Re-recognition of the Dajiuhu Wetland in Shennongjia Mountains,Central China

The Dajiuhu wetland,a famous sub-alpine wetland located in the the Shennongjia Mountains,north-subtropical region of Central China,has suffered from adverse impacts of unsustainable human practices over the past 60 years.The Dajiuhu wetland reflects the development process that has been accompanied by human activities.Based on field survey data,high resolution remote sensing image and historical records,the present paper provided a review on exploitation and restoration of the wetland.The results showed that the Dajiuhu wetland degraded quickly from 1950 to 2005.During that time,bog shrinkage,lake disappearance,biodiversity decline,sphagnum reduction,and vegetation succession from wetland communities to terrestrial communities in the Dajiuhu wetland,which were the main manifestations of the wetland degradation.Human activities,such as agricultural reclamation and construction of drainage works,have been the main factors resulting in ecological degradation of the wetland since 1986.Poverty and the short-term economic benefits had been the driving forces for wetland drainage and reclamation over the past years.     

华东地区燕山期花岗质岩浆与成矿作用关系研究

华东地区是我国重要的钨、铜、铁、钼、金、银、铀、铅、锌等多种金属矿产的产业基地。本文系统总结了华东地区钦杭成矿带和武夷山成矿带等重要多金属成矿带的燕山期岩浆活动与成矿作用的时空演化规律,提出燕山期区域成岩成矿作用可划分为早、晚两期四个阶段。(1)燕山早期早阶段(180~165Ma),以I型花岗岩及埃达克质岩石为主,主要分布在钦杭结合带东段以及武夷山成矿带的闽西南坳陷区内,形成一系列斑岩型及矽卡岩型铜铅锌银多金属矿床;其中埃达克质岩是俯冲板块挤压环境下加厚(或拆沉)下地壳重熔的产物;(2)燕山早期晚阶段(165~140Ma),以S型花岗岩以及钨锡、铌钽矿床为主,主要分布于南岭成矿带,另有少量非埃达克质I型花岗岩;(3)燕山晚期早阶段(145~120Ma),为区域由挤压向伸展过渡的构造转换期,在古太平洋板块斜向俯冲所导致的大规模伸展背景下,产生了S型与I-A型花岗岩共生的局面,其中S型火山-侵入杂岩与火山热液型铀铅锌矿床关系密切;在钦杭结合带东段一线出现A型花岗岩以及伴生的钨锡铌钽矿化,其年龄(135~125Ma)略晚于S型火山-侵入杂岩,在武夷山地区岩石类型则以I型为主,并与矽卡岩型以及石英脉型钨锡铁钼矿有关;(4)燕山晚期晚阶段(120~90Ma),在强烈的伸展背景以及俯冲带向洋迁移作用下,成岩成矿事件集中在武夷山以东的沿海地区,以出现晶洞花岗岩、过碱性花岗岩等高温、浅成、高分异花岗岩类为特征,但金属成矿作用则大多与富钾的I型花岗岩类有关,在多个矿集区内形成大量的浅成低温热液型铜金银矿床。钦杭成矿带和武夷成矿带之间的成岩-成矿时空差异性主要受控于古太平洋板块俯冲过程及基底物质组成。     

断裂对盖层封气综合能力破坏程度的研究方法及其应用

为了研究断裂在油气成藏与分布中的作用,在分析盖层封气综合能力及其研究方法的基础上,利用天然气在剩余压力作用下通过盖层向外渗滤散失压力梯度的大小,表征盖层封气综合能力的好坏;依据被断裂破坏前后盖层封气综合能力差值与被断裂破坏前盖层封气综合能力的比值,建立了一套断裂对盖层封气综合能力破坏程度的定量研究方法。以渤海湾盆地南堡凹陷南堡5号构造东二段泥岩盖层为例,对NP5-2断裂对东二段泥岩盖层封气综合能力的破坏程度进行了定量研究。结果表明:南堡5号构造NP5-2断裂对东二段泥岩盖层封气综合能力的破坏程度较高,除L6测线处为弱破坏程度和L1、L5、L8测线处为中等破坏程度外,其余5条测线处均可达到较强和强破坏程度;且NP5-2断裂对东二段泥岩盖层封气综合能力的破坏程度西部强于东部,这与东二段泥岩盖层之下储气层中目前已发现的天然气主要分布在断裂东部相吻合。该方法用于定量研究断裂对盖层封气综合能力破坏程度是可行的。     

黑龙江省初霜冻变化特征研究及预测方法

利用黑龙江省1961-2013年地面测站62站资料和月环流特征量、北半球500 hPa高度场等资料,采用气候统计方法,选取秋季地面最低温度≤ 0℃的初日作为初霜冻日期,分析了初霜冻日期的时空变化特点,北半球500 hPa月平均环流演变特征,影响初霜冻早晚的特征量因子,为初霜冻趋势预测提供依据。结果表明：黑龙江省初霜冻日期呈现显著推迟的趋势,推迟约8.2 d,平均推迟5 d以上的年份均在1988年以后出现;平均初霜冻日期分布是由北开始出现并向南推进,平原则普遍晚于同纬度的山区,EOF分析初霜冻的发生除具有一致性气候特征外,还具有南北相反和东西相反的变化趋势;初霜冻偏早年时,北半球500 hPa环流从前期到同期在黑龙江省北部至极地区域有大范围的负距平,反之,若是正距平,初霜冻易偏晚;影响初霜冻早晚的特征量的因子有欧亚（亚洲）经向环流型、鄂霍茨克海高压、阿留申低压、东亚大槽强度以及西太平洋副热带高压、极涡、AO等。     

Impact,Mechanism,Monitoring of Land Subsidence in Coastal Cities(Annual Work of IGCP 663)

正Land subsidence is a worldwide geohazard consisting in the lowering of the ground surface due to natural and human-induced processes occurring in the shallow and deep subsoil.Over the last two decades,land subsidence has caused damages and widespread impacts to a variety of infrastructures in coastal cities (Ma et al.,2011;Liu et al.,2016;Minderhoud et al.,2018).Meanwhile,it is particularly alarming as it reduces the ground     

HOME GARDENS IN AMAZONIAN PERU: DIVERSITY AND EXCHANGE OF PLANTING MATERIAL*

ABSTRACT. This article examines how peasant farmers build and maintain agrobiodiversity in home gardens found in two traditional peasant communities along the Marañón River in the Peruvian Amazon. Data were gathered through household and garden surveys as well as in‐depth interviews with garden tenders in an upland mixed agricultural village and a lowland fishing village. Substantial variations in cultivated plant diversity were encountered in gardens between and within the villages, which are found to be related to differential exchange of seeds, cuttings, suckers, and other planting material as well as to specific garden and household characteristics. Planting material flows along multiple pathways—from gift giving and purchase to inheritance and scavenging—to the gardens, reflecting a complex and often extensive network of exchange that enables the establishment and maintenance of home garden plant diversity in seemingly isolated and small communities. Further research is needed to identify broader geographical and sociocultural patterns of agrobiodiversity in Amazonia.     

广义WKB法在波场模拟中的应用研究

针对地震勘探中的波场模拟和反演困难等问题，本文从二维波动方程出发，采用Fourier变换得到了赫姆霍兹方程，并创造性地提出了一种全新的近似解法－广义WKB法；该法可以更加近似赫姆霍兹方程，且它的解中包含WKB的近似值.数值模拟显示了WKB法与广义WKB求解的异同.结果表明：广义WKB法是WKB法的一种推广，在求解非线性波数问题时具有更好的优势.     

矿产资源评价的新探索

矿产资源评价作为一种围绕特定区域内矿产勘查而进行的长期性、系统性和前期性的综合研究,是与矿产勘查密不可分,并贯穿于矿产勘查全过程的一项重要工作.文章针对矿产资源评价过程中存在的多源、异构、异地信息的共享、地、物、化、遥信息的简单叠加或脱节、基础数据与典型矿床的研究内容脱节等诸多问题进行了有益的探索和研究,并取得了一定的效果,为矿产资源评价提供了新的思路和途径.     

城镇土地集约利用与转变增长方式 综合评价研究 ——-以北京市海淀区北部新区为例

对城镇土地集约利用及其增长方式转变进行科学合理评价, 是提升城镇土地整理与管理 水平, 最大限度提高土地集约利用效率, 确保可持续发展的重要手段。按照科学性、可比可量性、 适中性、层次性、公平性和目标导向性等原则, 综合考虑土地集约利用的经济、社会和生态效益, 从转变增长方式的角度, 构建城镇土地集约利用与转变增长方式综合评价指标体系。通过熵技术 支持下的AHP 模型与专家群民主决策支持下定性指标定量转化的赋权方法确定评价指标的权 系数; 采用模糊隶属度函数法对评价指标进行量化处理; 在此基础上, 构建基于指标体系的多目 标多层次模糊综合测度模型计算综合评价指标值。以北京市海淀区北部新区为例进行综合评价 研究, 评价结果显示, 目前北部新区城镇土地集约利用程度较低, 体现在水土资源利用、生态环境 友好等方面指数不高, 今后应进一步转变增长方式, 提高土地集约利用水平。     

Major Miocene geological events in southern Tibet and eastern Asia induced by the subduction of the Ninetyeast Ridge

Cenozoic adakitic rocks in the Gangdese changed from barren continental melts to ore-forming slab melts at ~ 23 Ma. The distribution and chemical characteristics of the ore-forming adakites point to an association with the Ninetyeast Ridge. The subduction of the thick, rigid Ninetyeast Ridge changed the geometry and rheology of the eastern Tibetan Plateau lithosphere and asthenosphere, restrained the eastward escape of asthenospheric mantle as well as continental fragments, and promoted the uplift and building of the Tibetan Plateau, which consequently changed the tectonic and climatic regimes in eastern Asia.