中原邙山黄土与末次间冰期以来古季风特征

中原邙山赵下峪剖面出露S10以上黄土地层,厚度大于172.1m。末次间冰期S1古土壤厚15.7m,末次冰期L1黄土厚达77.3m,其中晚冰阶L1LL1黄土、间冰阶L1SS1古土壤和早冰阶L1LL2黄土分别厚41.6m、13.2 m和22.5 m。邙山黄土是厚度最大的晚更新世黄土地层剖面之一,记录了丰富的气候环境变化信息。用SPECMAP氧同位素曲线确定的阶段界限的日历年龄为标定点和磁化率年龄模式,获得相应的时间标尺,据以计算出S2以上各层段的平均沉积速率和分辨率。邙山黄土倒数第二间冰期以来不同冰期或冰阶与间冰期或冰阶的粒度、平均沉积速率和分辨率有很大的差异,其中以末次冰期晚冰阶L1LL1黄土的平均沉积速率为最高,达3.45 mm／a,而末次问冰期S1古土壤的沉积速率亦高达0.28 mm／a。本文主要根据赵下峪剖面的磁化率和>45μm粗颗粒含量变化曲线,并与格陵兰GRIP冰心和深海SPECMAP氧同位素曲线对比,讨论末次间冰期以来古季风特征及其相互关系。     

川西漳腊黄土地层与气候变化

川西高原风成黄土广泛分布,其中漳腊盆地黄土剖面厚约9.5 m。根据磁化率、粒度和地层特征,并通过与金川黄土和甘孜黄土剖面的对比,可将漳腊黄土地层划分为冰后期S0古土壤、末次冰期L1复合黄土、末次间冰期S1复合古土壤、倒数第二冰期L2黄土等4个地层单位,其中L1复合黄土可细分为L1L1、L1S1、L1L2、L1S2和L1...     

四川金川黄土地层

马厂剖面中黄土-古土壤序列共厚15．5m,根据岩性、磁性地层特征、磁化率、CaCO3含量和光释光测年结果,将金川黄土划分为冰后期S0古土壤,末次冰期1-1黄土,末次间冰期S1古土壤、倒数第二冰期L2黄土和倒数第二间冰期S2古土壤等5个地层单位;其中,S1复合型古土壤又可细分为S1LL1、S1LL2黄土和S1SS1、S1SS2和S1SS3古土壤等5个次级地层单位。金川黄土沉积始于中更新世晚期,其底界的年龄人致为200ka BP,其磁化率变化反映了最近200ka来的高原季风演化和气候环境变迁,5个磁化率高值段指示了5个夏季风环流增强的时段,4个磁化率低值段则代表了4次夏季风减弱的时期。     

渭南黄土剖面十五万年以来的主要地层界线和气候事件──年代学方面的证据

本文在渭南黄土剖面所测得的年龄结果和时间标尺研究的基础上，结合粒度、磁化率等气候曲线的分析，对该剖面十五万年以来一些主要地层界线和气候事件的年龄进行了初步讨论，结果如下：１)Ｓ１／Ｌ２界线位于剖面１１８０ｃｍ处，从时间标尺上可知其年龄为１２８８００ａＢ．ｐ．，同末次间冰期起始的年龄相一致；２)Ｌ１／Ｓ１的地层界线年龄为７４２２０ａＢ．Ｐ．，同ＳＰＥＣＭＡＰ曲线中末次间冰期的结束年龄相吻合；３)渭南剖面所指示的末次盛冰期约在２００００～１８０００ａＢ．Ｐ．之间；４)在２００００～１８０００ａＢ．Ｐ．之间的末次盛冰期，有一段不足１０００ａ的快速堆积期，其堆积速率是中国黄土平均堆积速率的１０倍以上。     

渭南黄土剖面十五万年以来的主要地层界线和气候事件──年代学方面的证据

本文在渭南黄土剖面所测得的年龄结果和时间标尺研究的基础上，结合粒度、磁化率等气候曲线的分析，对该剖面十五万年以来一些主要地层界线和气候事件的年龄进行了初步讨论，结果如下：１）Ｓ１／Ｌ２界线位于剖面１１８０ｃｍ处，从时间标尺上可知其年龄为１２８８００ａＢ．ｐ．，同末次间冰期起始的年龄相一致；２）Ｌ１／Ｓ１的地层界线年龄为７４２２０ａＢ．Ｐ．，同ＳＰＥＣＭＡＰ曲线中末次间冰期的结束年龄相吻合；３）渭南剖面所指示的末次盛冰期约在２００００～１８０００ａＢ．Ｐ．之间；４）在２００００～１８０００ａＢ．Ｐ．之间的末次盛冰期，有一段不足１０００ａ的快速堆积期，其堆积速率是中国黄土平均堆积速率的１０倍以上。     

末次间冰期以来渭南黄土剖面高分辨率古气候时间标尺

利用细颗粒热释光技术对渭南剖面重要地层界线处的 7个样品进行了年龄测定 ,并在此基础上 ,结合已发表数据利用多项式回归方法建立了渭南剖面高分辨率的古气候时间标尺 ,其中S0 /L1- 1,L1- 1/L1- 2 ,L1- 4/L1- 5 ,L1- 5 /S1,S1/L2的界线年龄分别为 1.1,2 .5 ,5 .1,7.6 ,12 .8ka ,除了L1- 4/L1- 5的界线年龄与氧同位素 3阶段的起始年龄差距较大之外 ,它们与SPECMAP深海氧同位素 5以上各阶段的界线年龄可进行较好的对比 ,而L1- 4/L1- 5的界线年龄与北太平洋风尘记录的氧同位素年龄却有很好的一致性 .     

浑善达克沙地南缘晚更新世黄土-古土壤序列的高分辨率磁性气候记录

浑善达克沙地处于季风边缘区,目前对该区域末次间冰期以来的古气候演化历史及其动力学机制尚不清楚。文章以浑善达克沙地南缘山间低洼地带北沟剖面总厚度4.72 m(未见底)的黄土-古土壤序列为研究对象,开展了光释光测年和精细的岩石磁学、环境磁学、地球化学和漫反射光谱分析。结果表明:1)该剖面记录了末次间冰期以来完整的风成堆积历史,并通过东亚夏季风指标(Rb/Sr及χARM/χ)与深海氧同位素曲线的对比建立了13万年来该黄土-古土壤序列精细的年龄模式;2)在黄土高原上常规的用来指示成壤强度和夏季风强度的磁参数并不完全适用于干旱-半干旱地区(400 mm等降水线附近)的风成黄土,而地球化学指标在指示季风边缘区的地球化学风化过程上表现出一定的合理性,北沟剖面复杂的磁信号可能是对末次冰期季风边缘区显著减弱的夏季风的阈值响应;3)在末次间冰期东亚夏季风可以延伸到内蒙古中东部,北沟剖面记录了浑善达克沙地南缘末次间冰期以来区域古季风的演化历史。     

河南邙山晚更新世黄土的环境记录

数十年来,黄土高原的古环境研究受到了高度重视并取得重大进展,但对其东南部的研究却相对较薄弱。位于黄土高原东南边缘的邙山塬因受气候、构造等营力的交互作用而发育巨厚的黄土地层,记录了东亚古环境演变的详细信息。笔者近年来对邙山黄土地层进行了深入研究,以黄土高原经典的洛川剖面为参照,对位于河南省荥阳市北邙乡刘沟村的赵下峪剖面进行了详细划分。邙山黄土S10以上黄土-古土壤序列,总厚度达172.1m,其中末次间冰期S1古土壤厚15.7m,末次冰期L1黄土厚77.3m,是由早冰阶L1LL1黄土、间冰阶L1SS1古土壤和晚冰阶L1LL2黄土组成的复合黄土     

中原邙山黄土地层

位于黄土高原与华北平原过渡带上的中原黄土地层,以邙山赵下峪剖面为其典型代表。据光释光和热释光测年及磁性地层研究结果,该剖面从邙山塬面至黄河河床出露S₀-S₁₀黄土-古土壤序列,总厚度172.1m,B/M界线记录于S₈古土壤层顶部,以厚层晚更新世S₁古土壤(15.7m)和巨厚L₁黄土(77.3m)为其特色。赵下峪剖面上末次间冰期以来的平均沉积速率明显增大,其中以末次冰期晚冰阶L₁LL₁黄土的沉积速率最大,高达34.5mm/a。在邙山黄土堆积过程中,倒数第二冰期末(相当于L₂顶部),约150ka B P,发生了风尘沉积速率的突变,其原因是此时黄河贯通三门峡东流,给风尘源区带来丰富的物质。同时赵下峪剖面的磁化率曲线所示,黄土-古土壤的磁化率强弱,并不简单地反映夏季风强度,也要受到沉积速率变化的影响。      

青藏高原黄土堆积典型元素相对含量变化与古气候意义

青藏高原东北部黄土分布广厚,较好的记录了第四纪古气候变化的信息。为了从地球化学的角度寻找能更好指示高原气候变化的代用指标,本文对西宁盆地湟水河高级阶地之上的大墩岭黄土剖面顶部末次间冰期以来(S1古土壤层之上)沉积的黄土—古土壤系统取样,并做了易迁移元素(Sr、Ca)与难迁移元素(Rb、Zr、Ti)的含量变化分析。结果发现,水迁移能力差别较大,矿物组成不同的元素(或氧化物)比值Rb/Sr、Ti/Sr、Zr/CaO比较灵敏的指示了高原末次间冰期以来古气候,特别是古降水变化信息,而且其与常用的磁化率指示的中国北方古气候变化及深海沉积氧同…     

Reconstruction of High Resolution Timescale in Weinan Loess Section of Late Quaternary

TheWeinanloesssectionislocatedatNanjiangVillage(34"21'N,lO9"3l'E),YangguoTown,Weinan,ShaanxiProvince,whichisoneofthecontinuousloesssequencedis-coveredofthelasto.l5MaB.P.,whichhassoforbeenthebestdatedbyboththeAMSl4CandTL(Liuetal.,l994),andisusedasastratigraphicstandard.Basedontheorbitaltuningmethod(Dingetal.,l99l)lapreliminaryhighresolu-tiontimescaleofthissectionhasbeenestab1ished(Liuetal.,l995).Howeverlinrecentyears,increasingeffortshavebeenmadetodocumentsub-orbitalscaleclimaticvariat…     

Luminescence dating of loessic sediments from the Loess plateau, China

Loess/palaeosol sequences from the Loess plateau in China were investigated by combined infrared optically stimulated luminescence (IRSL) and thermoluminescence (TL) dating techniques in order to study the luminescence properties of the loessic sediments and to provide a direct chronological link for correlation and position of the last interglacial soil in Central Asia and the Loess plateau in China. Sensitivity changes were found for all samples through artificial bleaching of the samples. The greatest sensitivity changes, of up to 50%, were found for very old loess samples designated to be older than the Matu-yama/Brunhes magnetic boundary and hence older than 788,000±1,800 years. The upper dating limit, as investigated by the very old loess samples, ranges from 250,000 to 300,000 years, if the TL additive dose method is applied. The chronological position of the last interglacial soil S1 at the section near Lanzhou indicates luminescence age estimates ranging from 82,000 to 75,000 years for the marine-isotope stage 5 to 4 transition. However, the loess from below S1 yielded luminescence age estimates between 153,200±14,200 and 110,100±20,100 years for TL and IRSL additive dose methods, respectively. Thus, a direct correlation between the S1 and the first intercalated pedocomplex PC1 in Central Asia is most likely. Received: 31 March 1998 / Accepted: 25 October 1998     

早期智人古老型——智人大荔亚种的年代

文中综合研究了有关大荔人头骨化石的产出地层、伴随出现的古生物化石、古气候演变的条件等 ,结合用热释光技术测定地层年代这一基本思路 ,将大荔人的生存年代确定为不老于 30万年。     

Thermoluminescence dating of coarse-grain quartz from the Malan loess at Zhaitang section, China

Thermoluminescence (TL) ages were obtained for five loess samples taken from the Zhaitang section near Beijing, China, using the coarse-grain quartz technique. The paleodose values have been determined by the method of total sample bleaching and regeneration of the TL growth curve. The method appears to be suitable for the age determination of loess samples up to about 150,000 yr where the annual dose-rate values are of the order 3–4 mGy/yr. This limit is a function of the total accumulated dose. The ages are in good agreement with those obtained by a fine-grain TL technique and are consistent with geological and geomagnetostratigraphic evidence.     

Luminescence chronology of late pleistocene loess-paleosol and tephra sequences near Fairbanks, Alaska

Thermoluminescence (TL) and infrared-stimulated luminescence (IRSL) sediment-dating methods have been applied to paleosol- and tephra-bearing loess sequences younger than marine oxygen isotope stage (MIS) 7 at three important sites. TL ages indicate the development of significant paleosols ∼75,000 and ∼30,000 yr ago in the loess sequence at the Gold Hill site. Relatively minor soil development occurred ∼70,000 and ∼48,000 yr ago. Like the ∼75,000-yr-old soil, the 30,000-yr-old soil is apparently of global extent, and consistent in timing with inferred warm intervals elsewhere (e.g., Greenland, Europe, western and central China). At Birch Hill, replicate TL dating of primary loess combined with two earlier TL results from the same site, and with an earlier mean fission-track-glass-shard age of 140,000 ± 10,000 yr for the associated Old Crow tephra, yield a more precise numeric age of 142,300 ± 6600 yr for this Alaska/Yukon chronostratigraphic marker ash bed. Three of the TL ages at the Halfway House site are difficult to interpret, but combined with other evidence, they indicate: (1) the upper 5-6 m of loess from Halfway House is not part of the Gold Hill Loess (equivalent to pre-MIS 5 age) as long thought by T.L. Péwé, but rather is much younger; (2) the regionally significant variegated tephra, found in the Fairbanks and Klondike areas and previously thought to be older than MIS 5, has an age of 77,800 ± 4100 yr (late MIS 5).     

沉积岩中自生伊利石K-Ar定年研究——存在问题及原因讨论

在浙江长兴煤山全球二叠系一三叠系界线层型剖面中界线附近采集黏土岩样品。对其中的伊利石／蒙皂石成岩间层I／S进行K—Ar测年实验研究，来探讨沉积岩中自生伊利石K—Ar测年在确定沉积地层时代方面的可行性。结果表明，沉积岩中成岩间层I／S的K—Ar年龄在没有碎屑含钾矿物混入的情况下，比其对应的地层时代要年轻，其原因主要有两条，一是因为泥岩中的自生伊利石来自于蒙皂石的伊利石化，而蒙皂石的伊利石化受很多因素控制，需要一定的时间才能完成；另一原因是由于蒙皂石伊利石化过程中存在着放射性成因^40Ar的扩散丢失。     

黄土高原黄土地层的对比及细分

将前人对黄土高原黄土地层划分的研究成果进行全面总结、分析,结合洛川、宝鸡、西峰3个经典剖面,利用土壤 地层学、沉积学、磁性地层学、古生物学、年代学、地球化学等研究方法对黄土高原的黄土地层进行详细对比以及进一步 细分。将早、中更新世界线调整为B/M极性倒转开始的对应层位——L9顶部。根据岩性和气候旋回周期的差异性等,将离 石黄土三分,S8/L9作为离石黄土内部划分的一条新界线,S1~L5划分为上离石黄土,S5~S8划分为中离石黄土,L9~L15划分为 下离石黄土。在分析过程中发现关键层位（S0,L1,S1,S5,L9,L15,L33） 的年龄具有差异性。     

TL dating of malan loess in gansu province

TL dating technique is of great advantage for determining the initial time of storing energy (T₀) in an object to be analyzed. The sample is required to have undergone at least one thermal event, permitting all the residual storage to release. As a result, TL dating technique has found wide application in geochronology of pottery. The determination of T₀ of loess is mainly based on the fact that fine particles of which loess is composed will lose their storage in the process of transportation by wind. In our experiment TL dating technique was adopted to determine the ages of fine quartz grains, and the results were corrected for those of shine-fading experiment. TL dating of Malan loess specimens from Mt. Gaolanshan, Liugouhe near Lanzhou, Mt. Qijiadashan in Jingning and Baichaoyuan in Huining gave the age values of 2.6±0.1, 3.6±0,3. 4.7±0.5 and 10.0±0.6×10⁴ yr, respectively. The values indicate that the Malan loess began depositing in Late Pleisotocene, but the initial time and acumulation rate are different under different morphological conditions from place to place.