黑龙江省东南部张广才岭群新兴组的形成时代及物源

为确定张广才岭群新兴组的形成时代和物源,本文测定了其碎屑锆石和岩浆锆石的年龄。在新兴组中测得的两组碎屑锆石(LA- ICP- MS U- Pb)产生多组谐和年龄,BP18R15样品91个测点最小峰值(谐和)年龄为260Ma (41个点),BP18R83样品100个分析点最小峰值(谐和)年龄为253Ma (52个点)。锆石绝大多数呈自形—半自形晶,显示典型振荡岩浆生长环带或条痕状吸收,且Th/U值相对较高,暗示其岩浆成因。以此确定新兴组沉积下限为晚二叠世之后。结合侵入于新兴组的正长花岗岩年龄为210 ±1Ma,表明张广才岭群新兴组形成于晚二叠世—晚三叠世之间,而非前人所确定的新元古代。从新兴组中碎屑锆石的年龄频数可看出,新兴组的沉积物主要来源于周边晚古生代地质体以及次要的中元古代、新元古代、早古生代和早中生代地质体。前寒武纪碎屑锆石的存在暗示新兴组沉积时,区域地表或浅部曾存在一些具有类似年龄的前寒武纪残余地质体。新兴组几乎所有沉积物源来自松嫩- 张广才岭地块,暗示松嫩- 张广才岭地块与佳木斯- 兴凯地块及华北地块的拼合应晚于晚二叠世。     

地理学视角下城市高温热浪脆弱性评估研究进展

全球气候变化及快速城市化增加了极端天气事件的发生频率,高温热浪作为其中的典型效应,增加了与热相关的健康风险,越来越受到气象学、医学与地理学学者的关注。论文系统梳理了高温热浪的定义,从地理学视角,以空间评估作为切入点,总结分析了高温热浪脆弱性评估中的空间指标、空间制图方法与空间对策等方面的研究进展,指明该领域已从单一视角逐步深入到气象学、医学、地理学等复合学科的交叉研究,地理学作为桥梁将气象学与医学有机结合,为脆弱性评估提供空间指标参数、为制图提供思路与方法,并提供空间对策连接规划和风险预警等实践工作。未来的研究展望包括：空间指标综合各学科研究需要、集成各学科优势进行构建,空间制图在社区小尺度到区域大尺度的耦合机理分析基础上探讨跨区域研究表达方式,空间对策针对不同风险人群采取差异化研究,为城市适应气候变化提供科学依据。     

Comparison of Methods for Evaluating the Forage-livestock Balance of Alpine Grasslands on the Northern Tibetan Plateau

Livestock grazing is one of primary way to use grasslands throughout the world, and the forage-livestock balance of grasslands is a core issue determining animal husbandry sustainability. However, there are few methods for assessing the forage-livestock balance and none of those consider the dynamics of external abiotic factors that influence forage yields. In this study, we combine long-term field observations with remote sensing data and meteorological records of temperature and precipitation to quantify the impacts of climate change and human activities on the forage-livestock balance of alpine grasslands on the northern Tibetan Plateau for the years 2000 to 2016. We developed two methods: one is statical method based on equilibrium theory and the other is dynamic method based on non-equilibrium theory. We also examined the uncertainties and shortcomings of using these two methods as a basis for formulating policies for sustainable grassland management. Our results from the statical method showed severe overgrazing in the grasslands of all counties observed except Nyima (including Shuanghu) for the entire period from 2000 to 2016. In contrast, the results from the dynamic method showed overgrazing in only eight years of the study period 2000-2016, while in the other nine years alpine grasslands throughout the northern Tibetan Plateau were less grazed and had forage surpluses. Additionally, the dynamic method found that the alpine grasslands of counties in the northeastern and southwestern areas of the northern Tibetan Plateau were overgrazed, and that alpine grasslands in the central area of the plateau were less grazed with forage surpluses. The latter finding is consistent with field surveys. Therefore, we suggest that the dynamic method is more appropriate for assessment of forage-livestock management efforts in alpine grasslands on the northern Tibetan Plateau. However, the statical method is still recommended for assessments of alpine grasslands profoundly disturbed by irrational human activities.     

大洋钻探与冲绳海槽地质

本文简要回顾大洋钻探计划实施十余年来所取得的成果，评述了西太平洋边缘海盆的研究概况，提出东海大陆边缘的重大地质问题是陆缘的构造演化历史和动力学过程，弧后扩张中心的热液成矿作用以及海洋沉积层序记录的古气候和古海洋环境变化，指出矿物－地球化学在大洋钻探研究中的重要性。     

New Maikhanellid Shells and Siphogonuchitid Spicule Bundles from the Cambrian Fortunian Stage of South China

Maikhanellids are a distinct group of Cambrian Fortunian small shelly fossils by the cap-shaped profiles and scaly shell ornamentation. According to the individual shell shape and ornamentation feature types of 50 maikhanellids fossils which were collected from Xixiang botia, we confirmed the family Maikhanellidae content of six genera, which are Maikhanella, Ramenta, Purella, Ramentoides, Yunnannopleura and Mediata. Unlike the halkieriid animals whose shells and spicules are articulated on different body parts, maikhanellids were presumably yielded by siphogonuchitid spicules penetrating the intermediate matrix (the "spicule shell" hypothesis), and this is the reason that some researchers treated maikhanellids and co-occurring siphogonuchitids as synonyms. The affinities of Maikhanellids and siphogonuchitids remain debatable. Here, we report three dimensionally phosphatized maikhanellid shells and siphogonuchitid spicule bundles from the Cambrian Fortunian small shell faunas of South China. They differ from all the previously reported maikhanellids and siphogonuchitids, and may represent new types. The intact and smooth surface underneath the partially preserved scales of the shells challenges the "spicule-shell" hypothesis. The present siphogonuchitid spicules differ from the maikhanellid scales in size, morphology, and .arrangement pattern, thus the spicules might not be derived from the shells. Whether the shells and spicule bundles were articulated on different body parts of the same animals remains unknown.     

Spatio-temporal analysis of the geographical centroids for three major crops in China from 1949 to 2014

Spatial distribution changes in major crops can reveal important information about cropping systems. Here, a new centroid method that applies physics and mathematics to spatial pattern analysis in agriculture is proposed to quantitatively describe the historical centroids of rice, maize and wheat in China from 1949 to 2014. The geographical centroids of the rice area moved 413.39 km in a 34.32° northeasterly (latitude 3.08°N, longitude 2.10°E) direction at a speed of 6.36 km/year from central Hunan province to Hubei province, while the geographical centroids of rice production moved 509.26 km in the direction of 45.44° northeasterly (latitude 3.22°N, longitude 3.27°E) at a speed of 7.83 km/year from central Hunan province to Henan province. The geographical centroids of the maize area and production moved 307.15 km in the direction of 34.33° northeasterly (latitude 2.29°N, longitude 1.56°E) and 308.16 km in the direction of 30.79° northeasterly (latitude 2.39°N, longitude 1.42°E), respectively. However, the geographical centroids of the wheat area and production were randomly distributed along the border of Shanxi and Henan provinces. We divided the wheat into spring wheat and winter wheat and found that the geographical centroids of the spring wheat area and production were distributed within Inner Mongolia, while the geographical centroids of winter wheat were distributed in Shanxi and Henan provinces. We found that the hotspots of crop cultivation area and production do not always change concordantly at a larger, regional scale, suggesting that the changing amplitude and rate of each crops’ yield differ between different regions in China. Thus, relevant adaptation measures should be taken at a regional level to prevent production damage in those with increasing area but decreasing production.     

基于Sentinel-1雷达影像的成都市地面沉降InSAR监测分析

利用2017-03~2018-03共30景Sentinel-1A SAR数据,分别采用PSI和SBAS技术获取成都市主城区地面形变分布信息,结合地面水准资料对InSAR结果进行精度评估,并初步分析地面沉降的原因。结果表明,成都市大部分区域稳定,平均形变速率主要集中在-5~5 mm/a;地面沉降主要位于一环线以外地区,地铁5、6号线主要站点及周边不均匀沉降明显,最大沉降速率达到20 mm/a;在成华区和锦江区等部分新建城区有不同程度的地面沉降,速率为5~15 mm/a,PSI和SBAS结果相关性较高。     

基于黑土地保护目标的省级尺度土地类型划分研究——以黑龙江省为例

为提升对土地资源的质的了解程度,优化资源利用方式和方向,实现黑土地保护目标和“藏粮于地、藏粮于技”战略要求,以黑龙江省作为典型研究区域,考虑黑土地保护与利用需求,并借鉴地球关键带理念,从气候影响、地貌条件、地质条件、土壤特性、水文分布5个维度构建三级分类,基于GIS平台采用空间叠置法对主导因素中级分类进行叠加和综合,进行省级尺度土地类型划分。结果表明,黑龙江省共划分为39个土地类,2 121个土地型和4 945个土地组。黑龙江省土地类型单元较丰富,类型单元面积分布不均衡,低级单元相比高级单元属性更丰富,黑土区的土地类型单元呈现出不同的数量特征和空间分布特征。类型单元可反映区域的自然地理规律。空间组合结构上主要有对称式空间组合结构、重复式空间组合结构、镶嵌式空间组合结构3种结构形式。土地类型数量和结构呈现的规律性分布可为黑土地的农业生产布局优化奠定基础。     

高原复杂地理参数对雷电活动的影响分析

雷电活动参数作为反映区域雷电活动特征的重要指标,地形对其影响不容忽视。利用2014—2018年青海省地闪数据、数字地形高程数据以及HWSD土壤数据集,定量分析海拔、坡度、坡向以及土壤电阻率对青海省地闪分布特征的影响。结果表明：（1） 青海省地闪主要集中在海拔3150~4850 m、坡度0~35°的地区,其中东北坡向地闪次数最多,东南坡向地闪次数最少,地闪对应的土壤电阻率主要集中于100 Ω·m。（2） 地闪密度随海拔的升高先增大后减小,随坡度的增大而减小;地闪平均强度随海拔的升高先减小后增大,随坡度的增大而增大。（3） 选取92°27′00″~97°44′24″E、31°40′48″~34°16′48″N地闪活跃区域,对其1 km×1 km网格内地闪数据与地理参量平均值进行相关性分析,所选区域内地闪密度与平均海拔呈正相关关系,与平均坡度呈负相关关系;而地闪强度与平均海拔呈负相关关系,与平均坡度呈正相关关系。