Mineralogical, chemical, and crystallographic properties of supergene jarosite-group minerals from the Xitieshan Pb-Zn sulfide deposit, northern Tibetan Plateau, China     

Lei Chen  Jian-Wei Li  R. O. Rye  W. M. Benzel  H. A. Lowers  Ming-Zhong He 《Mineralogy and Petrology》2013,107(4):487-499

Supergene jarosite-group minerals are widespread in weathering profiles overlying Pb-Zn sulfide ores at Xitieshan, northern Tibetan Plateau, China. They consist predominantly of K-deficient natrojarosite, with lesser amounts of K-rich natrojarosite and plumbojarosite. Electron microprobe (EMP) analyses, scanning electron microcopy (SEM) investigation, and X-ray mapping reveal that the jarosite-group minerals are characterized by spectacular oscillatory zoning composed of alternating growth bands of K-deficient and K-bearing natrojarosite (K₂O >1 wt.%). Plumbojarosite, whenever present, occurs as an overgrowth in the outermost bands, and its composition can be best represented by K_0.29Na_0.19Pb_0.31Fe_2.66Al_0.22(SO₄)_1.65(PO₄)_0.31(AsO₄)_0.04(OH)_7.37. The substitution of monovalent for divalent cations at the A site of plumbojarosite is charge balanced by the substitution of five-valent for six-valent anions in XO₄ at the X site. Thermogravimetric analysis (TGA) of representative samples reveal mass losses of 11.46 wt.% at 446.6 °C and 21.42 wt.% at 683.4 °C due to dehydroxylation and desulfidation, respectively. TGA data also indicate that the natrojarosite structure collapses at 446.6 °C, resulting in the formation of NaFe(SO₄)₂ and minor hematite. The decomposition products of NaFe(SO₄)₂ are hematite and Na₂SO₄. Powder X-ray diffraction (XRD) analyses show that the jarosite-group minerals have mean unit-cell parameters of a?=?7.315 Å and c?=?016.598 Å. XRD and EMP data support the view that substitutions of Na for K in the A site and full Fe occupancy in the B site can considerably decrease the unit-cell parameter c, but only slightly increase a. The results from this study suggest that the observed oscillatory zoning of jarosite-group minerals at Xitieshan resulted mainly from substitutions of K for Na at the A site and P for S at the X site.  相似文献   

黏弹性双相介质参数反演的同伦方法   总被引：4，自引：1，他引：3       下载免费PDF全文

田迎春  章梓茂  马坚伟  杨慧珠 《地球物理学报》2009,52(9):2328-2334

本文以介质的动态时域响应（位移、速度、加速度）作为反演的依据,对黏弹性双相介质的材料参数进行了反分析研究.根据附加条件,并考虑到由于测量误差和测量数据的不充分造成的反演问题的不适定性,将黏弹性双相介质的参数反演问题转化为非线性泛函的极小值问题,然后应用大范围收敛的同伦方法求出使泛函极小的根作为反问题的解.最后,以二维半空间黏弹性双相介质模型为例进行了数值反演分析,数值结果表明本文方法在参数的反演过程中目标函数稳定收敛,且具有一定的抗“噪声”干扰性能;与利用速度和加速度信息反演的结果相比,利用位移信息反演的结果具有较高的精度和抗噪声能力.  相似文献   

Origin of the Tongshankou porphyry–skarn Cu–Mo deposit,eastern Yangtze craton,Eastern China: geochronological,geochemical, and Sr–Nd–Hf isotopic constraints     

Jian-Wei Li  Xin-Fu Zhao  Mei-Fu Zhou  Paulo Vasconcelos  Chang-Qian Ma  Xiao-Dong Deng  Zorano Sérgio de Souza  Yong-Xin Zhao  Gang Wu 《Mineralium Deposita》2008,43(3):315-336

The Tongshankou Cu–Mo deposit, located in the westernmost Daye district of the Late Mesozoic Metallogenic Belt along the Middle-Lower reaches of the Yangtze River, eastern China, consists mainly of porphyry and skarn ores hosted in the Tongshankou granodiorite and along the contact with the Lower Triassic marine carbonates, respectively. Sensitive high-resolution ion microprobe zircon U–Pb dating constrains the crystallization of the granodiorite at 140.6 ± 2.4 Ma (1σ). Six molybdenite samples from the porphyry ores yield Re–Os isochron age of 143.8 ± 2.6 Ma (2σ), while a phlogopite sample from the skarn ores yields an ⁴⁰Ar/³⁹Ar plateau age of 143.0 ± 0.3 Ma and an isochron age of 143.8 ± 0.8 Ma (2σ), indicating an earliest Cretaceous mineralization event. The Tongshankou granodiorite has geochemical features resembling slab-derived adakites, such as high Sr (740–1,300 ppm) and enrichment in light rare earth elements (REE), low Sc (<10 ppm), Y (<13.3 ppm), and depletion in heavy REE (<1.2 ppm Yb), and resultant high Sr/Y (60–92) and La/Yb (26–75) ratios. However, they differ from typical subduction-related adakites by high K, low MgO and Mg#, and radiogenic Sr–Nd–Hf isotopic compositions, with (⁸⁷Sr/⁸⁶Sr) _t  = 0.7062–0.7067, ɛ _Nd(t) = −4.37 to −4.63, (¹⁷⁶Hf/¹⁷⁷Hf) _t  = 0.282469–0.282590, and ɛ _Hf(t) = −3.3 to −7.6. The geochemical and isotopic data, coupled with geological analysis, indicate that the Tongshankou granodiorite was most likely generated by partial melting of enriched lithospheric mantle that was previously metasomitized by slab melts related to an ancient subduction system. Magmas derived from such a source could have acquired a high oxidation state, as indicated by the assemblage of quartz–magnetite–titanite–amphibole–Mg-rich biotite in the Tongshankou granodiorite and the compositions of magmatic biotite that fall in the field between the NiNiO and magnetite–hematite buffers in the Fe³⁺–Fe²⁺–Mg diagram. Sulfur would have been present as sulfates in such highly oxidized magmas, so that chalcophile elements Cu and Mo were retained as incompatible elements in the melt, contributing to subsequent mineralization. A compilation of existing data reveals that porphyry and porphyry-related Cu–Fe–Au–Mo mineralization from Daye and other districts of the Metallogenic Belt along the Middle-Lower reaches of the Yangtze River took place coevally in the Early Cretaceous and was related to an intracontinental extensional environment, distinctly different from the arc-compressive setting of the Cenozoic age that has been responsible for the emplacement of most porphyry Cu deposits of the Pacific Rim.  相似文献   

Textures,trace elements,and Pb isotopes of sulfides from the Haopinggou vein deposit,southern North China Craton: implications for discrete Au and Ag–Pb–Zn mineralization     

Zhan-Ke Li  Jian-Wei Li  David R. Cooke  Leonid Danyushevsky  Lejun Zhang  Hugh O’Brien  Yann Lahaye  Wen Zhang  Hai-Jun Xu 《Contributions to Mineralogy and Petrology》2016,171(12):99

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Re–Os and U–Pb geochronology of the Laochang Pb–Zn–Ag and concealed porphyry Mo mineralization along the Changning–Menglian suture,SW China: implications for ore genesis and porphyry Cu–Mo exploration     

Xiao-Dong Deng  Jian-Wei Li  Xin-Fu Zhao  Hong-Qiang Wang  Liang Qi 《Mineralium Deposita》2016,51(2):237-248

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伊通盆地莫里青断陷双二段岩性油气藏成藏特征     

吕东美  柳蓉  连晓亮  朱建伟  林波  陈敬武 《世界地质》2016,35(2):470-479

岩性油气藏是伊通盆地莫里青断陷的主要油气藏类型,其中双阳组是莫里青油田勘探主要目的层。通过分析岩芯、录井、测井及试油测试资料,双二段由上至下可以分为5个砂组,各个砂组均主要发育水下扇和扇三角洲沉积砂体,且主要集中分布在西北缘同生断裂控制下的靠山凹陷附近。同时,莫里青断陷发育较厚的暗色泥岩,较高的有机质丰度,达到了好烃源岩的标准。双二段各个砂组砂体属于低孔低渗储层,在剖面上主要呈"泥包砂"特征,其近烃源岩分布的特征有利于形成小而肥的透镜状砂体油气藏。试油结果表明,产油量大于1 t/d的井80%分布在双二段的四砂组,是双二段主要油气产层。该岩性油气藏在平面上主要分布在靠山凹陷的伊22和伊39两个井区附近的水下扇砂体中。  相似文献   

舟山近海环境DNA保存方法的建立及优化   总被引：1，自引：0，他引：1  

陈治  陈建威  王晓艳  高天翔  刘岩 《海洋与湖沼》2019,50(5):1098-1107

近年来,环境DNA(environmentalDNA,eDNA)技术开始被广泛应用于水生生物多样性研究。本文通过绝对定量和高通量测序技术对舟山近海高浊度水样eDNA的保存方法进行了建立和优化。研究结果如下:(1)"酒精+低温"保存法的eDNA获得量是"酒精+常温"保存法的0.78—1.06 (7d)、0.89—1.80 (15d)、1.05—2.75 (30d)和2.69 (60d)倍;(2)酒精保存法(低温、常温)存在eDNA富集物渗漏及滤膜黏附现象;(3)短期内冷冻保存样品的eDNA获得量是酒精保存样品获得量的1.25—1.59倍(7d)和1.07—1.20倍(15d);(4)酒精保存法的eDNA降解速率慢于冷冻保存法,长期内酒精保存样品的eDNA获得量是冷冻保存样品获得量的1.99—2.10倍(30d)和2.84—7.64倍(60d);(5)二次富集(过滤)能显著提高eDNA获得量,富集组eDNA浓度是未富集组浓度的1.60—4.95倍("酒精+低温")和1.21—2.04倍("酒精+常温");(6)"酒精+低温"保存的样品在高通量测序总丰度、各鱼种分丰度、物种多样性指数等多个方面优于冷冻保存样品;(7)微生物(micro-organism)的eDNA降解速率慢于大生物(macro-organism),不同界(Kingdom)的eDNA最优保存方法可能并不相同。本研究首次建立了舟山近海高浊度水样eDNA最适保存方法,为相似水域的eDNA保存提供了借鉴参考。  相似文献   

罗氏沼虾(Macrobrachium rosenbergii)幼体新暴发病病原阴沟肠杆菌的分离鉴定   总被引：1，自引：0，他引：1  

陈雪峰  杨国梁  高强  夏正龙  濮剑威  慎佩晶  黄振远 《海洋与湖沼》2015,46(6):1467-1477

2010 年, 浙江湖州部分罗氏沼虾(Macrobrachium rosenbergii)育苗场在幼体培育阶段, 暴发 了幼体大规模发病死亡的新病害。从2 个育苗场6 个发病育苗池的发病幼体匀浆液中分离得到6 株 优势生长菌株(编号为NTH01、NTH02、NTH03、316D、316X、316C), 菌落形态较为一致。取代表 菌株NTH01, 以浸泡方式进行人工回感, 结果菌株NTH01 能够导致幼体发病死亡, 且症状与生产表 现一致。经形态学观察、生理生化鉴定、16S rRNA 与gyr B 基因序列系统发育关系构建, 鉴定菌株 NTH01 为阴沟肠杆菌(Enterobacter cloacae).以阴沟肠杆菌omp A 基因片段为靶序列, 建立了PCR 检测方法, 对另外5 株优势菌进行检测, 结果该5 株菌都是阴沟肠杆菌。2011 年, 对4 个发病育苗场 幼体与亲虾进行检测, 结果发病幼体中分离的优势菌检测呈阳性, 亲虾肝胰腺与肠道组织检测到该 菌存在, 但亲虾不表现病症。对30 种抗生素的药敏试验结果表明, 菌株NTH01 对恩诺沙星、氧氟 沙星、庆大霉素等6 种抗生素敏感, 对发病幼体进行针对性用药, 效果明显。本试验结果表明, 阴沟 肠杆菌是导致罗氏沼虾育苗期间幼体大规模发病死亡的致病菌。  相似文献   

Geochemistry of geopressured hydrothermal waters in the Niigata Sedimentary Basin, Japan     

Hui-Long  Xu  Jian-Wei  Shen Xue-Wu  Zhou 《Island Arc》2006,15(1):199-209

Abstract   Geothermal waters in the Niigata Sedimentary Basin, central Japan, are divided into four groups based on their chemical composition (i.e. Na-SO₄-type, Na-SO₄-Cl-type, Na-Cl-type and Na-Cl-HCO₃-type). The Na-SO₄-type geothermal water forms as a consequence of water–rock interaction and generally occurs in the outer part of the basin. The Na-Cl-type geothermal water is further subdivided into the original Na-Cl-type geopressured thermal water and the mixed Na-Cl-type geothermal water, in terms of its geochemical and isotopic composition. The original Na-Cl-type geopressured thermal water originates from a geopressured hydrothermal system containing the altered fossil formation waters that are sealed at depth. It moves up to the upper part of the depositional succession or the ground, and generally does not mix with groundwater that is of meteoric origin. This type of water is cooled by heat conduction. The concentration of Cl^– in this type of thermal water is very similar to that in seawater. The δD and δ¹⁸O values are approximately constant and independent of temperature. The original Na-Cl-type geopressured thermal water is distributed mainly along anticlinal axes in folded Neogene formations. The mixed Na-Cl-type geothermal water is related to the expulsion activity of the geopressured hydrothermal system and occurs mostly along active faults. It is formed by shallow groundwater of meteoric origin being mixed with geopressured hydrothermal water when the geopressured hydrothermal system was expulsed along active faults by paroxysmal tectonic events.  相似文献   

Timing and duration of supergene mineralization at the Xinrong manganese deposit,western Guangdong Province,South China: cryptomelane <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar dating     

Jian-Wei Li  Paulo Vasconcelos  Wei Zhang  Xiao-Dong Deng  Nurdan Duzgoren-Aydin  Dai-Rong Yan  Jian-Qiang Zhang  Ming-An Hu 《Mineralium Deposita》2007,42(4):361-383

Supergene Mn-oxide deposits are widely distributed in Guangxi, Guangdong, Yunnan, and Hunan Provinces, South China, accounting for 18% of the total Mn reserves in the country. Direct dating of supergene Mn enrichment, however, is lacking. In this paper, we present high-resolution ⁴⁰Ar/³⁹Ar ages of Mn oxides from the Xinrong Mn deposit, western Guangdong, to place numerical constraints on the timing and duration of supergene Mn enrichment. A total of ten cryptomelane samples, spanning a vertical extent of 67 m, were dated using the ⁴⁰Ar/³⁹Ar laser incremental heating technique, with seven samples yielding well-defined plateau or pseudo-plateau ages ranging from 23.48 ± 0.91 to 2.06 ± 0.05 Ma (2σ). One sample yields a staircase spectrum that does not reach a plateau; the spectrum, however, indicates the presence of two or more generations of Mn oxides in the sample, whose ages are best estimated at 22.34 ± 0.31 and 10.2 ± 0.86 Ma, respectively. The remaining two samples gave meaningless or uninterpretable results due to significant ³⁹Ar recoil and contamination by old phases. The ⁴⁰Ar/³⁹Ar data thus reveal a protracted history of weathering and supergene Mn enrichment that started at least in the end of the Oligocene or beginning of Miocene and extending into the latest Pliocene. Staircase-apparent age spectra, resulting from banded or botryoidal samples, yield an average growth rate of Mn oxides at 0.6–0.7 × 10⁻³ mm kyr⁻¹. The values indicate that a 1-mm grain of Mn oxides may host minerals precipitated during a time span of ca. 1.5 m.y., and accumulation of Mn oxides to form economic deposits under weathering environments may take millions of years. The distribution of weathering ages shows that the oldest Mn oxides occur on the top of the profile, whereas the youngest minerals are found at the bottom, suggesting downward propagation of weathering fronts. However, two samples located at the intermediate depths of the profile yield ages comparable with those occurring at the highest elevations. Such a complexity of age distribution is interpreted in terms of preferential penetration of Mn-rich weathering solutions along more permeable fault zones, or as a result of multi stages of dissolution and re-precipitation of Mn oxides. A synthesis of geochronological and geological data suggests that formation of the Xinrong deposit was a consequence of a combination of favorable lithological, climatic, and structural conditions. Because the climatic and structural conditions are similar among the provinces of South China during the Cenozoic, the geochronological results obtained at Xinrong may also have implications for the timing of supergene Mn enrichment throughout South China.  相似文献