Mineralogical Characteristics of Exsolved Spinel in the Panzhihua V-Ti Magnetite Deposit, Sichuan: Implications for the Mineralization Process     

ZHANG Zhibin  HUANG Fei  XING Miaomiao  WAN Quan  GAO Wenyuan  GAO Shang  CHEN Zhenyu  CAI Jianhui 《《地质学报》英文版》2018,92(5):1784-1797

Spinel exsolution is widespread in titanomagnetite from the Fe-Ti oxide gabbro of the Panzhihua intrusion, Emeishan Large Igneous Province, SW China. However, little research has been conducted into the implications of patterns in the mineralogical characteristics of the spinel for spatial variation in the controls on the exsolution mechanism and, hence, the formation process of the ore deposit. This study selected the Lanjiahuoshan Ore Block in the Panzhihua V-Ti magnetite deposit to explore this issue, systematically studying exsolution textures in the titanomagnetite through petrographic observation and the integrated use of in-situ microanalysis. The results show that the exsolved spinel gradually becomes finer-grained and less abundant from the center to edge and the bottom to top of the ore bodies. Compositionally, there is an inverse correlation between the size of exsolved spinel grains and their Mg# value. In addition, there is compositional zonation in the spinel interiors, with a gradual increase in the Mg content and decrease in Fe content from the core to the rim. The analysis suggests that fractional crystallization of ferrotitanium magma with a high oxygen fugacity in a shallow magma chamber caused compositional differences in the primary magnetite solid solution in different parts of the Panzhihua intrusion. Additionally, the thermal evolution of the magnetite solid solution differed in different parts of orebody, bringing about variations in spinel development. Together, these effects resulted in spatial variation in the abundance, grain size, and morphology of spinel in different parts of the orebody and intrusion that follows an identifiable distribution law. Furthermore, the compositional zonation of exsolved spinels reflects the rapid growth of exsolution features in a high-temperature environment. Thus, the size, morphology, abundance, and composition of spinel exsolution features in titanomagnetite provide a valuable petrogenetic tool for estimating the maturity and formational environment of the deposit.  相似文献   

Indium Mineralization in the Yejiwei Sn‐Polymetallic Deposit of the Shizhuyuan Orefield,Southern Hunan,China     

《Resource Geology》2018,68(1):22-36

The Y ejiwei deposit, which is located in the southern H unan W –Sn –Pb –Z n M etallogenic B elt in south C hina, is a large‐scale porphyry–skarn–veinlet‐type deposit containing 806 t I n. M ineralization occurs as porphyry‐type S n (stockworks), skarn‐type S n–C u, marble‐hosted‐type S n–C u (veinlet), and vein‐type P b–Z n ores. Thirty‐five ore samples were collected from the Y ejiwei deposit for bulk and mineral chemical composition, microscopic observation and electron microprobe analyses. The porphyry‐type S n ores contain variable amounts of I n (2.3–76 ppm; mean of 17.4 ppm) with local I n enrichment (226 ppm) and 1000 × I n/Z n values are 3.8–52.4. The skarn‐type C u–S n ore is richest in I n (12.3–214 ppm; mean of 114 ppm), and 1000 × I n/Z n values are 2.4–117. In contrast, the In content of the marble‐hosted‐type C u–S n ores is relatively low (7.4–34.9 ppm; mean of 20.3 ppm), and 1000 × I n/Z n is in the range of 0.61–5.5, and the vein‐type P b–Z n ores in the external zone contain the lowest I n contents (7.2–17.0 ppm; mean of 12.1 ppm) with 1000 × I n/Z n values of 0.07–0.09. The ore minerals in the deposit include pyrite, pyrrhotite, cassiterite, and I n‐bearing minerals of sphalerite, chalcopyrite, and stannite. Although only trace amounts of sphalerite are hosted in the porphyry ores, the sphalerite contains the highest I n content (0.27–10.1 wt.% I n) in the deposit. We observed the highest I n contents of all I n‐bearing sphalerite reported in C hina. The I n contents of sphalerite in the skarn‐type ore range from 0.15 to 0.56 wt.%, whereas the marble‐hosted‐, and vein‐type ores have lower I n contents (0.00–0.04, and 0.03–0.06 wt.%, respectively). The In resources of the Y ejiwei deposit are mainly hosted in skarn ores of the No. 31 and No. 32 orebodies. The genesis of I n in the Y ejiwei deposit was closely related to the shallow intrusive environment of related igneous rocks. As W –S n–M o–B i–C u–P b–Z n–A g mineralization is widespread in south H unan, this study would suggest a focus on skarn‐type S n–Z n deposits for the future prospecting of I n resources.  相似文献   

柴达木盆地北缘Ⅳ级成矿单元划分     

潘彤 《世界地质》2018,37(4):1137-1148

根据找矿工作的需要,在全面收集前人研究成果的基础上,以大地构造演化为基础,以区域成矿规律为主线,突出研究区域内地层、构造、岩浆岩带和相关矿产的成矿作用,反映最新的找矿成果。针对柴达木北缘单元之多样性、复杂性及独特性,系统阐述了柴达木北缘Ⅳ级成矿单元划分的划分方案,柴达木北缘Ⅳ级成矿单元划分为9个Ⅳ级成矿亚带。并详细研究了所划分出的9个成矿亚带的成矿作用、成矿类型及成矿属性等。  相似文献   

滇西临沧花岗岩中段离子吸附型稀土矿成矿特征研究   总被引：2，自引：0，他引：2       下载免费PDF全文

张民  李杨  何显川  冯俊龙  郑瑶  王宏坤  杜金刚  王书山 《沉积与特提斯地质》2018,38(4):37-47

滇西临沧花岗岩中段岩性主体为黑云母二长花岗岩,是离子吸附型稀土矿的天然成矿母岩。研究区湿热的气候使得在地势相对平缓的中山地区形成巨厚的花岗岩风化带,依据风化程度由地表至基岩依次分为腐殖土层、亚黏土层、全风化层、半风化层、弱风化层和新鲜基岩。全风化层是本区离子吸附型稀土矿的主要赋矿层位,该层位元素地球化学特征显示,经过风化后稀土元素发生了富集和分馏,稀土矿化是以轻稀土为主。轻稀土又以La和Ce这两种元素为主。依据本区不同地貌类型建立了倾缓的山脊、平缓的山顶和低缓的山丘3种离子吸附型稀土矿成矿模式。  相似文献   

Microbial nitrogen transformations in sediments and inorganic nitrogen fluxes across the sediment/water interface on the South Island West Coast,New Zealand     

Heinrich F. Kaspar  Rodney A. Asher  Ian C. Boyer 《Estuarine, Coastal and Shelf Science》1985,21(2):245-255

In January 1982, sediment microbial N transformations and inorganic N fluxes across the sediment/water interface were studied at nine sites off the South Island West Coast, New Zealand. The sediments showed a great variety in physical, chemical and biological properties. The sediment organic matter had a molar $\text{C}\text{N}$ ratio of 5.9–10.9, and the total $\text{N}\text{P}$ ratio was 1.2–4.0. The denitrification capacity in the top 7.5 cm of sediment was 0.1–77.2 mmol N m^?2 day^?1 and generally declined with increasing sediment depth. The in situ denitrification rate was 0.02–1.84 mmol N m^?2 day^?1 and highest activities were generally found in surface sediments and at 6–7.5 cm depth. Denitrification accounted for 82–100% of total nitrate reduction. Net N mineralization was indirectly estimated at 0.6–2.4 mmol N m^?2 day^?1, and the experimental determination of this N transformation gave 0.6–3.2 mmol N m^?2 day^?1. Denitrification accounted for 3–75% of net N mineralization. The diffusive flux of ammonium and nitrate across the sediment/water interface was 0.1–0.7 and 0.1–0.6 mmol N m^?2 day^?1, respectively.  相似文献   

The Grey System and prediction of geological and mineral resources     

Jun Lan  Hua-xiang Cheng 《Mathematical Geology》1992,24(6):653-662

The Grey System is a method for making quantitative predictions using the similarity between a parent sequence and a set of subsequences. It has previously been used for non-geological problems, but here we demonstrate its use in ore prediction. Our example is from our work on known Cu deposits distributed in the Panzihua-Xichang region of Sichuan Province to set up a Grey prediction model for an unknown deposit in a similar type of environment. The following steps were carried out: (1) a sift selection was first made by logical information processing of the initial data from the known deposits, (2) data on seven deposits belonging to the same general rock type were obtained, and (3) a Grey prediction model was set up and used to make predictions about an unknown deposit in the same type of environment.  相似文献   

表生成矿系统微生物氧化机制     

关广岳 《国土资源》1994,(Z1)

一系列硫化物矿床氧化带的研究表明，微生物的氧化效果应当引起人们的注意。不同气候区氧化作用对比研究，可以认为干旱地区以化学反应为主，湿润地区则以化学－生物化学联合作用占优势，当微生物参与氧化反应时，传统的硫化物－硫酸盐－氢氧化物－氧化物的反应系统被打乱，而是氧化－还原协调进行，巧妙配合，这是微生物生命活动的需要，是一种动态平衡的演化过程。  相似文献   

浙江A村金矿的矿化特征及成矿条件分析     

潘志龙 《浙江国土资源》1996,(2)

本文阐述了A村金矿点的地质环境及其金矿化特征和矿化类型，认为该金矿点是与花岗岩类岩石有关的金矿化类型。关在研究其成矿条件的基础上，提出了若干寻找同类型金矿的找矿标志。  相似文献   

Gold-Platinoid Mineralization of Metasomatically Altered Ultramafites in Precambrian Protrusions of Mamynsky Geoblok     

V.G.Khomich  V.P.Molchanov  N.G.Boriskina 《东北亚地学研究》2003,(2)

On the contiguous territories of Russia and Chi-na,along the left and right banks of the Amur Riv-er (Heilongjiang Province of China,and Amur Oblast' of Russia),among the Late Mesozoic ter-rigenous and volcano-plutonic formations,several Precambrian prot…  相似文献   

兰坪坳陷上三叠统原油地球化学及有机成矿意义     

郭海花  常象春  张金亮 《地球科学与环境学报》2003,25(4):1-5

兰坪坳陷金顶矿区下含矿层产有多层稠油,储层主要为上三叠统三合洞组的灰岩和角砾状灰岩.原油地球化学特征表明有机母质是多源性的,并以低等水生藻类贡献为主,沉积水体介质以还原性占优势,具有较高盐度,有机质热演化处于成熟-高成熟阶段,生物降解改造较为强烈.铅锌金属与稠油的共生、金属硫化物的有机生物硫特征、有机质富集地区矿化强烈等均表明有机质参与了金属成矿.按照不同世代有机质与金属成矿作用机理,本区有机成矿主要以配合作用及吸附、还原作用为主.  相似文献