摘要
通过对黄河极细砂中普通角闪石单矿物的电子探针测试,采用以23个氧为标准,计算了69个角闪石的阳离子系数,由化学计量限制估算其Fe3+、Fe2+浓度平均值和相应的其他阳离子数值,产生它们可能的晶体结构分子式以及有关的晶体化学特征数值。研究表明:虽然黄河角闪石主要化学组成分异性较大,但都具有高硅、高钙、镁、低碱性的特征;晶体化学分类都属于钙角闪石组,出现10个角闪石种,种类相对简单,投影集中,以镁角闪石为主,占50%以上,其次是浅闪石,其晶体化学特征可作为与其它沉积体角闪石的鉴别依据;通过几种晶体化学图件判别,角闪石成因以中酸性岩浆岩为主,其次是变质成因,岩浆成因的角闪石的生成岩浆以壳幔混合源为主,幔源次之,变质成因的角闪石生成于中温、中压以下的变质环境。黄河角闪石以其最常见的种类和成因为特征,表明其原始来源的广泛性和稳定性,可作为我国北方上地壳陆源沉积物的标准化物质。
The chemical composition of amphibole in the surface sediments of the Huanghe River is studied by means of the electron microprobe analysis. The cation coefficients of the 69 amphibole are calculated on the basis of oxygen measurement. Limited by the stoichiometry, the average coefficients of Fe^3＋ , Fe^2＋ and other relevant cation are es- timated. According to the cation coefficients, the possible molecular formulas of the crystal structure and corre- sponding crystal-chemical characteristics are obtained. The results show that although the amphiboles of the Huanghe River have a large variation in the chemical composition, they are all characterized by high content＇s sili con, calcium, magnesium and low alkalinity. According to crystallochemical classification, the 69 amphiboles whose spices are relatively simple all belong to the calcic amphibole. It contains ten kinds of hornblende; the pro- jected spots are concentrating in the graphics of classification of the calatic amphiboles, including more than 50 % of magnesiohornblende and small amount of edenite. The characteristics of crystallochemistry of these can provide identification basis for distinguishing the Huanghe River sediments form other sedimentary body. The crystallo- chemistry-genesis illustration demonstrates that the 69 hornblendes are mainly derived from the intermediate-acid- ic magmatites, and then are metamorphic origin rocks. And the magmatic origin type of amphiboles is originated from a crust-mantle mixed source （mainly） and a mantle source （secondly）, while the metamorphic genesis origin type comes in metamorphic environments below middle pressures and middle temperatures. Amphibole in the Huanghe River whose species and features are most common indicate that their original sources are universal and stable, and can be used as standardized material in the upper crustal terrigenous sediments in northern China.
出处
《海洋学报》
CAS
CSCD
北大核心
2013年第1期131-143,共13页
基金
国家海洋局第一海洋研究所海洋沉积与环境地质国家海洋局重点实验室开放基金资助项目(MASEG200803)
关键词
角闪石
晶体化学
成因分析
物源
黄河
amphibole
crystallochemistry
genetic analysis
provenance
Huanghe River
