曾俊杰,李康宁,严 康,火兴达,张建鹏.西秦岭早石炭世巴都组碎屑岩地球化学特征及对构造背景、物源区的指示[J].甘肃地质,2021,(1):41-48
西秦岭早石炭世巴都组碎屑岩地球化学特征及对构造背景、物源区的指示
Geochemical Characteristics,Constraints on Provenance and Tectonic Setting of Early   Carboniferous Badu Formation in the Western Qinling Mountains
  
DOI:
中文关键词:  西秦岭  巴都组  构造环境  物源
英文关键词:West Qinling  Badu Formation  provenance  tectonic setting
基金项目:本文为国家重点研发计划深地资源勘查开采专项“深部矿产资源三维找矿预测评价示范”课题(编号:2017YFC0601506)“甘肃省玛曲—合作地区资源潜力评价与深部找矿预测示范”专题;甘肃省基础地质调查研究项目“甘肃玛曲—合作整装勘查区深部找矿预测”;中国地质调查局项目“甘肃省夏河—合作地区金矿整装勘查区矿产调查与找矿预测”(编号:12120100000160901-60、12120100000160901-49)的成果。
作者单位
曾俊杰 甘肃省地矿局第三地勘院甘肃 兰州 730050 
李康宁 甘肃省地矿局第三地勘院甘肃 兰州 730050 
严 康 甘肃省地矿局第三地勘院甘肃 兰州 730050 
火兴达 甘肃省地矿局第三地勘院甘肃 兰州 730050 
张建鹏 甘肃省地矿局第三地勘院甘肃 兰州 730050 
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中文摘要:
      西秦岭早石炭世巴都组出露于夏河—合作断裂以北,为一套滨浅海相陆源碎屑岩建造,主要岩性为石英砂岩、长石石英砂岩。砂岩成熟度较高,总体上具有高硅低铝、高钾低钠的特点。ω(SiO2) = 76. 47% ~ 80. 32%,平均78. 67%;ω(Al2O3) = 9. 32% ~ 10. 4%,平均9. 72%;ω(K2O) = 2. 03% ~ 2. 33%,平均2. 15%;ω(Na2O) = 1. 46% ~ 1. 87%,平均1. 64%。稀土元素总量较低,ΣREE为75. 15 × 10-6 ~ 107. 26 × 10-6,平均值88. 86 × 10-6,经球粒陨石标准化可以看出轻重稀土分异明显,Eu具有明显的负异常(δEu = 0. 76 ~ 1. 13,平均值0. 65),经北美页岩标准化Eu具有正异常(δEu = 1. 17 ~ 1. 74,平均值1. 32);亏损高场强元素Nb、Ta、Ti、HREE及Sr,富集大离子亲石元素Rb、U、Th、Zr,具有与大陆上地壳和PAAS相似的分布。通过碎屑岩主微量元素地球化学、结合区域地质背景综合判断,早石炭世巴都组源区构造背景为活动大陆边缘和大陆岛弧,碎屑来源于稳定沉积岩区,主要为北秦岭造山带,可能是前泥盆系再旋回沉积物或隆起的基底岩石提供。
英文摘要:
      Early Carboniferous Badu Formation in the West Qinling is a set of shore shallow marine terrigenous clastic rock formation exposed to the north of Xiahe-Hezuo fault,and its main lithology is quartz sandstone and feldspathic quartz sandstone. The maturity of sandstone is high,which has the characteristics:SiO2 and K2O is higher,Al2O3 and Na2O is lower. SiO2 contents range from 7. 47% to 80. 32%,78. 67% on average; Al2O3 contents range from 9. 32% to 10. 4%,9. 72% on average; K2O contents range from 2. 03% to 2. 33%, 2. 15% on average; Na2O contents range from 1. 46% to 1. 87%,1. 64% on average. The total amount of rare earth elements is relatively low,Σ REE contents range from 75. 15 × 10-6 to 107. 26 × 10-6,with an average of 88. 86 × 10-6. It can be seen from the chondrite standardization that the heavy and light rare earth differences are obvious, Eu has obvious negative anomalies(δEu = 0. 76 ~ 1. 13,with an average of 0. 65),Eu has positive anomalies(Eu = 1. 17 ~ 1. 74,with an average of 1. 32) through the North American shale standardization,and Nb,Ta,Ti, HREE and Sr have high field strength loss,Rich in large ion lithophile elements as Rb,U,Th and Zr,it has similar distribution with the continental upper crust and PAAS. According to the geochemistry of the major and trace elements of the clastic rocks and the comprehensive judgment of the regional geological background,the structural background of the source area of Badu formation in the Early Carboniferous is the active continental margin and the continental island arc,and the clastic rocks are mainly from the stable sedimentary rock area,which is mainly provided by the North Qinling Orogenic Belt,possibly the pre Devonian gyrating sediments or the uplifted basement rocks.
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