This paper deals with the high\|K, potassic dike rocks in two types of gold ore fields at Linglong and Dayigezhuang, Northwest Jiaodong. The rocks can be divided into three types, i.e., (1) lamprophyre, (2) andesite p...This paper deals with the high\|K, potassic dike rocks in two types of gold ore fields at Linglong and Dayigezhuang, Northwest Jiaodong. The rocks can be divided into three types, i.e., (1) lamprophyre, (2) andesite porphyrite, and (3) dacite porphyrite, based on their geological occurrence and space\|time relationship with gold mineralization. These rocks were the products of early, synchronous and late mineralization, respectively. Element geochemistry shows that variations in chemical composition of major oxides follow the general rules of magmatic fractional crystallization. The fractional crystallization of mineral phases of augite in the early stage (namely in the lamprophyre stage) and hornblende and plagioclase in the late stage (namely from the andesite\|porphyrite to dacite porphyrite stage) controlled the magma evolution. The rocks are enriched in alkali and have higher K\-2O and lower TiO\-2 contents, as well as strongly enriched in large ion lithophile elements such as Ba, Sr and Rb, and LREE but strongly depleted in transition elements such as Cr and Ni. Rb is depleted relative to Sr and Ba, and Rb/Sr ratios are low. Volatile constituents are abundant. These characteristics indicate that the initial magma originated from the metamorphic subduction ocean\|crust that had been intensively contaminated by crustal materials, and retrogressive metamorphism is characterized by low\|degree partial melting during back\|arc spreading. Varying degrees of partial melting and different emplacement environments may be the main causes for the evolution of the rocks and mineralization in different degrees in the two gold ore fields at Linglong and Dayigezhuang, Shandong.展开更多
Based on the content of radioactive elements (U, Th, K) of strata in two drill holes in the Fuzhou basin, and combined with the result of spore_pollen analysis, the relationship between radioactivity and lithology and...Based on the content of radioactive elements (U, Th, K) of strata in two drill holes in the Fuzhou basin, and combined with the result of spore_pollen analysis, the relationship between radioactivity and lithology and deposit environments is discussed and the results show that the content of radioactive substances is related to the granularity and lithology in sediment, and it is higher in argillaceous sediment (e.g. silt and clay), lower in sand sediment and in the middle in gravels between the above two kinds of sediment. The content of radioactive substances is also related to paleoclimate. A warm and humid environment is propitious to the deposition of radioactive substances, while a cool and dry climate is just the reverse.展开更多
文摘This paper deals with the high\|K, potassic dike rocks in two types of gold ore fields at Linglong and Dayigezhuang, Northwest Jiaodong. The rocks can be divided into three types, i.e., (1) lamprophyre, (2) andesite porphyrite, and (3) dacite porphyrite, based on their geological occurrence and space\|time relationship with gold mineralization. These rocks were the products of early, synchronous and late mineralization, respectively. Element geochemistry shows that variations in chemical composition of major oxides follow the general rules of magmatic fractional crystallization. The fractional crystallization of mineral phases of augite in the early stage (namely in the lamprophyre stage) and hornblende and plagioclase in the late stage (namely from the andesite\|porphyrite to dacite porphyrite stage) controlled the magma evolution. The rocks are enriched in alkali and have higher K\-2O and lower TiO\-2 contents, as well as strongly enriched in large ion lithophile elements such as Ba, Sr and Rb, and LREE but strongly depleted in transition elements such as Cr and Ni. Rb is depleted relative to Sr and Ba, and Rb/Sr ratios are low. Volatile constituents are abundant. These characteristics indicate that the initial magma originated from the metamorphic subduction ocean\|crust that had been intensively contaminated by crustal materials, and retrogressive metamorphism is characterized by low\|degree partial melting during back\|arc spreading. Varying degrees of partial melting and different emplacement environments may be the main causes for the evolution of the rocks and mineralization in different degrees in the two gold ore fields at Linglong and Dayigezhuang, Shandong.
基金This project was granted bythe National Developmentand Reform Commission.Item Number:20041138
文摘Based on the content of radioactive elements (U, Th, K) of strata in two drill holes in the Fuzhou basin, and combined with the result of spore_pollen analysis, the relationship between radioactivity and lithology and deposit environments is discussed and the results show that the content of radioactive substances is related to the granularity and lithology in sediment, and it is higher in argillaceous sediment (e.g. silt and clay), lower in sand sediment and in the middle in gravels between the above two kinds of sediment. The content of radioactive substances is also related to paleoclimate. A warm and humid environment is propitious to the deposition of radioactive substances, while a cool and dry climate is just the reverse.
