CAJ | 학술논문

哈尔里克奥姆尔塔格碱性花岗岩(OMAG)侵入于小铺东二长花岗岩中.该岩体岩性较均一,呈灰紫色,主要矿物组合为石英、钾长石、钠长石、碱性角闪石和霓石;化学成分上富硅、碱,贫钙、镁,低铝;富Rb、Th、U和Zr,Ga/AI比值大(3.18×10~4～3.56×10~4),贫Ba、Sr,岩石中Co、Cr、V和Ni等过渡元素显著亏损,U、Hf、Zr和Nb等高场强元素的含量高;稀土总量较高,配分模式右倾,并具有显著的负铕异常;LA-ICP-MS锆石~(206)Pb/~(238)U加权平均年龄为287.6±2.1Ma;具有正的ε_(Nd)(t)值(+4.96),较低的(~(87)>Sr/~(86)Sr);值(0.70159).同样侵入于小铺东二长花岗岩中的恰干昆多沟含角闪石石英正长岩(QGQS)也呈灰紫色,其结构和构造与OMAG非常相似.两个岩体在主量元素和REE图解上均呈现有规律的分布和一致的演化趋势.从QGQS到OMAG,SiO_2含量增加(从64.71%～64.83%到71.23%～74.31%)、全碱含量降低(从11.72%～11.79%到8.49%～9.87%)和Al_2O_3含量减少(从16.09%～16.19%到11.44%～13.34%)、稀土总量减少(从592.3×10~(-6)～656.0×10~(-6)到273.9×10~(-6)～405.9×10~(-6))、轻/重稀土比值降低(从18.2～20.1到4.4～6.0)、稀土配分曲线从平滑到Eu显著亏损.基于OMAG的岩相学、矿物学、地球化学、锆石年代学和与QGQS的对比研究,笔者认为奥姆尔塔格碱性花岗岩可能是由石英正长岩母岩浆经过分离结晶作用演化的产物,且这种石英正长岩岩浆起源于亏损地幔;根据哈尔里克造山带地质演化历史的分析,这两个岩体均形成于紧随主碰撞后的挤压-伸展转折阶段.
합이리극오모이탑격감성화강암(OMAG)침입우소포동이장화강암중.해암체암성교균일,정회자색,주요광물조합위석영、갑장석、납장석、감성각섬석화예석;화학성분상부규、감,빈개、미,저려;부Rb、Th、U화Zr,Ga/AI비치대(3.18×10~4～3.56×10~4),빈Ba、Sr,암석중Co、Cr、V화Ni등과도원소현저우손,U、Hf、Zr화Nb등고장강원소적함량고;희토총량교고,배분모식우경,병구유현저적부유이상;LA-ICP-MS고석~(206)Pb/~(238)U가권평균년령위287.6±2.1Ma;구유정적ε_(Nd)(t)치(+4.96),교저적(~(87)>Sr/~(86)Sr);치(0.70159).동양침입우소포동이장화강암중적흡간곤다구함각섬석석영정장암(QGQS)야정회자색,기결구화구조여OMAG비상상사.량개암체재주량원소화REE도해상균정현유규률적분포화일치적연화추세.종QGQS도OMAG,SiO_2함량증가(종64.71%～64.83%도71.23%～74.31%)、전감함량강저(종11.72%～11.79%도8.49%～9.87%)화Al_2O_3함량감소(종16.09%～16.19%도11.44%～13.34%)、희토총량감소(종592.3×10~(-6)～656.0×10~(-6)도273.9×10~(-6)～405.9×10~(-6))、경/중희토비치강저(종18.2～20.1도4.4～6.0)、희토배분곡선종평활도Eu현저우손.기우OMAG적암상학、광물학、지구화학、고석년대학화여QGQS적대비연구,필자인위오모이탑격감성화강암가능시유석영정장암모암장경과분리결정작용연화적산물,차저충석영정장암암장기원우우손지만;근거합이리극조산대지질연화역사적분석,저량개암체균형성우긴수주팽당후적제압-신전전절계단.
The Omortage alkaline granite (OMAG) was intruded in the Xiaopudong monzogranite of the Kelameili-Harlik orogenic belt. The rock of the OMAG is massive, grayish purple and mainly composed of quartz (21% ～ 35%), k-feldspar (61% ～77%), albite (4% ±), alkaline amphibole (1% ～4%) and aegirine (< 1%). Chemically, the OMAG is rich in silica and alkali, and poor in Ca, Mg and Al. It is also enriched in Rb, Th, U, Zr, Hf and Nb with Ga/Al values between 3.18×10~4 ～3.56×10~4, but depleted in Ba, Sr, Co, Cr, V and Ni. The OMAG shows higher ∑ REE and right-inclined distribution patterns with strongly negative Eu anomalies (δEu =0.26 ～0.33). Zircon LA-ICP-MS U-Pb isotope determination gave an age of 287.6±2.1Ma for the OMAG. The OMAG is higher in ε_(Nd) (t) (+4.96) and lower in (~(87)Sr/~(86)Sr)_i(0.70159) . The Qiagankunduogou hornblende-bearing quartz-syenite (QGQS), which was also intruded in the Xiaopudong monzogranite, exhibits very similar texture, structure and grayish-purple in comparison with the OMAG. Plots of these two plutons show regular distribution on the major elements and REEs diagrams, and indicating consistent evolutional trends. From QGQS to OMAG, SiO_2 increases from 64.71% ～ 64.83% to 71.23% ～ 74.31%, whereas ALK (Na_2O + K_2O) deceases from 11.72% ～11.79 % to 8.49%～9.87 %, Al_2O_3 from 16.09%～16.19% to 11.44% ～ 13.34%, ∑ REE from 592.3×10~(-6) ～ 656.0×10 ~(-6) to 273.9×10~(-6) ～ 405.9×10~(-6), and the ratio of LREE/HREE from 18.2 ～ 20.1 to 4.4～6.0 with distribution patterns varying from being smooth to intensive Eu depletion. Based on comparative study between the OMAG and OGQS in petrography, mineralogy, geochemistry and zircon chronology, it is concluded that the Omortage alkaline granites (OMAG) was derived from the quartz-syenite parental magma by fractional crystallization, the quartz-syenite magma came from the depleted-mantle-sourced. Geological evolution of the Harlik orogen indicates that these two plutons were formed during tectonic conversion of post-collision from compression to extension.