Recently, a, new type of skarn Sn ore formed bY B-F-metasomatism has been found in the central part of the Malage ore field at Gejiu, Yunnan Province, which contains 1--7% Sn. The principal Sn minerals are nordenkioel...Recently, a, new type of skarn Sn ore formed bY B-F-metasomatism has been found in the central part of the Malage ore field at Gejiu, Yunnan Province, which contains 1--7% Sn. The principal Sn minerals are nordenkioeldine hydromagno-cassitcrite, hydro eassiterite, etc., accounting for about 4%. Cassiterite is rarely seen (less than 0.2%).Outward from the interior of skarns are distinguished four alteration zones. Ore solutions were rich in AL and Si in the early stage of skarnization, and became enriched in Fe, Mg, Sn, B, F, H2O, etc. in the late stage. Two episodes of hydrothermal metasomatism of B and F took place during post-skarnization, and the different alteration zones may be due to reaction between B-and F-bearing hydrothermal solutions and country reeks (calcareous carbonates). The stability of the metasomatic minerals in controlled by the volatile components μB2O3, μCO2, μF2O-1 and μF(OH)-1. It has been concluded from the discussion in terms of the system CaO-SnO2-SiO2-H2O-B2O3-CO2 Fo-1 F2 o-1 proposed by Burr (1978) and the topological diagrams on chemical composition constructed by the author that nordeuskioeldine was formed in the exhaustion of Si at about 400℃ in the skarn environment, where metallogenetic conditions are characterized by rich oxygen but poor sulfur, and high boron hut low fluorine, while hydromagno-cassiterite and hydro-cassiterite were formed at the lower temperature (about 150℃) by hydrothermal metasomatism of fluorine. In comparison with the metallogenetic conditions for adjacont inner-skarn Sn ores and other Sn ore deposits at Gejiu, the role of the characteristic elemental association Sn-B-F is emphasized in this paper.展开更多
The Xi Ujumqin meteorite fell in Aug. 1980 at Xi Ujumqin County, Nei Monggol, China.This chondrite can be classified as L6 type based on the bulk chemical analysis (6wt% metal iron, 24% total iron, olivine Fa-26) and ...The Xi Ujumqin meteorite fell in Aug. 1980 at Xi Ujumqin County, Nei Monggol, China.This chondrite can be classified as L6 type based on the bulk chemical analysis (6wt% metal iron, 24% total iron, olivine Fa-26) and the textural feature of complete intergrowth of the chondrules with the matrix, The Mianchi meteorite is a type Hs chondrite that fell in Sep, 1980 at Mianchi County,Henan, China. Apart from porphyritic, barred, radial, cryptocrystanine chondrules, many intermediate-type or mixed-type chondrules are observed in the Mianchi meteorite under the microscope. It is suggested that the origin of chondrules showing different textures depend on the primeval compositions and cooling rates,展开更多
根据岩石成分与磁性,已将个旧花岗岩杂岩体划分为高磁性与低磁性两大系列:第一组高磁性相,很可能属于特殊的Ⅰ型花岗岩,并与氧化型夕卡岩锡矿的形成有关;第二组低磁性相,属于 S 型花岗岩,与还原型锡石硫化物夕卡岩锡矿的形成有关。在矿...根据岩石成分与磁性,已将个旧花岗岩杂岩体划分为高磁性与低磁性两大系列:第一组高磁性相,很可能属于特殊的Ⅰ型花岗岩,并与氧化型夕卡岩锡矿的形成有关;第二组低磁性相,属于 S 型花岗岩,与还原型锡石硫化物夕卡岩锡矿的形成有关。在矿物共生组合分析、相平衡、相图研究的基础上,系统地测定了个旧主要工业类型锡矿床(还原型锡石硫化物夕卡岩锡矿)形成的热力学参数,阐明其成因机理,还原夕卡岩主要造岩硅酸盐矿物钙铁辉石,通过反应(3)进行硫化反应,形成大量的磁黄铁矿。这是一条硫的缓冲平衡反应曲线,因此,所有热力学参数,如温度、硫逸度、氧逸度等均在比较严格和狭窄的范围内变化。通过自然界反应的产物证实了 Gamble 相图的应用范围。展开更多
文摘Recently, a, new type of skarn Sn ore formed bY B-F-metasomatism has been found in the central part of the Malage ore field at Gejiu, Yunnan Province, which contains 1--7% Sn. The principal Sn minerals are nordenkioeldine hydromagno-cassitcrite, hydro eassiterite, etc., accounting for about 4%. Cassiterite is rarely seen (less than 0.2%).Outward from the interior of skarns are distinguished four alteration zones. Ore solutions were rich in AL and Si in the early stage of skarnization, and became enriched in Fe, Mg, Sn, B, F, H2O, etc. in the late stage. Two episodes of hydrothermal metasomatism of B and F took place during post-skarnization, and the different alteration zones may be due to reaction between B-and F-bearing hydrothermal solutions and country reeks (calcareous carbonates). The stability of the metasomatic minerals in controlled by the volatile components μB2O3, μCO2, μF2O-1 and μF(OH)-1. It has been concluded from the discussion in terms of the system CaO-SnO2-SiO2-H2O-B2O3-CO2 Fo-1 F2 o-1 proposed by Burr (1978) and the topological diagrams on chemical composition constructed by the author that nordeuskioeldine was formed in the exhaustion of Si at about 400℃ in the skarn environment, where metallogenetic conditions are characterized by rich oxygen but poor sulfur, and high boron hut low fluorine, while hydromagno-cassiterite and hydro-cassiterite were formed at the lower temperature (about 150℃) by hydrothermal metasomatism of fluorine. In comparison with the metallogenetic conditions for adjacont inner-skarn Sn ores and other Sn ore deposits at Gejiu, the role of the characteristic elemental association Sn-B-F is emphasized in this paper.
文摘The Xi Ujumqin meteorite fell in Aug. 1980 at Xi Ujumqin County, Nei Monggol, China.This chondrite can be classified as L6 type based on the bulk chemical analysis (6wt% metal iron, 24% total iron, olivine Fa-26) and the textural feature of complete intergrowth of the chondrules with the matrix, The Mianchi meteorite is a type Hs chondrite that fell in Sep, 1980 at Mianchi County,Henan, China. Apart from porphyritic, barred, radial, cryptocrystanine chondrules, many intermediate-type or mixed-type chondrules are observed in the Mianchi meteorite under the microscope. It is suggested that the origin of chondrules showing different textures depend on the primeval compositions and cooling rates,
文摘根据岩石成分与磁性,已将个旧花岗岩杂岩体划分为高磁性与低磁性两大系列:第一组高磁性相,很可能属于特殊的Ⅰ型花岗岩,并与氧化型夕卡岩锡矿的形成有关;第二组低磁性相,属于 S 型花岗岩,与还原型锡石硫化物夕卡岩锡矿的形成有关。在矿物共生组合分析、相平衡、相图研究的基础上,系统地测定了个旧主要工业类型锡矿床(还原型锡石硫化物夕卡岩锡矿)形成的热力学参数,阐明其成因机理,还原夕卡岩主要造岩硅酸盐矿物钙铁辉石,通过反应(3)进行硫化反应,形成大量的磁黄铁矿。这是一条硫的缓冲平衡反应曲线,因此,所有热力学参数,如温度、硫逸度、氧逸度等均在比较严格和狭窄的范围内变化。通过自然界反应的产物证实了 Gamble 相图的应用范围。
