CAJ | 학술논문

甘肃省肃北县东南的三个洼塘一带发育大量侵入岩体，其中出露规模最大的是三个洼塘岩体，该岩体南部及北西部侵入长城纪朱龙关群，北东侵入北大河岩群，岩体岩性主要为二长花岗岩和花岗闪长岩。岩石组合类型和岩石地球化学研究分析表明，三个洼塘岩体SiO2含量67.49%~71.61%，平均69.48%，Na2O含量3.47%~4.25%，K2O含量2.60%~4.44%，铝饱和指数A/CNK=0.99~1.32，稀土元素总量为100.75×l0-6~198.15×l0-6，(La/Yb)N=4.95~28.95，球粒陨石标准化分布模式图总体呈右倾型，LREE相对富集，HREE相对亏损，Eu异常不明显。上述特征表明三个洼塘岩体为过铝质钙碱性S型花岗岩，是上地壳物质部分熔融的产物。通过与前人对该地区出露肃北岩体的研究结果进行对比发现，两者在构造位置、成因类型、稀土元素、形成环境等都存在很大相似性。因此，认为其应属同一构造时期的产物，经历了大致相似的演化过程，均为加里东期陆陆碰撞作用的产物。
감숙성숙북현동남적삼개와당일대발육대량침입암체，기중출로규모최대적시삼개와당암체，해암체남부급북서부침입장성기주룡관군，북동침입북대하암군，암체암성주요위이장화강암화화강섬장암。암석조합류형화암석지구화학연구분석표명，삼개와당암체SiO2함량67.49%~71.61%，평균69.48%，Na2O함량3.47%~4.25%，K2O함량2.60%~4.44%，려포화지수A/CNK=0.99~1.32，희토원소총량위100.75×l0-6~198.15×l0-6，(La/Yb)N=4.95~28.95，구립운석표준화분포모식도총체정우경형，LREE상대부집，HREE상대우손，Eu이상불명현。상술특정표명삼개와당암체위과려질개감성S형화강암，시상지각물질부분용융적산물。통과여전인대해지구출로숙북암체적연구결과진행대비발현，량자재구조위치、성인류형、희토원소、형성배경등도존재흔대상사성。인차，인위기응속동일구조시기적산물，경력료대치상사적연화과정，균위가리동기륙륙팽당작용적산물。
Intrusive rocks extensive occur in the Sangewatang area of the southeast Subei Coutry, Gansu Province,and the Sangewatang pluton is the biggest one in the region.The pluton intruded into Changcheng Period Zhulongguan Group in the west and south,and Dahe Group in the northeast,is mainly composed of granodiorite and monzonitic granite.Based on detailed field survey,through study on the rock assemblage and geochemistry, the SiO2 content in the pluton is 67.49%~71.61%,average is 69.48%,Na2O content is 3.47%~4.25%,K2O content is 2.60%~4.44%, aluminum saturation index A/CNK=0.99~1.32,and the total rare earth element (REE) between 100.75×l0-6 and 198.15×l0-6.On the Chondrite-normal-ized REE patterns,shows right deviation and enrichment in light rare earth element (LREE) and depletion in heavy rare earth element (HREE) with (La/Yb)N=4.95~28.95.Moreover,no pronounced Eu anomaly.Combined with geochemical characteristics,the Sangewatang granites have a peraluminous calc-alkaline S-type affinity, showing that it is a product of partial melting from upper crust.Compared with the Subei pluton located nearby,we find that there are many similarities between them in structural location, petrogenesis,composition of REE,tectonic setting and so on.So we think that they should be products of the same tectonic event and underwent the similar evolution process.In general,they resulted from the continent-continent collision during Caledonian.