Discovery of Borax-bearing Mirabilite Beds in Dong Co, Northern Tibet, and Its Palaeoclimatic Significance   总被引：3，自引：0，他引：3  

WEI Lejun  ZHENG Mianping  LIU Xifang  CAI Keqin  NIE Zhen Institute of Mineral Resources  Chinese Academy of Geological Sciences  Beijing China University of Geosciences  Beijing Open Laboratory of Saline Lake Resources & Environment  Chinese Academy of Geological Sciences  Beijing Fei Zhenbi 《《地质学报》英文版》2002,76(3):271-282

The authors investigated lacustrine chemical sediments on terrace-I of Dong Co-a salt lake in the interior of the northern Tibetan Plateau and firstly discovered borax and a complete sedimentary section with five pure mirabilite beds. According to the sedimentary characteristics of rhythmic layering, palaeotemperatures for the formation of the cold-phase mineral-mirabilite-at the profiles and 14C dating, the authors applied the theory and method of comparative salinology in the study of the history of the palaeoclimate and palaeoenvironment of Dong Co in the early and middle Holocene and drew the conclusion that the salt lake had experienced the following climatic evolution: the warm and moist stage (>8470 a BP and possibly to 10500 a BP)→cold and dry stage (8470-8170 a BP)→warm and moist stage (8170-7590 a BP)→stage of repeated climatic oscillations (7590-7400 a BP, alternation of three dry oscillations and three moist oscillations in a generally cold climatic background)→cold and dry stage (7400-6  相似文献   

西藏洞错硼砂芒硝层的发现及其古气候意义   总被引：5，自引：6，他引：5       下载免费PDF全文

魏乐军  郑绵平  刘喜方  蔡克勤  乜贞 《地质学报》2002,76(2):261-271

通过调查藏北高原腹地盐湖——洞错的Ⅰ级阶地湖相化学沉积,首次发现硼砂及赋存5层纯芒硝层的完整沉积剖面,依据韵律层的沉积特征研究和~(14)C测年,针对剖面中出现的冷相盐类矿物——芒硝,应用比较盐湖学的理论和方法,指出洞错在全新世早、中期经历了潮湿温暖期(>8470 a BP,可能至10500 a BP±)→寒冷干旱期(8470～8170 a BP)→潮湿温暖期(8170～7590 a BP)→气候频繁波动期(7590～7400 a BP,寒冷大背景下三干三湿的气候演替)→寒冷干旱期(7400～6940 a BP)→潮湿温和期(6940～6620 a BP)→寒冷干旱期(6620～6410a BP)→温暖湿润期(6410 a BP以后)的演变序列。  相似文献   

Origins of polycyclic aromatic hydrocarbons in estuarine sediments     

James L. Lake  Curtis Norwood  Crandall Dimock 《Geochimica et cosmochimica acta》1979,43(11):1847-1854

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Trend of Salt Lake Changes in the Background of Global Warming and Tactics for Adaptation to the Changes   总被引：5，自引：0，他引：5  

ZHENG Mianping  QI Wen  JIANG Xianfeng  ZHAO Yuanyi  LI Minghui Open Laboratory of Saline Lake Resources  Environment  Chinese Academy ofGeological Sciences  Beijing R & D Center for Saline Lakes  Epithermal Deposits  Chinese Academy of Geological Sciences  Beijing 《《地质学报》英文版》2004,78(3):795-807

Salt lakes are a mirror of climatic changes and provide holographic records of environmental changes of lakes. According to a study of geological hazards in typical salt lake areas in China and other regions, the authors explain how geological hazards in salt lake areas are caused by natural agents and how humans can seek benefits, avoid hazards and reduce losses on the premise that they have monitored and mastered the trend of salt lake changes in advance and even can store flood and recharge water in lakes and extract saline resources. The climate  相似文献   

兴海县土地资源的开发与保护     

王岩  周笃珺 《青海国土经略》2001,(2)

通过分析兴海县土地利用状况、潜力及存在的问题,指出了土地资源合理利用的必要性;在明确土地开发利用与保护的原则和方向的基础上,提出了土地开发利用与保护的对策措施。  相似文献   

盐湖资源与环境的地球科学系统研究     

胡东生 《青海国土经略》1995,(2)

根据现代科学技术水平的发展,定义了盐湖资源与环境的科学概念,表述了盐湖资源的范畴和内涵,对盐湖的水面位、相环境、成岩作用、变质作用及反馈作用进行了详悉论述;对盐湖系统研究的几个关键性问题及发展方向和应用前景进行了讨论。  相似文献   

Bivalve shellfish harvesting and consumption in New Zealand, 2011: data for exposure assessment     

N King  R Lake 《新西兰海洋与淡水研究杂志》2013,47(1):62-72

We provide an overview of bivalve molluscan shellfish (BMS) availability to New Zealanders. Data on commercial production (aquaculture) and harvesting, non-commercial (recreational and customary) harvesting and international trading (imports, exports) of BMS were assembled. These data were transformed to estimate the total weight (greenweight and meatweight) of each BMS species, and all BMS species, available to New Zealand domestic consumers in 2011. An estimated 68,000 tonnes greenweight, or 13,000 tonnes meatweight, of BMS were available. Mussels (mostly commercially-produced Perna canaliculus) accounted for 96% of the total available BMS by meatweight. Non-commercially harvested BMS were 1% of the total available BMS. BMS availability was estimated as 8 g/person/day for the total New Zealand population and 407 g/person/day for shellfish consumers. These estimates were comparable to published national consumption data. The results can be used as inputs to exposure assessment. Food availability is a useful estimate where consumption data are limited.  相似文献   

A standardised sampling protocol for robust assessment of reach-scale fish community diversity in wadeable New Zealand streams     

Bruno O David  Mark P Hamer  Kevin J Collier  Mike D Lake  Graham M Surrey  Kate McArthur 《新西兰海洋与淡水研究杂志》2013,47(3):177-187

The New Zealand fish fauna contains species that are affected not only by river system connectivity, but also by catchment and local-scale changes in landcover, water quality and habitat quality. Consequently, native fish have potential as multi-scale bioindicators of human pressure on stream ecosystems, yet no standardised, repeatable and scientifically defensible methods currently exist for effectively quantifying their abundance or diversity in New Zealand stream reaches. Here we report on the testing of a back-pack electrofishing method, modified from that used by the United States Environmental Protection Agency, on a wide variety of wadeable stream reaches throughout New Zealand. Seventy-three first- to third-order stream reaches were fished with a single pass over 150–345 m length. Time taken to sample a reach using single-pass electrofishing ranged from 1–8 h. Species accumulation curves indicated that, irrespective of location, continuous sampling of 150 stream metres is required to accurately describe reach-scale fish species richness using this approach. Additional species detection beyond 150 m was rare (<10%) with a single additional species detected at only two out of the 17 reaches sampled beyond this distance. A positive relationship was also evident between species detection and area fished, although stream length rather than area appeared to be the better predictor. The method tested provides a standardised and repeatable approach for regional and/or national reporting on the state of New Zealand's freshwater fish communities and trends in richness and abundance over time.  相似文献   

西乡群三郎铺组和大石沟组火山岩U-Pb定年及岩石成因研究   总被引：3，自引：1，他引：2  

徐学义  陈隽璐  李向民  马中平  王洪亮  夏林圻  夏祖春  李平 《岩石学报》2010,26(2):617-632

三郎铺组不整合上覆于孙家河组之上,与大石沟组呈连续过渡关系,两者均为一套火山沉积岩系。三郎铺组火山岩主要为玄武岩和流纹岩,大石沟组火山岩包括玄武岩、安山岩、流纹岩。大石沟组流纹岩LA-ICPMS锆石U-Pb定年揭示流纹岩形成时代为803.0±5.3Ma,属新元古代岩浆作用产物。元素地球化学和三郎铺组特有的陆相火山岩结构表明火山岩形成大陆板内伸展环境,属亚碱性火山岩系。三郎铺组玄武岩和流纹岩组成双峰式火山岩套,微量元素比值对模拟结果表明玄武岩浆来源于岩石圈地幔中原始石榴石二辉橄榄岩的部分熔融,部分熔融程度约为7%; 三郎铺组流纹岩浆源岩可能为白勉峡组下部的玄武质岩石,岩浆起源于斜长石稳定的下地壳源区或部分熔融形成的原生岩浆在上升过程中,经历了较为显著的斜长石结晶分异作用过程。大石沟组玄武岩、安山岩和流纹岩具有相同的微量元素比值、ε(t)值和t_DM,为同一母岩浆分离结晶的产物。玄武岩浆起源于原始石榴石二辉橄榄岩约10%的部分熔融,玄武岩浆分离结晶后残余岩浆比例约70%时形成安山岩浆,残余岩浆比例约20%~30%时产生流纹岩浆; 分离结晶的主要矿物包括斜长石和铁钛氧化物。三郎铺组和大石沟组均是新元古代晚期大陆裂谷作用的岩浆响应。  相似文献   

Properties of galaxy clusters: mass and correlation functions     

F. Governato  †  A. Babul  T. Quinn  P. Tozzi  C. M. Baugh  N. Katz  G. Lake 《Monthly notices of the Royal Astronomical Society》1999,307(4):949-966

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