贵州盘州地区中三叠统关岭组底部绿豆岩地球化学特征及沉积环境分析

何承真; 张超; 孟昕卓; 周忠清

何承真,张超,孟昕卓,周忠清.贵州盘州地区中三叠统关岭组底部绿豆岩地球化学特征及沉积环境分析[J].贵州地质,2023,40(3):224-232

贵州盘州地区中三叠统关岭组底部绿豆岩地球化学特征及沉积环境分析

Analysis of Geochemical Characteristics and Sedimentary Environment of Mung Bean Rocks at the Bottom of the Middle Triassic Guanling Formation in Panzhou area，Guizhou

投稿时间：2023-04-14

DOI：

中文关键词: 锂绿豆岩地球化学沉积环境关岭组盘州地区

英文关键词:Lithium Mung bean rock Geochemistry Sedimentary environment Guanling formation Panzhou area

基金项目:

作者	单位
何承真	贵州省煤田地质局159队，贵州贵阳550081 贵州省黔美基础工程公司，贵州贵阳550081
张超	贵州省煤田地质局159队，贵州贵阳550081
孟昕卓	贵州省煤田地质局159队，贵州贵阳550081
周忠清	贵州省煤田地质局159队，贵州贵阳550081 贵州省黔美基础工程公司，贵州贵阳550081

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中文摘要:

为了查明盘州地区绿豆岩中锂多金属富集情况，本次工作在盘州地区中三叠统关岭组底部地层中共采集21件绿豆岩样品。分析测试结果显示，Li的含量介于5767×10-664137×10-6之间(平均33243×10-6)，最高含量相当于014%的Li2O含量；轻稀土元素(LREE)含量介于9597×10-651612×10-6之间(平均25778×10-6)，最高含量相当于006%的REE2O3含量，高于风化壳离子吸附型稀土矿床轻稀土最低工业品位005%0098%。通过对盘州地区绿豆岩进行系统的微量元素和稀土元素地球化学分析表明:绿豆岩大部分微量元素含量与上陆壳元素丰度几乎相符，相对富集Li、Y、Cs、Rb等稀有元素，亏损Tl、Ba、Sr、Cd、In等分散元素和过渡元素Ni；稀土元素总量(∑REE)介于10837×10-658976×10-6之间，平均值为29570×10-6，稀土元素配分模式图显示轻稀土富集的右倾型分布特征，具有较明显的负Eu异常；(La/Yb)CN、(La/Sm)CN和(Gd/Yb)CN显示，轻重稀土之间分馏明显、轻稀土分馏中等、重稀土分馏程度不明显；由稀土元素Eu异常和La/Yb-ΣREE图解可知，绿豆岩母岩来源于沉积岩、花岗岩和碱性玄武岩—大陆拉斑玄武岩的混合，其中沉积岩组分来源于北侧的泸州隆起区，母岩中的花岗岩和碱性玄武岩—大陆拉斑玄武岩组分则与火山喷发有关；绿豆岩铈异常(Ceanom)、Sr/Ba和Rb/Sr说明，盘州地区绿豆岩总体形成于气候温暖潮湿的半局限台地，处于淡水—半咸水沉积环境，水体呈弱还原—氧化状态。

英文摘要:

In order to investigate the enrichment of lithium and multiple metals in the mung bean rocks of the Panzhou area，21 samples of mung bean rocks were collected from the bottom strata of the Guanling formation of the Middle Triassic in the Panzhou areaThe analytical test results showed that the content of Li ranged from 5767×10-6 to 64137×10-6(average 33243×10-6)，with the highest content equivalent to 014% Li2O content，which is much higher than the boundary grade of 006% for solid and exposed salt mineral depositsThe content of light rare earth elements(LREE)ranged from 9597×10-6 to 51612×10-6(average 25778×10-6)，with the highest content equivalent to 006% REE2O3 content，which is higher than the lowest industrial grade of 005% to 0098% for light rare earths in weathered crust ion-adsorption type rare earth depositsThe systematic trace element and rare earth element geochemical analysis of the mung bean rocks in the Panzhou area showed that the content of most trace elements in the mung bean rocks is almost consistent with the abundance of upper continental crust elements，with relative enrichment of rare elements such as Li，Y，Cs，and Rb，and depletion of dispersed elements such as Tl，Ba，Sr，Cd，and In，and transition elements such as NiThe total amount of rare earth elements(∑REE)ranged from 10837×10-6 to 58976×10-6，with an average value of 29570×10-6The rare earth element distribution pattern diagram showed a right-skewed distribution characteristic of light rare earth enrichment，with a significant negative Eu anomaly(La/Yb)CN，(La/Sm)CN，and(Gd/Yb)CN showed that there is obvious fractionation between light and heavy rare earths，moderate fractionation of light rare earths，and unclear fractionation of heavy rare earthsBased on the interpretation of the rare earth element Eu anomaly and La/Yb-ΣREE diagram，it can be inferred that the mung bean rocks source rock is a mixture of sedimentary rocks，granite，and alkaline basalt-continental rift tholeiite，with the sedimentary rock component originating from the Luzhou uplift area on the north side，and the granite and alkaline basalt-continental rift tholeiite components in the source rock being related to volcanic eruptionsThe cerium anomaly(Ceanom)，Sr/Ba，and Rb/Sr of the mung bean rocks indicate that it was formed in a warm and humid semi-restricted platform environment in the Panzhou area，in a freshwater to brackish water sedimentary environment，with the water body in a weakly reduced-oxidized state

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