摘要
水泉沟碱性岩体是冀北著名的控矿碱性杂岩体,岩体由二长岩类、正长岩类及碱长正长岩类组成。各类岩石间无明显的界线,一般为渐变过渡关系。岩石化学组成总的特征是贫硅、富碱,铝含量中至高,反映了随着岩浆演化,碱质交代加强,岩体属于碱性—偏碱性岩体。通过对该岩体铅同位素、钕锶同位素图解研究,样品投点于地幔与大陆壳演化线之间,少量于陆壳演化线之上,说明铅、锶同位素不是单一来源,原始物质来源于地幔,推测岩浆自地幔上侵过程中有壳源物质加入。对比K-Ar法测年数据和^(39)Ar-^(40)Ar法年龄测试结果,认为水泉沟碱性岩体形成于288～327.4 Ma,属海西晚期。
The Shuiquangou alkaline intrusive is well known as the alkaline complex rocks for the ore - controlling in northwest- ern Hebei Province. The complex intrusive rocks consist of monzonite, syenite and alkaline feldspar syenite. There are no apparent boundaries among these intrusive rocks, but generally gradual contact boundary. The general characteristic of the chemical compositions of these intrusive rocks is poor in silicon and rich in alkaline, and the aluminum content is medium to high, which reflects the alkaline metasomatism was strengthened with the magmatic evolution, and the intrusive rocks belong to the alkaline and or alkaline - bearing rock mass. Based on the studies on lead isotope and neodymium - strontium isotope of the rock mass, most of isotope samples plotted on the isotope diagram are between mantle and continental crust evolution line, few are above the continental crust evolution line, which indicated that lead and strontium isotopes are not a single source. The original ore - forming material should come from the man- tle, it is speculated that crust - source materlal anticipated the magma during the invasion process of the mantle. By comparing the dat- ing data of K - Ar measurement and 39 Ar - 40 Ar measurement, it is interpreted that the Shuiquangou alkaline rock mass were formed in age of 288 -327.4 Ma, which is equal to the late Hercynian period.
出处
《矿产勘查》
2013年第4期441-446,共6页
Mineral Exploration
关键词
碱性岩
同位素
上地幔
成因
冀西北水泉沟
alkaline rock
isotope
upper mantle
genesis
Shuiquangou, northwestern Hebei Province
作者简介
[第一作者简介]刘海田，男，1963年生，高级工程师，从事固体矿产勘查与研究工作。
