Zircon U-Pb geochronology,geochemistry and petrogenesis of syenogranite from Angeer Yinwula area in Inner Mongolia     

LIU Hanlun  WANG Keyong  LI Jian  CAI Wenyan  TANG Wenhao  WANG Changhong 《世界地质(英文版)》2019,(2):78-90

The study presents the results of U-Pb dating of zircons and whole-rock geochemical analyses of syenogranite in Angeer Yinwula area, China, with the aim of determining its formation time, petrogenesis and regional setting. Zircon U-Pb data obtained by LA-ICP-MS indicate that the syenogranite formed in the Early Cretaceous(136.1±0.9 Ma). Geochemically, the rock is characterized by high SiO_2(76.63%--77.58%) and Na_2O+K_2O(8.00%--8.32%), low MgO(0.02%--0.04%) and TFe_2O_3(0.51%--0.84%), and is enriched in LREEs and LILEs, depleted in HREEs and HFSEs. It belongs to high-K calc-alkaline, metaluminous-weakly peraluminous, exhibiting an affinity to I-type granite. All these characteristics implied that the syenogranite in this region derived from crust-mantle mixed source. Overall, the regional geology, geochronology and geochemical features suggest that the formation of the syenogranite was related to the subduction of the Paleo-Pacific Ocean.  相似文献   

红层盆地岩性差异对丹霞地貌发育的控制   总被引：2，自引：0，他引：2  

刘鑫  郭福生  陈留勤  李馨敏  刘富军 《山地学报》2019,(2):214-221

陆相红层盆地的岩性在横向上和纵向上都有比较明显的变化,导致发育的丹霞地貌形态迥异。本文以赣东北信江盆地、粤北丹霞盆地、陕北地区为例,采用对比分析、数值模拟等研究手段,总结了红层盆地中常见的岩石及地貌类型,提出岩性在丹霞地貌坡面演化过程中的关键作用。在信江盆地中,龙虎山、龟峰等挺拔高耸的山峰主要发育在盆地南缘的河口组厚层砾岩中,而盆地中部贵溪、弋阳地区的近圆形山丘则产在塘边组大型交错层理风成砂岩中;与其类似,丹霞山的赤壁陡崖主要发育在丹霞组厚层砾岩夹风成砂岩中;相反,陕北地区波浪状地貌主要发育在洛河组风成砂岩中。利用河道-山坡综合地形演化(CHILD)地貌模拟软件,假设在同样的构造抬升和河流侵蚀作用下,分别模拟了细砂岩、细砾岩、中砾岩构成的山体坡面的演化过程。模拟结果显示,细砂岩山体易形成较为平缓的坡面,中砾岩易形成陡峻崖壁和巷谷,而介于二者之间的细砾岩则形成较为明显的沟壑系统。CHILD模拟结果与实地观测一致。因此,红层岩性差异在丹霞地貌演化过程中扮演了重要的角色,也是未来地貌定量模拟研究中需要考虑的关键因素。  相似文献   

中国东北地区人为活动对森林景观格局及鹿科动物生境的影响（英文）     

吴文  李月辉  胡远满  常禹  熊在平 《地理学报(英文版)》2019,(7):1098-1112

Species abundance and habitat distribution are two important aspects of species conservation studies and both are affected by similar environmental factors. Forest resource inventory data in 2010 were used to evaluate the patterns of habitat for target species of Cervidae in six typical forestry bureaus of the Yichun forest area in the Lesser Xing’an Mountains, northeastern China. A habitat suitability index(HSI) model was used based on elevation, slope, aspect, vegetation and age of tree. These five environmental factors were selected by boosted regression tree(BRT) analysis from 14 environmental variables collected during field surveys. Changes in habitat caused by anthropogenic activities mainly involving settlement and road factors were also considered. The results identified 1780.49 km2 of most-suitable and 1770.70 km2 of unsuitable habitat areas under natural conditions, covering 16.38% and 16.29% of the entire study area, respectively. The area of most-suitable habitat had been reduced by 4.86% when human interference was taken into account, whereas the unsuitable habitat area had increased by 11.3%, indicating that anthropogenic disturbance turned some potential habitats into unsuitable ones. Landscape metrics indicated that average patch area declined while patch density and edge density increased. This suggests that as habitat becomes fragmented and its quality becomes degraded by human activities, cervid populations will be threatened with extirpation. The study helped identify the spatial extent of habitat influenced by anthropogenic interference for the local cervid population. As cervid species clearly avoid human activities, more attention should be paid on considering the way and intensity of human activities for habitat management as fully as possible.  相似文献   

Land use and landscape change driven by gully land consolidation project: A case study of a typical watershed in the Loess Plateau     

Li  Yurui  Li  Yi  Fan  Pengcan  Sun  Jian  Liu  Yansui 《地理学报(英文版)》2019,29(5):719-729

Journal of Geographical Sciences - Exploring the impact of land consolidation on the changes of local land use and the landscape patterns is important for optimizing land consolidation models and...  相似文献   

The response of spiders to less-focused non-crop habitats in the agricultural landscape along the lower reach of the Yellow River   总被引：1，自引：1，他引：0  

Hou  Xiaoyun  Ding  Shengyan  Zhao  Shuang  Liu  Xiaobo 《地理学报(英文版)》2019,29(7):1113-1126

Journal of Geographical Sciences - Non-crop habitats have been suggested to impact local biodiversity significantly in agricultural landscapes. However, there have been few studies of the effects...  相似文献   

现代长江水下三角洲浅地层地震相特征     

王远  严学新  王治华  赵宝成  战庆 《海洋地质与第四纪地质》2019,(2):114-122

利用传统的地震相分析方法,分析总结现代长江水下三角洲浅地层地震剖面反射波的几何形态、内部反射结构、连续性、振幅等特征,形成对长江水下三角洲各典型地震相特征的认识,圈定相应的地震相范围,并结合钻孔资料,解释了长江口范围三角洲前积、浅海沉积、古河道等各沉积相的分布。结果表明,现代长江水下三角洲浅地层各地震相特征明显。典型的三角洲前积地震相主要分布在长江口外东北部,其余大部为典型浅海沉积地震相,且浅海地震相特征向口内逐渐变弱,表现为浅砂或淤泥型地震相,向口外逐渐有晚更新世基底地震相出露,并发育古河道地震相,此外,浅层气地震相嵌入区内各个地震相范围。  相似文献   

中甸岛弧带构造格架及斑岩铜矿前景   总被引：48，自引：0，他引：48  

曾普胜  王海平  莫宣学  喻学惠  李文昌  李体刚  李红  杨朝志 《地球学报》2004,25(5):535-540

中甸岛弧带属于中国西南三江构造-岩浆-成矿带中义敦岛弧的南端,其中有2条蛇绿混杂岩带存在,即EW向展布的洛吉蛇绿混杂岩带和近NS向分布的属都蛇绿混杂岩带.前者是中甸岛弧带与扬子地台的构造分界线,而后者则将岛弧带内的东、西两个火山岛弧带分开.西部岛弧带较早,活动时期为250～237 Ma;而东部岛弧带相对较晚,活动时期在218～203 Ma.从岛弧带活动时段(250～203 Ma)分析,属都蛇绿混杂岩带所对应的洋盆(属都洋)的活动时段当在250 Ma之前后,与甘孜理塘洋活动时段相近.属于峨眉山大火成岩省的一部分.2条蛇绿混杂岩带内的玄武岩的岩石学特征均表现为大洋拉斑玄武岩.中甸地区岛弧带内东、西两个斑岩带的斑岩型铜矿的找矿远景极大,尤以东斑岩带前景最佳,普朗斑岩铜矿床远景规模在大型以上.中甸斑岩铜矿将成为中国又一重要的斑岩铜(多金属)矿矿产地,具有极好的找矿前景.  相似文献   

公路路基下伏空洞地质背景研究   总被引：2，自引：0，他引：2  

姚文光  张志沛 《西北地质科学》1999,20(1):42-56

公路路基下伏空洞为天然和人工产生,严重危害公路路基的稳定．笔者通过对空洞的地质背景研究,分析了空洞成因、类型及演化规律;将空洞上覆的岩层划分为冒落带、裂隙带、弯曲带等３个带,阐明了覆岩的岩性和构造特征,总结了影响冒落的因素、地表的破坏形式和地表变形特征,建立起了地质模式和工程地质模式．  相似文献   

加强保护特色地质景观—北京延庆辛家栅子硅化木化石群     

赵兴国 《城市地质》1999,11(4):26-27

介绍了北京市延庆县千家店乡辛家栅子村北坡及上德隆湾村南坡发育的硅化木化石群的位置及其产出的地质特征、现存状态, 并提出了采取保护措施的建议  相似文献   

中国煤型气区的构造环境、典型气藏及勘探方向Ⅱ——中、新生界煤型气     

陶明信  徐永昌  陈践发  沈平 《沉积学报》1999,(4)

本篇论述中、新生界煤型气的有关问题。中生界煤型气资源集中分布在北方,气源岩以侏罗纪煤系为主,以西北区资源前景最好。其中吐—哈盆地最具代表性,构造环境反转是本区煤层气形成并富集的特殊构造条件。新生界煤型气资源则集中分布于大陆架裂谷系,第三纪煤系为主力气源岩,裂谷高温构造环境是源岩热演化生烃的有利条件,而背斜—断层圈闭是最有利成藏的构造类型。崖13-1气田为本区典型代表并具自生自储的特点。  相似文献