广西隆安都结剖面下石炭统都安组上部鲕粒类型及其地质意义^*          下载免费PDF全文

巩恩普  杨臻元  黄文韬  关长庆  张永利  苗卓伟  王立芙  李骁  王俊杰 《古地理学报》2021,23(1):125-141

鲕粒是一类特殊的沉积颗粒,为古气候和古海洋环境的重要指示器。为了深入认识此类特殊颗粒的成因机制、形成环境及地质意义,对广西隆安地区都结剖面下石炭统都安组上部含鲕粒地层开展了古生物学、沉积学和岩相学研究。研究区共识别出5种主要的鲕粒类型: 放射状纹层鲕粒(O1)、规则同心放射状纹层鲕粒(O2)、不规则同心放射状纹层鲕粒(O3)、泥晶鲕粒(O4-A和O4-B)和复合鲕粒(O5)。各类鲕粒的显微组构和沉积环境指示其具有不同的形成过程,其中水动力条件影响和控制着鲕粒的发育和分布情况。研究区含鲕粒地层形成于维宪期末—谢尔普霍夫期,恰好对应早石炭世晚期冰川作用的开始。受冰川作用影响,全球海平面频繁波动,研究区地处低纬度地区并以浅滩和潮坪沉积环境为主,为鲕粒的形成提供了适宜的水体条件,即温暖、动荡的浅水环境。此外,含鲕粒岩层内广泛发育钙质微生物和微生物席,说明微生物活动在研究区较为常见,可能与鲕粒的形成过程具有一定的关联。  相似文献   

小兴安岭平顶山一带早侏罗世花岗岩类年代学、地球化学特征及其地质意义     

尹志刚  宫兆民  王春生  刘松杰  张圣听  王冠群  周小刚  张志浩 《吉林大学学报(地球科学版)》2021,51(1):107-125

小兴安岭平顶山大地构造位于兴蒙造山带东段,隶属松嫩地块。本文对小兴安岭平顶山一带碱长花岗岩和正长花岗岩进行了锆石U-Pb年代学和岩石地球化学研究,以确定其形成时代、岩石成因及大地构造背景。结果显示：碱长花岗岩形成于（189±3） Ma,正长花岗岩形成于（191±3） Ma,同为早侏罗世岩浆事件演化的产物;岩石具有高硅（w（SiO₂）为75.00%~77.60%）、富碱（w（K₂O+Na₂O）为7.13%~9.00%）、贫镁（w（MgO）为0.05%~0.45%）、贫钙（w（CaO）为0.17%~1.10%）、低磷钛（w（P₂O₅）为0.01%~0.07%,w（TiO₂）为0.09%~0.23%）的特点,A/CNK值为0.94~1.17,属于准铝质-弱过铝质、高钾钙碱性系列岩石;亏损高场强元素Nb、P、Ti、Ta和大离子亲石元素Ba、Sr,Rb、K、Th、Hf等元素具有明显的正异常;稀土元素总量（w（ΣREE））为（38.76~297.13）×10^-6,稀土配分曲线显示为轻稀土略微富集、重稀土较为平坦缓向倾斜的右倾型,具明显的负Eu异常。锆石饱和温度值及地球化学特征等多种证据显示,岩石为高分异的I型花岗岩。结合小兴安岭区域构造演化特征分析,研究区早侏罗世花岗岩类为松嫩地块与佳木斯地块沿嘉荫—牡丹江缝合带碰撞拼合后伸展环境下的产物,岩浆起源于下地壳火成岩物质的部分熔融。  相似文献   

德宏州国土空间开发格局驱动力研究   总被引：1，自引：0，他引：1  

周峻松  魏晓燕  孙越凡  程亮 《测绘科学》2018,(7):61-66

针对云南省德宏州国土空间开发格局形成机制复杂的问题,该文提出了一种基于冗余分析(RDA)的驱动力研究方法。使用景观格局指数对各乡镇建设用地空间格局进行定量分析,以自然和社会经济数据作为潜在的驱动因子,利用RDA方法对驱动因子进行约束性排序,分析得出人口和经济因素是主要驱动因素。人口众多、经济发达的乡镇,建设用地相对面积较大,并且建设用地更趋向于聚集。此外,自然因素、农业因素、政策因素等,也与人口和经济因素有联动作用,驱动国土空间形态与结构的形成。提出新的驱动力分析方法,一方面探讨冗余分析方法在国土空间开发格局驱动力分析中的应用潜力;另一方面为云南省第一次地理国情普查成果的深化应用提供典型应用示范。  相似文献   

气象科技成果业务应用的痛点和机制改革探索     

黄海洪  黄小燕  李玉红 《气象研究与应用》2019,40(1):96-98,95

以需求为牵引,问题为导向,分析气象科技成果应用的新需求,找出了传统气象科技成果应用的痛点和机制管理的弊端,并以天气预报科技成果业务转化为例,提出了科技成果应用新型管理体系的设想。新型管理体系的构建原则及体系框架,对新管理体系的实施关键环节进行了分析。新型管理模式可望有效改进传统管理体系存在的问题,明显提高科技成果转化的效益,使科技成果真正为气象业务现代化建设提供有力的科技支撑。  相似文献   

Analysis of Cloud Scale Error of Low Resolution Satellite Based on GF-4 and Its Influence on Downward Radiation Calculation     

Chuanxiang Yi  Xiaozhou Xin  Jichao Hu  Hailong Zhang  Xiaojun Li  Wei Gong 《地球科学进展》2018,33(4):425-434

In order to study the scale error of low resolution meteorological satellite cloud detection and its impact on the calculation of downlink radiation, cloud detection using high resolution stationary satellite GF-4 data and error analysis were carried out. Firstly, the cloud detection of GF-4 data is carried out by using visible channel threshold method and time series method, and the error of cloud detection results of Himawari-8 and FY-2 (FY-2G, FY-2E) is analyzed based on the results of GF-4 cloud detection.In the study area, FY-2G, FY-2E and Himawari-8 cloud images could distinguish the clouds and clear sky. The main reason for the error was the scale effect produced by different spatial resolution satellites(the differences caused by cloud detection algorithms are not discussed here).Most of the errors occurred in the areas of thin clouds and broken clouds.High resolution data could detect broken clouds, while low resolution data lead to false and missed detection. On this basis, the error of remote sensing calculation of short wave radiation was analyzed,and it was found that the error of the actual cloud amount in the pixel would bring significant error to the estimation of the downward radiation.The relative error of the instantaneous downward radiation in the selected test area was -173.52%, and the maximum relative error of shortwave radiation was -20.20%.The results show that the high resolution stationary satellite data can significantly improve the estimation accuracy of the downlink shortwave radiation in the regions with more broken clouds.  相似文献   

Provenance and tectonic significance of late Mesoproterozoic detrital zircons from the Tonian system,northern margin of the North China Craton   总被引：1，自引：0，他引：1  

Xiaopeng Dong  Jianmin Hu  Wangbin Gong  Yong Yang  Yi Zhao 《International Geology Review》2018,60(15):1773-1791

The involvement of the North China Craton (NCC) in the assembly or breakup of Rodinia has long been debated. Studies of palaeomagnetism, mafic sills (dikes), igneous events, and sedimentary records have led to contrasting opinions on this topic. No igneous events related to the late Mesoproterozoic assembly of Rodinia have been reported in the NCC. However, the authors found numerous late Mesoproterozoic zircons in the Tonian system on the northern margin of the NCC. The Tonian Zhulazhagamaodao formation is composed of meta-sandstone, siltstone, slate, carbonate, and dolomine of the littoral to neritic facies and occurs mainly in the western part of the Bayan Obo–Zhaertai–Langshan rift. U–Pb dating of detrital zircons from the Tonian system reveals age peaks at 1079 ± 23 Ma, 1092 ± 22 Ma, 1175 ± 50 Ma, 1175 ± 18 Ma, 1260 ± 45 Ma, 1266 ± 16 Ma, and 1270 ± 26 Ma, which correspond to the timing of Rodinia assembly. Considering that coeval igneous rocks and orogenic belts developed mostly in the Laurentia–Baltica cratons, we propose that these cratons supplied clastic material to the northern margin of the NCC and that they had a close spatial relationship between each other during the Tonian.  相似文献   

Zircon and cassiterite U-Pb ages,petrogeochemistry and metallogenesis of Sn deposits in the Sibao area,northern Guangxi: constraints on the neoproterozoic granitic magmatism and related Sn mineralization in the western Jiangnan Orogen,South China     

Chen  Lei  Wang  Zongqi  Yan  Zhen  Gong  Jianghua  Ma  Shouxian 《Mineralogy and Petrology》2018,112(4):437-463

Mineralogy and Petrology - A number of Sn deposits associated with Neoproterozoic granites are located in the western Jiangnan Orogen of northern Guangxi. The distribution of Sn mineralization is...  相似文献   

Impacts of climate change on flow regime and sequential threats to riverine ecosystem in the source region of the Yellow River     

Xiaoyan Wang  Tao Yang  Bin Yong  Valentina Krysanova  Pengfei Shi  Zhenya Li  Xudong Zhou 《Environmental Earth Sciences》2018,77(12):465

Climate change is expected to have substantial impacts on flow regime in the Upper Yellow River (UYR) basin that is one of the most important biodiversity hotspots in the world. These impacts will most possibly exert negative effects on the habitat availability for riverine species. Thus, it is necessary to understand the alteration of river flow regime under climate scenarios. In this paper, we use the modified hydrological model HBV in conjunction with three general circulation models under three representative concentration pathways (RCP 2.6, 4.5, and 8.5) to address changes in flow regime under climate change for the UYR basin in the mid-term (2050s) and end-term (2080s) of the twenty-first century. Flow regime is quantified using the Indicators of hydrological alteration approach. Thereafter, the potential threats to riverine ecosystem in the UYR basin are identified based on the projected alterations of various flow characteristics and their ecological influences. The results showed that the magnitude of monthly flow would increase during the dry period. The date of the annual 1-day minimum streamflow will likely shift toward earlier time under different scenarios, and significant increases in magnitude of annual minimum flow of different durations were detected under both RCP 4.5 and 8.5 scenarios in the 2080s. In addition, assessments of the modification degree of the overall flow regime revealed that climate change would remarkably modify (medium level) the overall flow regime in the UYR basin, particularly by the end of the twenty-first century or under the high emission scenarios. Besides, destruction of habitat and reduced availability of food induced by substantially increased hydrological instability in the 2080s would make two endangered fishes more vulnerable in the UYR basin. These findings provide insights into potential adaptive countermeasures for water resource management and environmental system restoration in the Upper Yellow River.  相似文献   

A generic method to organize boundaries of complex polygons for embedded devices     

Hongbo Gong  Meng Zhang  Jianfei Wang  Liqiu Meng 《Arabian Journal of Geosciences》2018,11(10):238

Based on an analysis of drawbacks in the existing graphical display of complex area objects in embedded system, the paper introduces a new method termed as consecutive boundary organization (CBO) which is able to convert a large number of separate polygons belonging to the same area object into a single consecutive stroke fitting for quick display. The working principle of the CBO method is demonstrated in three cases that can typically occur to the real-world concept “lake”: (1) a lake with an island in it, (2) a lake with multiple islands, and (3) the nested lake-island-lake. In spite of complicated inclusion relationships, the CBO method can always construct an integral stroke with neither information loss nor redundancy. Experiments with a real dataset of lakes and islands from North America have proved the feasibility and efficiency of the CBO method. Due to its generic nature, the CBO method can be applied to any other complex area objects with multiple polygons and inclusion levels.  相似文献   

Geochemistry,geochronology, and Sr–Nd isotopic compositions of Permian volcanic rocks in the northern margin of the North China Block: implications for the tectonic setting of the southeastern Central Asian Orogenic Belt     

Ji  Zejia  Zhang  Zhicheng  Chen  Yan  Li  Ke  Yang  Jinfu  Qian  Xiaoyan 《International Journal of Earth Sciences》2018,107(6):2143-2161

International Journal of Earth Sciences - The southeastern part of the Central Asian Orogenic Belt (CAOB), which records the collision of the North China Block (NCB) with the South Mongolian...  相似文献