近10年来东北农牧交错区土地利用变化研究

东北农牧交错区是典型的生态环境脆弱区,土地利用变化直接影响到当地居民的生活质量以及环境—经济的协调发展状况。本文基于对典型样点土地利用变化数据的量化分析,解析了近10年来东北农牧交错区土地利用的数量结构变化、土地利用程度的变化和土地利用变化的区域差异,以便为土地资源的可持续利用提供科学依据。     

The Quaternary faunas and climatic fluctuation in the tropical zone of China

About 70 examples of Quaternary fauna in China's tropics are enumerated in this paper. Of which about 40% of the examples can be found even in cooling stages, showing the smaller amplitude of climatic fluctuation during Quaternary. According to the temporal and spatial distribution of tropical faunas, the following characters of climate variation can be evidenced: two main cycles in Early Pleistocene, three main cycles in Middle Pleistocene, two main cycles in Late Pleistocene and Holocene Megathermal. The drop in temperature during the Latest Glacial Period and Neoglaciation has not endangered the existence of tropical faunas. With influence of cooling fluctuation during historical period, some faunas have removed southwards progressively, but disappearance of these animals in China's tropics was mainly the result of artificial factors.     

山东铜岭金矿的矿体定位构造

铜岭金矿位于山东省乳山市东南部,产在三佛山斑状二长花岗岩中,为含金石英脉型金矿。在三佛山岩体边部发育弧形脉岩群,铜岭金矿就位于该弧形脉岩群的弧顶外端,走向ＮＷ,与区内脉岩群垂直,据此提出铜岭金矿受三佛山岩体构造控矿的看法。铜岭金矿矿体的定位还受蚀变带宽度变化的影响,往往产于蚀变带狭缩处与膨大处的转换部位。铜岭金矿矿石金品位及矿体厚度在走向和倾向上均呈串珠状或波状变化。     

青藏高原东北缘壳幔过渡带研究

利用穿过青藏高原东北缘的两条地震测深剖面提供的PMP波形资料，研究了该区不同构造单元壳幔过渡带的复杂性、频谱特征和速度模型．结果表明, 鄂尔多斯盆地和陵中盆地Moho具有稳定的构造特征，壳幔耦合为简单的一级间断面；海原地震区和巴颜喀拉地块与柴达木地块结合带莫霍面具有明显的活动迹象，壳幔耦合为复杂的高、低速相间的多层壳幔过渡带，总厚度达到20多千米．不同构造单元的莫霍面差异性反映了研究区壳幔耦合层的非均匀特征；海原地震区和玛沁断裂壳幔过渡带的细结构差异, 则反映了两个陆 陆碰撞带不同的深部物质结构与地块之间的相互作用结果．      

西华山钨矿床中熔融包裹体的初步研究与矿床成因探讨

过去一直认为西华山黑钨矿石英脉是高中温热液充填而成。研究发现，在黑钨矿石英脉的绿柱石中存在与流体（气液）包裹本共生的流体－熔体包裹体和熔融包裹体，表明形成黑钨矿石英脉的成矿流体是一种岩浆－热液过渡性流体，并讨论了熔融体与金属成矿作用的关系。     

3500aBP我国北方农牧交错带降水突变的幅度与速率

考古信息与历史文献记载一样是环境演变研究中独具特色的信息源。文章以考古信息为依据对中国北方农牧交错带地区 35 0 0aBP前后降水突变的幅度与速率进行了推断。中国北方农牧交错带分布在年降水量 2 5 0～ 40 0mm的地区 ,降水变化对该地带的影响十分显著。在位于北方农牧交错带内的内蒙古中南部及陕北、晋西北地区 ,大量的考古遗存详细记录了 35 0 0aBP前后该地区内土地利用性质的时空变化过程 ,可以用来定量地估算 35 0 0aBP降水突变的幅度和速率。 42 0 0～34 0 0aBP期间 ,在内蒙古中南部及陕北、晋西北地区先后发育了朱开沟文化和李家崖文化。文化的演变过程可分为两个阶段 :从朱开沟一期到朱开沟二期为第一阶段 (cal.40 0 0～ 380 0aBP) ,在朱开沟文化区发生了从农业文化转变为农牧交错文化、进而变为畜牧业文化的过程 ,相当于从农业区的北界变为农牧交错区的北界 ;从朱开沟文化二期结束到李家崖文化为第二阶段 (cal.380 0～ 34 0 0aBP) ,期间农牧交错带的北界显著地向东南退缩。上述考古学文化的变化可以看作是人类对 35 0 0aBP前后降水突变的响应。 40 0 0aBP前后是从农业文化向半农半牧文化转变的临界点 ,其降水量大致与现代农牧交错带南界的降水量相当 ,为 35 0～ 40 0mm ;380 0aBP前后是从半     

Seawater Intrusion in the Longkou Laizhou Area,Shandong1

Abstract The extensive intrusion (covering an area of 83.7-238.3 km² and accounting for 18.6-31.5% of the total area of the plain), the presence of a transitional zone 1.5-6.0 km in width, and the interconnection in distribution between the seawater intrusion district and the region lower than the sea level caused by the strong drop of the groundwater level are major characteristics of the seawater intrusion in the study area. Cation exchange played an important role during the formation of chemical composition of the groundwater in the seawater intrusion district.     

等鞭金藻属(等鞭金藻目)1新种——湛江等鞭金藻(Isochrysis zhanjiangensis sp.nov)及其超微结构的观察

描述了从广东湛江南三岛沿岸采集、分离的等鞭金藻1新种———湛江等鞭金藻,应用电镜技术观察了湛江等鞭金藻运动细胞的超微结构.电镜观察证明,其运动细胞表面覆盖2~4层鳞片,鳞片有两种类型,一种较大,椭圆形;另一种较小,圆形.细胞顶端具有2条等长的平滑的鞭毛,两鞭毛间具有一条退化的定鞭(haptonema),很短,仅有1~2条微管.湛江等鞭金藻鞭毛过渡区中央轴丝与周边微管之间有5~6条螺旋条纹.两个金褐色色素体位于细胞两侧.3条类囊体为一组,无带片层.每个质体内侧具1个单层膜包裹的裸露的蛋白核.蛋白核内常具1对横列的类囊体.高尔基器位于鞭毛基体基部.线粒体长管状,具多个不分枝或分枝的脊.细胞中下部具1个至多个金藻昆布糖(Chrysolaminaran)颗粒.细胞核位于两质体之间、细胞基部.     

近50年华北地区极端气候分析

Climate extremes for agriculture-pasture transitional zone, northem China, are analyzed on the basis of daily mean temperature and precipitation observations for 31 stations in the period 1956-2001. Analysis season for precipitation is May-September, i.e., the rainy season. For temperature is the hottest three months, i.e., June through August. Heavy rain events, defined as those with daily precipitation equal to or larger than 50 mm, show no significant secular trend. A jump-like change, however, is found occurring in about 1980. For the period 1980-1993, the frequency of heavy rain events is significantly lower than the previous periods. Simultaneously, the occurring time of heavy rains expanded, commencing about one month early and ending one month later. Long dry spells are defined as those with longer than 10 days without rainfall. The frequency of long dry spells displays a significant (at the 99% confidence level) trend at the value of 8.3% /10a. That may be one of the major causes of the frequent droughts emerging over northern China during the last decades. Extremely hot and low temperature events are defined as the uppermost 10% daily temperatures and the lowest 10% daily temperatures, respectively. There is a weak and non-significant upward trend in frequency of extremely high temperatures from the 1950s to the mid-1990s. But the number of hot events increases as much as twice since 1997. That coincides well with the sudden rise in mean summer temperature for the same period. Contrary to that, the fiequency of low temperature events have been decreasing steadily since the 1950s, with a significant linear trend of-15%/10a.     

Nanoscale Pore Characteristics of the Upper Permian Mudrocks from a Transitional Environment in and around Eastern Sichuan Basin,China

Nanoscale pore characteristics of the Upper Permian Longtan transitional mudrocks and their equivalent strata Wujiaping Formation marine mudrocks in and around the eastern Sichuan Basin was investigated using field emission scanning electron microscopy (FE-SEM) and low-pressure N2 adsorption experiments. The results indicate that the Upper Permian mudrock is at a mature stage with total organic carbon (TOC) values ranging between 0.47% and 12.3%. The Longtan mudrocks mainly contain vitrinite, and their mineral composition is primarily clay. In contrast, the Wujiaping mudrocks are dominated by sapropelinite and solid bitumen, and their mineral compositions are mainly quartz and a notably high amount of pyrite. The FE-SEM reveals that clay mineral pores and microcracks are the common pore types in the Longtan mudrocks. The specific surface area and pore volume depend on the clay content but are negatively correlated with the TOC. The generation of nanometer pores in the Longtan mudrocks is caused by high clay mineral contents. Meanwhile, the Wujiaping mudrock mainly contains OM pores, and the pore parameters are positively correlated with the TOC. The OM pore development exhibits remarkable differences in the Longtan and Wujiaping mudrocks, which might be related to their sedimentary facies and maceral fractions. Vitrinite and inertinite appear as discrete particles in these mudrocks and cannot generate pores during thermal maturation. Sapropelinite often contains many secondary pores, and solid bitumen with large particles, usually with several pores, is not the major contributor to the pore system of the investigated mudrock.