| 粤东晚三叠世小水组早侏罗世金鸡组古气候及构造背景的矿物和地球化学记录 |
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| 引用本文： | 许中杰,程日辉,王嘹亮,张莉.粤东晚三叠世小水组早侏罗世金鸡组古气候及构造背景的矿物和地球化学记录[J].吉林大学学报(地球科学版),2015(3):712-723. |
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| 作者姓名： | 许中杰 程日辉 王嘹亮 张莉 |
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| 作者单位： | 1. 吉林大学地球科学学院,长春,130061;2. 广州海洋地质调查局,广州,510075 |
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| 基金项目： | 国家自然科学基金项目，国家专项(XQ 200703 |
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| 摘 要： | 对揭西灰寨剖面上三叠统小水组和惠州黄洞剖面下侏罗统金鸡组采集的泥岩和砂岩样品进行了全岩分析和ICP-MS微量、稀土元素测试和矿物成分分析,根据元素含量及其比值的变化,提出了粤东揭西地区晚三叠世小水组和惠州地区早侏罗世金鸡组水体整体为还原、厌氧环境,以干燥炎热气候为主。小水组w(∑REE)较大,轻稀土富集(LREE/HREE为10.86和15.63),重稀土较稳定(w(∑HREE)为6.09×10-6和7.99×10-6),Eu负异常(δEu为0.67和0.87);金鸡组轻稀土富集(LREE/HREE=7.29~10.03),重稀土较稳定(w(∑HREE)为(15.39~19.72)×10-6),Eu负异常(δEu=0.59~0.65)。泥岩稀土元素分布模式图和源岩判别图解显示,小水组和金鸡组源岩来自上地壳的沉积岩、花岗岩和玄武岩,小水组下部样品沉积物源岩较上部要深,金鸡组上部沉积物源岩较中下部要深。Dickinson图解、K2O/Na2O-w(SiO2)、Zr-Th、La-Th-Sc、Th-Co-Zr/10判别图解和稀土元素特征值显示,晚三叠世揭西地区的构造背景为弧后伸展盆地,有被动大陆边缘特性,但也有大陆岛弧(由安第斯大陆边缘弧转变而来)的特性,其物源来自火山弧造山带。早侏罗世黄洞地区为弧后挤压盆地,具有被动陆缘特性,沉积物物源来自于切割的岩浆弧。
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| 关 键 词： | 粤东 上三叠统 下侏罗统 小水组 金鸡组 元素地球化学 古气候 构造背景 |
Mineral and Elemental Geochemistry Records of the Paleoclimate and the Tectonic Background in Late Triassic Xiaoshui Formation Early Jurassic Jinji Formation in East Guangdong |
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| Xu Zhongjie,Cheng Rihui,Wang Liaoliang,Zhang Li.Mineral and Elemental Geochemistry Records of the Paleoclimate and the Tectonic Background in Late Triassic Xiaoshui Formation Early Jurassic Jinji Formation in East Guangdong[J].Journal of Jilin Unviersity:Earth Science Edition,2015(3):712-723. |
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| Authors: | Xu Zhongjie Cheng Rihui Wang Liaoliang Zhang Li |
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| Abstract: | The whole rock analysis,the ICP MS trace,the rare earth elements test,and the mineral composition analysis were made to the mudstone and sandstone samples collected from Jiexi Huizhai Upper Triassic Xiaoshui Formation and Huizhou Huangdong Lower Jurassic Jinji Formation.Based on the changes of the element content and the ratios, the water was in a reductive and anaerobic environment as a whole;and it was mainly in a dry and hot climate during the Late Triassic Xiaoshui Formation in Jiexi area and the Early Jurassic Jinji Formation in Huizhou area in east Guangdong.The∑REE is high,the LREE is rich (LREE/HREE are 10.86 and 15.63),and the HREE is more stable (∑HREE are 6.09×10 -6 and 7.99 × 10 -6 )with a negative Eu anomaly (δEu are 0.67 and 0.87 )in Xiaoshui Formation.The LREE is rich (LREE/HREE = 7.29 10.03 ),the HREE is more stable (∑HREE=(15.39 1 9.72)×10 -6 )with a negative Eu anomaly (δEu=0.59 0.65)in Jinji Formation. The mudstone REE distribution diagram and the source rock discrimination diagram show that the Xiaoshui Formation and Jinji Formation source rocks were from the sedimentary rocks,granite,and basalt of the upper-crust.The sediment source rocks of Xiaoshui Formation in the lower part were deeper than the ones in the upper part.The sediment source rocks of Jinji Formation in the upper part were deeper than the ones in the middle-lower part.Based on the Dickinson diagram,the discrimination diagrams of K2 O/Na2 O SiO2 ,Zr Th,La Th Sc,Th Co Zr/10,and the REE characteristics values,the tectonic background of Late Triassic Jiexi area was the back-arc extensional basin.It presents the feature of a passive continental margin and also the continental island arc (transformed by the Andean continental margin arc ). The provenance was from the volcanic arc orogenic belt. Huangdong area was the back-arc extrusion basin in Early Jurassic with the passive continental margin characteristics.The sediment provenance is from the cut magmatic arc. |
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| Keywords: | east Guangdong Upper Triassic Lower Jurassic Xiaoshui Formation Jinji Formation element geochemistry paleoclimate tectonic background |
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