A 2500-year sea level change record in Fildes Peninsula, Antarctica

A detailed record of sea level changes during the last 2500 years is preserved in the northernwest coast of Fildes Peninsula in Antarctica. Fourteen marine alga layers were deposited in the beach with an altitude of 2.80 m, and one diatom layer deposited in the ancient lake on the terrace with an altitude of 6.84 m. A radiocarbon age of 695±70 aBP was obtained for the modern marine alga, and the age was used in correction for the carbon reservoir effect of the marine alga. Sea level fell 4.98 m from the 4th century B.C. to the early 13th century, at an average of -0.31 cm/a, then rose about 0.78 m during the early 13th to the middle 18th century, at an average of 0.14 cm/a. It has risen about 0.16 m since the middle 18th century, at an average of 0.07 cm/a.     

华北克拉通恒山地区晚太古代变质火山岩的地球化学特征及构造意义

对恒山地区出露的变质火山岩开展岩相学、地球化学、锆石U-Pb年代学和Hf同位素研究,旨在确定其形成时代,探讨岩石成因及地球动力学意义。锆石U-Pb定年结果表明,这些变质火山岩喷发于新太古代晚期(2508±20Ma)。地球化学分析结果显示,恒山变质火山岩由变质玄武岩和变质玄武安山岩组成,SiO₂(45.51%～62.67%)、FeO_T (4.43%～15.72%)和MgO (3.75%～8.14%)含量变化幅度大,是幔源岩浆经单斜辉石、角闪石和磁铁矿分离结晶的产物。这些变质火山岩富集轻稀土(LREE)和大离子亲石元素(LILE),亏损重稀土(HREE)和高场强元素(HFSE),具有相对高的Th含量和Th/Yb比值,呈现钙碱性岛弧火山岩的特征。结合不相容元素比值Nb/Yb,Zr/Yb和(Nb/La)_N的特点,推测其来源于俯冲带具流体交代特征的富集地幔源区。结合区域构造背景,推断恒山变质火山岩形成于新太古晚期大陆弧环境。     

THE COMPARISON OF LANZHOU LOESS PROFILE WITH VOSTOK ICE CORE IN ANTARCTICA OVER THE LAST GLACIATION CYCLE

Loess near Lanzhou in the late Pleistocene is very sensitive to climatic fluctuations. The Beiyuan terrace profile in Linxia City, of which the curve of susceptibility tallies with the trend of isotopic curves of Vostok 2083 m ice core in Antarctica, is 35m thick. There are five layers of paleosols under Malan loess(L_1). Upper three layers (S_(1-a),S(1-b)and S_(1-c) correspond to three warm stages in last interglaciation, Interstadial of Last Glacial (C stage in Antarctic ice core)was clearly recorded in the Beiyuan profile, in which three layers of paleosols and two of loess were formed. The lowest section of the profile belongs to penultimate glaciation, in which fossils of cold-drought-resistant mammal and mollusc have been discovered.     

后过渡金属催化剂制备烯烃/极性单体共聚物

综述了近年来采用后过渡金属催化剂催化乙烯等α-烯烃与极性单体共聚合的研究进展。     

A new Euprox from the Late Miocene of Yuanmou,Yunnan Province,China,with interpretation of its paleoenvironment

The Yuanmou Basin of Yunnan Province is a hotspot for the research of early homind evolution and its environmental background.During the implementation of the Program“Research of the Origin and Evolution of Early Man and Its Environmental Baqckground” from 1998 to 2001,a huge quantity of hominoid and mammal fossils were collected.The present report systematically describes an Euprox robustus sp.nov.identified during the recent laboratory work on the collected material.Euprox is a group of earliest cervids with true antlers.The new species is the third one of the genus discovered in China.Judged by its morphologic characteristics,the new species feed on juicy and tender leaves of dicotyledon.It implies that the vegetation of its epoch in the Yuanmou Basin is a kind of southern subtropical evergreen forest and the climate is humid and temperate with evident seasonality.The latter is mostly influenced by the monsoon and secondly by the latitude.     

Initial organic geochemical investigation on Late Neoproterozoic-Early Cambrian sediments in the Yangtze region, China

Totally 19 samples of typical Upper Proterozoic-Lower Cambrian sedimentary rocks were collected and analyzed for an organic geochemical investigation. Almost all these rocks have high TOCs, super-maturities and similar biomarker distribution. As an exception, however, the Sinian Nantuo Tillite shows much lower TOCs and little phytane and pristane in comparison with those in other strata, which implies a very faint photosynthetic process, and a restricted euphotic zone and quite limited sunlight within the sedimentary water column during the Sinian glaciation age in the western Yangtze region providing an evidence for palaeo-oceanic environment of the Neoproterozoic Snowball Earth age.     

Isotopic evolution of the terminal Neoproterozoic and early Cambrian carbon cycle on the northern Yangtze Platform, South China

Profound geotectonic, climatic and biological changes occur during the terminal Neoproterozoic and its transition into the early Cambrian. These are reflected in temporal variations of the chemical and isotopic composition of seawater. We are studying a sequence of sedimentary rocks at the Shatan section, northern Yangtze Platform, Sichuan Province of China. This succession comprises, in ascending stratigraphic order, predominantly calcareous sediments of the Sinian upper Dengying Formation and black shales of the lower Cambrian Guojiaba Formation (time equivalent of Niutitang Fm.). Paleoenvironmental setting represents shallow-water shelf deposits. The objective of our study is to provide temporal records for the isotopic compositions of organic and carbonate carbon throughout this time interval. Organic carbon isotope values display a range between -35.8‰ and -30.1‰ with clear stratigraphic variations. Carbonate carbon isotope data vary between -3.5‰ and +0.5‰. These secular variations are interpreted to reflect perturbations of the global carbon cycle, specifically changes in the fractional burial of organic carbon. However, local conditions have further affected the isotopic signals.     

北淮阳带新元古代花岗质侵入体的特征及大地构造意义

近些年来 ,在北淮阳带地层研究方面的主要进展之一 ,是将以前建立的一些变质岩群解体成不同时代、不同性质的构造地层或岩石地层单位 ,并重新厘定了它们的含义和分布。最近从原卢镇关群、佛子岭群、梅山群中识别出了较多变形花岗质岩体 ,马文璞等运用单颗粒锆石 U- Pb法测得四个变形花岗岩的年龄为 74 4± 9Ma和 665± 3 9Ma,属新元古代。岩石化学和元素地球化学分析表明 ,这些变形花岗岩的 R1 变化主要范围为 1 93 4～ 2 768,Ga/Al值位于1 .72～ 3 .61范围内。在 Zr,Nb,Ce,Y - Ga/A l图解上 ,它们主要落入后造山 ( PA)型花岗岩区 ;在 R1 - Ga/Al图解上 ,也属于后造山 ( PA)型花岗岩。上述事实可能意味着 ,Rodinia泛大陆的汇聚发生在新元古代变形花岗岩侵入之前 ,但随后即开始了拉张活动     

袁世凯与晚清宪政改革——兼谈袁世凯与宫廷各派之间的关系

袁世凯不仅促成了清廷预备立宪,而且还在预备立宪的过程中,做了一些别人做不到的事情。袁世凯在直隶试行立宪政治与改革,实际上是配合中央的宪政改革而进行的,其目的是为地方仿行立宪作出表率。尤其地方自治的实行,为接受新式教育的绅商活跃于各级地方政府的政治舞台创造了条件,有利于改变传统的地方和基层权力结构,使地方政治体制逐渐发生转型,朝着民主政治的方向发展。袁世凯的所作所为对近代中国政治的近代化起了一定的推动作用。     

济阳坳陷上第三系储层特征及天然气藏形成条件分析

济阳坳陷上第三系是胜利油田的主要产油气层段之一，也是今后进一步进行天然气勘探开发工作的主力目的层位。本文从上第三系储层的类型及其展布规律、岩性、储集物性、微观孔隙结构等方面，详细分析了天然气储层的特征。并在此基础上，讨论了天然气藏的形成条件及天然气富集规律。研究表明，天然气对储层储集物性的要求比石油更具广泛性；天然气藏的形成除必须具备一定的储层条件外，更重要的是受控于生成运移条件、盖层条件及一定构造背景等。