Abstract Basalt geochemistry can be used as a diagnostic indicator for determining the tectonic setting of origin, because specific plate tectonic settings often impart distinctive geochemical characteristics. For example: (1) mid-ocean ridge basalts (MORB) and oceanic island basalts (OIB) have clearly distinguishable trace element and Sr-Nd isotope geochemical characteristics; (2) arc related basalts, including IOAB (intra-oceanic arc basalts), IAB (island arc basalts) and CAB (continental arc basalts), exhibit following distinguishing features: all are characterized by low Nb/La ratios ( 1, “hump-shaped” OIB-like trace element patterns and moderate positive ɛNd values that distinguish them from the arc related ones; whereas, the contaminated continental intraplate basalts are characterized by pronounced negative Nb, Ta and Ti anomalies, but their concentrations of incompatible trace elements are conspicuously higher than those of subduction-zone basalts that also distinguishes them from the arc related ones; (4) an important difference between back-arc basin basalts (BABB) and the MORB is that the former exhibit both MORB-like and arc-like geochemical characteristics; (5) most oceanic plateau basalts (OPB) show diagnostic geochemical characteristics of enriched MORB (E-MORB) to transitional MORB (T-MORB); only the Kerguelen Plateau is an exception; the early (pre 90 Ma) volcanism of the Kerguelen Plateau is associated with the Early Cretaceous break-up of Gondwana and displays features of continental flood basaltic volcanism; with time, the tectonic setting of the Kerguelen plume-derived volcanism changed from a rifted continental margin setting (133–118 Ma) through a young, widening ocean (118–40 Ma), finally to an oceanic intraplate setting (~40 Ma to the present). Tectonic discrimination diagrams should not be used in isolation, but can still be useful as part of holistic geochemical characterization. For example: (1) MORB and OIB are distinguishable from each other in the 3Tb-Th-2Ta diagram; (2) the arc related basalts, including IOAB, IAB and CAB, constantly plot in the arc-related basalts fields in the Th/Yb-Ta/Yb diagram; (3) the 3Tb-Th-2Ta diagram can be utilized to fully illustrate both MORB-like and arc-like characteristics of BABB; (4) some discriminant diagrams (such as Zr/Y-Zr, Th/Yb-Ta/Yb, 3Tb-Th-2Ta and Hf/3-Th-Nb/16 diagrams) can be used to distinguish continental intra plate basalts from arc related ones; (5) although there are not any discrimination diagrams published that delineate an OPB field, some trace element diagrams can still reveal diagnostic characteristics of the OPB.

中文翻译：

---

玄武岩地球化学作为构造环境的诊断指标

摘要 玄武岩地球化学可作为确定起源构造环境的诊断指标，因为特定的板块构造环境往往赋予独特的地球化学特征。例如：（1）洋中脊玄武岩（MORB）和大洋岛玄武岩（OIB）具有明显可区分的微量元素和Sr-Nd同位素地球化学特征；(2) 弧相关玄武岩，包括 IOAB（洋内弧玄武岩）、IAB（岛弧玄武岩）和 CAB（大陆弧玄武岩），表现出以下显着特征：均以低 Nb/La 比率为特征（1，“驼峰”形”OIB 样微量元素模式和适度的正 ɛNd 值，将它们与弧相关的区分开来；而被污染的大陆板内玄武岩的特征是显着的负 Nb、Ta 和 Ti 异常，但它们的不相容微量元素的浓度明显高于俯冲带玄武岩，这也将它们与弧相关玄武岩区分开来；(4)弧后盆地玄武岩(BABB)与MORB的一个重要区别是前者同时具有MORB状和弧状地球化学特征；(5) 大部分大洋高原玄武岩(OPB)显示出富集MORB(E-MORB)到过渡MORB(T-MORB)的诊断地球化学特征；只有凯尔盖朗高原是个例外；凯尔盖朗高原的早期（90 Ma 之前）火山活动与冈瓦纳大陆早白垩世的破裂有关，并显示出大陆洪水玄武岩火山活动的特征；随着时间的推移，凯尔盖朗羽状火山活动的构造环境从裂谷大陆边缘环境（133-118 Ma）转变为年轻的、海洋扩大（118-40 Ma），最终形成大洋板块内环境（~40 Ma至今）。构造区分图不应单独使用，但仍可作为整体地球化学特征的一部分使用。例如：（1）MORB和OIB在3Tb-Th-2Ta图中是可以区分的；(2) 弧相关玄武岩，包括IOAB、IAB和CAB，在Th/Yb-Ta/Yb图的弧相关玄武岩场中不断绘制；(3) 3Tb-Th-2Ta图可以充分说明BABB的类MORB和类弧特性；(4) 一些判别图(如Zr/Y-Zr、Th/Yb-Ta/Yb、3Tb-Th-2Ta和Hf/3-Th-Nb/16图)可用于区分大陆板块内玄武岩和弧相关的；(5) 尽管没有发布任何描述 OPB 字段的区分图，