新疆准噶尔盆地西北部二叠纪玄武岩浆作用流体介质条件:流体化学组成及碳同位素制约

发布时间：2018-01-16 12:09

本文关键词：新疆准噶尔盆地西北部二叠纪玄武岩浆作用流体介质条件:流体化学组成及碳同位素制约　出处：《岩石学报》2017年01期 　论文类型：期刊论文

【摘要】：准噶尔盆地西北部深层分布着大量的二叠纪玄武岩,其发育的流体介质条件缺乏系统研究。本文采用二叠纪玄武岩岩心样品,对基质中的流体化学组成和碳同位素组成进行分步加热质谱法分析,结果表明二叠纪玄武岩的流体组成中H_2O的含量极高(平均13789mm3.STP/g),次要组分为CO_2、O_2、H_2S和N2等,CO_2和CH_4的δ~(13)C值(分别为-28.9‰~-15.8‰和-36.8‰~-21.9‰)位于地壳与甲烷氧化来源组分的范围内;CH_4、C_2H_6、C_3H_8和C_4H_(10)等甲烷同系物的碳同位素组成随碳数增高总体具有正序分布特征,400~800℃温度段释出CH_4的δ~(13)C值(-25‰左右)明显重于200~400℃的(-35‰左右),部分样品400~800℃的CH_4-C_3H_8存在碳同位素反序分布的特征,显示幔源流体挥发份特征,其中混入大量的沉积有机质热裂解成因烃类气体,应为俯冲蚀变大洋板片的沉积物脱出流体挥发份。大量的H_2O指示岛弧俯冲的再循环流体的加入,甲烷氧化来源特征的CO_2和CH_4碳同位素组成揭示经历了长期的风化过程,表明相关岩浆作用后遭受长期的抬升。
[Abstract]:In the northwest of Junggar Basin deep distribution of a large number of Permian basalts, lack of systematic study on the development of the fluid medium. This paper uses the Permian basalt composition of core samples, stepwise heating mass spectrometric analysis of fluid chemical composition and carbon isotope matrix. The results show that the high content of fluid composition in the Permian basalts (average 13789mm3.STP/g), H_2O the secondary component is CO_2, O_2, H_2S and N2, CO_2 and CH_4 (13) ~ Delta C value (-28.9% ~-15.8% and -36.8% ~-21.9%) in the crust and the range of components in the source of methane oxidation; CH_4, C_2H_6, C_3H_8 and C_4H_ (10) carbon isotope of methane homologs the composition with the carbon number increased with the overall positive distribution, the temperature of 400~800 DEG C release section CH_4 (13) ~ Delta C value (-25%) was significantly heavier than the 200~400 C (-35%), some samples of 400~800 C CH_4-C_3H_8 There are characteristics of carbon isotope reverse order distribution, mantle volatiles, which are mixed with a lot of sedimentary organic matter pyrolysis of hydrocarbon gas, should be subducted altered oceanic slab sediment prolapse volatiles. Adding a large number of H_2O indicates the island arc subduction recycling fluid, CO_2 and CH_4 of carbon isotope of methane the composition of oxidation characteristics and sources revealed through long-term weathering, suggesting that magmatism after suffering long-term uplift.

【作者单位】：兰州大学地质科学与矿产资源学院甘肃省西部矿产资源重点实验室;中国科学院地质与地球物理研究所甘肃省油气资源研究重点实验室;
【基金】：国土资源部公益性行业科研专项(201511020) 国家自然科学基金项目(41472070、41372095) 兰州大学中央高校基本科研业务费(lzujbky-2015-64) 高等学校博士学科点专项科研基金项目(20120211110023) 甘肃省西部矿产资源重点实验室开放基金(WCRMGS-2014-04) 中国地质调查局项目(12120114044401)联合资助
【分类号】：P618.13;P597
【正文快照】： 1.兰州大学地质科学与矿产资源学院,甘肃省西部矿产资源重点实验室,兰州7300002.中国科学院地质与地球物理研究所,甘肃省油气资源研究重点实验室,兰州7300001.Key Laboratory of Mineral Resources in Western China(Gansu),School of Earth Sciences,Lanzhou University,Lanz

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