南岭地区早侏罗世成矿作用——来自粤北大顶铁锡矿床LA-ICP-MS和Ar-Ar年代学证据   总被引：1，自引：0，他引：1  

程顺波  付建明  马丽艳  卢友月  王晓地  夏金龙 《地质学报》2016,90(1):163-176

近来南岭地区陆续见有早侏罗世成岩作用的报道,但是否存在同期成矿作用尚无定论。本文报道了大顶矿区石背岩体二长花岗岩、花岗闪长岩和大顶矽卡岩铁锡矿体的高精度同位素年龄数据,确认该地区存在早侏罗世成矿事件。石背岩体二长花岗岩和花岗闪长岩的LA-ICP-MS锆石U-Pb年龄分别为187.5±1.8 Ma(MSWD=0.81)和186.9±2.0 Ma(MSWD=1.15),大顶矽卡岩铁锡矿体中的金云母~(39)Ar-~(40)Ar坪年龄为185.9±1.2 Ma,等时线年龄为184.5±2.6 Ma(MSWD=0.83)。该矿床成矿作用是南岭地区首例有精确年龄报道的早侏罗世的成矿事件,为南岭成矿带矿产调查评价工作提供了一种新的选择。早侏罗世岩浆岩岩性组合、空间展布特点以及中侏罗世才开始的太平洋板块西向挤压过程,说明大顶矿床的成岩成矿过程更可能是受华南印支运动晚期的后造山伸展作用或者垮塌过程控制。  相似文献   

Modern pollen assemblages of the forest communities and their relationships with vegetation and climate in northern China     

LI Yuecong  XU Qinghai  ZHANG Liyan  WANG Xueli  CAO Xianyong  YANG Xiaolan 《地理学报》2009,19(6):643-659

53 pollen traps and surface samples were collected in order to detect the characteristics of pollen assemblages and their relationships with vegetation and climate in 16 forest communities located in 10 mountains in northern China. The results show that 72% of the pollen taxa (80 taxa) are the same between the traps and the surface samples. The dominant taxa in the plant communities are consistent with the main pollen taxa in the pollen assemblages at the same sites. In Pinus plant communities, both Pinus pollen influx and concentration are higher, indicating the high pollen productivity and good pollen preservation ability of Pinus. In Picea and Abies plant communities, Picea and Abies have lower pollen influxes but higher concentrations, suggesting their low pollen productivities but better pollen preservation abilities. In Betula and Quercus plant communities, Betula and Quercus have higher pollen influxes but lower concentrations, revealing their high pollen productivities but poor pollen preservation abilities. The study of relationships between pollen and vegetation with discriminant analysis shows that pollen assemblages from both trap and surface samples can reflect the characteristics of different communities and distinguish different ecological areas, but surface samples can reflect the dominant components of communities much better than the traps. The study on correlations between pollen assemblages and climate with DCCA reveals that significant correlations exist between pollen assemblages and mean temperature of the coldest month (r = 0.84 for trap samples, r = 0.72 for surface samples), and then annual mean precipitation (r = 0.73 for trap samples, r = 0.71 for surface samples).  相似文献   

环杭州湾城市规划及产业发展对湿地保护的影响   总被引：8，自引：0，他引：8  

任丽燕  吴次芳  岳文泽  刘勇  陆张维 《地理学报》2008,63(10):1055-1063

根据浙江省环杭州湾产业带2005 年TM 影像和2005-2020 年城市规划数据, 利用GIS 空间分析方法, 分析了规划期间建设用地扩展对湿地的侵占威胁, 并对湿地退缩的潜在风险 进行分析。结果表明： ① 环杭州湾产业带湿地资源丰富, 类型多样, 分布广泛, 现状建设用地在空间上与湿地交错分布, 关系十分密切。② 未来15 年, 城市建设用地扩展规模大、速 度快, 将侵占大面积湿地, 主要是分布在杭州湾南岸湿地围垦区的坑塘、养殖水面类湿地;宁波、杭州、慈溪是湿地退缩最严重的区域。③ 由于现状建设用地与湿地空间分布紧密相关, 湿地被建设用地侵占的潜在风险整体上较大, 且随着建设用地的扩展, 对湿地的侵占有加剧的趋势。④ 建设用地增长幅度及其规划布局对湿地减少有重要影响, 应通过调整建设用地规划、湿地占用补偿、城市湿地公园建设等措施, 加强湿地保护。  相似文献   

三疣梭子蟹幼体中肠腺发育的组织学和细胞学研究   总被引：3，自引：0，他引：3  

朱丽岩  郑家声  王梅林  姜明  刘晓云  徐怀恕 《中国海洋大学学报(自然科学版)》2000,30(4)

将蚤状幼体 I期 (Z1)到仔蟹共六期三疣梭子蟹幼体固定 ,作横切、纵切和平切的连续切片 ,观察中肠腺的解剖学及组织学特征 ,并研究其细胞的超微结构。三疣梭子蟹的中肠腺起自前、中肠交界处 ,分左右两部分 ,每部分三叶 ,由总管与幽门胃和中肠相通 ,中肠腺管的长度和数量随幼体发育而增加。管壁的上皮细胞在各期幼体均可分为四种类型 :E-细胞 (胚细胞 )、F-细胞 (纤维细胞 )、R-细胞 (吸收细胞 )和 B-细胞 (分泌细胞 ) ,它们在中肠腺管中的分布位置和功能各有不同。  相似文献   

甲壳纲(Crustacea)十足目(Decapoda)动物消化系统研究进展     

Zhu Liyan 《中国海洋大学学报(自然科学版)》2000,30(Z1):115-121

综述国内外甲壳纲十足目动物成体消化道、消 化腺结构以及幼体消化系统发育等方面的研究成果,并对该领域与国外的差距及今后的研究 方向进行了探讨。  相似文献   

基于虚拟偏移距方法的各向异性转换波保幅叠前时间偏移   总被引：2，自引：1，他引：1  

张丽艳  刘洋 《应用地球物理》2008,5(3):204-211

In this paper, we use the method of pseudo-offset migration （POM） to complete converted wave pre-stack time migration with amplitude-preservation in an anisotropic medium. The method maps the original traces into common conversion scatter point （CCSP） gathers directly by POM, which simplifies the conventional processing procedure for converted waves. The POM gather fold and SNR are high, which is favorable for velocity analysis and especially suitable for seismic data with low SNR. We used equivalent anisotropic theory to compute anisotropic parameters. Based on the scattering wave traveltime equation in a VTI medium, the POM pseudo-offset migration in anisotropic media was deduced. By amplitude-preserving POM gather mapping, velocity analysis, stack processing, and so on, the anisotropic migration results were acquired. The forward modeling computation and actual data processing demonstrate the validity of converted wave pre-stack time migration with amplitude-preservation using the anisotropic POM method.  相似文献   

黑龙江中西部跨断层土壤氢气初步分析     

李继业  赵谊  任建辉  康健  石伟  秦丽岩  马龙辰 《地震地磁观测与研究》2019,40(4):108-113

地质构造运动多伴随地下气体的逸出,观测并研究地下逸出气体,会抓住某些地下构造活动信息。作为地球化学观测的灵敏指标之一,地下逸出的氢气能够指示断裂活动的过程。地处松辽盆地黑龙江中西部地区多年来已开展多期跨断层土壤氢气野外测量工作,利用积累的观测数据,初步分析该地区跨断层土壤氢气背景动态变化及构造活动、地震活动特征,以便为地震孕育过程中断层氢气演化异常判定提供依据,为建立区域地震短期预测动态方法提供思路。  相似文献   

夏季滇池和入滇河流氮、磷污染特征   总被引：6，自引：1，他引：5  

余丽燕  杨浩  黄昌春  黄涛  余艳红  姜泉良  刘大庆  李帅东 《湖泊科学》2016,28(5):961-971

为探讨滇池入湖河流水体营养盐空间分布特征及其对滇池水体富营养化的影响,2014年7月采集了入滇4类典型河流(城市纳污型河流、城乡结合型河流、农田型河流、村镇型河流)及滇池水样,分析其氮、磷浓度.结果表明:4条入湖河流总氮(TN)、总磷(TP)、硝态氮和氨氮污染均较严重;河流水体中TN、TP平均浓度大小为:农田型河流(大河)村镇型河流(柴河)城乡结合型河流(宝象河)城市纳污型河流(盘龙江),其中农田型河流(大河)水体TN、TP污染最为严重;在夏季,4条入湖河流水体中TN、TP浓度从上游向下游增加趋势比较明显,表明氮、磷沿河流不断富集;氮磷比分析表明,夏季河流输入氮、磷营养盐有利于藻类的生长,并且滇池浮游植物生长主要受TN浓度限制;夏季滇池南部入湖河流水体的TN、TP浓度高于北部入湖河流,该特征与滇池水体中TN、TP污染分布状况相反,推测滇池北部富营养化的主要影响因素是内源释放.因此,在今后的滇池水体富营养化研究中,应对滇池内源释放进行深入研究.  相似文献   

Petrogenesis of volcanic rocks from Eastern Manus Basin: indications in mineralogy and geochemistry     

Xia ZHAO  Liyan TIAN  Jianhui SUN  Peng HUANG  Yan LI  Yue GAO 《海洋湖沼学报（英文）》2021,(1):89-109,中插1-中插24

To understand the petrogenesis and magma evolution history in the Eastern Manus Basin(EMB),geochemistry of pyroxene and plagioclase mineral phenocrysts in basaltic andesites and dacites were reported.The plagioclase-melt thermometry showed that,plagioclase in dacites crystalized in 1027.2–1028.5°C under 3.37–5.08 kbar,whereas in basaltic andesite was 1181.4–1187.0°C under 1.79–4.46 kbar.Pyroxene compositions and invariable La/Sm vs La values of whole rock powders indicate that lavas were erupted in rapid cooling rate and mainly controlled by fractional crystallization(FC).In addition,oscillatory zonings in plagioclase and pyroxene phenocrysts indicated small local perturbations and degassing episodes in the magma chamber.Some high Mg#clinopyroxene antecrysts were found in EMB lavas.The highest Mg#of parental EMB melts is 69,which falls into the range of initial partial melts from upper mantle peridotite source(68–75).In terms of isotopic compositions,the EMB lavas most likely originated from Indian-type MORB mantle which was infl uenced by subduction components.In details,the subduction components are mainly derived from the dehydration of a subducted altered oceanic crust,and the contribution of sediment infl uence is minor.The Pb isotopic compositions and end member modeling further suggest that the source of subduction components is more likely from the Pacifi c Plate instead of the Solomon Plate.  相似文献   

南极普里兹湾沉积物中生物硅对粒度测量结果的影响          下载免费PDF全文

王丽艳  李广雪 《极地研究》2020,32(1):25-36

为了探讨生物硅对沉积物粒度测量结果的影响, 本文采用两种不同前处理方法对普里兹湾重力柱状样品进行了粒度测试。结果表明, 生物硅对沉积物的平均粒径以及黏土、粉砂、砂组分的影响较小, 而对沉积物的分选、偏态、峰态以及粒度频率分布的影响较显著。结合两组粒度组分相关性分析以及各粒级含量累积减小值, 认为生物硅对沉积物中砂、粉砂、黏土级组分含量的影响逐渐减小, 这也造成未去除生物硅的沉积物粒度测量结果偏粗。另外, 通过对比发现普里兹湾沉积物中生物硅粒径主要分布在<3Φ、5.25Φ—7.25Φ、8.75Φ—9.75Φ的粒径范围。极地研究中, 沉积物粒度结果为重建古环境变化提供重要参考, 本文研究认为在普里兹湾海域沉积物粒度研究中去除生物硅对研究结果有积极作用。  相似文献