格罗夫山地区陨石回收

中国南极考察队于 1 998～ 2 0 0 0年两次对东南极格罗夫山地区进行了陨石回收工作 ,共回收 32块陨石 ,根据 1 5、1 6次队回收的陨石的分布范围、密度和岩石化学类型的差异性 ,初步确定格罗夫山阵风悬崖一带是一个新的陨石富集区。     

大兴安岭东北部兴华渡口群地球物理特征及其地质意义

黑龙江省大兴安岭东北部五号桥地区的兴华渡口群属于早-中元古代层状变质岩系,是大兴安岭地区最古老的地层,是金矿的初始矿源层,对金矿的形成具有重要意义。与前震旦纪混合花岗岩相比,兴华渡口群具有密度高、磁性强的特点。地质填图结果表明,兴华渡口群一般呈大小不等的块体产于前震旦纪混合花岗岩中。大兴安岭东北部重力场和磁场的高值异常,表明这一地区存在着规模较大的兴华渡口群。根据重磁异常特征,并对其进行位场换算处理和综合地质解释,推断出兴华渡口群在本区的分布范围和分布形态,确定兴华渡口群基本隐伏在混合花岗岩下,局部地段呈块状沿东西、南北两个方向凸起。兴华渡口群的重磁异常特点及其地质特征为研究该区地质构造及其演化、圈定找矿靶区具有指导意义。     

念青唐古拉山主峰地区第四纪砾石层砾组分析

通过对念青唐古拉山脉主峰地区的第四纪砾石层的砾组分析,作者从基岩地层和砾性分析、砾度和砾态分析中,阐述了念青唐古拉山脉北坡和南坡不同成因的第四纪砾石层的来源、成因及搬运方式。念青唐古拉山主峰地区的3次冰期砾石层中,每次冰期的冰碛物中的砾石在岩石成分、砾度、球度、风化程度上都有明显差异。这种差异反映了青藏高原隆升过程中对念青唐古拉山不同岩石的剥蚀作用。      

《山海经》中的“东山”区位地理考古研究

《山海经》是一部中国最古老的地理著作。其中“五藏山经”篇中所讲的西、南、北、中山都分布在中国大陆,只有东山的记述在国内一直找不到,三千多年来我国古书上多“无注”或称“其山水无可考”。美国女学者亨利埃特·默茨(HenrietteMertz)通过实地考察后所写的《淡淡的墨迹(Palegnk-TosoOreientRecordsofChineseExplorationinAmerica1953)》证明“东山”海外部分竟分布在美洲大陆,它们就是落基山脉、内华达山脉、喀斯喀特山脉以及海岸山脉,它们的距离,山峰数与动植物的种类与《山海经》记载的都基本相同。该书主题提示这样写的:“《山海经》-印第安人-中国的影响-美洲-中国人的发现和探索”。书中结语还特别强调:“对于在4000年左右,就已踏着白雪皑皑的山顶和峻峭的山峰而徒步考察无畏的中国人后面,我们所能做的,首先要向他们顶礼膜拜、鞠躬致敬。”     

利用树轮重建秦岭地区历史时期 初春温度变化

采用树木年轮气候学方法,利用秦岭地区树轮长年表资料重建秦岭地区历史时期初春温度,表明各气象站点重建序列与器测序列均呈显著的正相关关系,其中重建序列与实测记录的相关系数最高可达0.7以上,其他站的相关系数取值也均接近或超过0.6,说明重建序列能较好地反映秦岭地区的初春温度变化。对重建序列的分析结果表明,近300年来秦岭地区的初春温度变化存在明显的冷暖时段：1715~1740年、1773~1804年和1893~1958年三个时段的初春温度相对较高,持续时间分别为26年、32年和66年;而1741~1772年、1805~1892年、1959~1992年三个时段的初春温度相对较低,持续时间分别为32年、88年和34年,在整体上具有升温快速降温缓慢的特征。重建结果的变化趋势与其他相关研究结果极为一致。但是在20世纪后期,无论是在重建序列还是在器测序列中至少到1992年均未反映出明显的增温趋势。秦岭西部地区初春季节变冷与增暖的幅度均大于秦岭中东部地区。此外,秦岭地区初春温度变化具有100年左右、50~60年、7~8年以及2~3年等准周期变化特征。     

天山玛纳斯河源鹿角湾冰川地貌与冰期序列

在鹿角湾冰川区40 km²的考察范围内,共发育了18个冰斗.按斗底高度的不同,可以将18个冰斗分成3个高度等级,分别代表了3次雪线高度不同的冰进.冰斗朝向以偏北为主,说明水热条件对冰斗发育是限制因素.18号冰斗和2号冰斗朝向偏南,说明其所代表的冰进阶段水热条件组合有利于冰川的长期存在,从而发育了大规模的向阳冰斗.鹿角湾冰川共发育了10道保存比较完整的冰碛垄,按冰碛垄表面特征和产出位置,结合测年资料,将10道冰碛垄划分为5套冰碛地层.对冰碛垄上所采冰碛土样品进行年代测试的结果是:冰碛丘陵上组地层属于小冰期沉积,较早的两次冰进结束时间为(680±60)a BP和(250±60)a BP;冰碛丘陵组地层属于新冰期沉积,3次冰进结束年代分别为:(4.2±0.4)ka BP,(2.9±0.3)ka BP,(1720±60)a BP;末次冰期晚期结束年代为1.1~1.2 ka BP.其它几次冰进阶段未能取得可信的测年数据.     

Estimation of catchment yield and associated uncertainties due to climate change in a mountainous catchment in Australia

This paper examines the impacts of climate change on future water yield with associated uncertainties in a mountainous catchment in Australia using a multi‐model approach based on four global climate models (GCMs), 200 realisations (50 realisations from each GCM) of downscaled rainfalls, 2 hydrological models and 6 sets of model parameters. The ensemble projections by the GCMs showed that the mean annual rainfall is likely to reduce in the future decades by 2–5% in comparison with the current climate (1987–2012). The results of ensemble runoff projections indicated that the mean annual runoff would reduce in future decades by 35%. However, considerable uncertainty in the runoff estimates was found as the ensemble results project changes of the 5^th (dry scenario) and 95^th (wet scenario) percentiles by ?73% to +27%, ?73% to +12%, ?77% to +21% and ?80% to +24% in the decades of 2021–2030, 2031–2040, 2061–2070 and 2071–2080, respectively. Results of uncertainty estimation demonstrated that the choice of GCMs dominates overall uncertainty. Realisation uncertainty (arising from repetitive simulations for a given time step during downscaling of the GCM data to catchment scale) of the downscaled rainfall data was also found to be remarkably high. Uncertainty linked to the choice of hydrological models was found to be quite small in comparison with the GCM and realisation uncertainty. The hydrological model parameter uncertainty was found to be lowest among the sources of uncertainties considered in this study. Copyright © 2015 John Wiley & Sons, Ltd.     

Soil moisture temporal stability and spatio-temporal variability about a typical subalpine ecosystem in northwestern China

Knowledge of the spatial–temporal variability of soil water content is critical for water management and restoration of vegetation in semi-arid areas. Using the temporal stability method, we investigated soil water relations and spatial–temporal variability of volumetric soil water content (VSWC) in the grassland–shrubland–forest transect at a typical semi-arid subalpine ecosystem in the Qilian Mountains, northwestern China. The VSWC was measured on 48 occasions to a depth of 70 cm at 50 locations along a 240-m transect during the 2016–2017 growing seasons. Results revealed that temporal variability in VSWC in the same soil layer in the three vegetation types and averaged across vegetation types tended to exhibit similar patterns of a decrease with increasing soil depth. Temporal stability in each vegetation type was stronger with an increase in soil depth. However, the results of temporal stability determined with standard deviation of relative difference (SDRD) disagreed with those based on the Spearman's rank correlation coefficient; the forest site had the highest Spearman rank correlation coefficient while the shrubland—the smallest SDRD in the 0–20 cm soil layer. Correlation analyses of VSWCs between two vegetation types indicated that soil water was related among all three vegetation types at the 0–20, and 0–70 cm soil layer, but in the 20–40 and 40–70 cm soil layers, significant correlation (p < .01) occurred only between adjacent vegetation types. In the upper soil layer (0–20 cm), soil water relations were mainly affected by surface runoff. In the lower soil layer (20–40 and 40–70 cm), soil water relations among the three vegetation types were highly complex, and probably resulting from a combination of root distribution and activity, interflow, and the impact of deep soil freeze–thaw dynamics. These results suggest that the factors affecting soil water are complex, and further research should address the relative importance of and interactions among different determining factors.     

大兴安岭西坡二道河子铅锌银矿床银的赋存状态、迁移形式及沉淀机制

二道河子铅锌银多金属矿床是一个中型浅成热液矿床,它产于大兴安岭西坡得耳布干成矿带中段的晚中生代“双峰式”火山岩区。根椐野外矿脉的穿插关系和室内矿相学研究,将热液成矿期划分为四个成矿阶段,即：石英-黄铁矿阶段(Ⅰ)、石英-多金属硫化物阶段(Ⅱ)、石英-闪锌矿-方铅矿-银矿物阶段(Ⅲ)和石英-方解石-黄铁矿阶段(Ⅳ)。采用显微镜和电子探针(EPMA)微区技术对矿床中的硫化物和银矿物进行分析,结果表明,银的存在形式主要为可见银(>1μm),其次为不可见银(<1μm)。可见银主要以显微包体银和独立银矿物的形式存在,而不可见银主要呈次显微包体银和晶格银;显微(次显微)银常以浑圆状或不规则状分布在硫化物内部或硫化物和石英颗粒间隙,独立银矿物呈脉状或集合体状主要分布于方铅矿(偶见闪锌矿)脉的裂隙和边缘,晶格银赋存在方铅矿中,含量极少。结合前人研究成果,认为成矿早期(石英-黄铁矿阶段)成矿热液中的金属元素(如Ag、Cu、Fe、Pb和Zn元素等)以氯络合物形式运移,伴随着流体不混溶/沸腾作用,硫氢络合物成为主要的迁移形式。随着温度、压力的降低和大气降水的参与,成矿流体自下而上运移,并先后经历...     

大兴安岭南段黄岗梁地区早白垩世岩浆作用的时代、成因及其构造意义

大兴安岭南段黄岗梁地区早白垩世碎斑熔岩和钾长花岗岩代表大兴安岭南段最广泛的一次岩浆活动产物,二者LA-ICPMS锆石U-Pb年龄都为137.7±1.2Ma。该地区岩石大都具有高硅、钾,贫钙、镁,低铝的特点,体现了高度演化的高钾钙碱性-碱性系列特点;铝饱和指数显示其为准铝质-弱过铝质花岗岩。岩石稀土元素总量为116.98×10-6~350.51×10-6,具有强烈的负Eu异常,富集大离子亲石元素(如Rb、Ba、Th、U等)及高场强元素(如Nd、Zr、Hf等),亏损Ba、Sr、P、Ti、Nb等强不相容元素,显示出高分异I型花岗岩的特征。研究区早白垩世岩浆岩具有较高的全岩εNd(t)值(-0.8~+0.9)和正的锆石εHf(t)值(+1.9~+18.3),以及年轻的Nd模式年龄(993~855Ma)和Hf模式年龄(888~561Ma),表明其来源于新生的陆壳,可能有少量古老陆壳物质的参与。综合区域地质资料及大兴安岭南段的岩浆演化特征,这些早白垩世岩浆作用应形成于区域性伸展的构造背景,主体可能与蒙古-鄂霍茨克洋构造体系下的后造山伸展垮塌有关。