In Situ U‐Th‐Pb Dating and Sr‐Nd Isotope Analysis of Bastnäsite by LA‐(MC)‐ICP‐MS     

Yue‐Heng Yang  Fu‐Yuan Wu  Qiu‐Li Li  Yamirka Rojas‐Agramonte  Jin‐Hui Yang  Yang Li  Qian Ma  Lie‐Wen Xie  Chao Huang  Hong‐Rui Fan  Zi‐Fu Zhao  Cheng Xu 《Geostandards and Geoanalytical Research》2019,43(4):543-565

Bastnäsite is the end member of a large group of carbonate–fluoride minerals with the common formula (REE) CO₃F·CaCO₃. This group is generally widespread and, despite never occurring in large quantities, represents the major economic light rare earth element (LREE) mineral in deposits related to carbonatite and alkaline intrusions. Since bastnäsite is easily altered and commonly contains inclusions of earlier‐crystallised minerals, in situ analysis is considered the most suitable method to measure its U‐Th‐Pb and Sr‐Nd isotopic compositions. Electron probe microanalysis and laser ablation (multi‐collector) inductively coupled plasma‐mass spectrometry of forty‐six bastnäsite samples from LREE deposits in China, Pakistan, Sweden, Mongolia, USA, Malawi and Madagascar indicate that this mineral typically has high Th and LREE and moderate U and Sr contents. Analysis of an in‐house bastnäsite reference material (K‐9) demonstrated that precise and accurate U‐Th‐Pb ages could be obtained after common Pb correction. Moreover, the Th‐Pb age with its high precision is preferable to the U‐Pb age because most bastnäsites have relatively high Th rather than U contents. These results will have significant implications for understanding the genesis of endogenous ore deposits and formation processes related to metallogenic geochronology research.  相似文献   

雄安新区蓟县系雾迷山组岩溶热储特征、主控因素及有利区预测^*          下载免费PDF全文

鲁锴  鲍志东  季汉成  刘金侠  王贵玲  马峰  郭瑞婧  曹瑛倬  杨飞  符勇  李潇博  华盈鑫  阙宜娟  李宗峰  许西挺  胡先才 《古地理学报》2019,21(6):885-900

雄安新区蓟县系雾迷山组中赋存丰富的地热资源,研究雾迷山组岩溶热储特征及优质储集层发育的主控因素是地热资源勘探的基础。综合运用野外剖面、岩心、薄片、钻井、测井、录井等地质与地球物理资料,对雾迷山组岩溶热储特征和演化过程进行了深入研究,明确了优质储集层形成的控制因素,预测了有利靶区。结果表明,雾迷山组岩溶热储主要岩性为晶粒白云岩、颗粒白云岩、微生物白云岩、硅质白云岩和角砾白云岩等,溶蚀孔洞、裂缝及其组合为主要的储集空间类型。雾迷山组热储平均孔隙度为3.18%,平均渗透率为91.48×10^-3 μm²;其中角砾白云岩物性最好。雾迷山组岩溶热储经历了沉积—准同生期成孔(雾迷山沉积期)、Ⅰ期表生增孔(雾迷山沉积期后至青白口纪前)、Ⅰ期埋藏减孔(青白口纪前至三叠纪)、Ⅱ期表生增孔(三叠纪—古近纪)、Ⅱ期埋藏减孔(新近纪—第四纪)5个阶段,岩性及岩相、成岩作用和构造应力是雾迷山组有利热储形成的主控因素。藻云坪—云坪相、表生岩溶、埋藏溶蚀、准同生岩溶、岩溶高地—斜坡和地层裂缝段比率大于0.4的6项叠合区是研究区最有利的岩溶热储发育区。  相似文献   

冀东秦家峪中元古界高于庄组锰矿成因: 来自矿物学和地球化学的制约          下载免费PDF全文

靳松  马鹏飞  郭华  余文超  许灵通  林茜 《地球科学》2022,47(1):277-289

冀东秦家峪锰矿赋存于中元古界蓟县系高于庄组二段底部含锰岩系内,其成因尚不明确.以秦家峪锰矿ZK58-2钻孔样品为研究对象,通过显微薄片观察、电子探针分析及全岩地球化学分析等方法,探讨了高于庄组锰矿的锰质来源和沉积环境对成矿的贡献.显微薄片观察、电子探针分析表明,原生矿带中含锰矿物主要为菱锰矿、铁镁菱锰矿、钙菱锰矿、锰方...  相似文献   

Origin of sulphate in the unsaturated zone and groundwater of a loess aquifer     

Yin Long  Tianming Huang  Fen Zhang  Zhenbin Li  Baoqiang Ma  Yiman Li  Zhonghe Pang 《水文研究》2021,35(4):e14166

The use of the sulphate mass balance (SMB) between precipitation and soil water as a supplementary method to estimate the diffuse recharge rate assumes that the sulphate in soil water originated entirely from atmospheric deposition; however, the origin of sulphate in soil and groundwater is often unclear, especially in loess aquifers. This study analysed the sulphur (δ³⁴S-SO₄) and oxygen (δ¹⁸O-SO₄) isotopes of sulphate in precipitation, water-extractable soil water, and shallow groundwater samples and used these data along with hydrochemical data to determine the sources of sulphate in the thick unsaturated zone and groundwater of a loess aquifer. The results suggest that sulphate in groundwater mainly originated from old precipitation. When precipitation percolates through the unsaturated zone to recharge groundwater, sulphates were rarely dissolved due to the formation of CaCO₃ film on the surface of sulphate minerals. The water-extractable sulphate in the deep unsaturated zone (>10 m) was mainly derived from the dissolution of evaporite minerals and there was no oxidation of sulphide minerals during the extraction of soil water by elutriating soil samples with deionized water. The water-extractable concentration of SO₄ was not representative of the actual SO₄ concentration in mobile soil water. Therefore, the recharge rate cannot be estimated by the SMB method using the water-extractable concentration of SO₄ in the loess areas. This study is important for identifying sulphate sources and clarifying the proper method for estimating the recharge rate in loess aquifers.  相似文献   

Energy flux partitioning and evapotranspiration in a sub‐alpine spruce forest ecosystem          下载免费PDF全文

Zhu Gaofeng  Lu Ling  Su Yonghong  Wang Xufeng  Cui Xia  Ma Jinzhu  He Jianhua  Zhang Kun  Li Changbin 《水文研究》2014,28(19):5093-5104

In this study, we examined the year 2011 characteristics of energy flux partitioning and evapotranspiration of a sub‐alpine spruce forest underlain by permafrost on the Qinghai–Tibet Plateau (QPT). Energy balance closure on a half‐hourly basis was H + λE = 0.81 × (R_n ? G ? S) + 3.48 (W m^?2) (r² = 0.83, n = 14938), where H, λE, R_n, G and S are the sensible heat, latent heat, net radiation, soil heat and air‐column heat storage fluxes, respectively. Maximum H was higher than maximum λE, and H dominated the energy budget at midday during the whole year, even in summer time. However, the rainfall events significantly affected energy flux partitioning and evapotranspiration. The mean value of evaporative fraction (Λ = λE/(λE + H)) during the growth period on zero precipitation days and non‐zero precipitation days was 0.40 and 0.61, respectively. The mean daily evapotranspiration of this sub‐alpine forest during summer time was 2.56 mm day^?1. The annual evapotranspiration and sublimation was 417 ± 8 mm year^?1, which was very similar to the annual precipitation of 428 mm. Sublimation accounted for 7.1% (30 ± 2 mm year^?1) of annual evapotranspiration and sublimation, indicating that the sublimation is not negligible in the annual water balance in sub‐alpine forests on the QPT. The low values of the Priestley–Taylor coefficient (α) and the very low value of the decoupling coefficient (Ω) during most of the growing season suggested low soil water content and conservative water loss in this sub‐alpine forest. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Long-term simulation of large-scale urbanization effect on the East Asian monsoon   总被引：1，自引：0，他引：1  

Jin-Ming Feng  Yong-Li Wang  Zhu-Guo Ma 《Climatic change》2015,129(3-4):511-523

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Calibration method affects the measured δ2H and δ18O in soil water by direct H2Oliquid–H2Ovapour equilibration with laser spectroscopy     

Hongxiu Wang  Bingcheng Si  Dyan Pratt  Han Li  Xiaojun Ma 《水文研究》2020,34(2):506-516

The direct H₂O_liquid–H₂O_vapour equilibration method utilizing laser spectroscopy (DVE-LS) is a way to measure soil pore water stable isotopes. Various equilibration times and calibration methods have been used in DVE-LS. Yet little is known about their effects on the accuracy of the obtained isotope values. The objective of this study was to evaluate how equilibration time and calibration methods affect the accuracy of DVE-LS. We did both spiking and field soil experiments. For the spiking experiment, we applied DVE-LS to four soils of different textures, each of which was subjected to five water contents and six equilibration times. For the field soil experiment, we applied three calibration methods for DVE-LS to two field soil profiles, and the results were compared with cryogenic vacuum distillation (CVD)-LS. Results showed that DVE-LS demonstrated higher δ²H and δ¹⁸O as equilibration time increased, but 12 to 24 hr could be used as optimal equilibration time. For field soil samples, DVE-LS with liquid waters as standards led to significantly higher δ²H and δ¹⁸O than CVD-LS, with root mean square error (RMSE) of 8.06‰ for δ²H and 0.98‰ for δ¹⁸O. Calibration with soil texture reduced RMSE to 3.53‰ and 0.72‰ for δ²H and δ¹⁸O, respectively. Further, calibration with both soil texture and water content decreased RMSE to 3.10‰ for δ²H and 0.73‰ for δ¹⁸O. Our findings conclude that the calibration method applied may affect the measured soil water isotope values from DVE-LS.  相似文献   

Correction to: Discrete dynamical Pareto optimization model in the risk portfolio for natural disaster insurance in China     

Ma  Shujian  Jiang  Juncheng 《Natural Hazards》2019,96(3):1437-1437

Natural Hazards - The original article, Discrete dynamical Pareto optimization model in the risk portfolio for natural disaster insurance in China, in Natural Hazards (2018) 90: 445–460, was...  相似文献   

江苏非物质文化遗产的时空分布及其影响因素   总被引：2，自引：0，他引：2  

韩顺法  徐鹏飞  马培龙 《地理科学》2021,41(9):1598-1605

以江苏为例,运用地理学相关方法将非遗的时空分布可视化,并探讨其分布的影响因素。研究表明：江苏非遗在时间上呈“迂回向南”发展轨迹,其数量和类型在不同阶段具有明显差异;在空间上呈聚集性分布,分别在苏州、扬州、南京、常州、镇江和南通形成6个高密度核心;通过地理探测器分析,得知河流水系、政策导向、历史文化和经济等因素对非遗的时空分布有较大影响。由此得出重视江苏大运河文化带建设、将非遗纳入文化生态系统内整体性保护、正视非遗与经济合理互动等启示。  相似文献   

Reconstruction of the Cenozoic deformation of the Bohai Bay Basin,North China     

Yinbing Zhu  Shaofeng Liu  Bo Zhang  Michael Gurnis  Pengfei Ma 《Basin Research》2021,33(1):364-381

A well‐constrained plate deformation model may lead to an improved understanding of sedimentary basin formation and the connection between subduction history and over‐riding plate deformation. Building quantitative models of basin kinematics and deformation remains challenging often due to the lack of comprehensive constraints. The Bohai Bay Basin (BBB) is an important manifestation of the destruction of the North China Craton, and records the plate kinematic history of East Asia during the Cenozoic. Although a number of interpretations of the formation of the BBB have been proposed, few quantitative basin reconstruction models have been built to test and refine previous ideas. Here, we developed a quantitative deformation reconstruction of the BBB constrained with balanced cross‐sections and structural, stratigraphic and depositional age data. Our reconstruction suggests that the basin formation process was composed of three main stages: Paleocene‐early Eocene (65–42 Ma) extension initiation, middle Eocene‐early Oligocene (42–32.8 Ma) extension climax and post‐Oligocene (32.8–0 Ma) post‐extensional subsidence. The deformation of the BBB is spatially heterogeneous, and its velocity directions rotated clockwise during the basin formation process. The reconstruction supports the interpretation that the BBB formed via strike‐slip faulting and orthogonal extension and that the basin is classified as a composite extensional‐transtensional basin. We argue that the clockwise rotation of the basin velocity field was driven by the counter‐clockwise rotation in the direction of Pacific Plate subduction. The kinematics of the BBB imply that the Pacific Plate may have been sufficiently coupled to the over‐riding East Asian Plate during the critical period of Pacific Plate reorganization. The new reconstruction provides a quantitative basis for studies of deformation processes not only in the vicinity of the BBB, but also more broadly throughout East Asia.  相似文献