Re–Os geochronology of the Cambrian stage-2 and -3 boundary in Zhijin County,Guizhou Province,China     

Shuaichao Wei  Yong Fu  Houpeng Liang  Zhihua Ge  Wenxi Zhou  Guangzhe Wang 《中国地球化学学报》2018,37(2):323-333

The black shale series that formed in the Ediacaran–Cambrian transition are important stratigraphic records of the co-evolution of the paleo-ocean, -climate, and -biology. In this study, we measured Re–Os isotopic compositions of the black shale in the Niutitang Formation from the Gezhongwu section in Zhijin, Guizhou Province. The samples had high Re and Os contents, with Re ranging from 21.27 to 312.78 ng/g and Os ranging from 0.455 to 7.789 ng/g. The Re–Os isotope isochron age of 522.9 ± 8.6 Ma implies deposition of the Niutitang black shale predated the Chengjiang Fauna, providing an age constraint for the expansion of oceanic anoxia in the study area. The initial ¹⁸⁷Os/¹⁸⁸Os ratio of 0.826 ± 0.026 indicates that enhanced continental weathering might have triggered the expansion of the oceanic anoxia.  相似文献   

A brief review of the interaction between tectonic, climatic and surface processes over multiple temporal and spatial scales     

Jing Liu Zeng  Jinyu Zhang  Yukui Ge  Wei Wang  Linsen Zeng  Gen Li  Xu Lin 《《地质学报》英文版》2018,92(Z1):151-151

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高分遥感技术在西昆仑大红柳滩-俘虏沟地区地质找矿中的应用          下载免费PDF全文

王辉  秦绪文  范玉海  杨金中  金谋顺  张少鹏  廖友运  杨晨  崔胜  贺小龙  匡经水  郭鹏程 《中国地质》2018,45(6):1289-1301

在西昆仑大红柳滩-俘虏沟地区,以WorldView-2高空间分辨率数据为主要信息源,在标准影像图制作基础上,针对性地进行图像增强处理,突出相关控矿要素和矿化信息,开展地质矿产遥感解译;利用ASTER数据开展矿化蚀变有关的遥感异常信息提取,配合适量的野外调查验证,发现了4种极具找矿前景的矿化带类型：①大红柳滩（含稀有金属）花岗伟晶岩带1处;②大红柳滩层控型铁多金属矿化带1处;③俘虏沟燕山期花岗岩有关热液脉型铁、铅、银、铜矿化区1处;④俘虏沟层控型含铜铅锌银的菱铁-赤铁矿矿化带4处;通过遥感综合分析,圈定遥感找矿靶区11处,其中A级遥感找矿靶区5处、B级遥感找矿靶区3处、C级遥感找矿靶区3处,为后续区域地质矿产调查项目规划部署和矿产资源勘查评价提供依据。因此,高分遥感技术在西昆仑地区矿产地质综合调查中作用显著,可实现找矿工作的快速突破,值得在相同或类似区域进一步推广应用。  相似文献   

Correlation analysis between drought indices and terrestrial water storage from 2002 to 2015 in China     

Yajie Zhang  Yao Li  Jing Ge  Gaopeng Li  Zhisheng Yu  Haishan Niu 《Environmental Earth Sciences》2018,77(12):462

Drought monitoring is a key topic in environmental monitoring and assessment although there is still a need to determine the correlation between drought monitoring indices and remote sensing products. We analyzed the correlation between the self-calibrating Palmer Drought Severity Index (sc_PDSI), the Standardized Precipitation Index and the Standardized Precipitation Evapotranspiration Index (SPEI) and terrestrial water storage monitored through the Gravity Recovery and Climate Experiment (GRACE) on a monthly timescale from 2002 to 2015 in China. As a consequence of anomalies in the soil water budget, the highly significant correlation between the sc_PDSI and the GRACE satellite-observed terrestrial water storage suggested that these two datasets are the most suitable for use in monitoring droughts. In comparing the three drought indices, the sc_PDSI was introduced as a means of drought monitoring in the Yangtze, Pearl, Huaihe, Southeast and Songhua River Basins, whereas the SPEI was found to be more applicable to other major river basins, such as the Inland River Basin. These diverse spatial behaviors are caused by the differences between the hydrological droughts characterized by these three drought indices.  相似文献   

Spatial and temporal variations of suspended solid concentrations from 2000 to 2013 in Poyang Lake,China     

Juanle Wang  Eryang Chen  Ge Li  Lu Zhang  Xiaoming Cao  Yongjie Zhang  Yujie Wang 《Environmental Earth Sciences》2018,77(16):590

Concentrations of suspended solids in lakes can affect the latter’s primary productivity and reflect changes in sediment deposition. Determining the temporal and spatial distribution of suspended solid concentrations has important significance in lake water environmental management; this is particularly urgent for Poyang Lake, the largest freshwater lake in China. In this study, suspended solid concentration inversion models for Poyang Lake were created using a semi-empirical method with regression analysis between continuously measured suspended solid concentration data and multi-band moderate-resolution imaging spectroradiometer images for spring, summer, autumn, and winter from 2009 to 2012. The coefficient of determination (R²) is from 0.6 to 0.9 and the average relative error for the accuracy verification was between 10 and 30%. The seasonal distributions of suspended solid concentrations in Poyang Lake from 2000 to 2013 were then obtained using optimal reversal models. The results showed that the seasonal variation in suspended solid concentrations had a “W” shape in which high spring and autumn and low summer and winter values. The suspended solid concentrations increased annually from 2000 to 2013 and were mainly distributed in the northern and central portions of the lake, with lower values along the shorelines. Further analysis indicated that the large difference in water level between the wet and dry seasons is an important factor in explaining these seasonal variations. Moreover, the suspended solid concentrations were poorly correlated with water temperature and chlorophyll-a concentration but more highly correlated with the deferred chlorophyll-a concentration.  相似文献   

丹霞山世界地质公园蜂窝状洞穴特征及成因分析   总被引：1，自引：0，他引：1  

陈留勤  李馨敏  郭福生  李鹏程  李余亮  刘鑫 《地质论评》2018,64(4):895-904

蜂窝状洞穴以其精致的形貌和众说纷纭的成因吸引着科研人员和普通大众的兴趣。丹霞山世界地质公园蜂窝状洞穴主要产于晚白垩世丹霞组二段(锦石岩段)风成砂岩的崖壁上。本文以园区长老峰锦石岩寺和睡美人禄意堂两处蜂窝状洞穴为研究对象,通过野外实地调查,了解洞穴生长环境,定量统计分析其形态特征,并采集砂岩样品进行显微镜下观察,探讨洞穴形成与盐风化作用的关系。研究表明:蜂窝状洞穴所在的岩性主要为中—细粒长石岩屑砂岩,发育大型高角度交错层理,渗透性较好;洞穴开口均向下朝向锦江,有利于来自锦江河流的湿润水汽较长时间地保持在小洞内部;洞穴开口基本服从泰森多边形分布。因此,碎屑颗粒相对比较均匀的风成砂岩为丹霞山蜂窝状洞穴的发育提供了重要的岩石基础,锦江河流为盐风化提供了必要的湿润水汽和盐分。在初始发育阶段,从岩壁上最适合盐风化作用的若干个点开始形成细小的坑洼,逐步向同层位扩张。单个小洞穴由于盐风化作用,洞穴内部风化速率大于洞穴开口边缘,导致蜂窝状洞穴内部空间扩大较快。然后,蜂窝状洞穴的发育突破纹层的限制,逐步加大、变深而呈泰森多边形规则分布。最终,随着洞穴加深,在重力、风力的影响下,蜂窝状洞穴隔壁减薄失稳,洞穴消亡。  相似文献   

基于数据密度确定分布区域的方法：以TAS图解分析为例   总被引：2，自引：0，他引：2       下载免费PDF全文

葛 粲顾海欧  汪方跃李修钰  周宇章袁 峰 《地质科学》2018,(4):1240-1253

为了客观地确定数据点投图后分布的主要区域,本文提出了一种基于数据密度确定数据主要分布区域的方法。利用该方法可以更加直观地了解数据分布,并可以作为数据清洗的预处理手段。本文基于GEOROC大数据,以全碱对硅（TAS）图解为例,进行了分析和验证。通过提取GEOROC 数据库中与TAS 图解相关的岩石样本中SiO₂、Na₂O、K₂O 和烧失量含量数据,通过数据常规清洗和归算,最终获得24 个种类合计13.3 万条有效数据。通过数据投点、分区统计和提取80% 数据的分布区域,验证了24种岩石样品与TAS图解的吻合程度。通过综合研究分析发现,有6类岩石的数据分布与TAS图解定义区域基本一致,18类岩石的数据分布与TAS图解定义区域有系统性偏差。大数据研究证明了TAS图解的不足之处,利用全碱和SiO₂作为指标,难以实现提升总体分类的准确性。  相似文献   

丹阳天王寺边坡稳定性评价及防治措施     

余成  葛伟亚  常晓军 《江苏地质》2018,42(2):345-348

针对苏南地区典型露采边坡的地层岩性及地质构造特点,以极限平衡理论为基础,运用GeoStudio软件中的SLOPE/W模块和VADOSE/W模块计算分析江苏丹阳天王寺边坡在天然工况、暴雨工况及地震工况下的稳定性。结果表明:天然工况下,潜在滑动面分布范围最小,稳定性最高,存在滑动的危险性;暴雨工况下,潜在滑动面分布范围有所增大,稳定性降低,边坡滑动的可能性较大;地震工况下,潜在滑动面分布范围最广,稳定性最低,边坡滑动的可能性很大。基于上述结果,提出防治措施。  相似文献   

西藏班戈错水菱镁矿藻类成矿实验及其成因分析     

蒋天明  姬连敏  程怀德  李斌凯  李刚  马海州  张西营  李长忠  马学海  张鹏程 《地质论评》2021,67(5):67060004-67060004

目前关于天然水菱镁矿的形成认识主要有蒸发沉积成因和生物成因两类。前人在室内成功制备出水菱镁矿矿物,证实了该矿物的无机成因理论,但是实验结晶条件明显高于西藏班戈错的寒冷气候条件和水化学条件,并且班戈错湖水通过自然蒸发结晶也难以形成水菱镁矿矿物,而这一认识与周边阶地上正在形成水菱镁矿的现象相矛盾。因此,自然蒸发沉积可能不是现阶段班戈错水菱镁矿的主要形成过程,而已有研究表明,藻类具备诱导形成碳酸盐矿物的能力,本文利用西藏班戈错Ⅲ湖湖水及其藻类开展室内模拟实验,并与无藻类的湖水自然结晶结果相对照,探讨藻类生命活动与班戈错水菱镁矿的成因联系。研究发现,藻类不仅能够适应高盐度盐水环境（矿化度117.3 g/L）,并且在其光合作用过程中还能显著提高周围水体pH值（最高可达10.564）,诱导并促进球碳镁石在藻类网状节点处结晶沉淀,该矿物进一步脱水即能够形成水菱镁矿矿物;而人为提高班戈错Ⅲ湖湖水Mg2+浓度也仅能结晶形成三水菱镁矿矿物,无球碳镁石或水菱镁矿结晶析出。因此,西藏班戈错水菱镁矿的形成过程与藻类生物成矿作用密切相关,但是有关球碳镁石向水菱镁矿转变的具体条件以及藻类成矿作用的具体分子机制仍不清楚,有待于进一步研究。  相似文献   

柴达木盆地一里坪盐湖富锂卤水特征、储层物性及富水区分析     

赵艳军  焦鹏程  汪明泉  张大义  朱振光  胡宇飞 《地质学报》2021,95(7):2062-2072

一里坪盐湖是柴达木盆地中一个典型的富锂卤水矿床,具有重大的经济价值.本文以查明盐湖深部卤水分布为目的,从卤水储层的空间分布特征和储层物性的角度对富水区进行预测,为卤水开发提供依据.研究区位于一里坪成盐盆地沉积中心区域,晚更新世末期以来,以沉积浅湖相的含淤泥和黏土粉砂岩,盐湖相的含粉砂和黏土的石盐岩为特征.在垂向上,由上下两套石盐岩夹中部粉砂岩组成一里坪富锂卤水的储层;平面上,研究区北部主要为浅湖相,往南过渡为盐湖相,石盐岩厚度在东南部最大.对储层厚度、孔隙度和给水度的分析表明,第Ⅱ矿层孔隙型和晶间型卤水优质储层均位于研究区东部,可作为卤水资源勘查开采的重点区域.  相似文献