黄土高原西部红粘土岩石磁学性质及其指示的亚洲内陆中中新世气候变化特征     

赵辉  强小科  敖红  徐新文  孙玉芳  陈艇 《第四纪研究》2012,32(4)

对黄土高原西部庄浪红粘土进行详细岩石磁学分析表明,沉积物磁性由磁铁矿和赤铁矿主导,并且含有一定量的磁赤铁矿.中中新世大暖期红粘土中磁铁矿、磁赤铁矿含量显著升高;中中新世大暖期前后红粘土中的磁铁矿含量相对较低,赤铁矿相对含量较高,但并未显示较强的磁赤铁矿信息.磁性矿物的整体粒径表现为以SP,SD和PSD颗粒为主,MD颗粒较少.庄浪红粘土磁化率在16.5 ～ 13.8Ma出现峰值,与当时的夏季风强盛、降水丰富、成壤作用较强造成的亚铁磁性矿物相对含量增加密切相关.在全球气候变暖的中中新世大暖期,综合庄浪岩石磁学特征以及陆地和海洋的其他证据可以推测当时东亚冬、夏季风可能同时增强.  相似文献   

Re–Os Age of Molybdenite from the Daheishan Mo Deposit in the Eastern Central Asian Orogenic Belt,NE China     

Chunming Han  Wenjiao Xiao  Brian F. Windley  Guochun Zhao  Bexun Su  Songjian Ao  Jien Zhang  Zhiyong Zhang  Bo Wan  Bin Cui  Wenjun Qu  Andao Du 《Resource Geology》2014,64(4):379-386

The Daheishan Mo deposit is located in the eastern part of the Central Asian Orogenic Belt, NE China. Rhenium and osmium isotopes of molybdenites from the Daheishan deposit were used to determine the age of mineralization. Rhenium concentrations in molybdenite samples are between 17 and 30μg g^?1. Analysis of seven molybdenite samples yields an isochron age of 168.0 ± 4.4 Ma (2σ). Based on the geological history and spatial‐temporal distribution of the granitoids, it is proposed that the Mo deposits in eastern China were related to the subduction of the Paleo‐Pacific plate during Jurassic time.  相似文献   

Laser probe <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar dating for quartz from auriferous quartz veins in the Shihu gold deposit,western Hebei Province,North China     

Ye Cao  Shengrong Li  Huafeng Zhang  Chong Ao  Zhenzhen Li  Xiaobin Liu 《中国地球化学学报》2010,29(4):438-445

The Shihu gold deposit is situated in the central shear zone of the Meso-Cenozoic Fuping metamorphic core complex in the middle-northern part of the Taihang Mountains. This kind of gold deposits named after ‘Shihu type’ widely occurs in this region. Gold-bearing quartz veins are their most important industrial orebodies. Detailed laser ⁴⁰Ar/³⁹Ar geochronology of the mineralized quartz veins in the study area reveals details of its tectono-magmatic history. The ⁴⁰Ar/³⁹Ar ages for the quartz are between 134.4 Ma and 155.9 Ma with a mean age of 141±4 Ma on the isochron line and 139±7 Ma on the inverse isochron line, respectively, which is interpreted to be the best estimate of the crystalline age of the quartz veins. The gold mineralization was most likely related to an underplating event that took place in the northern part of the Taihang Mountain at ca. 140 Ma. The timing of gold mineralization in the area is similar to those observed in other major gold-producing provinces in the NCC. This episode is simultaneous with those in the eastern NCC, indicative of a widespread late Yanshanian metallogenic event that was a response either to the subduction of the Izanagi-Pacific plate beneath eastern China or to the removal of the Early Cretaceous lithosphere in the eastern NCC. The ore-forming material sources may be the Early Precambrian metamorphic basement, instead of intermediate-acid rock bodies and dykes.  相似文献   

福建龙永煤田顶峰山井田童子岩组沉积环境及其演化   总被引：1，自引：1，他引：0  

许福美  黄文辉  吴传始  郭玉森  吴志杰  敖卫华 《地质科学》2010,45(1):324-332

运用沉积学、古生物地层学、层序地层学等方法对福建龙永煤田童子岩组地层及其内主要煤层的沉积特征进行了详细的研究。结果表明童子岩组是一套海陆交互相的沉积,其沉积序列共分为三个沉积旋回,每个旋回都是以海侵开始,以海退结束,每一旋回缓慢海退背景都是由一系列的次级快速海进或海退事件构成。由于不断受到海陆两方面的影响,形成童子岩组中煤层的泥炭沼泽发育呈现出波动式特征,由此导致泥炭沼泽类型呈跳跃式演化,构成了包括碎屑滨岸、障壁岛—潟湖、泥炭坪、潮坪、潮汐三角洲和河控三角洲等沉积相在内的复杂沉积体系。  相似文献   

基于HBV模型的太子河流域致洪临界雨量的确定          下载免费PDF全文

刘鸣彦  孙凤华  周晓宇  侯依玲  赵春雨  易雪  崔妍  敖雪 《沙漠与绿洲气象(新疆气象)》2021,15(5):109-115

以太子河流域为研究区域,基于流域内的气象水文数据、数字高程模型及土地利用等资料,采用HBV水文模型对流域的水文过程进行模拟,通过对模型参数的率定与验证,评估了HBV模型在该流域径流模拟的适用性,确定了适合太子河流域的最优化参数,结合水位-流量关系曲线,推算太子河流域不同等级洪水致洪临界雨量。结果表明: HBV模型对太子河流域的径流模拟效果较好,率定期与验证期Nash效率系数与确定性系数均超过0.60,模型中积雪和融雪模块(CFR)、土壤含水量计算模块(BETA)与响应模块(KUZ2、UZ1、PERC)中的这些参数最为敏感,模型基本模拟出了洪水对降水的响应过程。通过建立的HBV水文模型,结合小林子水文站的水位-流量关系曲线,以警戒水位、保证水位作为不同等级洪水的判别条件,推算得到了不同起始水位下太子河流域动态临界雨量指标,临界雨量随起始水位的升高而有所减小。  相似文献   

ERA5-Land、MERRA2气温、降水数据在呼伦贝尔地区的适用性研究          下载免费PDF全文

曲学斌  姜凤友  辛孝飞  敖孟奇  王彦平 《沙漠与绿洲气象(新疆气象)》2022,16(5):24-30

利用1981—2019年呼伦贝尔地区16个气象站观测数据，结合相关系数、均方根误差、散点斜率等方法，对ERA5-Land和MERRA2再分析月气温、降水数据的区域适用性进行评估。研究表明：ERA5-Land、MERRA2两套再分析气温、降水数据与观测数据对比，整体相关性较高、误差较低、本地适用性较高，但也均存在低观测值时再分析数据的高估和高观测值时再分析数据的低估现象。ERA5-Land的月气温数据略优于MERRA2，而月降水数据差于MERRA2。ERA5-Land的年降水量在2005年之后出现明显的低估，降水量被低估的月份主要为6—8月，建议在再分析数据使用前对其进行系统偏差订正，以提高数据的适用性。  相似文献