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1.
The Quaternary: its character and definition   总被引:5,自引:0,他引:5  
The Quaternary, is characterised by the development of widespread glaciations in mid-northern latitudes. As a chronostratigraphic term it has attracted vigorous debate. The Quaternao; as accepted by the International Union for Quaternary Research and proposed by the International Commission on Stratigraphy, begins at 2.6 Ma within a 2.8-2.4 Ma interval of profound change in Earth's climate system.  相似文献   

2.
Glacial deposits in locally-glaciated mountain regions are often expressed through their surface form and the study of these deposits constitutes a major branch of geomorphology. Studies of glacial depositional records in mountain areas have often neglected formal stratigraphical procedure resulting in an ad hoc development of quasi-stratigraphical nomenclature. Here, a formal stratigraphical procedure is recommended, since this enables a systematic approach to the subdivision of glacial deposits in mountain regions. Moreover, such an approach facilitates, in some instances, the development of a formal chronostratigraphy that can be compared to regional and global geological time scales. This is important in locally-glaciated mountain regions where glacial deposits represent one of the most important records of cold stage environments. Given that glacial landforms represent a key component of the Quaternary record, maintaining a formal link between geomorphological and geological stratigraphical procedure is a fundamental requirement of a consistent and comparable stratigraphical framework.  相似文献   

3.
4.
唐古拉山地区第四纪冰川作用与冰川特征   总被引:2,自引:2,他引:2  
自中更新世以来,唐古拉山地区发生过3次更新世冰川作用(即昆仑冰期、倒数第二次冰期和末次错冰期)和2次全新世晚期冰进(即新冰期和小冰期冰进).昆仑冰期(最大冰期)发生在中更新世早期(0.80~0.60MaBP),不仅是本区最早的一次冰期,而且也是冰川规模最大的一次冰期,当时的冰川规模比现代冰川大16~18倍;倒数第二次冰期发生在中更新世晚期(0.30~0.135MaBP),比现代冰川大13~15倍;末次冰期发生在晚更新世晚期,应分为末次冰期早冰阶(75.0~58.0kaBP)和晚冰阶(32.0~15.0kaBP,23.0kaBP时达到极盛),但在唐古拉山地区截止目前还未找到早冰阶的冰川遗迹,因此,只对末次冰期的晚冰阶(LMG)进行了探讨.LMG时,冰川规模比现代冰川大10倍;新冰期发生在全新世高温期后,冰碛物的14C测年为(3540±160)aBP,冰川规模略大于现代冰川;小冰期发生在15~1世纪,冰川规模已接近于现代冰川.由于青藏高原的上升,对高原腹部地区引起的干旱化过程和水分严重不足,使唐古拉山地区的冰川自昆仑冰期以来,冰川规模一次比一次明显的减小.  相似文献   

5.
湖南浏阳大围山第四纪冰川地质自1970年代发现以来,对大围山第四纪冰川遗迹特征及形成条件还没有过系统论述。根据以往资料并结合实地考察结果,得出大围山第四纪冰川地质遗迹特征,并对其成因进行初步探讨。  相似文献   

6.
韩同林 《地球学报》1995,16(1):107-110
西伯利亚含盐地位于西伯利亚地台。含钾盐系属下寒武统安加拉组,岩盐层总厚600余米,钾盐层厚70-150m,共有钾石盐岩和钾石盐-光卤石岩6层。钾石盐层中KCl含量达35%-45%,MgCl2和水下溶物含量均小于1%,含盐盆地四周以堡礁带和陆岛与广海相隔,含钾坳陷处于地台上坳陷最深部位。  相似文献   

7.
张通  效存德  秦翔  侯典炯  丁明虎 《冰川冻土》2012,34(5):1059-1066
冰川地形特征的研究是构建冰川流动模型的基础. 根据探地雷达获取的冰川厚度数据(2009年)和1∶5万地形图(1974年), 得到沿珠穆朗玛峰东绒布冰川主流线的冰厚度分布以及5条冰川槽谷的形态特征. 结果表明: 沿东绒布冰川主流线的平均表面坡度约为0.08, 平均厚度约为190 m, 最大厚度约为320 m (海拔6 300 m); 在1974-2009年间沿冰川主流线冰厚度平均减薄约30 m; 东绒布冰川表碛覆盖区与白冰区尚未分离, 目前很可能是一条停滞冰川, 冰川末端位于海拔5 540 m附近(下游方向); 东绒布冰川槽谷形态接近于V型, 而不是U型(b指数变化范围约为0.7~1.3).  相似文献   

8.
秦大河  姚檀栋 《冰川冻土》2011,33(2):223-226
我国杰出的地理学家、冰川学家、中国共产党优秀党员、中国科学院院士、中国现代冰川科学的开拓者和奠基人施雅风先生,因病医治无效,于2011年2月13日18时35分在江苏省人民医院不幸逝世,享年93岁.施雅风先生是江苏海门人,生于1919年3月21日.1942年毕业于浙江大学史地系,  相似文献   

9.
Dust is important in the Earth environment system. However; the role of dust in climate change remains largely unknown. A better understanding of the temporal and spatial variability of the dust accumulation in Asia forms an important step towards establishing the link between dust deposition and climate change. Here, a summary is given for the timing of the onset and expansion of loess deposition in Asia beginning in the early, Miocene. Recent progress on some aspects of loess chronology and palaeoenvironmental reconstruction is also reviewed.  相似文献   

10.
云南大理点苍山是大理冰期的命名地,保存有确切的末次冰期冰川作用遗迹.对点苍山冰碛物石英砂进行了扫描电镜形态特征分析,获得了其石英砂形态特征及其频率,并在冰川成因的典型特征的频率上取得了新的认识.扫描电镜分析表明,点苍山冰碛物石英砂形态特征主要为:石英砂形状主要为次棱角状、尖棱角状和多棱角状,边缘多可见次棱脊和棱脊磨损,表面起伏度高;机械特征主要有贝壳状断口、平行解理面、裂隙、粘附碎片、擦痕、机械V形坑;化学特征主要有蚀坑和蚀缝、蜂窝状溶蚀表面、无定形硅沉淀和硅质薄膜.在石英砂表面与冰川作用密切相关的擦痕的频率为8%~32%;粘附碎片的频率为16%~40%;裂隙的频率为12%~32%.通过对点苍山冰碛物的石英砂扫描电镜分析,得出该第四纪海洋性冰斗冰川和悬冰川的石英砂形态特征及其频率.该冰碛物石英砂原始形态特征明显,机械特征频率不高,是近源堆积的冰碛物石英砂的典型形态特征.  相似文献   

11.
释光测年是可对冰川地貌进行直接定年的一种测年技术,已被广泛应用于冰川沉积测年中,推动了第四纪冰川研究的深入发展。但冰川沉积释光测年还没有达到标准化的程度,实际应用中仍有不少问题需要探究,其中最受关注的是冰川沉积物释光信号晒退不完全的问题,即样品在埋藏前因曝光机会有限导致信号没有归零或仅部分归零。冰川沉积释光信号晒退程度与地貌部位和沉积环境密切相关。冰川沉积释光采样需注意几个方面:(1)详细的地貌学和沉积学调查及对采样点的选择;(2)较适合释光测年的冰水沉积和冰缘风成沉积采集及其与冰川作用期次的联系;(3)冰碛夹层中的冰水砂透镜体的选取;(4)冰碛垄采样时垂直与水平方向上的考量;(5)岩石释光测年的发展使砾石成为当前第四纪冰川释光测年采样的一种选择。室内进行释光等效剂量测试时,也有几个关键的选择:(1)粗颗粒石英光释光测年是末次冰期以来冰川作用的首选方法;(2)如果样品年代老于石英测年上限,或者石英不适合测试,则可考虑钾长石后红外高温释光测年方法;(3)单颗粒、小测片和岩石释光埋藏测年技术可以鉴别样品的晒退情况,是目前最适合冰川沉积释光测年的几种选择;(4)如有条件,尝试用不同矿物、不同粒径、不同方法进行测试对比和交叉检验。要获得第四纪冰川释光测年的最佳年代学结果,地貌学、沉积学和年代学的结合是非常必要的。  相似文献   

12.
This paper presents the first release of an Informational System(IS)devoted to the systematic collection of all available data relating to Pliocene-Quaternary faults in southern East Siberia,their critical analysis and their seismotectonic parameterization.The final goal of this project is to form a new base for improving the assessment of seismic hazard and other natural processes associated with crustal deformation.The presented IS has been exploited to create a relational database of active and conditionally active faults in southern East Siberia(between 100°-114° E and 50°-57° N)whose central sector is characterized by the highly seismic Baikal rift zone.The information within the database for each fault segment is organized as distinct but intercorrelated sections(tables,texts and pictures,etc.)and can be easily visualized as HTML pages in offline browsing.The preliminary version of the database distributed free on disk already highlights the general fault pattern showing that the Holocene and historical activity is quite uniform and dominated by NE-SW and nearly E-W trending faults;the former with a prevailing dip-slip normal kinematics,while the latter structures are left-lateral strike-slip and oblique-slip(with different proportion of left-lateral and normal fault slip components).These faults are mainly concentrated along the borders of the rift basins and are the main sources of moderate-to-strong(M≥5.5)earthquakes on the southern sectors of East Siberia in recent times.As a whole,based on analyzing the diverse fault kinematics and their variable spatial distribution with respect to the overall pattern of the tectonic structures formed and/or activated during the late Pliocene-Quaternary,we conclude they were generated under a regional stress field mainly characterized by a relatively uniform NW-SE tension,but strongly influenced by the irregular hard boundary of the old Siberian craton.The obtained inferences are in an agreement with the existing models of the development of  相似文献   

13.
东北是否发育第四纪冰川及其范围、性质与冰期问题,始终没有定论。在对长白山及大兴安岭冰川遗迹厘定基础上,进行了专项调查,并采用地理信息系统(GIS)、遥感(RS)及全球定位系统(GPS)的3S技术,采取钻探测图、孢粉、泥砾粒度与渗透性分析及14C定年等方法,在长白山及大兴安岭发现了冰蚀谷及泥砾堆积等新的冰川遗迹,进一步肯定了两座山地第四纪冰川的存在及其多期性。在小兴安岭首次发现冰蚀岩墙等冰川遗迹,填补了研究空白,证明小兴安岭也曾发育第四纪冰川。综合多种信息,确定长白山与大兴安岭分别有4次冰期和3次间冰期,小兴安岭至少有1次冰期。最后构建了可以与国际对比的冰期序列,重建了区域第四纪冰川环境演化模式:早更新世早期冷干,中晚期偏暖湿;中更新世早期冷湿,中晚期暖湿;晚更新世早期冷稍湿,中期暖湿,晚期冷干。  相似文献   

14.
The Huanghuachang section near Yichang, southern China meets the requirements of Global Stratotype Section and Point (GSSP) for the base of the Middle Ordovician Series and the yet-to-be-named third stage of the Ordovician System (or lower stage of Middle Ordovician Series). The conodont succession at the section is complete across the Lower to Middle Ordovician series boundary and several excellent phylogenetic lineages of Baltoniodus, Trapezognathus, Periodon, and Microzarkodina are represented. The definition of the base of the Middle Ordovician is proposed to be the first appearance datum (FAD) of Baltoniodus? triangularis in the section. It is followed closely by the FAD of Microzarkodina flabellum, which is taken as a reasonable proxy for the boundary. This level approximates the boundary between the lower and upper intervals of the Azygograptus suecicus graptolite Biozone, and nearly coincides with the base of the Belonechitina henryi chitinozoan Biozone.The proposed GSSP for the base of the international Middle Ordovician Series is located in a roadside exposure at the base of Bed (SHod) 16, 10.57 m above the base of the Dawan Formation in the measured Huanghuachang section near Yichang City, southern China. The same faunal succession is also recorded from the Chenjiahe (formerly Daping) section, 5 km to the north of the Huanghuachang section. The proposed boundary horizon can be recognized and correlated globally with high precision in both relatively shallow-water carbonate facies as well as in deep-water graptolite facies.  相似文献   

15.
广西第四纪水川遗迹之初步观察   总被引:1,自引:0,他引:1  
孙殿卿  徐煜坚 《地质论评》1944,9(Z2):171-200
  相似文献   

16.
1934年,李四光来到江西庐山,看着眼前完美的U型谷、冰擦痕和冰臼,他彻底地被震撼了。这,就是存在了至少50万年的第四纪冰川啊。而在20世纪初,一些外国专家断言“中国绝不可能有第四纪冰川遗迹”。  相似文献   

17.
孙殿卿  徐煜坚 《地质论评》1946,11(Z1):127-132
关于广西第四纪冰川遗迹,承丁骕先生再为讨论,不但论?问题本身,并且还告诉我们对于一个问题如何看法及一个科学论文如何写法。在此必须声明者,我们一点没有轻视别人的  相似文献   

18.
论广西第四纪冰流遗迹   总被引:2,自引:1,他引:1  
丁骕 《地质论评》1945,10(Z1):55-58
迩来冰川遗迹,时有发现,但因此种现象在我国尚属稀见,不免有见仁见智之岐,近读论评九卷三四合期孙殿卿、徐煜坚二先生所著广西第四纪冰川遗迹之文後,以文中资料格於印刷,未能应有尽有,自不无疑窦之处。骕未亲历其境所疑容有未当,但仍述出之者,在求二先生便事实更为明晰,俾同好由  相似文献   

19.
周口店第四纪冰川现象的观察   总被引:2,自引:0,他引:2  
一、引言北京西山巍然岫立于华北平原的两边,远望好像一排断崖突起。但细观之,山前和真正大平原的分界处,并非截然高下断割,其间还有隐约在望而行列不整的一群起伏无常的矮低丘陵,盘桓曲绕于大山之前和平原的边际。再注目眺望西山的内部,其形势也很复杂;有些部分是秃兀圆调的岭头;有的是锯齿(山敖)牙的脊背;有的是突然崛起的孤峰;又有峭壁危崖环抱的斗窟和潭涧。此外还有陡坡、梯阶、悬谷、危崖等和直沟、幽谷错综其间。各种山形或宽、或窄、或大、或小、或险、或夷无不随其  相似文献   

20.
沈永平 《冰川冻土》2011,33(6):1444-1446
由施雅风先生主编,赵井东、王杰副主编,14位主要参编者共同撰写的《中国第四纪冰川新论》(New Understanding of Quaternary Glaciations in China)专著,已于2011年6月由上海科学普及出版社出版发行.全书为16开全彩色铜版纸精装本  相似文献   

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