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1.
对内蒙古呼伦湖盆地扎赉诺尔地区晚第四纪湖泊沉积物进行了沉积学（沉积构造、结构、垂向层序等）和＾１４Ｃ年代地层学研究，并逐层识别出地层剖面的各种沉积相类型，包括开阔湖、近岸带、滨岸沙滩、滨岸沼泽和滨岸沙丘等不同类型沉积，依此恢复了３０ｋａＢ．Ｐ．以来的湖泊演化和湖面波动历史。其中１３￣１１ｋａＢ．Ｐ．是湖面最高时期；１０．９￣１０．６ｋａＢ．Ｐ．的低湖面可能与新仙女木事件有关。 相似文献
2.
１９９２年１０月,在江汉平原沔城钻探,取得总长５６．１８ｍ的柱状岩芯。根据Ｍ１孔湖泊沉积岩性及所含文化遗物,＾１４Ｃ年代测定,以及深受人类活动影响的气候与环境指标如孢粉,频率磁化率,化学元素Ｐ等分析,结合该区文化遗址的时空分布,揭示了沔城地区中晚全新世人类活动的时间序列及与古气候,古环境的关系：６．７－３．５ｋａＢＰ该区气候温暖湿润,为河间洼地和浅湖环境;２．５－１．７ｋａＢＰ湖泊稳定,均无人类居 相似文献
3.
运用最大熵谱方法，对若尔盖深钻８００ｋａＢ．Ｐ．以来有机碳同位素序列进行了频谱分析，结果表明；１）０－８００ｋａＢ．Ｐ该地区存在有准８０ｋａ，６０ｋａ，４１ｋａ和２０ｋａ的周期，其中４１ｋａ和２０ｋａ的周期来米氏计算的地倾角及岁差周期较一致；２）０－４８０ｋａＢ．Ｐ，以１００ｋａ周期为主，其次为４１ｋａ和２０ｋａ，与米氏计算的各天文周期相一致；３）４８０－８００ｋａＢ．Ｐ．出现有１１５ｋａ，３３ｋ 相似文献
4.
根据ＤＣ９３－１孔孢粉组合、总有机碳（ＴＯＣ）、总氮（ＴＮ）、碳氮比（Ｃ／Ｎ）、有机碳同位素δ＾１３Ｃｒｏｇ、磁化率（ｘ）、频率磁化率（ｘｆｄ）等资料,结合＾１４Ｃ、＾２１０Ｐｂ和＾１３７Ｃｓ测年,汗池地区１３ｋａ以来的古环境演化历史经历了以下几个阶段：１３－１０．２ｋａＢＰ,气候偏凉湿,湖水深度不大;１０．２－７．５ｋａＢＰ,气候向暖湿过渡,湖水渐深：７．５－４．０ｋａＢＰ,气候暖湿,水热条件达 相似文献
5.
依据Ｍ１孔孢粉组合特征及＾１４Ｃ年龄数据,结合孢粉数理统计分析,重建了江汉平原沔阳地区一万多年来的古季风气候变迁序列。研究结果表明,该区气候经历了六个阶段的变化。６．７－４．４ｋａＢＰ间。为水热配置最佳时期。夏季降水显著增多;３．９－１２．７ｋａＢＰ,气温有所下降,但有效湿度很高,为古云楚泽扩张时期,其湿度的增加既受锋面降水带的影响,同时恙长江南移,河床迅速抬高有关。约６ｋａＢＰ后,人类活动在本区 相似文献
6.
通过云南鹤庆钻孔（ＨＱ孔）顶部８．１１ｍ岩芯剖面样品的多项环境指标的综合分析,重建了云南鹤庆盆地３０ｋａＢＰ以来的古气候环境演化历史。研究表明,该区气候在千年时间尺度上表现为冷湿与暖干组合交替的特点,未次冰盛期,为明显的冷湿环境,表现为最高湖面。盆地于晚冰期,约１４．２ｋａＢＰ始被切开,造成环境指标的大变化;进入全新世后,则以温干环境为主导,出现数次冷事件,手者是与东南季风区刊物比较研究的桥梁。 相似文献
7.
定量化是过去全球气候变化研究的必然趋势，突变事件的诊断是古气候定量化研究中极其重要的过程。本文运用Ｍ－Ｋ法和ｔ检验法对ＲＨ孔有机碳同位素序列进行了气候突变诊断研究。结果发现，近８００ｋａＢＰ来该区气候存在明显的突变，且突变开始于４７０ｋａＢＰ。进一步的研究发现４７０ｋａＢＰ开始的这一气候突变事件与青藏高原的构造隆升有密切的关系。 相似文献
8.
新疆古牧地断裂是一条全新世活动断裂,全新世以来有４ 次明显的断错活动,历次活动的ＴＬ时间分别为１１．０３±０．８９ ｋａＢ．Ｐ．,９．７３±０．７９ ｋａＢ．Ｐ．,８．３２±０．６７ ｋａＢ．Ｐ．和６．８２±０．５４～４．８７±０．３９ ｋａＢ．Ｐ．,断错活动间隔为１．３±０．１～２．０±０．１５ ｋａ。全新世时期累积垂直断距大于５．０３ｍ ,平均活动速率大于０．４１ ｍ ｍ ／ａ 相似文献
9.
本文使用含有陆面过程的９层大气环流谱模式（ＡＧＣＭ＋ＳＳｉＢ）,在地球轨道参数和下垫面边界条件驱动下,对２１ｋａＢＰ的气候进行模拟试验。结果表明,２１ｋａＢＰ时中国东部干旱,西部和青藏高原湿润,全国普遍降温。该模拟结果基本捕捉了由古湖泊资料和孢粉资料重建的气候特征。对模式输出的大气环流场和降水场的分析揭示出,２１ｋａＢＰ东亚夏季风环流明显减弱,而青高原夏季风环流增强;冬季风环流较现在略有增强。该模 相似文献
10.
本从ＰＤＲ－２数字化近源（６．２ｋｍ≤△≤４２ｋｍ）台网记录的丽江余震中初选了７４个地震，初定了震中位置，震中方位角。用相应的台网数据处理技术，研究了丽江地震序列的体波谱。对震级２．５≤Ｍ≤５．７、地震矩２１．４０≤ｌｏｎｇＭ０≤２３．２８的地震，得出了丽江地区地震系列的震源参数；以及Ｐ波、Ｓ波的ｌｏｇＭ０与Ｍｄ的关系式分别为：ｌｏｇＭ０＾ｐ＝０．６２Ｍｄ＋１９．９３；ｌｏｇＭ０＾ｓ＝０．５９Ｍ 相似文献
11.
以内蒙古锡林郭勒盟苏尼特右旗的察干淖尔盐湖为研究对象,利用OSL(Optically Stimulated Luminescence)测年技术和DEM(Digital Elevation Model)数字高程模型,重建湖面波动历史,探讨湖泊形成与环境变化过程.通过对察干淖尔盐湖周边大量的野外考察,发现湖泊周围存在海拔高程为1020、978和973 m的三级古湖岸阶地,其OSL测年结果分别为29.2±1.3、18.4±0.8及8.2 8.0 ka.通过湖岸阶地高程恢复的上述3个时期的古湖面积分别为3600、500和400 km~2.与现今的干旱盐湖景观迥然不同. 相似文献
12.
Two sediment cores, one 396 cm long from west Taihu Lake, another 246 cm long from east Taihu Lake, are interpreted from the analysis of their magnetic susceptibility, total organic carbon, total nitrogen, total pigments, organic carbon isotope, hydrogen index, saturated hydrocarbons, 14C dating and surficial sediment conditions. The west Taihu Lake core is the longest one studied in this lake so far, and has provided us the most complete environmental and climatic information for this lake. The results from the west Taihu lake core indicate that Taihu Lake has undergone the following stages:from ca.14 300 to 13 300 aB.P. Taihu Lake was in low lake-level, and there existed exposed features from the proxies reflecting arid paleoclimate. From ca.13 300 to 12 400 aB.P. an arid transitional stages occurred with a slightly warmer and wetter climate. From ca. 12 400 to 10 900 aB.P. a period of large climatic fluctuation occurred and from 10900-10 000 aB.P. a warm period developed with deep water and strongly reducing sediments. During ca.10 000-7 200aB.P., a cool transitional period alternating with a warm climate occurred. It was warm and wet during 7 200-5 700aB.P.; some proxies changed violently in 5 050aB.P., reflecting obvious changes in material source and a probable interruption of sedimentation. The east Taihu Lake history from ca. 6 550 to 6 450 aBP, the climate was cold and dry, and gradually turned warm and wet in ca. 6 450-6 050 aBP. It was warm and wet in ca. 6 050-5 800 aBP and had a cold tendency in 5 800-ca. 5 000 aBP. An abrupt change occurred at ca. 5 000 aBP, and the lake sediment in the uppmost part was disturbed by wave action indicating shallow water conditions. 相似文献
13.
The systemic analyses have been carried out in this paper to the paleolake shorelines, paleolake sediments and paleoclimatic proxies of 20 lakes, in which there were 12 kaBP dating data on the Tibetan Plateau. The results showed that the paleolake level had apparently risen during 14-11 kaBP, the glaciers melting period, in the Tibetan area and Northwest China. Especially, much more increasing amplitude supplied by thawy glaciers water occurred than in the best period of Holocene. The temperate-humid climate around 12 kaBP appeared in the Tibetan area and even in the whole China. This event may be compared with the Bolling/Allerod warm period which was reflected by Europe and Greenland ice core records. It showed that the B/A event was not a regional one in the North Atlantic area. 相似文献
14.
中国北方季风边缘区的湖泊对环境的反应很敏感,乌拉盖高毕是位于内蒙古高原东北部的一个已干涸的内陆封闭湖泊.研究剖面总厚度为405 cm,根据取得的9个AMS 14C及光释光测年数据,建立了51.9 ka BP以来的年代序列.结合岩性的变化、粒度组分分析、粒度参数(标准偏差、偏度、峰度等)及Rb/Sr比值特征进行了详细的分析,恢复了乌拉盖高毕湖泊沉积记录的5万年来的环境演化过程.将0~405 cm的剖面划分为4个较大的气候阶段:51.9-44.1 ka BP(405~343 cm),气候为干冷期,各环境指标显示为滨湖沉积,湖泊水位较低;44.1-28.5 ka BP(343~130 cm),气候为温湿期,湖泊逐渐扩张,湖泊水位升高;28.5-11.38 ka BP(130~35 cm),气候转冷,湖面萎缩,并在盛冰期出现砂楔,该阶段后期湖泊干涸;11.38 ka BP至今(35~0 cm),气温回升. 相似文献
15.
古昆仑湖位于昆仑山垭口昆仑河谷地,大约在200kaBP前已开始沉积,沉积物为一套灰、灰绿、土黄色粉砂质、砂质粘土,厚约7m.在纳赤台西北剖面5.6-2.4m层段产较多微体化石,介形类有8属12种:Ilyocypris biplicata(Koch),I.bradyi Sars,Eucypris crassa(Mller),E.elliptica(Baird),E.rischtanica Schneider,Candona candida(Mller),Stenocypriscf.major(Baird),Cypridopsis obesa Brady Robertson,Prionocypris gansenensis Huang,Potamocypris villosa(Jurine),P.cf.wolfi Brehm和Limnocythere dubiosa Daday等.轮藻类有Chara aliensis Z.Wang,Chara gansenensis S.Wang和Charasp.根据U系法测年,含化石地层的年龄大约为168-90kaBP,属于倒数第二次冰期至末次间冰期早期.按生物组合和沉积物特征分析,古昆仑湖区在183-90kaBP的环境气候变化大致有两个大的期次、6个小期次:(1)183-130kaBP冷湿期,湖区环境较冷湿,湖泊水质较淡,水温不高.早期(约183-170kaBP),湖面较宽,水体较深,环境动荡,化石贫乏;中期(约170-151.3kaBP),湖面有一定收缩,水质含盐度有所提升,水温仍不高,湖区环境湿度较大;晚期(约151.3-130kaBP),化石贫乏,生态环境、水质条件可能与早期类同.(2)130-90kaBP凉湿期,湖内生态环境较好,生物门类中除介形类外,出现沉水性植物轮藻类,且介形类生物量较前期有很大增加,属种分异度较好.早期(约130-105kaBP),偏冷湿;中期(约105-98kaBP),凉湿,为生物大发展大繁盛时期;晚期(约98-90kaBP),偏凉湿,在98-93kaBP,环境不宜生物生息,化石贫乏;约93-90kaBP,生态环境有所改善,有介形类3属5种,但生物量较小. 相似文献
16.
通过对嘎顺淖尔XK1孔沉积岩芯的岩性特征及多种环境代用指标的综合分析,初步认为:中更新世早中期,29．6 -42．5m(推测时代为距今218．3 kaBP以前),气候温凉偏干,滨湖与洪积相交替;距今218．3-172．8 kaBP气候温凉偏湿, 湖泊面积扩大,以滨浅湖-浅湖沉积为主,并一度出现半深湖环境;距今172．8-93．4 kaBP,沉积环境为湖滨相与洪积相交替,气候特点是冷凉干旱;距今93．4-67．4 kaBP,沉积环境以淡水浅湖为主,夹湖滨相．气候温偏湿;距今67．4-54．0 kaBP ,湖滨相沉积为主,气候温凉偏干;距今54-48．9 kaBP,气候暖湿的浅湖环境,气温较高;距今48．9-42．6 kaBP,凉而且干旱的气候特点,沉积相为湖滨相;42．6-0 kaBP,气候暖湿、凉干交替,浅湖相为主． 相似文献
17.
藏西北结则茶卡湖面到高位湖岸线间湖泊记录发育,沿岸湖积物中3个U系年龄分别为14.2±1.2kaBP、38.0±3.5 kaBP和41.6±3.2 kaBP,6个浅井沉积物中CaO、MgO、NaCl、LiCl、B2O3的含量与沉积物形成时代和环境有一定的关联性.在中更新末期,该湖可能处于高湖位期,随着晚更新世初期以来气候变干,湖面开始下降,湖泊逐渐萎缩,湖水盐度逐渐增加,Ca和Mg含量变高,但在30kaBP左右,气候有过短暂湿润期,湖水出现返淡趋势,之后湖水进一步浓缩,湖水中Na、B、Li含量显著增高,盐湖大约在15kaBP左右形成. 相似文献
18.
青海湖是我国最大的内陆湖泊,流域面积29661km~(2),水面高程超过3000m,受人为活动影响相对较少,基本上还处于半自然状态。水量平衡计算结果表明,有观测资料的近30年来,青海湖处于负平蘅状态,水位下降了2.96m,平均每年下降10.2cm。如果未来湖区的气候大体保持过去的情况,水位将再下降5.8m,经过57年才能平衡。如果考虑“温室效应”所引起的西北地区未来气候变化,水位亦将下降,每年平均下降10.1cm。 相似文献
19.
Since 40 kaBP, the current endorheism on the Tibetan Plateau had experienced at least four lake-explanding events, at 40-28 kaBP, 19-15 kaBP, 13-11 kaBP, 9.0-5.0 kaBP, respectively. The 40-28 kaBP and 9.0-5.0 kaBP lake-expanding events, corresponding to the global warming periods, were mainly determined by the abundant summer monsoon rainfall brought by strong Indian monsoon, aroused by enhanced solar radiation at earth orbital precessional cycle. The 40-28 kaBP lake-expanding event, also called the great lake period or the pan-lake period, for several great lake groups had come into being by the interconnection of the presently isolated and closed lake catchments. The total lake area over the Tibetan Plateau was estimated at least up to 150000 km2, 3.8 times of the present, and the lake supply coefficients were about 3–10. The 9.0-5.0 kaBP lake-expanding, with a total lake area of 68000 km2, less than the above mentioned reflected the Indian monsoon rainfall less than that of 40-28 kaBP. The expanded lakes at 19-15 kaBP and 13-11 kaBP, distributed in these basins with more or less existing glacial, indicated plenty of glacial meltwater discharged to balance evaporation on expansive lake surface. At the same time, the enhanced precipitation by the westerlies at 19-15 kaBP and by Indian monsoon at 13-11 kaBP plays an important role in maintaining the high lake level. Heinrich events greatly affected the evolution of climate system over the Tibetan Plateau, and thus gave a clear boundary of the high lake level change in the late Quaternary. 相似文献
20.
Located at the northeastern margin of the Qinghai-Tibet Plateau (QTP) in the Asian interior, the Lake Qinghai is sensitive to environmental change and thus an outstanding site for studying paleoenvironmental changes. Thick deposits in the Lake Qinghai provide important geological archives for obtaining high-resolution records of continental environmental history. The longest drilling core obtained from the Lake Qinghai, named Erlangjian (ELJ), reached about 1109 m and was investigated to determine its clay mineral assemblage and grain size distributions. Clay mineralogical proxies, including type, composition, and their ratios, as well as the illite crystallinity (KI) and chemical index (CI), in combination with grain size data, were used for reconstructing the history of paleoenvironmental evolution since the late Miocene in the Lake Qinghai Basin. The clay mineral records indicate that the clay mainly comprise detritus originating from peripheral material and has experienced little or no diagenesis. The proportion of authigenic origin was minor. Illite was the most abundant clay mineral, followed by chlorite, kaolinite, and smectite. Variations of clay mineral indexes reflect the cooling and drying trends in the Lake Qinghai region, and the grain size distribution is coincided with the clay minerals indexes. The paleoclimatic evolution of the Lake Qinghai Basin since the late Miocene can be divided into five intervals. The climate was relatively warm and wet in the early of late Miocene, then long-term trends in climate change character display cooling and drying; later in the late Miocene until early Pliocene the climate was in a short relatively warm and humid period; since then the climate was relatively colder and drier. These results also suggest multiple tectonic uplift events in the northeastern QTP. 相似文献
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