Alkaline Intrusives at the East Foot of the Taihang‐Da Hinggan Mountains: Chronology, Sr, Nd and Pb Isotopic Characteristics and Their Implications
Alkaline Intrusives at the East Foot of the Taihang‐Da Hinggan Mountains: Chronology, Sr, Nd and Pb Isotopic Characteristics and Their Implications
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DOI：
10.1111/j.1755-6724.2000.tb00493.x
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发表时间：
2000-12
期刊：
影响因子：
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通讯作者：
Yan Guohan;Xu Baoliang;Mu Baolei;Wang Guan-yu;Chang Zhaoshan;Chen Ting-li;Zhao Yongchao;W. Xiaofang;Zhang Renhu;Qiao Guangsheng;Chu Zhuyin
中科院分区：
文献类型：
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作者：
Yan Guohan;Xu Baoliang;Mu Baolei;Wang Guan-yu;Chang Zhaoshan;Chen Ting-li;Zhao Yongchao;W. Xiaofang;Zhang Renhu;Qiao Guangsheng;Chu Zhuyin
根据Rb - Sr等时线测年结果，认为太行山—大兴安岭东麓碱性侵入带形成于135 ~ 122 Ma之间。南段和北段碱性侵入岩具有完全不同的Sr、Nd、Pb同位素特征，南段岩石均为正的[Sr(t)]和负的[Nd(t)]，而北段则相反。在Sr(t)与Nd(t)的对比图上，南方的样品集中在富集的地幔演化趋势线附近，而北方的样品则集中在富集的地幔演化趋势线附近。在Pb同位素组成图上，南段样品大部分位于地幔Pb演化线及其附近，北段样品大部分位于地幔Pb演化线与造山带之间。上述同位素特征不仅表明南段碱性侵入岩烃源岩与富集地幔储层物质密切相关，而北段碱性侵入岩烃源岩则与富集地幔储层物质密切相关，还揭示了华北地台以下上地幔富集，内蒙古地槽以下上地幔亏缺。
Based on the Rb‐Sr isochron dating results, this paper suggests that the alkaline intrusive belt at the east foot of the Taihang‐Da Hinggan Mountains were formed between 135 and 122 Ma. And the alkaline intrusives in the north and south sections of this belt have entirely different Sr, Nd and Pb isotopic characteristics, i.e., all the rocks in the south section have positive ɛSr(t) and negative ɛNd(t) values and all those in the north have the opposite values. On the ɛSr(t) versus ɛNd(t) correlation diagram, the samples from the south are concentrated along the enriched mantle evolution trend lines and nearby, while those from the north fall along the depleted mantle trend lines and nearby. On the Pb isotope composition diagram, most of the samples from the south section fall on the mantle Pb evolution line and nearby, while those from the north lie between the Pb evolution lines of the mantle and the orogenic belt. The above‐stated isotopic characteristics not only indicate that the source rocks of the alkaline intrusives in the south section have a close connection to materials from the enriched mantle reservoir, while those in the north are related to materials from the depleted one, but also reveal that the upper mantle below the North China platform is enriched and that below the Inner Mongolia geosyncline is depleted.