Formation of green-core clinopyroxene in continental basalts through magmatic differentiation and crustal assimilation: Insights from in-situ trace element and Pb isotopic compositions
Formation of green-core clinopyroxene in continental basalts through magmatic differentiation and crustal assimilation: Insights from in-situ trace element and Pb isotopic compositions
复制标题
通过岩浆分异和地壳同化在大陆玄武岩中形成绿核单斜辉石：来自原位微量元素和铅同位素组成的见解
DOI：
10.1016/j.lithos.2021.106587
复制
发表时间：
2022-01
期刊：
影响因子：
3.5
通讯作者：
Lixu Deng
中科院分区：
文献类型：
--
作者：
Xianlei Geng;Zhengwei Liang;Wen Zhang;Yongsheng Liu;Zhaochu Hu;Lixu Deng
绿核单斜辉石（GCPX）广泛存在于不同的岩浆和不同的构造环境中。由于其特殊的结构和成分环带，它通常被认为是外来长英质熔体和一些独特的地质作用（如，岩浆混合作用、地幔交代作用和下陆壳再循环作用。然而，这一前提受到了挑战，其更复杂和神秘的起源比以前认为的。为了探讨大陆玄武岩中GCPX的潜在成因，本文对华北东部费县和四合屯原始玄武岩中GCPX的原位微量元素和Pb同位素组成进行了研究。研究结果表明，除四合屯外，费县地质公园还可分为三种类型。无论这些GCPX的类型，其周围的边缘被认为是从玄武质寄主岩浆结晶的过度生长。费县1型GCPXs的Mg#（67-86）范围较宽，微量元素模式类似于与玄武质寄主岩浆平衡的单斜辉石，Pb同位素比值似熔岩，表明它们是从与玄武质寄主岩浆有遗传关系的分异熔体中结晶出来的。费县2型、费县3型和四合屯GCPXs的微量元素特征与华北克拉通富辉石麻粒岩、含石榴子石麻粒岩和富辉长岩麻粒岩捕虏体中的单斜辉石特征相同或相似，表明其来源于玄武岩浆上升过程中的下地壳麻粒岩围岩。我们的工作表明，GCPX可以简单地通过大陆玄武岩浆的两种常见岩浆过程形成（即，结晶分异和地壳同化），并强调尽管可能，但不需要额外的外来长英质熔体和独特的地质过程。在使用GCPX作为特定岩浆过程的指标之前，需要全面的数据（例如，微量元素和同位素组成），应仔细研究其确切的起源，特别是对于那些在大陆岩浆。此外，GCPXs可能提供有关下地壳结构和成分的有价值的信息，并为揭示岩浆提取过程中地壳同化和消化及其对玄武岩浆成分的影响提供了一个窗口。
Green-core clinopyroxene (GCPX) widely occurs in diverse magmas and various tectonic settings. Due to its special textual and compositional zonation, it is usually considered as solid evidence for involvement of exotic felsic melt and some unique geological processes (e.g., magma mixing, mantle metasomatism and recycling of foundered lower continental crust (LCC)). However, this premise is challenged by its more complicated and enigmatic origins than previously thought. To explore potential origins of GCPXs in continental basalts, here we investigate in-situ trace element and Pb isotopic compositions of the GCPXs in the Feixian and Sihetun primitive basalts from the eastern North China Craton (NCC). The results show that the Feixian GCPXs can be subdivided into three types in addition to the Sihetun GCPXs. Regardless of the types of these GCPXs, their surrounding rims are regarded as overgrowths that crystallized from the basaltic host magmas. The wide range of Mg# (67–86), trace element patterns similar to those of clinopyroxene equilibrated with the basaltic host magmas and host lava-like Pb isotopic ratios of the Feixian type-1 GCPXs suggest that they have crystallized from differentiated melts genetically related to the basaltic host magmas. Besides unradiogenic Pb isotopic ratios, the Feixian type-2, type-3 and Sihetun GCPXs are characterized trace element signatures that are identical or similar to those of clinopyroxenes in pyroxene-rich granulite, garnet-bearing granulite and feldspar-rich granulite xenoliths from the NCC, respectively, indicating their derivation from lower crustal granulite wall rocks during the ascending of the basaltic host magmas. Our work suggests that GCPXs can be simply formed through the two common magmatic processes of continental basaltic magmas (i.e., crystallization differentiation and crustal assimilation) and highlights that exotic felsic melt and unique geological processes are not additionally required despite being possible. Before using GCPXs as an indicator of specific magmatic processes, comprehensive data (e.g., trace element and isotopic compositions) should be carefully investigated for their exact origins, especially for those in continental magmas. Additionally, GCPXs may provide valuable information about the structure and composition of the lower crust and a window to unravel crustal assimilation and digestion during magma extraction and their influence on compositions of basaltic magmas.
登录
查看更多内容
影响因子：
3.5
作者：
Neng Jiang;R. Carlson;Jinhui Guo
通讯作者：
Neng Jiang;R. Carlson;Jinhui Guo
影响因子：
3.5
作者：
Zi-Zhen Wang;Jia Liu;Q. Xia;Yan-Tao Hao;Qin-Yan Wang
通讯作者：
Zi-Zhen Wang;Jia Liu;Q. Xia;Yan-Tao Hao;Qin-Yan Wang
山东莒南下地壳捕虏体及其对华北克拉通下地壳性质的影响
影响因子：
3.5
作者：
英基丰,张宏福;汤艳杰
通讯作者：
汤艳杰
影响因子：
3.8
作者：
Wen Zhang;Zhaochu Hu;Lu Yang;Yongsheng Liu;K. Zong;Haijin Xu;Haihong Chen;Shan Gao;Lei Xu-Lei
通讯作者：
Wen Zhang;Zhaochu Hu;Lu Yang;Yongsheng Liu;K. Zong;Haijin Xu;Haihong Chen;Shan Gao;Lei Xu-Lei
影响因子：
3.5
作者：
M. Jankovics;Z. Taracsák;G. Dobosi;A. Embey-Isztin;A. Batki;S. Harangi;C. Hauzenberger
通讯作者：
M. Jankovics;Z. Taracsák;G. Dobosi;A. Embey-Isztin;A. Batki;S. Harangi;C. Hauzenberger