CAJ | 학술논문

准噶尔盆地石炭纪发育区域性的火山岩建造,火山岩岩性以中基性为主,主要为玄武岩、玄武安山岩,同时发育少量酸性的流纹岩,基本属于钙碱性系列.样品全碱(Na_2O+K_2O=2.99%～8.07%)和TiO_2(0.30%～2.57%)含量较高,K_2O含量(0.13%～3.29%)较低,稀土元素含量(∑REE)中等.球粒标准化的REE配分表现轻稀土元素(LREE)相对于重稀土元素(HREE)富集((La/Yb)_N=2.47～7.45)、轻重稀土分异的特征,部分样品的Eu和大部分样品的Ce显示轻微的负异常(δEu=0.543～1.088,δCe=0.787～0.987).微量元素具有大离子亲石元素(LILE)富集及高场强元素Nb、Ta亏损的特征,大部分样品(Rb/Yb)_N均远大于1.这些特征结合元素相关环境判别图解表明,准噶尔盆地石炭纪火山岩是原始岩浆经历了一定程度分异作用后的产物,以板内大陆环境为主,兼具有部分岛弧特征,形成于俯冲碰撞造山期后伸展背景下,火山岩所具有的岛弧特征是碰撞前混染弧组分的继承.
준갈이분지석탄기발육구역성적화산암건조,화산암암성이중기성위주,주요위현무암、현무안산암,동시발육소량산성적류문암,기본속우개감성계렬.양품전감(Na_2O+K_2O=2.99%～8.07%)화TiO_2(0.30%～2.57%)함량교고,K_2O함량(0.13%～3.29%)교저,희토원소함량(∑REE)중등.구립표준화적REE배분표현경희토원소(LREE)상대우중희토원소(HREE)부집((La/Yb)_N=2.47～7.45)、경중희토분이적특정,부분양품적Eu화대부분양품적Ce현시경미적부이상(δEu=0.543～1.088,δCe=0.787～0.987).미량원소구유대리자친석원소(LILE)부집급고장강원소Nb、Ta우손적특정,대부분양품(Rb/Yb)_N균원대우1.저사특정결합원소상관배경판별도해표명,준갈이분지석탄기화산암시원시암장경력료일정정도분이작용후적산물,이판내대륙배경위주,겸구유부분도호특정,형성우부충팽당조산기후신전배경하,화산암소구유적도호특정시팽당전혼염호조분적계승.
Territorial volcanic formation develop in Carboniferous period in Junggar basin. The volcanic rocks mainly composed of intermediate-basic basalts and basaltic andesites, including a few acidic rhyolites. They belong to calc-alkalic series. Volcanic rock samples have relatively high alkali ( Na_2O + K_2O =2.99%～8.07% ), TiO_2 (0.30%～2.57% ) contents, medium rare earth element contents and relatively low K_2O (0.13%～3.29% ) contents. Chondrite normalized REE patterns shows the characteristic of LREE enrichment ((La/Yb)_N=2.47～7.45) and differentiation, with weak Eu anomalies (δEu=0.543～1.088) and Ce anomalies (δCe =0.787～0.987). These samples are enriched in LILE but relatively depleted in HFSE (Nb, Ta), and have high (Rb/Yb) (>1). These characteristics, along with element correlation diagram, indicate that the Carboniferous volcanic rocks in Junggar basin are certain differential production of primitive magma, mainly generated in intra-plate continental setting, with island are environments partially. These volcanic rocks are from extensional setting of post-collisional period. Their island-arc characteristics are inherited from pre- collisional are component.