基于成分数据分析和能谱-面积分形模型的鄂西黄陵背斜化探异常识别     

王会敏 《地质与勘探》2023,59(6):1240-1249

鄂西黄陵背斜地区虽已发现众多矿点,但是矿床规模较小,找矿潜力不明。由于区内植被茂盛、覆盖严重,致使地质异常信息被削弱或掩盖,对进一步找矿工作造成了严重干扰。本次研究使用成分数据分析和能谱-面积（S-A）分形模型识别与金矿化相关的异常,结果表明：（1）等距对数比（ILR）变换后的主成分分析结果相比对数（Log）变换更能够反应元素的共生组合规律,第一主成分（PC1）元素组合为Au-Cu-Ag,且Au元素占有最大的载荷,与金矿密切相关,PC1元素组合异常的分布模式与矿点的分布更加吻合;（2） S-A方法抑制了黄陵背斜区域水系沉积物的背景模式,增强了异常模式;（3）根据地质特征和以往勘查工作情况,圈定了三处找矿远景区,为该地区金矿下一步勘查工作提供了重要依据。  相似文献   

Microscale Simultaneous Measurement of Carbon and Nitrogen Isotopes on Natural Diamond     

Akizumi Ishida  Kouki Kitajima  Ko Hashizume  Michael J. Spicuzza  Alexander Zaitsev  Daniel J. Schulze  John W. Valley 《Geostandards and Geoanalytical Research》2023,47(3):569-578

Simultaneous analysis of carbon and nitrogen isotope ratios by SIMS was applied for the first-time to a natural diamond from the Kelsey Lake kimberlite, State Line Distinct, Colorado (UWD-1). This in situ procedure is faster, reduces sample size for analysis, and measures both isotope ratios from a single ~ 10 μm diameter pit, a critical advantage for zoned diamonds. The carbon isotope ratio (expressed as δ¹³C_VPDB) of the bulk UWD-1 crystal, determined by the conventional combustion method in the present study, is -5.9‰ ± 0.2‰ (VPDB, 2s). Nitrogen mass fraction ([N]) and isotope ratio (expressed as δ¹⁵N_Air) were determined by stepwise combustion and gas-source mass-spectrometry, resulting in 553 ± 64 μg g^-1 and -6.7‰ ± 1.1‰ (Air, 2s), respectively. Secondary ions of ¹²C₂^-, ¹²C¹³C^-, ¹²C¹⁴N^-, and ¹²C¹⁵N^- were simultaneously measured by SIMS using three Faraday cups and one electron multiplier. The spot-to-spot reproducibility of δ¹³C and δ¹⁵N values for the UWD-1 (178 spots on sixteen chips, 10 μm spots), were 0.3‰ and 1.6‰, respectively (2s). While ¹²C¹⁴N^-/¹²C₂^- ratios, which are an indicator for [N], varied up to 12% among these sixteen chips, such variation did not correlate with either δ¹³C or δ¹⁵N values. We propose that UWD-1 is a suitable reference sample for microscale in situ analysis of δ¹³C and δ¹⁵N values in diamond samples.  相似文献   

应用重力场模型GL1500E和LLR天平动参数估算月核大小及其组成     

钟振  张腾  段炼  李毅  朱化强 《武汉大学学报(信息科学版)》2021,(2)

针对月核大小及密度估计问题,利用高分辨率重力场模型GL1500E的二阶位系数和LLR(lunar laser ranging)天平动参数,考虑月核分层为外核和内核的情况,结合非线性粒子群优化算法,对月核大小和组成进行了估计。大批量的统计结果表明,大概率分布的外核半径rc1约为469 km,内核半径rc2约为303 km,外核密度ρc1约为4613 kg/m3,内核密度ρc2约为7004 kg/m3,月幔密度ρm约为3340 kg/m3。月幔密度非常接近地质研究结果3360 kg/m3,内外核半径与近期其他研究结果相近,估算的月核大小与密度组成具有一定的参考价值。若月核由纯铁和硫化亚铁组成,则研究表明,内核大部分由纯铁组成,外核大部分由硫化亚铁组成。  相似文献   

防城河口湾鱼类群落结构及其与环境因子关系研究     

何思璇  何斌源 《热带海洋学报》2019,38(5):86-97

文章根据2016年5月、8月、11月和2017年2月在防城河口湾海域进行的渔业资源和环境调查数据, 研究了河口湾鱼类群落结构及其空间和季节变化, 分析了鱼类群落结构与主要环境因子的关系。结果表明: 全年调查共渔获鱼类95种, 隶属于2纲12目37科69属, 适温性以暖水性鱼类为主, 生态类型以底层和近底层鱼类为主。其中, 春季60种, 夏季59种, 秋季54种, 冬季46种, 夏—秋季间种类相似性指数最高。全年优势种为褐菖鲉Sebastiscus marmoratus和长鳍篮子鱼Siganus canaliculatus, 主要种有黄鳍棘鲷Acanthopagrus latus、条马鲾Equulites rivulatus、李氏?Callionymus richardsoni和真赤鲷Pagrus major等10种; 夏、秋季的最大优势种均为长鳍篮子鱼, 春、冬季的最大优势种分别为褐菖鲉和条马鲾。全湾鱼类年均资源密度为45836尾·km ^-2和 435.21kg·km ^-2, 资源密度具有明显的空间差异和季节变化。全年各站位种数变化范围在2~21种, 多样性指数H′在0.468~4.031, 丰富度指数d在0.120~1.926, 均匀度指数J在0.181~0.969。聚类分析、单因子相似性分析(ANOSIM)及相似性百分比(SIMPER) 分析表明该海域鱼类群落存在一定程度的时空异质性。相关性分析表明影响防城河口湾鱼类群落结构的主要环境因子为水温、盐度和硝酸盐。  相似文献   

Nutrient Fluxes in Rainfall,Throughfall, and Stemflow in Pinus densata Natural Forest of Tibetan Plateau     

《洁净——土壤、空气、水》2017,45(7)

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青海德令哈蓄集银铅矿床地质与S-Pb同位素组成及其成矿学意义     

陈敏  薛春纪  赵文涛  薛万文  谷强 《岩石矿物学杂志》2020,39(4):454-468

蓄集矿床是宗务隆构造带内发现的重要银铅矿床。蓄集银铅矿床赋存于石炭-二叠系宗务隆群果可山组灰岩夹千枚岩地层中,矿体呈脉状、透镜状、似层状,明显受近东西走向的断裂构造控制,矿体围岩蚀变主要为硅化和绢云母化,矿石矿物主要为方铅矿和银黝铜矿,脉石矿物主要为石英,矿石具有斑杂状和网脉状构造。对该矿床开展了S-Pb同位素组成分析。硫同位素分析结果表明矿石中硫化物矿物δ~(34)S值变化于5.0‰～8.4‰之间,显示硫主要为岩浆来源,有少量地层的贡献;铅同位素分析结果表明,矿石~(206)Pb/~(204) Pb=17.896～17.922,~(207)Pb/~(204) Pb=15.589～15.617,~(208) Pb/~(204) Pb=38.072～38.166,与围岩铅同位素组成(~(206) Pb/~(204) Pb=17.94～18.976,~(207)Pb/~(204) Pb=15.600～15.696,~(208) Pb/~(204) Pb=38.106～40.943)较为相似,而与蓄集峡口闪长岩铅同位素组成(~(206) Pb/~(204) Pb=18.144～18.589,~(207)Pb/~(204) Pb=15.623～15.636,~(208)Pb/~(204) Pb=38.790～39.033)相差较大,反映成矿物质主要来自围岩地层宗务隆群果可山组。综合分析认为,蓄集银铅矿床与宗务隆构造带晚二叠世岩浆活动关系密切,应属岩浆热液为主的热液充填-交代成因类型。  相似文献   

凤太矿集区东塘子铅锌矿床S、Pb同位素组成对成矿物质来源的示踪     

张革利  田涛  王瑞廷  高卫宏  常宗东 《中国地质》2020,47(2):472-484

东塘子铅锌矿床是秦岭成矿带中典型的铅锌矿床之一,前人对东塘子铅锌矿床成矿作用研究较多,但受限于测试手段及认识的局限性,多年来对其物质来源的认识仍未统一。本文在充分研究东塘子铅锌矿床地质特征的基础上,开展了相关样品的S、Pb同位素分析,分析对象包括了不同类型的铅锌矿石,讨论了该铅锌矿床的成矿物质来源、区内岩浆岩与铅锌成矿的关系等。研究表明:东塘子铅锌矿床矿石硫化物δ34S值变化范围为1.8‰～12.5‰,平均7.50‰,计算获得成矿流体中总硫δ34S∑S为7.7‰,显示海水硫酸盐(蒸发膏岩)与岩浆硫的混合来源特征。矿石铅同位素组成稳定,铅源主要来自富U-Th-Pb的上地壳与深部,可能与深部岩浆活动有关。研究结果表明,东塘子铅锌矿床的成矿过程与南秦岭印支期大规模多阶段构造-岩浆-流体活动密切相关,为下一阶段区内找矿工作提供了新的思路。  相似文献   

Threshold criterion for debris flow initiation in seasonal gullies   总被引：1，自引：0，他引：1  

Yang Wang  Peng Cui  Zhaoyin Wang  Shuangqing Liang 《国际泥沙研究》2017,32(2)

A series of flume experiments were done to investigate the effect of grain composition on the critical gradient and discharge of debris flows initiated in seasonal gullies. The results indicated that the critical gradient and discharge for debris flow initiation decrease initially, and then increase as the mass content of fine particles (<2 mm) increases. As the mass content of fine particles increases, the angle of repose, permeability of widely graded gravel soils, and the incipient motion conditions of the coarse grains in non-uniform sediments decrease at first, and then increase. The mass content of fine particles of all inflection points is the same. The theoretical model based on the combination of hydrodynamic force and shear stress is more applicable to the prediction of the critical gradient for debris flow initiation. The critical discharge model considering the effect of non-homogeneity of the soil and the size of coarse and fine grains provides a more accurate prediction of debris flow initiation than other models based on the mean diameter.  相似文献   

An Investigation of the Factors Affecting Saline Ice Melting Processes and Desalination          下载免费PDF全文

Yue Zhang  Jingsong Yang  Rongjiang Yao 《洁净——土壤、空气、水》2018,46(8)

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The Rumuruti chondrite group     

Addi Bischoff  Nadia Vogel  Julia Roszjar 《Chemie der Erde / Geochemistry》2011,(2):101-133

Since 1994, the Rumuruti (R) chondrites have been recognized as a new, well-established chondrite group differing from carbonaceous, ordinary, and enstatite chondrites. The first R chondrite, Carlisle Lakes, was found in Australia in 1977. Meanwhile, the number has increased to 107 (December, 2010). This group is named after the Rumuruti meteorite, the first and so far the only R chondrite fall. Most of the R chondrites are breccias containing a variety of different clasts embedded in a clastic matrix. Some textural and mineralogical characteristics can be summarized as follows: (a) the chondrule abundance in large fragments and in unbrecciated rocks is ∼35–50 vol%; (b) Ca,Al-rich inclusions are rare; (c) the olivine abundance is typically 65–78 vol%; (d) the mean chondrule diameter is ∼400 μm; (e) in unequilibrated R chondrites, low-Ca pyroxene is dominating, whereas in equilibrated R chondrites it is Ca-rich pyroxene; (f) the typical olivine in a metamorphosed lithology is ∼Fa_38–40; (g) matrix olivine in unequilibrated, type 3 fragments and rocks has much higher Fa (∼45–60 mol%) compared to matrix olivines in type 4–6 lithologies (∼Fa_38–41); (h) spinels have a high TiO₂ of ∼5 wt%; (i) abundant different noble metal-bearing phases (metals, sulfides, tellurides, arsenides) occur. The exception is the metamorphosed, type 5/6 R chondrite La Paz Icefield 04840 which contains hornblende, phlogopite, and Ca-poor pyroxene, the latter phase typically occurring in low-grade metamorphosed R chondrites only.In bulk composition, R chondrites have some affinity to ordinary chondrites: (a) the absence of significant depletions in Mn and Na in R chondrites and ordinary chondrites is an important feature to distinguish these groups from carbonaceous chondrites; (b) total Fe (∼24 wt%) of R chondrites is between those of H and L chondrites (27.1 and 21.6 wt%, respectively); (c) the average CI/Mg-normalized lithophile element abundances are ∼0.95 × CI, which is lower than those for carbonaceous chondrites (≥1.0 × CI) and slightly higher than those for ordinary chondrites (∼0.9 × CI); (d) trace element concentrations such as Zn (∼150 ppm) and Se (∼15 ppm) are much higher than in ordinary chondrites; (e) the whole rock Δ¹⁷O of ∼2.7 for R chondrites is the highest among all meteorite groups, and the mean oxygen isotope composition is δ¹⁷O = 5.36 ± 0.43, δ¹⁸O = 5.07 ± 0.86, Δ¹⁷O = +2.72 ± 0.31; (f) noble gas cosmic ray exposure ages of R chondrites range between ∼0.1 and ∼70 Ma. More than half of the R chondrites analyzed for noble gases contain implanted solar wind and, thus, are regolith breccias. The 43 R chondrites from Northern Africa analyzed so far for noble gases seem to represent at least 16 falls. Although the data base is still scarce, the data hint at a major collision event on the R chondrite parent body between 15 and 25 Ma ago.  相似文献