Formation and Evolution of a Paleosol across the Lower Silurian-Lower Permian Boundary in Zunyi District, Northern Guizhou, China and Its Paleoenvironment and Paleoclimate Implications

This paper presents a set of bulk geochemical and mineralogical data from a paleoweathering profile located in Zunyi District, Northern Guizhou, China. It was formed at the top of the Hanjiadian Formation of the Lower Silurian. A truncated, argillic, gleyed, kryptic paleospodosol is recognized in the paleoweathering profile. Ratios of immobile elements (Ti/Zr, Ti/Al) and their binary (e.g., Nb vs. Zr/TiO2 and Th/Sc vs. Zr/Sc), triangular diagrams (La-Th-Sc, Th-Sc-Zr/10, Zr-Cr-Ga) reflect that the Gaojiayan paleosol is the product of in-situ weathering of gray-green silty mudstone of the underlying Hanjiadian Formation. Mass balance calculations indicate K enrichment and Na enrichment in the upper and lower portions of paleosol, respectively. These findings both are the results of transgression, which brings substantial concentrations of such elements as K, Na, and Sr. In particular, K enrichment is achieved by the illitization of kaolinite. The biological processes of terrestrial vascular plants also enhance K concentration, especially at the top of the paleosol. Na enrichment is a consequence of albitization and/or adsorption by clay minerals through cation exchange. The mass distributions and relative mass changes of rare earth elements (REEs) in the studied profile display characteristics of vertical zonation. Three peaks in total REEs content are observed, indicating two paleoclimatic or paleoenvironmental changes. Mineralogical characteristics indicate that the paleoclimate changed first from warm and humid to cold and dry and later, to dry and lightly warmer. The corresponding soil environment varies from weakly acidic to strongly alkaline and later, to weakly acidic. Mass translocation characteristics of REEs and several transition metals suggest that the Gaojiayan paleosol may have undergone top erosion.     

Podiform Chromitites and Mantle Peridotites of the Purang Ophiolite, Western Yarlung-Zangbo Suture Zone, Tibet: Implications for Partial Melting and Melt-Rock Interaction in Oceanic and Subduction-Related Settings

<正>The Purang ophiolite,which crops out over an area of about 650 km~2 in the western Yarlung-Zangbo suture zone,consists chiefly of mantle peridotite,pyroxenite and gabbro.The mantle peridotites are mostly harzburgite and minor lherzolite that locally host small pods of dunite.Some pyroxenite and gabbro veins of variable size occur     

我国城市规划中气候信息应用回顾与展望

城市规划中气候信息的应用经历了从早期的风玫瑰图利用到考虑风、温、湿、压等要素的气候适宜性分析以及目前关注城市通风环境、热环境以及污染敏感区的城市环境气候图技术的历程。气候信息获得的途径也从数量极为有限的基本气象观测站资料到空间加密的自动气象站资料、更精细的气象数值模式以及精细化地理信息技术的应用。同时,细化的技术导则和规范的建立以及不同行业间的联合发文有力推动了气候信息的实际应用。此外,研究展示了近年开展的伊犁、深圳、北京实际案例主要内容。最后,针对未来我国将根据大气环流特征和生态环境承载能力、走优化城镇空间布局和城镇规模结构的新型城镇化道路,从工作层面和技术层面给出了需要不断完善并深入研究的几个重点。     

Comparison of Simulated and Reconstructed Temperature in China during the past 2000 years

Studying climate changes over the past 2 000 years has important scientific significance in exploring climate variability on decadal to centennial timescales, assessing the natural and anthropogenic contribution to the climate warming, and understanding the effects of human activities in the past and future climate changes. Due to the scarcity of observation and uncertainty of reconstruction in this period, climate model is developed as a useful tool for studying paleoclimate.The Community Earth System Model (CESM) is one of the state-of-the-art climate models, but its performance in simulating the temperature in China has not been examined.The temperature datasets of observation/reanalysis (GHCN_CAMS) and reconstructions during the past 2000 years in China were used to examine the performance of CESM. The comparison between the annual average temperatures of GHCN_CAMS reanalysis and simulation showed that the model well reproduced the spatial distributions and upward trend of the annual average temperature in China, and the comparison with reconstructions in five sub-regions of China indicated that the simulation were in good consistent with the average temperature changes of reconstructionson decadal time scales. On the centennial time scale, the average temperature fluctuations of simulation in the regions of China were in accord with reconstructions generally except for Central East and Tibet.There existed three warm periods of simulated temperature variation in China over the past 2000 years, including 0-540AD, 800-1250AD and 1901-2000AD, and two cold periods involving the 551-721AD and 1400-1850AD, which had some discrepancies with reconstructions. And the discrepancies between simulation and reconstructions might be related to uncertainties of the resolution, external forcing and parameterization of the subgrid-scale process in the model.     

帽峰山地区典型小流域主要森林类型土壤渗透性

采集帽峰山地区典型小流域主要林地类型(青冈林、毛竹林、凤尾竹林、桉树林)原状土样进行土壤剖面(0~20 cm、20~40 cm、40~60 cm)渗透系数及其相关因子的实验研究,结果表明:各种林地类型土壤渗透系数在剖面上均表现出从上到下递减的特点,毛竹、青冈、凤尾竹、桉树林的土壤剖面渗透系数变化范围分别为13.64~4.91、10.49~3.63、8.16~2.96、7.92~3.71 m/d。由于20~40 cm、40~60 cm土层渗透系数差异性相对较小,土壤渗透性剖面可简化为上、下两个亚层,上部亚层渗透系数是下部亚层的1.89~2.42倍。各种林地类型土壤渗透系数与孔隙度、根密度呈正相关,与干容重呈负相关,与根径关系相关性方向具有不确定性。不同林地类型土壤渗透系数与干容重、根密度、根径之间的相关程度存在较大差异,但均表现出与孔隙度之间存在良好相关性。     

塔里木块体北部泥盆—石炭纪陆缘构造演化:盆地充填序列与物源体系约束

陆缘洋-陆转换或盆-山转换复杂多变,沉积作用活跃,但迄今认识有限。文中基于对陆块和造山带地层格架的梳理和建立,选择塔里木块体北缘与南天山之间两条较完整的泥盆—石炭系典型剖面开展盆地与沉积序列研究。泥盆纪—早石炭世维宪早期发育碱性玄武岩、放射虫硅质岩和浊积岩,而早石炭世维宪晚期—晚石炭世发育序列清晰的中厚层状碳酸盐岩、碎屑岩及其混合沉积组合,指示洋-陆转换已经发生。进一步重点分析了其中砂岩碎屑重矿物样品19个、碎屑锆石同位素年代学(U-Pb及Hf)样品12个,结合砂岩骨架组分特征综合解析了物源体系与构造演变机制。研究表明,泥盆纪—早石炭世维宪早期,塔里木块体北缘东部发育不稳定和差异显著的碎屑组合,并具有接近地层年龄的碎屑锆石,指示了由南向北相对近距离的源汇体系、活动陆缘和混杂沉积的特征;而西部砂岩呈现的较高的成分成熟度和来自塔里木陆块相当数量的锆石年代学特征,则具有被动大陆边缘沉积属性。早石炭世维宪晚期—晚石炭世,塔里木块体北缘东部成分成熟度增高,并出现了一定数量的来自塔里木陆块的碎屑锆石,以及相当部分390~460Ma锆石的εHf(t)显示特征的正值,具有主体再旋回混合造山带的物源构造属性、中-近距离源-汇体系和残留海沉积特征;而在塔里木块体北缘西部,较之前更加明显的较高砂岩成分成熟度和来自塔里木陆块的大量锆石年代学特征,说明具有远距离源汇体系特征,可能指示了更加广阔的残留洋或残留海沉积。这说明尽管南天山洋在早石炭世维宪期以后已经关闭,但直到晚石炭世仍未明显造山。塔里木块体北缘东、西部泥盆—石炭纪陆缘构造及相关盆地系统演化存在显著差异,是中亚地区陆缘裂解、多岛洋闭合、(微)陆块聚合复杂性的体现。     

四川省华蓥市矿山地质灾害问题及其防治研究

四川省华蓥市矿产资源丰富,矿业经济发展迅速,由采矿导致的地质灾害问题也日趋严重。矿山地质灾害是华蓥市突出的地质环境问题之一,各类地质灾害隐患总计92处。对华蓥市矿业开发存在的一系列矿山地质灾害进行了分析,对它们的成因进行了研究。针对华蓥市矿山地质灾害的特点,依据"以人为本"的原则确定治理对象,分别从滑坡与不稳定斜坡.崩塌.泥石流及地面塌陷4个方面提出具体的防治措施及建议。     

北京山区泥石流自动监测预警系统的建立与应用

自动监测预警系统,是目前山区突发地质灾害预警预报有效的预警模式。本系统是在详细调查的基础上,以调查数据为底层分析数据库,以.net为语言运行环境,经所建立的预警模型分析计算后,产生预警预报产品,进行预警发布。     

准噶尔盆地白垩系烃源岩与原油地球化学特征

准噶尔盆地白垩系含油气系统理论上具备一定的勘探能力,但研究程度较低。为加深对该问题的理解,分析了白垩系的烃源岩和原油地球化学特征,并进一步结合地质背景,探讨了勘探潜力。结果发现,白垩系发育有一定数量和规模的泥质烃源岩,存在有机碳TOC含量大于1.0%的样品,类型以Ⅱ型为主,目前主体处于低成熟—成熟演化阶段,因此可望具有一定的生烃,特别是生油潜力。油源对比发现白垩系的确有过原油生成,典型地球化学特征表现为轻碳同位素(-29.6‰~-27.9‰)、低Pr/Ph值(0.54~1.01)、高伽马蜡烷丰度(伽马蜡烷/C30藿烷=0.29~0.53),反映属于一类还原和盐度环境中有机质所生原油。这类原油主要分布在盆地南缘白垩系烃源岩的沉积中心区,表现出源控特征。这些认识可供国内外其他白垩系油气地质研究时类比考察。