阿拉善荒漠草地几种灌木对土壤有效态养分的影响   总被引：8，自引：6，他引：2  

郭丁  裴世芳  俞斌华  傅华 《中国沙漠》2009,29(1):95-100

对阿拉善荒漠草地广泛分布的几种灌木、半灌木土壤有效态常量和微量营养元素的“肥岛”效应进行了研究。结果表明：①霸王、白刺、红砂和沙冬青提高了灌丛根部土壤速效Na、K、Fe和Mn 的含量,而降低了灌从根部土壤速效Ca、Mg的含量;驼绒藜除对土壤速效Mg含量有显著影响外,对其他元素无显著的影响。②霸王、白刺和沙冬青对速效Na、K、Fe和Mn有明显的富集作用,对速效Ca负富集作用;红砂对速效Na有极强的富集作用,EA、EB分别为37.59和52.93;除红砂和驼绒藜对速效Mg有富集作用外,其余灌丛对速效Mg无富集作用。③灌丛周围土壤pH值与速效K、Fe和Zn含量呈显著负相关,与Ca呈正相关,与速效Na无相关性。霸王、白刺、沙冬青周围土壤速效Mg含量与pH值也呈显著正相关;除了霸王外,其他灌木周围土壤速效Mn含量都与pH值呈负相关。  相似文献   

青藏高原东北缘基底结构研究——玛多—共和—雅布赖剖面上地壳地震折射探测          下载免费PDF全文

郭文斌  嘉世旭  段永红  王夫运 《地球物理学报》2016,59(10):3627-3636

利用青藏高原东北缘玛多-共和-雅布赖人工地震测深剖面的沉积盖层及上地壳折射波Psed、Pg走时,使用正则化方法反演该剖面基底速度结构,并通过射线数分布、分辨率分析等手段分析反演结果的可靠程度,得到了沿剖面850km近地表沉积盖层及结晶基底结构性质及构造变化特征,揭示了巴颜喀拉块体中段、东昆仑—西秦岭褶皱带、祁连褶皱带东侧及阿拉善块体等四个一级地质构造单元以及各块体内部若干次级构造沉积盖层介质岩性及厚度,结晶基底性质及被改造特征,在此基础上分析了(沿测线)青藏高原东北缘与外围阿拉善块体、高原内部块体间上部地壳构造耦合以及与地表构造形态关系.  相似文献   

浅析阿拉善盟风能资源特征与区划     

刘志宁  刘颖  刘和平  张勇 《内蒙古气象》2012,(3):32-34

文章拟对阿拉善盟风能资源特征进行分析,据此做出合理的风能资源利用区划,为进一步开发利用风能资源提供参考依据。  相似文献   

内蒙古阿拉善左旗乌兰尚德地区志留系圆包山组笔石化石的发现及其地质意义     

王挨顺  马云飞  张宝艳  武力军  张云学  邢志强  刘明君  杨富广  梁志宝  贾永琦  赵佳佳  张强  孙泽晨 《地质通报》2019,38(6):950-958

阿拉善盟阿拉善左旗杭乌拉山以北哈日奥布日格断凹陷盆地两侧,北东向出露770km2的哑地层,前人将其划为二叠系双堡塘组,但该套地层的岩性和岩石组合及层序特征,与内蒙古岩石地层所述的双堡塘组的现在定义和地质特征及区域变化完全相悖。采用现代沉积学理论和层序地层学方法,开展岩石组合、基本层序、沉积构造与沉积环境研究,划分出3个段级填图单元。根据发现的笔石化石和被晚泥盆世中粗粒黑云母花岗闪长岩侵入的关系,将地层时代确定为早志留世,改划为志留系圆包山组。泥盆纪区域变质变形作用使其发生浅变质和片理化变形,并形成轴向北东的复式向斜构造。后期叠加构造变形,形成紧闭倒转褶皱。志留系圆包山组的确定对本区地层划分和区域构造演化研究有重要意义。  相似文献   

内蒙古阿拉善地区二叠纪曼德林乌拉岩体年龄、成因及其地质意义   总被引：1，自引：0，他引：1  

张建军  张磊  王涛  史兴俊 《地质通报》2019,38(10):1675-1690

内蒙古阿拉善地块北缘及其邻区广泛出露早古生代—早中生代侵入岩,其时空分布、源区物质组成及成因对研究阿拉善北部地区构造演化乃至整个中亚造山带南缘晚期的演化具有重要意义。曼德林乌拉岩体位于阿拉善地块北部雅布赖-诺尔公-洪古尔玉林带西段,岩体以二长花岗岩为主,广泛发育岩浆暗色包体。这些镁铁质包体为岩浆结构,大多具有塑性外形,并具有多种不平衡结构和矿物组合,如斜长石环带、针状磷灰石等。LA-ICP-MS锆石U-Pb测年结果显示,曼德林乌拉二长花岗岩年龄为271±3Ma,花岗岩中发育的包体年龄为271±2Ma,表明该岩体形成于二叠纪,而非之前认为的中生代。二长花岗岩的锆石ε_(Hf)(t)值为-18.4～-10.1,相应的二阶段Hf模式年龄为1.8～2.3Ga;暗色包体中的13颗二叠纪锆石相应的ε_(Hf)(t)值为-23.6～-9.1,相应的二阶段Hf模式年龄为1.7～2.5Ga。锆石Hf同位素特征表明,形成花岗岩和镁铁质暗色包体的这2种岩浆均来自以古老地壳物质为主的源区,这与东段诺尔公—红古尔玉林地区的中酸性侵入岩相同。曼德林乌拉岩体花岗质岩和镁铁质暗色包体的岩石学、地球化学及同位素研究表明,它们可能也具有岩浆混合成因。这为阿拉善地块北缘区域在二叠纪发生广泛的壳幔相互作用提供了进一步证据。  相似文献   

Middle–Late Triassic sedimentation in the Helanshan tectonic belt: Constrain on the tectono-sedimentary evolution of the Ordos Basin,North China     

Jiaopeng Sun  Yunpeng Dong 《地学前缘(英文版)》2019,10(1):213-227

The Helanshan tectonic belt is located to the west of the Ordos Basin, and separates the Alxa (or Yinshan) Massif to the west from the Ordos block to the east. Triassic sedimentation in the Helanshan tectonic belt records important information about tectono-sedimentary process between the Alxa Massif and the Ordos block. Detailed geological mapping and investigation on the lithological package, sedimentary facies and paleocurrent orientation have been conducted on the Middle to Upper Triassic clastic rocks in the Helanshan tectonic belt. The succession is characterized by upward-fining sequence and comprises coarse grained alluvial-fluvial facies in the lower part as well as deltaic-lacustrine facies in the upper part. Based on detailed study and comparisons on the sedimentary sequence along various sections, the Middle to Upper Triassic strata have been revealed that show clear southeastward-deepening sedimentary differentiation and transgression from southwest to northeast, which are consistent with the southeastward flowing paleocurrent. These features indicate a southeastward-dipping paleogeography in the Helanshan tectonic belt, which was original western part of southeastward orientated fluvial-lacustrine system in the northwestern proto-Ordos Basin. Further to the east, the Triassic succession in the Ordos Basin displays gradually thickening and alluvial-fluvial system flowed from southeast to northwest, showing a huge thick sedimentary wedge in the western basin margin. Together with the Late Permian–Early Triassic closure of the Paleo-Asian Ocean to the north, the Late Triassic extensional structures and diabase dykes in the Helanshan tectonic belt, all the above sedimentary features could be mostly interpreted as records of an extensional basin correlated to post-collisional collapse of the Central Asian Orogenic Belt.  相似文献   

Early Carboniferous High Ba‐Sr Granitoid in Southern Langshan of Northeastern Alxa: Implications for Accretionary Tectonics along the Southern Central Asian Orogenic Belt     

ZHENG Rongguo  LI Jinyi  ZHANG Jin  XIAO Wenjiao  LI Yi 《《地质学报》英文版》2019,93(4):820-844

Voluminous granitoids are widely distributed in the Langshan region, northeast of the Alxa block, and record the evolutionary processes of the southern Central Asian Orogenic Belt. The Dabashan pluton was emplaced into the Paleoproterozoic Diebusige complex. Early Carboniferous zircon LA-ICP MS U-Pb ages were from 327 Ma to 346 Ma. The Dabashan pluton can be classified as monzogranite and syenogranite, and exhibits high K2O contents and K2O/Na2O ratios, which reveal a high-K calc-alkaline nature. The samples display strongly fractionated REE patterns, and are enriched in large ion lithophile elements (LILE) relative to high field strength elements (HFSE). The Dabashan plutons display unusually high Ba (823–2817 ppm) and Sr (166–520 ppm) contents and K/Rb ratios (315–627), but low Rb/Ba ratios (0.02–0.14), and exhibit fertile zircon Hf isotopic compositions [εHf(t)=?14 to ?20], which are comparable to those of typical high Ba–Sr granitoids. Based on the geochemical compositions of the samples, we suggest that subducted sediments and ancient crustal materials both played important roles in their generation. Basaltic melts were derived from partial melting of subcontinental lithophile mantle metasomatized by subducted sediment-related melts with residual garnet in the source, which caused partial melting of ancient lower crust. Magmas derived from underplating ascended and emplaced in the middle–upper crust at different depths. The resultant magmas experienced some degree of fractional crystallization during their ascent. Given these geochemical characteristics, together with regional tectonic, magmatic, and structure analysis data, an active continental margin environment is proposed for the generation of these rocks.  相似文献   

内蒙古阿拉善左旗克布勒铁铜矿地质特征及找矿标志     

冯骥  杨建军  李鹏 《地质与资源》2017,26(4):353-356

阿拉善左旗克布勒铁铜矿位于石炭纪石英闪长岩与渣尔泰山群曾隆昌组二段的外接触带,矿体总体产状与接触带产状一致,赋存在接触带上的夕卡岩体外侧及其附近围岩中,属于夕卡岩型矿床.石炭纪石英闪长岩为矿体的形成提供了热源和物源,北东向的断裂构造则为石英闪长岩的侵入和成矿热液提供了通道.在分析矿床成矿地质特征的基础上,总结了综合找矿标志.  相似文献   

对内蒙古阿拉善西部地下水流向问题的新认识     

张竞  王旭升  贾凤超  李国敏  董艳辉 《现代地质》2015,29(1):213-219

内蒙古阿拉善西部的水文地质研究程度很低,关于地下水的来源和流向仍然存在各种不同的认识,需要在沙漠腹地补充钻探资料加以验证。本研究在前人调查成果的基础上,选择巴丹吉林沙漠及其周边的4个控制点进行了水文地质钻探,获得关键性的含水层分布和地下水位数据,对地下水流向问题提出了新的认识。分析结果表明,阿拉善西部广泛发育厚度50 m以上的第四系孔隙含水层,与新近系和白垩系砂岩含水层一起构成主要的地下水渗透介质,使区域地下水流具有连续性。地下水总体自东向西、自南向北流动,水力梯度介于0.8‰与7.9‰之间。在区域尺度上,断裂带对浅层地下水的作用并不显著。  相似文献   

1927年古浪8级大震区及其周边地块的深部电性结构   总被引：13，自引：7，他引：6       下载免费PDF全文

詹艳  赵国泽  王继军  陈小斌  肖骑彬  黄哲  镇国钧 《地球物理学报》2008,51(2):511-520

沿穿过古浪大震震中区乐都—武威—白马岗北北东方向约340 km长的剖面,进行了16个测点的大地电磁探测.使用Robust技术处理观测数据,分析了视电阻率、阻抗相位、Swift二维偏离、最佳电性主轴方位角等参数,并采用NLCG二维反演技术对TE和TM两种模式的数据进行了二维反演模拟.结果表明：大通山—大坂山、西海原、皇城—双塔、龙首山和北大山5条断裂为明显的电性边界,其中西海原、皇城—双塔、龙首山和北大山断裂由西南向东北依次变浅变缓并在深部收敛于壳内低阻层上.沿剖面上地壳的电性构造较中下地壳的复杂,上地壳自西南向东北可分为中祁连隆起、北祁连褶皱带、冷龙岭隆起、武威盆地、潮水盆地和北大山隆起6个构造单元样式,显示与地表地质调查一致的构造格局;而在中、下地壳,武威盆地、潮水盆地和北大山隆起为一体,都属于阿拉善地块.中祁连和阿拉善地块电性成层性好,存在西南深、东北浅的壳内低阻层,北祁连褶皱带和冷龙岭隆起带电性结构复杂,高、低电阻体相间.1927年古浪地震震中区西南侧和上方区域的电阻率为高电阻率区,下方和东北侧区域为低电阻率区,处于电性结构明显呈台阶状陡变的地带,表明古浪地震是一次与断坡作用有关的地震.  相似文献