CAJ | 학술논문

云开地块西南缘的庞西垌复式岩体由外而内、由上而下依次为花岗片麻岩、片麻状花岗岩和花岗岩，即由高级变质岩渐变过渡至岩浆岩。X射线荧光光谱、等离子体质谱对三类岩石的分析结果表明，三类岩石皆属于过铝质岩石系列，造岩组分和微量元素具有渐变过渡的特征。在花岗片麻岩演化为花岗岩的熔融、分异过程中，Al2 O3，CaO ，MgO与TiO2等造岩组分含量逐渐增高，SiO2含量逐渐降低；稀土元素总量整体升高，稀土元素中轻稀土含量逐渐增高，而重稀土含量逐渐降低，显示出轻重稀土分异增强的特征，在多期演化过程中，形成了具有亲缘演化基因的庞西垌花岗质岩石系列。这表明云开地块表变质壳岩石的重熔可能是花岗质岩石的重要成因。其演化机制可能是，表壳岩石在发生熔融之后SiO2最先脱离母岩不断熔出，重稀土可能随着SiO2熔体逐渐向上富集；而Al2 O3，CaO ，MgO ，TiO2以及轻稀土相对SiO2则向下富集。
운개지괴서남연적방서동복식암체유외이내、유상이하의차위화강편마암、편마상화강암화화강암，즉유고급변질암점변과도지암장암。X사선형광광보、등리자체질보대삼류암석적분석결과표명，삼류암석개속우과려질암석계렬，조암조분화미량원소구유점변과도적특정。재화강편마암연화위화강암적용융、분이과정중，Al2 O3，CaO ，MgO여TiO2등조암조분함량축점증고，SiO2함량축점강저；희토원소총량정체승고，희토원소중경희토함량축점증고，이중희토함량축점강저，현시출경중희토분이증강적특정，재다기연화과정중，형성료구유친연연화기인적방서동화강질암석계렬。저표명운개지괴표변질각암석적중용가능시화강질암석적중요성인。기연화궤제가능시，표각암석재발생용융지후SiO2최선탈리모암불단용출，중희토가능수착SiO2용체축점향상부집；이Al2 O3，CaO ，MgO ，TiO2이급경희토상대SiO2칙향하부집。
Pangxidong composite granitoid pluton located in the southwestern margin of Yunkai massif .The metamorphic grade of this pluton increases from outside to inside ,that is ,banded‐augen granitic gneisses ,gneissoid granites and granites distribute in order from edge to core .X‐Ray Fluorescence Spectroscopy and Plasma Mass Spectrometry are conducted to study the geo‐chemical characteristics of the three types of rocks .The result shows that all the three types of rocks are peraluminous rocks and their contents of main elements and rare earth elements change gradually .From granitic gneisses to granites ,the contents of Al2 O3 ,CaO ,MgO ,TiO2 ,total rare earth elements and light rare earth elements increase ,but the contents of SiO2 and heavy rare earth elements decrease .It is suggested that the phylogenetic relationship exists between granitic gneisses ,gneissoid gran‐ites and granites during the multi‐stage tectonic evolution process .Furthermore ,the remelting of metamorphosed supracrustal rocks in Yunkai massif is probably an important cause of granitoid rocks forming .The evolutionary mechanism is probably that SiO2 and heavy rare earth elements were melt out from the protolith and gradually enriched upward ,but Al2 O3 ,CaO ,MgO , TiO2 and light rare earth elements enriched downward .