青藏高原东北部全新世常量元素地球化学特征及环境演变北大核心CSCD     

胡梦珺  庄静  孙文丽  郑登友  吉天琪  许澳康 《中国沙漠》2023,(2):11-20

对青藏高原东北部风成砂-古土壤序列泽库剖面(ZK剖面)常量元素氧化物含量及其比值进行分析,结合14C测年,揭示其常量元素地球化学特征,探讨了青藏高原东北部全新世环境演变。结果表明:(1)剖面沉积物的化学组成以SiO2、Al2O3、CaO为主,其中SiO2和CaO的标准差较高,对气候变化较为敏感。(2)自剖面底部向上SiO2含量和残积系数呈现先减少后增加的趋势,高值指示冷干的气候意义,CaO含量和退碱系数则相反,高值指示温湿的气候意义。(3)9.4 ka BP以来青藏高原东北部的气候经历了由温湿向冷干的转变过程,可划分为9.4~4.2 ka BP气候温湿期和4.2 ka BP至今气候冷干期;其中在6.6~6.2 ka BP、2.4~2.0 ka BP和1.7~1.5 ka BP存在次一级的气候波动。  相似文献   

东北哈尼泥炭腐殖化度古气候意义及区域对比     

程胜高  肖河  黄庭  周莹  胡忠霞  刘晓彤 《地球科学与环境学报》2014,(2)

不同地区泥炭腐殖化度指示的古气候意义存在着分歧。运用碱提取溶液吸光度法对东北哈尼泥炭腐殖化度进行测定,结合14C测年数据的年代框架,对比东北哈尼、神农架大九湖、青藏高原红原、福建天湖山地区泥炭腐殖化度气候代用指标,分析不同地区泥炭腐殖化度古气候意义异同的原因。结果表明:哈尼泥炭腐殖化度的古气候意义包含温度-湿度组合,较高的腐殖化度指示气候温暖潮湿,较低的腐殖化度指示气候干燥寒冷;从哈尼、红原、大九湖、天湖山泥炭腐殖化度时间序列的对比可以得出,虽然其古气候意义有所不同,但其记录的中国全新世古气候环境演变趋势大体相同,都反映了中国早全新世阶段的升温现象、中全新世的大暖期现象及晚全新世阶段的降温;温度、湿度、季风、经纬度及地质地貌等因素都对泥炭腐殖化度有影响,但水热条件是直接影响,其他因素通过对水热条件的改变而间接影响腐殖化度;阐述不同区域泥炭腐殖化度的古气候意义没有固定模式,需结合当地的地理位置、地质地貌、年均气温、季风、降水、植被等情况进行具体分析。  相似文献   

千山 东北大地上的一颗明珠     

金生 《资源导刊(河南)》2014,(11):52-57

辽宁千山系长白山支脉,辽河与鸭绿江的分水岭,是辽东半岛的脊骨。据地质考察,大约4亿年前,千山一带是一片海洋,到古生代末期开始隆起露出水面形成陆地。经历海陆沧桑5次变迁,1．8亿年前,形成现在典型的粗粒花岗岩地貌……  相似文献   

临潭 秦岭淮河零度等温线上的靓丽城市     

谭敏章 《中国地名》2014,(3):68-69

临潭,古称洮州,地处中国内陆青藏高原东北边缘,甘肃省南部,甘南藏族自治州东部。东邻岷县,北接康乐、渭源两县,与卓尼县插花接壤。临潭县地形西高东低,大多地区属高山丘陵地带,  相似文献   

雄师劲旅 激战华北显军威 金戈铁马 血战江南歼强敌 精锐兵锋 征战粤东肃顽匪 离开塔山的日子——英雄四纵（41军）入关南下征战战事录（连载十一）     

钟桂华 《中国地名》2014,(12):6-38

在中国人民解放战争初期,东北野战军第四纵队成功地进行了塔山一线阻击战。成功的塔山一线阻击战,保证了我军攻克锦州战役的胜利,保证了我军全歼廖耀湘“西进兵团”的胜利,保证了我军辽沈战役歼敌47万人的巨大胜利,为解放全东北以至全中国都做出了巨大的贡献。成功的塔山一线阻击战,在中国和世界军事史上都享有极高的盛誉,是我军军史上野战阵地坚守防御成功的光辉战例,是东北野战军第四纵队全体指战员们的骄傲。  相似文献   

琼东南盆地古近系沉降特征     

蔡佳  王华  崔敏 《海洋地质前沿》2014,30(4):14-19,27

在建立层序地层格架的基础上,对琼东南盆地古近系各个层位沉降史进行了回剥分析。研究表明,琼东南盆地古近系沉降中心不断迁移,沉积中心不断扩大,沉降速率随构造活动程度的变化而发生变化。琼东南盆地的12个凹陷可分为2个沉降梯队,西北及东南部总体上为非沉降区。通过选取各个凹陷中的典型点(最深位置)做出单点上的回剥模拟结果可知,琼东南盆地断陷期的3幕表现明显,构造沉降所占的比例逐渐减少,整体上琼东南盆地中央凹陷带东南区的沉降大于西北区。  相似文献   

琼东南盆地深水区东区凹陷带结构构造及其演化特征     

纪沫  张功成  杨海长  杨东升  李春雷 《海洋地质前沿》2014,30(9):26-35

琼东南盆地深水区东区凹陷带,即松南—宝岛—长昌凹陷,位于琼东南盆地中央坳陷东端。在大量地震资料解释的基础上,对38条主要断层进行了详细分析。获得以下认识:(1)琼东南盆地深水区东区凹陷带平面上表现为近EW向展布的平行四边形,剖面结构表现为自西向东由半地堑—不对称的地堑—半地堑有规律变化。(2)琼东南盆地深水区东区凹陷带断裂系统可划分控制凹陷边界断层、控制洼陷沉积中心断层和调节性断层3类。(3)琼东南盆地深水区东区凹陷带古近纪时期受到太平洋板块俯冲和南海海盆扩张的双重影响,构造应力场发生NW—SE→SN转变。构造演化可划分为3个阶段:～32Ma,应力场以区域性NW—SE向伸展为主,断裂系统以NE—SW向为主,控制凹陷边界;32～26Ma,以南海海盆近SN向拉张应力场为主,断裂系统以NWW—SEE向为主,断层活动控制凹陷沉积中心;26～Ma,区域性伸展与南海海盆扩张应力均逐渐减弱,NE—SW向和NWW—SEE向断裂继承性发育。(4)琼东南盆地深水区东区凹陷带内部主要断层在渐新统崖城组和陵水组沉积时期活动速率快,地形高差大、沉积水体深、沉积厚度大,控制了崖城组和陵水组的大规模沉积,有利于烃源岩的发育。圈闭以受断层控制的断鼻和断块为主,长昌主洼凹中隆起带发育2个最为理想的构造圈闭。  相似文献   

Land use effects on soil organic carbon,microbial biomass and microbial activity in Changbai Mountains of Northeast China   总被引：2，自引：0，他引：2  

Xiangmin Fang  Qingli Wang  Wangming Zhou  Wei Zhao  Yawei Wei  Lijun Niu  Limin Dai 《中国地理科学(英文版)》2014,24(3):297-306

Land use changes are known to alter soil organic carbon （SOC） and microbial properties, however, information about how conversion of natural forest to agricultural land use as well as plantations affects SOC and microbial properties in the Changbai Moun- tains of Northeast China is meager. Soil carbon content, microbial biomass carbon （MBC）, basal respiration and soil carbon mineraliza- tion were studied in five selected types of land use： natural old-growth broad-leaved Korean pine mixed forest （NF）; spruce plantation （SP） established following clear-cutting of NF; cropland （CL）; ginseng farmland （GF） previously under NF; and a five-year Mongolian oak young forest （YF） reforested on an abandoned GF, in the Changbai Mountains of Northeast China in 2011. Results showed that SOC content was significantly lower in SP, CL, GF, and YF than in NF. MBC ranged from 304.4 mg/kg in CL to 1350.3 mg/kg in NF, which was significantly higher in the soil of NF than any soil of the other four land use types. The SOC and MBC contents were higher in SP soil than in CL, GF, and YF soils, yielding a significant difference between SP and CL. The value of basal respiration was also higher in NF than in SP, CL, GF, and YF. Simultaneously, higher values of the metabolic quotient were detected in CL, GF, and YF soils, indicat- ing low substrate utilization of the soil microbial community compared with that in NF and SP soil. The values of cumulative mineral- ized carbon and potentially mineralized carbon （Co） in NF were significantly higher than those in CL and GF, while no significant dif- ference was observed between NF and SP. In addition, YF had higher values of Co and C mineralization rate compared with GF. The results indicate that conversion from NF into agricultural land （CL and GF） uses and plantation may lead to a reduction in soil nutrients （SOC and MBC） and substrate utilization efficiency of the microbial community. By contrast, soils below SP were more conducive to the preservation of soil organic matter, which was reflected in the comparison of microbial indicators among CL, GF, and YF land uses. This study can provide data for evaluating soils nutrients under different land use types, and serve as references for the rational land use of natural forest in the study area.  相似文献   

湘东北盛夏午后热对流降水分析     

《青海气象》2014,(4)

本文通过对2013年8月16日—19日影响湘东北地区盛夏午后对流性降水的幕阜山区EC850h Pa24小时预报风向、地形对湘东北午后热对流降水影响的分析,总结了湘东北盛夏午后热对流降水源地与低层风向的关系以及幕阜山、连云山对湘东北午后热对流降水的作用。  相似文献   

琼东南盆地深水区构造热演化特征及其影响因素分析   总被引：5，自引：1，他引：4  

王振峰  施小斌  杨军  黄保家  孙珍  WANG Yahui  蒋海燕  于传海  杨小秋 《海洋学报(英文版)》2014,33(12):107-117

To reveal the tectonic thermal evolution and influence factors on the present heat flow distribution, based on 154 heat flow data, the present heat flow distribution features of the main tectonic units are first analyzed in detail, then the tectonic thermal evolution histories of 20 profiles are reestablished crossing the main deep-water sags with a structural, thermal and sedimentary coupled numerical model. On the basis of the present geothermal features, the Qiongdongnan Basin could be divided into three regions: the northern shelf and upper slope region with a heat flow of 50–70 m W/m2, most of the central depression zone of 70–85 m W/m2, and a NE trending high heat flow zone of 85–105 m W/m2 lying in the eastern basin. Numerical modeling shows that during the syn-rift phase, the heat flow increases generally with time, and is higher in basement high area than in its adjacent sags. At the end of the syn-rift phase, the heat flow in the deepwater sags was in a range of 60–85 m W/m2, while in the basement high area, it was in a range of 75–100 m W/m2. During the post-rift phase, the heat flow decreased gradually, and tended to be more uniform in the basement highs and sags. However, an extensive magmatism, which equivalently happened at around 5 Ma, has greatly increased the heat flow values, and the relict heat still contributes about 10–25 m W/m2 to the present surface heat flow in the central depression zone and the southern uplift zone. Further analyses suggested that the present high heat flow in the deep-water Qiongdongnan Basin is a combined result of the thermal anomaly in the upper mantle, highly thinning of the lithosphere, and the recent extensive magmatism. Other secondary factors might have affected the heat flow distribution features in some local regions. These factors include basement and seafloor topography, sediment heat generation, thermal blanketing, local magmatic injecting and hydrothermal activities related to faulting and overpressure.  相似文献