PETROLOGY AND DATING OF NEO-ARCHAEAN INTRUSIVE ROCKS FROM GUYANG AREA, INNER MONGOLIA
-
摘要: 通过区调填图在固阳地区新发现了一套新太古代TTG质的侵入岩.这套岩石主要由闪长岩、石英闪长岩、英云闪长岩组成, 虽然遭受了一定程度的变质作用, 但仍保存了较完整的侵入岩外貌, 与太古宙灰色片麻岩在外貌上存在明显区别.岩石为钙碱性系列, 总体属TTG岩系的一部分.根据同位素资料确定岩石的年龄为2 40 0~ 2 5 0 0Ma, 属新太古代末期.Abstract: A suite of Neo-Archaean tonalitic-trondjemites-granodioritic intrusive rocks composed mainly of diorites, quartz diorites, and tonalites are discovered in Guyang district, Inner Mongolia through the regional mapping. Although these intrusive rocks have been metamorphosed to some extent, their relatively perfect appearances quite different from those of the Archaean gray gneisses can still be observed. These rocks within the calc-alkali series are a part of the TTG rock series. The isotopic dating indicates that the age of the rocks at 2 400-2 500 Ma, i.e. at the end of Neo-Archaean.
-
Key words:
- Neo-Archaean /
- intrusive rocks /
- isotope /
- Guyang, Inner Mongolia
-
图 3 固阳新太古代侵入岩w(An)-w(Ab)-w(Or)图解(图例同图 2)
A.英云闪长岩; B.花岗闪长岩; C.石英二长岩; D.奥长花岗岩; E.花岗岩
Fig. 3. w(An)-w(Ab)-w(Or)diagram of Neo-Archaean igneous rocks from Guyang
图 4 固阳新太古代侵入岩w(CaO)-w(Na2O)-w(K2O) 图解(图例同图 2)
Fig. 4. w (CaO)-w(Na2O)-w(K2O) diagram of Neo-Archaean igneous rocks from Guyang
图 5 固阳新太古代侵入岩w (Ca)-w (Na)-w (K) 图解(图例同图 2)
Fig. 5. w (Ca)-w(Na)-w (K) diagram of Neo-Archaean igneous rocks from Guyang
图 6 固阳地区新太古代侵入岩稀土配分曲线(图例同图 2)
Fig. 6. REE patterns of Neo-Archaean igneous rocks from Guyang
表 1 固阳新太古代侵入岩岩石化学成分
Table 1. Chemical compositions and related parameters of Neo-Archaean igneous rocks from Guyang
表 2 固阳新太古代侵入岩稀土元素分析结果
Table 2. Compositions of REE and related parameters of Neo-Archaean igneous rocks from Guyang
表 3 固阳新太古代侵入岩锆石U-Pb同位素分析
Table 3. Zircon U-Pb isotopic data of Neo-Archaean igneous rocks from Guyang
-
[1] 内蒙古自治区地质矿产局. 内蒙古自治区区域地质志[M]. 北京: 地质出版社, 1991.32~71, 360~439. [2] 内蒙古自治区地质矿产局. 内蒙古自治区岩石地层[M]. 武汉: 中国地质大学出版社, 1996.114~120. [3] Herveé Martin. Petrogenesis of Archaean trondhjemites, tonalites, and granodiorites from Eastern Finland: major and trace element geochemistry [J]. Journal of Petrology, 1987, 28(5): 921~953. [4] 林强, 吴福元, 刘树文. 华北地台东部太古宙花岗岩[M]. 北京: 科学出版社, 1992. 1~38. [5] 邱家骧. 应用岩浆岩岩石学[M]. 武汉: 中国地质大学出版社, 1991. 192~193. [6] Hervé Martin. Archaean and modern granitoids as indicators of changes in geodynamic processess[J]. Revista Brasileira de Geociencias, 1987, 17 (4): 360~365.