大兴安岭南段朝克乌拉地区晚侏罗—早白垩世辉长岩年代学和地球化学研究

基于内蒙古朝克乌拉地区开展的1∶5万区域地质调查工作,发现一期以辉长岩为主的基性岩浆活动。研究表明：朝克乌拉地区辉长岩锆石U- Pb年龄为142.6±0.5 Ma、145.1±2.1 Ma,显示岩石为晚侏罗—早白垩世产物。辉长岩为拉斑系列岩石,具有低硅、低钛、贫碱且高钠低钾特点,分异作用极弱,Eu异常不明显,微量元素Ba、Ta、Sr、Hf富集, Rb、Th、Nb、P亏损。辉长岩岩石地球化学显示其岩浆源区为亏损尖晶石二辉橄榄岩地幔发生30%以上的部分熔融形成,存在流体影响的地球化学特征。岩浆在演化过程中存在一定程度的分离结晶作用,地壳混染作用极其微弱。通过与贺根山蛇绿岩配套岩系的类比,结合研究区古生代至中生代构造背景和贺根山缝合带壳幔电性结构全面分析,推断晚侏罗—早白垩世辉长岩具有的岛弧印记特征为贺根山洋发育时期古岛弧环境的反映,辉长岩只是伸展背景下幔源岩浆沿深大断裂上涌作用的产物。     

Landscape evolution and glaciation of the Rwenzori Mountains, Uganda: Insights from numerical modeling

The Rwenzori Mountains are a high alpine mountain chain, about 40 × 80 km in size, just north of the equator in the western branch of the East African Rift System in Africa. The central part of the mountain chain is located in Uganda, and the highest peak, the Margherita Peak with 5119 m, lies on the border to the Democratic Republic of Congo. Topography is very pronounced, with steeply incised valleys and clear glacial landforms in the upper part of the mountain chain. The Rwenzori Mountains are an unusually high mountain chain located in the extensional setting of the East African Rift System, and the large elevation poses a challenging problem for geodynamists to explain.We have used the landscape evolution model ULTIMA THULE, which combines hillslope diffusion, fluvial erosion, and glacial abrasion and is driven by a climate driver, simulating the variations in temperature, precipitation, and relief over several glacial cycles. With a simulation time of 800 ka, we test the hypothesis of climate-tectonic interactions on the uplift of the Rwenzori Mountains.Our results show that a moderate cooling of around 6° causes widespread glaciation of the high mountain regions as observed during the peak glacial phases, and that morphological processes degrading the landscape allow for a tectonic uplift rate of around 0.5 mm a^− 1.     

长白山圆池泥炭沼泽演变及环境信息记录

通过分析长白山圆池泥炭剖面总有机碳含量、总正构烷烃含量、奇偶优势指数、(C23+C25)含量和2C31/(C27+C29)比值,讨论了泥炭发育不同时期植物输入情况,同时结合210Pb测年建立的年代序列来探讨该区的气候变化规律.研究结果显示,约1400年前,气候干冷,圆池尚没有出现沼泽化;1400年开始,气候稍暖,少量植物输入,圆池开始沼泽化;约从1860年至今,气候逐步转暖,大量植物输入,圆池沼泽化速度加快.     

武夷山甜槠天然林含碳率与碳贮量研究

选取武夷山甜槠天然林为研究对象,对其乔木层、灌木层、草本层、枯枝落叶层、土壤层进行了碳贮量研究．结果表明：乔木层不同器官的含碳率表现为：C皮〉C叶〉C干〉C枝〉根,灌木层不同器官的含碳率表现为：C干〉C枝〉C根〉C叶,草本层是地上部分含碳率大于地下部分,枯枝落叶层的含碳率表现为：C叶〉C枝〉C果,土壤层的含碳率随着土壤...     

Changes of cloud water chemical composition in the Western Sudety Mountains, Poland

The changing chemical composition of cloud water and precipitation in the Western Sudety Mountains are discussed against the background of air-pollution changes in the Black Triangle since the 1980s until September 2004. A marked reduction of sulphur dioxide emissions between the early 1990's and the present (from almost 2 million tons to around 0.2 million tons) has been observed, with a substantial decline of sulphate and hydrogen concentration in cloud water (SO₄²⁻ from more than 200 to around 70 μmol l^− 1; H⁺ from 150 to 50 μmol l^− 1) and precipitation (SO₄²⁻ from around 80 to 20–30 μmol l^− 1; H⁺ from around 60 to 10–15 μmol l^− 1) samples. At some sites, where fog/cloud becomes the major source of pollutants, deposition hot spots are still observed where, for example, nitrogen deposition can exceed 20 times the relevant critical load. The results show that monitoring of cloud water chemistry can be a sensitive indicator of pollutant emissions.     

普陀山植被对旅游干扰的响应研究

应用有序样方聚类法,把普陀山旅游区32个样方分为5个群落类型,分别是马尾松-青冈+檵木群丛、马尾松-青冈+檵木+红楠+窄基红褐柃群丛、马尾松+枫香+檵木-青冈+檵木群丛、马尾松+青冈-青冈+檵木群丛、马尾松+青冈-青冈+檵木+石栎群丛,并运用TW INSPAN对上述样方进行聚类分析。两种分类方法的结果具有极显著的关联,说明有序样方聚类法很好地揭示了旅游干扰和群落类型之间的关系,它更适合于旅游干扰分析中的聚类研究,在旅游干扰的研究中是一个有益且有效的尝试。     

祁连山区夏季降水过程天气分析

以500hPa盛行气流为主,参考FY-2D卫星云图云型特征,将2007年7～8月祁连山区的31次降水过程作天气分型。取30°～45°N范围500hPa110°E的格点平均位势高度与90°E平均位势高度之差值为分类标准。分成3个主型,西南气流型、西北气流型和平直西风气流型。西南气流型又分移动型和阻塞型两个副型。西北气流型分西北气流冷平流型和河套冷涡两个副型。用试验区中尺度自动站网的降水资料,探讨降水量与海拔高度和坡向的关系,分析产生降水过程各天气类型的环流特征及其降水强度,发现在不同的大尺度流型下,地形的动力和热力作用会造成迥然不同的地形强迫中尺度系统。     

Drought reconstruction in the Qilian Mountains over the last two centuries and its implications for large-scale moisture patterns

We present a composite tree-ring chronology from two sites of Qilian Juniper(Sabina przewalskii)in the northwestern Qilian Mountains(QM),Northwestern China.Precipitation in June was found to be the main limiting factor for tree-growth.The tree rings are also significantly and positively correlated with June precipitation over large areas of the northern Tibetan Plateau(TP).The authors thus consider that the tree- ring based drought reconstruction from 1803–2006 is representative of a large area drought hist...     

Geochemistry of granulite‐facies granitic rocks from Battye Glacier,northern Prince Charles Mountains,East Antarctica

Proterozoic basement outcrops in the vicinity of Battye Glacier, northern Prince Charles Mountains, are dominated by granulites and gneisses derived from felsic (granitoid) intrusive igneous rocks, and by pegmatites. Felsic orthopyroxene granulites, garnet leucogneisses and garnet pegmatites have major and trace element compositions of highly felsic, but not strongly fractionated, granites. The garnet leucogneisses and garnet pegmatites have S‐type characteristics, whereas the felsic granulites are probably I‐type, although their high Zr+Nb+Y+Ce abundances suggest possible A‐type affinities. Intermediate orthopyroxene ± clinopyroxene granulites mostly resemble I‐type quartz diorites, except for a small subgroup of samples (characterised by low Na₂O and K₂O, and high MgO, Ni, Cr and HREE) of uncertain affinities and significance. Element ratios involving LILE (e.g. K/Rb, Rb/Ba, Rb/Sr, K/La, La/Th) closely match those typical of the inferred granitoid protoliths, suggesting that these rocks have experienced relatively little LILE depletion (except possibly for U) during regional metamorphism. It is therefore inferred that metamorphism was probably broadly isochemical. Because the felsic and intermediate granulites and garnet leucogneisses are Sr‐depleted, Y‐undepleted and mostly have negative Eu anomalies they are inferred to be the products of partial melting of felsic crustal sources leaving plagioclase‐bearing residua. Plagioclase fractionation during crystallisation could also account for these characteristics, but K/Rb, Rb/Ba and Rb/Sr ratios in these rocks are not consistent with strong fractionation of feldspar. Garnet pegmatites differ chemically from garnet leucogneisses mainly in their lower Fe, Ti, Nb, Zn, Zr, Th and REE abundances and positive Eu anomalies, related to lower garnet, ilmenite and zircon contents in the garnet pegmatites. A genetic link between these two rock types, probably involving fractionation of these minerals during partial melting or crystallisation, is inferred. Incompatible‐element abundances suggest that generation of the Battye Glacier granitic magmas from felsic crust might have occurred in a mature continental magmatic arc possibly well removed from an active subduction trench or, perhaps, in an intracontinental setting.     

东天山库姆塔格发现辉长岩中钼的超常富集

在新疆东天山库姆塔格新发现了辉长岩中钼元素的超常富集,超过了目前的工业品位。从野外产状看,与钼矿化直接相关的岩石均为辉长岩,共两类:一是规模较小但全岩矿化的辉长岩脉;二是规模较大但没有矿化的辉长岩体;矿化的辉长岩脉穿插于非矿化的辉长岩体之中。虽然辉长岩体矿区东侧有中酸性岩浆岩存在,但野外产状和现有的物化探工作尚未发现钼矿化与中酸性岩浆岩有直接关系。无论辉长岩的形成与钼的富集是否属于同一次地质作用的产物,这都可能是一种尚未被认识的、全新的钼矿床(矿化)类型,具有重要的理论意义。