拉萨地块西部碰撞后富钾火山作用CO_(2)释放规模初探  

Preliminary study on CO_(2)output of post-collisional K-rich volcanism in western Lhasa terrane

作　　者：谢显刚 赵文斌 李晓光 李菊景 郭正府[2] 张茂亮 徐胜 XIE XianGang;ZHAO WenBin;LI XiaoGuang;LI JuJing;GUO ZhengFu;ZHANG MaoLiang;XU Sheng(School of Earth System Science,Tianjin University,Tianjin 300072,China;Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]天津大学地球系统科学学院,天津300072 [2]中国科学院地质与地球物理研究所新生代地质与环境重点实验室,北京100029 [3]中国科学院地质与地球物理研究所,岩石圈演化国家重点实验室,北京100029

出　　处：《岩石学报》2024年第7期2225-2237,共13页Acta Petrologica Sinica

基　　金：国家重点研发计划(2020YFA0607700);国家自然科学重点基金项目(41930642)联合资助。

摘　　要：估算地质历史时期火山活动的CO_(2)释放量对于理解地球深部碳释放及其气候环境效应具有重要意义。本文聚焦青藏高原拉萨地块西部的碰撞后富钾火山作用,以雄巴、赛利普、布嘎寺和麦嘎4个地区的富钾火山岩为例,开展了橄榄石、辉石等斑晶矿物中熔体包裹体的CO_(2)含量与脱气特征研究,结合火山岩体积和年龄等参数,估算了拉萨地块碰撞后富钾火山活动的CO_(2)释放量。结果表明,研究区火山岩熔体包裹体气泡中的CO_(2)含量约为0.61%~5.38%,雄巴、赛利普、布嘎寺和麦嘎火山岩的CO_(2)年释放量分别为(5.1±0.9)×10^(-5)Pg/yr、(1.3±0.6)×10^(-5)Pg/yr、(2.5±0.5)×10^(-4)Pg/yr和(1.5±0.2)×10^(-7)Pg/yr,共计约(3.2±0.6)×10^(-4)Pg/yr。粗略推算结果表明,拉萨地块碰撞后富钾火山作用的CO_(2)总释放规模约为0.006±0.001Pg/yr,与大陆碰撞带深部碳释放通量模型的计算结果相一致。本文的研究结果为地质历史时期印度-亚洲大陆碰撞导致的深部碳释放模拟提供了初步的实测数据参考。未来仍需在获取更多数据的基础上优化研究结果,以减小碰撞后火山作用的岩浆成分、规模、时空分布不均等导致的不确定性。Estimating volcanic CO_(2)output in the geological past is important for understanding Earth s deep carbon emission and its impact on climate and environment.Here we focus on the post-collisional K-rich volcanism in western Lhasa terrane,Tibetan Plateau.Taking the K-rich volcanic rocks in Xungba,Sailipu,Bugasi,and Maiga as examples,we studied on CO_(2)content and degassing features of melt inclusions in olivine and pyroxene.The CO_(2)output of post-collisional K-rich volcanism in Lhasa terrane was estimated by combining parameters such as volcanic volume and rock ages.Our results show that CO_(2)content of gas bubble in volcanic rock melt inclusions in study area are range from 0.61%to 5.38%,and the CO_(2)annual output of Xungba,Sailipu,Bugasi,and Maiga volcanic rocks is estimated at(5.1±0.9)×10^(-5) Pg/yr,(1.3±0.6)×10^(-5) Pg/yr,(2.5±0.5)×10^(-4) Pg/yr and(1.5±0.2)×10^(-7) Pg/yr,respectively,yielding a sum of~(3.2±0.6)×10^(-4) Pg/yr.Roughly extrapolating to the entire Lhasa terrane,the post-collisional K-rich volcanism may have a CO_(2)output of~0.006±0.001Pg/yr,consistent with the results of continental collision-derived CO_(2)flux model.Our results provide preliminary data for simulating deep CO_(2)emissions caused by the India-Asia collision during geological history.In the future,it is still necessary to optimize the research results based on obtaining more data to reduce the uncertainty caused by the differences in magma composition,eruption volume,and spatial-temporal distribution of post-collisional volcanic activity.

关 键 词：碰撞后富钾火山作用 熔体包裹体 CO_(2)释放量 拉萨地块 

分 类 号：P317[天文地球—固体地球物理学] P588.14[天文地球—地球物理学]