Volatile element chemistry during accretion of the earth     

《Chemie der Erde / Geochemistry》2020,80(1):125594

We review some issues relevant to volatile element chemistry during accretion of the Earth with an emphasis on historical development of ideas during the past century and on issues we think are important. These ideas and issues include the following: (1) whether or not the Earth accreted hot and the geochemical evidence for high temperatures during its formation, (2) some chemical consequences of the Earth’s formation before dissipation of solar nebular gas, (3) the building blocks of the Earth, (4) the composition of the Earth and its lithophile volatility trend, (5) chemistry of silicate vapor and steam atmospheres during Earth’s formation, (6) vapor - melt partitioning and possible loss of volatile elements, (7) insights from hot rocky extrasolar planets. We include tabulated chemical kinetic data for high-temperature elementary reactions in silicate vapor and steam atmospheres. We finish with a summary of the known and unknown issues along with suggestions for future work.  相似文献   

塔里木盆地玉北地区奥陶系储层成因研究     

张哨楠 《沉积与特提斯地质》2020,40(3):72-86

玉北地区奥陶系碳酸盐岩经历了加里东期和海西期构造作用的改造，东部断褶带和西部斜坡区断层发育，中部平台区断层不发育，导致勘探目的层鹰山组上部与鹰山组下部和蓬莱坝组储层发育特征的不同。鹰山组上部的储层主要受控于加里东期构造活动所造成的地层抬升暴露剥蚀，形成了以大气淡水溶蚀为主的储集空间类型；而鹰山组下部和蓬莱坝组储层则主要受到埋藏白云石化作用、硅化作用以及伴随着断层的形成而发育的裂缝和热液的改造作用的控制。氧碳同位素和⁸⁷Sr/⁸⁶Sr比值的分布特征也进一步证明了两种不同储层类型的主控因素。鹰山组上部洞穴中方解石的氧碳同位素值（δ¹⁸O_VPDB：-12～-4‰VPDB，δ¹³C：-3～1‰VPDB）比海水沉淀的方解石（δ¹⁸O_VPDB：-9.5～-7.5‰VPDB，δ¹³C：-1.5～0.5‰VPDB）在数值上明显偏负，说明洞穴中充填的方解石属于淡水成因。在鹰山组下部和蓬莱坝组白云岩储层中发育的鞍形白云石具有较低的氧同位素值（δ¹⁸O_VPDB：-10.7～-5.9‰VPDB）和高于海水的⁸⁷Sr/⁸⁶Sr值（均大于0.7094），因而被解释为热液成因，进一步说明这些地层中的溶蚀孔洞可能与热液改造有关。  相似文献   

Constructing durian terroir and geographical indications in Penang,Malaysia     

Christopher Airriess 《Singapore journal of tropical geography》2020,41(1):6-22

The tropical fruit durian in Southeast and East Asia has witnessed a surge in popularity in the past two decades to assume the rank of a fetishized commodity. This research investigates the construction of the multidimensional concept of terroir as applied to the durian economy of Penang, Malaysia based on personal interviews with orchard owners and state government officials to strategically embed the local in the global through the promotion of agritourism. While environmental terroir is a contingent dimension, the construction of a place bound cultural terror is anchored in a strong cultivation tradition, cultivar diversity, and a historical sense of community. This research deepens the cultural terroir dimension in two ways. First, it injects the otherwise aspatial concept of refinement to the cultural terroir narratives of orchard owners allowing the on-farm tourist consumption experience to be more geographically rooted. Second, it conceptually links cultural terroir to the marketing terroir instrument of the Balik Pulau geographical indication; while functioning as a governance tool to prevent fraud and to construct a place bound product valorization and differentiation within an expanding and larger scale durian economy, it also indirectly assists in preserving agro-diversity and local identity.  相似文献   

沉积物中硬质粘土层的研究进展          下载免费PDF全文

孔凡彪  徐树建  贾广菊 《山东国土资源》2018,34(3)

大量的钻孔资料表明,平原地区及其海域沉积物中普遍有硬质粘土层的存在。硬质粘土层在工程地质、地理学研究等方面具有重要的价值,它不仅是高层建筑的持力层,而且是研究全球环境变化事件、古气候演变的良好载体。该文阐述了硬质粘土层的一般特征、成因以及在粒度、地球化学元素、年代学、沉积环境等方面的研究进展,并展望了硬质粘土层在年代、物质来源和沉积环境等方面的研究方向,认为黄河三角洲硬质粘土层研究较少,需要开展大范围的、系统深入的、多学科的宏观和微观综合分析,挖掘硬质粘土层蕴含的古环境意义和应用价值。  相似文献   

新疆库车县盐水沟北铜矿床地质特征及成因探讨          下载免费PDF全文

刘传朋 《山东国土资源》2018,34(4)

盐水沟北铜矿区位于新疆库车县北部,其大地构造位置处于塔吉克-塔里木陆块区、塔里木陆块、塔里木北缘隆起、库车前陆盆地,区内构造活动强烈。铜矿床赋存于新近纪中新统康村组第一岩性段,矿体呈层状,严格受地层控制。区内共圈定10个铜矿体,矿石矿物主要为孔雀石、赤铜矿、水胆矾、自然铜等,矿体内无夹石,顶、底板围岩均为褐红色及浅红色粉质泥岩。该矿床为砂岩型铜矿床。  相似文献   

美国出口管制下中国外贸风险的省域地理差异     

姜辉 《地理科学》2020,40(10):1618-1626

从总贸易、出口、进口、外资和人员5个视角构建对美风险系数，测度和比较各省区市对美外贸风险的地理差异。结果表明：上海、浙江和福建与美国的进出口贸易规模最大，对美国市场的依赖程度最高，面临的综合外贸风险最大；河南尤其需要防范对美国的出口风险；海南、新疆、天津和西藏等需要加强从美国进口的风险管理；重庆除了需要防范对美出口风险外，还因为实际利用美资最多且依赖程度最大，亟需加强外资风险管理。宁夏和山西虽然从美国的引资规模不大，但是对美资的依赖程度最高，亟需提升外资多元化水平。从人员跨境流动风险来看，上海、北京和浙江面临的风险最大。中国各省区市在应对美国出口管制时应该加强外贸风险的识别和管理，针对不同的风险采取差别化的防范和化解措施。  相似文献   

东北地区水稻扩张的海拔优势区间分析     

黄莹泽  邱炳文  何玉花  张珂  邹凤丽 《地理科学进展》2020,39(9):1557-1564

及时掌握水稻的时空分布信息,对调整和优化农业生产结构至关重要。论文利用综合考虑植被物候和地表水变化的水稻自动制图方法,结合海拔、地表水体因素开展2001—2017年东北地区水稻分布的时空演变研究。通过889个地面调研点位对水稻分类结果验证,总体精度达90.66%,Kappa系数为0.8128。研究表明:① 21世纪初,东北地区水稻种植面积呈先略减后持续增加的趋势,2017年水稻种植面积达2001年的2.13倍。其中,水稻扩张面积的60%分布在三江平原,30%分布在松嫩平原,下辽河平原仅占不足5%。水稻扩张的海拔优势区间在200 m范围内,随着海拔的上升水稻扩张与地表水关系越来越密切。② 三江平原内,水稻扩张幅度在海拔30~70 m范围内逐渐增加,使优势区间从相对高度70 m缩减至40 m内,也使得分布优势逐渐趋向于距地表水体较远的区域。而松嫩平原和下辽河平原水稻种植分布的海拔优势区间始终分别保持在相对高度100 m、40 m内。③ 三江平原水稻的集中分布和急剧扩张,使水稻分布优势逐渐趋向于距地表水体远的区域,这将对地下水带来更大的压力;而松嫩平原水稻分布受地表水体影响较大,分布优势随着距地表水体距离的增加而减小。研究可为农业部门评估水资源承载力、保障农业可持续发展提供数据支撑及理论参考。  相似文献   

地理大数据挖掘——目标、内涵与研究问题     

裴韬  宋辞  郭思慧  舒华  刘亚溪  杜云艳  马廷  周成虎 《地理学报(英文版)》2020,30(2):251-266

  相似文献   

河西走廊西段戈壁灌木群落多样性及其分布格局研究          下载免费PDF全文

董雪  李永华  辛智鸣  段瑞兵  姚斌  包岩峰  黄雅茹  张正国 《干旱区地理》2020,43(6):1514-1522

通过野外样方调查河西走廊西段荒漠戈壁典型灌木群落多样性状况，研究探讨了 8 种典型 灌木群落物种多样性的空间分布格局及其与地理因子的关系，对荒漠戈壁植物群落的多样性的保 护和可持续发展具有重要意义。结果表明：(1) 8 个典型灌木群落 Shannon-Wiener 指数、Simpson 指 数、Margalef 指数和 Pielou 指数从高到低为：盐爪爪群落>麻黄群落>合头草群落>红砂群落>梭梭群 落>泡泡刺群落>多枝柽柳群落>沙拐枣群落；波动范围分别为 0.314 ~ 1.355、0.179 ~ 0.666、0.334 ~ 1.222 和 0.051 ~ 0.218，说明荒漠戈壁灌木群落物种多样性指数偏低，群落结构简单，物种组成稀 少。(2) 不同灌木群落内物种数越多，群落间 Jaccard 相似性系数越大。大部分灌木群落类型间 Jac? card 相似性在 0.20 ~ 0.60 之间，群落间相似水平较低，群落相对稳定。(3) 随着海拔的升高，Margalef 指数、Pielou 指数和 Shannon-Wiener 指数均呈先增加后降低的单峰型分布格局，最大值出现在海拔 2 000 m，且与海拔显著相关（P<0.05）；在经度梯度上，从东到西，Margalef 指数、Pielou 指数和 Shan? non-Wiener 指数呈递增格局，但与经度无显著相关性（P>0.05）；在纬度梯度上，从南到北，Margalef 指数、Pielou 指数和 Shannon-Wiener 指数呈显著递增趋势（P<0.05）。总体上，荒漠戈壁灌木群落物 种多样性呈现出明显的垂直（海拔）和纬度地带性分布格局。  相似文献   

Attribution analysis for water yield service based on the geographical detector method: A case study of the Hengduan Mountain region   总被引：1，自引：0，他引：1  

Dai  Erfu  Wang  Yahui 《地理学报(英文版)》2020,30(6):1005-1020

Ecosystem services, which include water yield services, have been incorporated into decision processes of regional land use planning and sustainable development. Spatial pattern characteristics and identification of factors that influence water yield are the basis for decision making. However, there are limited studies on the driving mechanisms that affect the spatial heterogeneity of ecosystem services. In this study, we used the Hengduan Mountain region in southwest China, with obvious spatial heterogeneity, as the research site. The water yield module in the In VEST software was used to simulate the spatial distribution of water yield. Also, quantitative attribution analysis was conducted for various geomorphological and climatic zones in the Hengduan Mountain region by using the geographical detector method. Influencing factors, such as climate, topography, soil, vegetation type, and land use type and pattern, were taken into consideration for this analysis. Four key findings were obtained. First, water yield spatial heterogeneity is influenced most by climate-related factors, where precipitation and evapotranspiration are the dominant factors. Second, the relative importance of each impact factor to the water yield heterogeneity differs significantly by geomorphological and climatic zones. In flat areas, the influence of evapotranspiration is higher than that of precipitation. As relief increases, the importance of precipitation increases and eventually, it becomes the most influential factor. Evapotranspiration is the most influential factor in a plateau climate zone, while in the mid-subtropical zone, precipitation is the main controlling factor. Third, land use type is also an important driving force in flat areas. Thus, more attention should be paid to urbanization and land use planning, which involves land use changes, to mitigate the impact on water yield spatial pattern. The fourth finding was that a risk detector showed that Primarosol and Anthropogenic soil areas, shrub areas, and areas with slope 5° and 25°–35° should be recognized as water yield important zones, while the corresponding elevation values are different among different geomorphological and climatic zones. Therefore, the spatial heterogeneity and influencing factors in different zones should be fully con-sidered while planning the maintenance and protection of water yield services in the Hengduan Mountain region.  相似文献