沉积物研究表明,河流沉积物由细粉砂级悬移组分和中砂至细砂级跃移组分叠加组成;封闭湖的碎屑沉积物主要是降水形成的地表径流搬运的细粉砂级悬移组分;风成砂由高度分选的近源跃移砂组分与细粒大气背景粉尘叠加组成;黄土由低空近源的悬移粉砂组分与高空运源悬移细粒组分叠加组成;北太平洋粉尘只有高空西风搬运的悬移细粒组分,该组分的粒度在中国沙漠、黄土高原和北太平洋的风成物中表现出一致性和成因上的内在联系,是该系统中高空悬移并分散于大气中的背景粉尘。 | 孙东怀 安芷生 苏瑞侠 吴锡浩 王苏民 孙千里 David Rea Jan Bloemendal | 2001 | 自然科学进展(国家重点实验室通讯)2001，11，3： | 119 |
| 2 | 磁赤铁矿的几种类型与特点分析显示文摘随着环境磁学的广泛开展和应用,最近20年来磁赤铁矿(γ-Fe2O3)被人们所日益熟悉.现在它已经被发现是一种地表十分常见的矿物,与磁铁矿常常相伴随,是氧化透水通气环境的很好指示矿物.它也是制造音乐和录像磁带的重要磁性材料,在工业有很广泛的用途.磁赤铁矿的人工合成一般由磁铁矿通过在低于300℃的氧化环境中加热几个小时甚至几天时间来形成.它受热不稳定而产生化学变化的磁学性质是其重要特点,即加热到250℃之后该矿物一般就会被不同程度转变成为赤铁矿.因此实际上无法测量其居里点.后来对人工合成磁赤铁矿样品研究进一步发现,该矿物受热可以部分热稳定,居里温度约为645℃.本文通过不同粒度人工磁铁矿系列样品进行热磁测量实验时发现,超细粒级(假单畴(PSD)和多畴(MD)细粒)磁铁矿在快速加热过程中,形成了完全热稳定的磁赤铁矿.而且,用同样的样品在另外加热炉中快速加热到700℃高温,并且在该温度停留10min,然后冷却下来,也可以达到相同的效果.即由此两个过程形成的磁赤铁矿,再从室温加到700℃的居里温度测量过程几乎达到百分之百可逆,即完全对热稳定性特点.我们用X衍射和穆斯堡尔谱技术来鉴定和确认加热前的磁铁矿和快速加热形成的磁赤铁矿(和赤铁矿),并且比较其磁铁矿的磁滞迴线、高温磁化强度、低温热退磁和低温磁化率特性,结果表明,这种过程通过超细磁铁矿加热快速氧化形成完全可逆具有热稳定性质的磁赤铁矿,可能暗示着在某些加热环境形成的磁赤铁矿也可能携带热剩磁.根据磁赤铁矿是否受热不稳定及其表现形式,将它详细分成4种类型探讨分析.受热后部分稳定和完全稳定的磁赤铁矿应当具备携带热剩磁的能力.人工合成磁赤铁矿的温度与其反应时间可能有个互补关系.磁赤铁受热后稳定与否可能与多种因素有关,如受纯度大小、受热温度高低和时间长短等影响,粒度大小可能也是重要因素之一.磁赤铁矿可能如同磁铁矿,也有不同粒级超顺磁(SP)、单畴(SD)和MD对应着不同的磁学特点.细粒PSD氧化的人工磁铁矿在低温磁学测量显示为Verwey转换被'抑制'的现象,其根本原因可能是,氧化后磁铁矿的内核直径实际上已经达到或者接近该矿物的SD粒径,所以它的Verwey转换显得被'抑制'. | 刘秀铭 John SHAW 蒋建中 Jan BLOEMENDAL Paul HESSE Tim ROLPH 毛学刚 | 2010 | 中国科学:地球科学2010，40，5： | 20 |
| 3 | Analysis on variety and characteristics of maghemite显示文摘Maghemite (γ-Fe2O3) is a very common mineral at the earth’s surface and also an important material for making music and video tapes. Maghemite is usually synthesized from magnetite under oxidizing conditions after a few hours or a few days below a temperature of 300°C. The magnetic property of thermal instability and the chemical action after heating is an important character for maghemite. That is, it will become hematite in certain proportion after being heated above 250°C. Maghemite is therefore actually unable to have its Curie temperature measured. But late using synthetic sample, maghemite was further found partially thermal stable with a measurable Curie temperature ~645°C. During our thermally magnetic experiments for a set of synthetic magnetite, we found that extra fined grain size (pseudo single domain (PSD) and small multi-domain (MD), mainly 1-10 μm) magnetite was formed to a completely thermally stable maghemite. This maghemite can also be produced by heating the same powder up to 700°C in an oven and keeping this temperature for 10 min, then cooling it down. When the generated maghemite by these two ways is heated from room temperature to 700°C, it shows almost fully reversible, or thermally stable. We used X-ray powder diffraction and Mssbauer spectroscopy to confirm the identity of this maghemite and compared its magnetic hysteresis, high temperature magnetization, low temperature thermal demagnetization, and low temperature susceptibility with those of the original preheated magnetite. Such quickly oxidized maghemite by heating to high temperature implies some types of maghemite formed in certain natural condition can carry a thermal remnant magnetization (TRM). Four types of maghemite were characterized and discussed according to their thermal stability. Among them, partially stable and fully thermally stable maghemite after heating should possess capability of carrying TRM. There is possibly a compensation of synthetizing maghemite between heating temperature and heating duration. The thermal stability of maghemite may be affected by a few factors, such as its purity (stoichiometry), heating temperature and duration. The grain size may be one of important factors. Maghemite might be similar to magnetite, having various magnetic properties corresponding to its grain size categories such as superparamagnetic (SP), single domain (SD) and MD. Low temperature measurement for PSD fine grain of synthetic magnetite shows a phenomenon of Verwey transition 'suppressed', its fundamental causes could be that the core diameter of oxidized magnetite is actually reach or approach SD size, so that its Verwey transition is shown 'suppressed'. | SHAW John BLOEMENDAL Jan HESSE Paul ROLPH Tim | 2010 | Science China Earth Sciences2010，53，8： | 3 |
| 4 | An as sessment of magnetic and geochemical indicators of weathe ring and pedogenesis at two contrasting sites on the Chinese Loess plateau显示文摘 | Jan Bloemendal LIU Xiumin SUN Youbin | 2008 | Palaeogeography Palaeoclimatology Palaeoecology2008，257，： | 1 |
| 5 | Identification of Greigite in the Pliocene Sediments of Qinghai Lake and Its Geological Significance显示文摘Objective The Qinghai Lake in North China is the largest interior plateau lake in Central Asia,and is sensitive to climate change and the environmental effects of Tibetan Plateau uplift.An almost continuous 626 m long sediment core was drilled in an in-filled part of the southern lake basin in the Scientific Drilling at Qinghai Lake. | FU Chaofeng Jan BLOEMENDAL QIANG Xiaoke Mimi J.HILL AN Zhisheng | 2016 | Acta Geologica Sinica(English Edition)2016，90，6： | 1 |
| 6 | Hydrological evolution during the last 15<ce:hsp sp='0.25'/>kyr in the Tso Kar lake basin (Ladakh, India), derived from geomorphological, sedimentological and palynological records显示文摘 | Bernd Wünnemann Dieter Demske Pavel Tarasov Bahadur S. Kotlia Christian Reinhardt Jan Bloemendal Bernhard Diekmann Kai Hartmann Joachim Krois Frank Riedel Nidhi Arya | 2010 | Quaternary Science Reviews2010，，9： | 1 |
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