溢流玄武岩成因过程中的岩浆补给作用:同位素证据（英文）
详细信息 查看官网全文
- 论文作者：俞恂 ; 陈立辉 ; 曾罡
- 年：2016
- 作者机构：南京大学地球科学与工程学院;同济大学海洋地质国家重点实验室;
- 英文论文关键词：Continental flood basalts ; mantle heterogeneity ; magmatic recharge ; crustal contamination
- 会议召开时间：2016-10-15
- 会议录名称：2016中国地球科学联合学术年会论文集（三）——专题5：西太平洋板块俯冲与东亚壳幔演化、专题6：前寒武纪地质与超大陆演化
- 语种：英文
- 分类号：P588.145;P597
- 学会代码：ZGDW
- 会议名称：2016中国地球科学联合学术年会
- 会议地点：中国北京
- 主办单位：中国地球物理学会、中国地震学会、全国岩石学与地球动力学研讨会组委会、中国地质学会构造地质学与地球动力学专业委员会、中国地质学会区域地质与成矿专业委员会
- 学会名称：中国地球物理学会
- 页数：1
- 文件大小：817k
- 原文格式：D
- 会议级别：全国
摘要
Continental flood basalts are thought to be the volcanic manifestations of large volumes of magma derived from Earth's mantle including mantle compositions with variable elemental and isotopic compositions(Zhang et al., 2006; Hooper et al., 2007; Sobolev et al., 2009, 2011). Understanding the compositional record of continental flood basalts is thus crucial for a better understanding of mantle compositional variations and ultimately the dynamics that lead to these variations. Radiogenic isotope systematics of melts derived from a mantle source may provide clues on the formation mechanisms(e.g., plume versus nonplume) of continental flood basalts. Isotopic compositions of continental flood basalts are essential to understand their genesis and to constrain the character of their mantle sources. Because of potential crustal contamination, it needs to be evaluated if and to which degree these basalts record primitive isotopic signals of their mantle sources and/or crustal signatures. This study examines the Sr, Nd, Hf, and Pb isotopic compositions of the late Cenozoic Xinchang-Shengzhou(XS) flood basalts, a small-scale continental flood basalt field in eastern China. The basalts show positive correlations between 87Sr/86 Sr and 143Nd/144 Nd, and negative correlations between 143Nd/144 Nd and 176Hf/177 Hf, which deviate from compositional arrays of crustal contamination and instead highlight variations in magmatic recharge intensity and mantle source compositions. The lava samples formed by high-volume magmatic recharge recorded signals of recycled sediments in the mantle source, which are characterized by moderate Ba/Th(91.9–106.5), excess 208Pb/204 Pb relative to 206Pb/204 Pb, and excess 176Hf/177 Hf relative to 143Nd/144 Nd. Thus, we propose that magmatic recharge buffers the original isotopic compositions of magmas against crustal contamination. Identifying and utilizing the isotope systematics of continental flood basalts generated by high volumes of magmatic recharge is thus crucial to trace their mantle sources.
Continental flood basalts are thought to be the volcanic manifestations of large volumes of magma derived from Earth's mantle including mantle compositions with variable elemental and isotopic compositions(Zhang et al., 2006; Hooper et al., 2007; Sobolev et al., 2009, 2011). Understanding the compositional record of continental flood basalts is thus crucial for a better understanding of mantle compositional variations and ultimately the dynamics that lead to these variations. Radiogenic isotope systematics of melts derived from a mantle source may provide clues on the formation mechanisms(e.g., plume versus nonplume) of continental flood basalts. Isotopic compositions of continental flood basalts are essential to understand their genesis and to constrain the character of their mantle sources. Because of potential crustal contamination, it needs to be evaluated if and to which degree these basalts record primitive isotopic signals of their mantle sources and/or crustal signatures. This study examines the Sr, Nd, Hf, and Pb isotopic compositions of the late Cenozoic Xinchang-Shengzhou(XS) flood basalts, a small-scale continental flood basalt field in eastern China. The basalts show positive correlations between 87Sr/86 Sr and 143Nd/144 Nd, and negative correlations between 143Nd/144 Nd and 176Hf/177 Hf, which deviate from compositional arrays of crustal contamination and instead highlight variations in magmatic recharge intensity and mantle source compositions. The lava samples formed by high-volume magmatic recharge recorded signals of recycled sediments in the mantle source, which are characterized by moderate Ba/Th(91.9–106.5), excess 208Pb/204 Pb relative to 206Pb/204 Pb, and excess 176Hf/177 Hf relative to 143Nd/144 Nd. Thus, we propose that magmatic recharge buffers the original isotopic compositions of magmas against crustal contamination. Identifying and utilizing the isotope systematics of continental flood basalts generated by high volumes of magmatic recharge is thus crucial to trace their mantle sources.
Continental flood basalts are thought to be the volcanic manifestations of large volumes of magma derived from Earth's mantle including mantle compositions with variable elemental and isotopic compositions(Zhang et al., 2006; Hooper et al., 2007; Sobolev et al., 2009, 2011). Understanding the compositional record of continental flood basalts is thus crucial for a better understanding of mantle compositional variations and ultimately the dynamics that lead to these variations. Radiogenic isotope systematics of melts derived from a mantle source may provide clues on the formation mechanisms(e.g., plume versus nonplume) of continental flood basalts. Isotopic compositions of continental flood basalts are essential to understand their genesis and to constrain the character of their mantle sources. Because of potential crustal contamination, it needs to be evaluated if and to which degree these basalts record primitive isotopic signals of their mantle sources and/or crustal signatures. This study examines the Sr, Nd, Hf, and Pb isotopic compositions of the late Cenozoic Xinchang-Shengzhou(XS) flood basalts, a small-scale continental flood basalt field in eastern China. The basalts show positive correlations between 87Sr/86 Sr and 143Nd/144 Nd, and negative correlations between 143Nd/144 Nd and 176Hf/177 Hf, which deviate from compositional arrays of crustal contamination and instead highlight variations in magmatic recharge intensity and mantle source compositions. The lava samples formed by high-volume magmatic recharge recorded signals of recycled sediments in the mantle source, which are characterized by moderate Ba/Th(91.9–106.5), excess 208Pb/204 Pb relative to 206Pb/204 Pb, and excess 176Hf/177 Hf relative to 143Nd/144 Nd. Thus, we propose that magmatic recharge buffers the original isotopic compositions of magmas against crustal contamination. Identifying and utilizing the isotope systematics of continental flood basalts generated by high volumes of magmatic recharge is thus crucial to trace their mantle sources.
引文
Yu,X.,Chen,L.-H.,Zeng,G.,2015a.Growing magma chambers control the distribution pattern of small-scale flood basalts.Sci.Rep.5,doi:10.1038/srep16824.
Yu,X.,Lee,C.-T.,Chen,L.-H.,Zeng,G.,2015b.Magmatic recharge in continental flood basalt:insight into Chifeng igneous province in Inner Mongolia.Geochem.Geophys.Geosyst.doi:10.1002/2015GC005805.
Yu,X.,Lee,C.-T.,Chen,L.-H.,Zeng,G.,2015b.Magmatic recharge in continental flood basalt:insight into Chifeng igneous province in Inner Mongolia.Geochem.Geophys.Geosyst.doi:10.1002/2015GC005805.