Carbonated mantle sources for Cenozoic intra-plate alkaline basalts in Shandong, North China
Carbonated mantle sources for Cenozoic intra-plate alkaline basalts in Shandong, North China
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华北山东新生代板内碱性玄武岩的碳酸盐化地幔来源
DOI：
10.1016/j.chemgeo.2010.02.009
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发表时间：
2010-04
期刊：
影响因子：
3.9
通讯作者：
Xu, Xi-Sheng
中科院分区：
文献类型：
--
作者：
Hofmann, Albrecht W.;Zeng, Gang;Chen, Li-Hui;Jiang, Shao-Yong;Xu, Xi-Sheng
板内碱性玄武岩的成因仍然存在争议，人们提出了三种来源：缺硅榴辉岩-辉石岩、角闪岩和碳化橄榄岩。在这里，我们通过分析中国北方山东省的新生代陆内碱性玄武岩来评估这些模型。山东省新生代玄武岩由早期的弱碱性岩石层序（碱性橄榄石玄武岩）和晚期的强碱性岩石层序（红硅岩和霞石）组成。与弱碱性岩石相比，强碱性岩石的SiO2(39.2~45.1wt.%)和Al2O3(10.3~13.8wt.%)含量较低，碱含量较高(Na2O+K2O=4.3~8.6wt.%)和CaO(8.0~12.6wt.%)，大多数不相容元素含量较高，Ca/Al值较高(0.7–1.3)、La/Yb (39.4–65.7) 和 Sm/Yb (6.1–9.9)。总体而言，原始地幔归一化蜘蛛图显示，强碱性岩石比弱碱性岩石具有更强的负K、Zr、Hf和Ti异常（Hf/Hf*=0.59~0.77，Ti/Ti*=0.46~0.71）。所有这些岩石都具有超球粒状 Zr/Hf 比率 (>44)。逆稀土元素 (REE) 模型表明，强碱性岩石和弱碱性岩石的熔化量分别为 <3% 和 3-10%。缺硅榴辉岩-辉石岩熔体和角闪石熔体都不能满足上述所有特征。这里我们更喜欢碳化地幔源，因为强碱性岩石的主要特征类似于碳酸岩（例如，大多数不相容元素的富集、高Ca/Al比、超球粒状Zr/Hf比以及负K、Zr、Hf和Ti异常）。由于干燥橄榄岩的固相线温度高于地幔中的碳酸化橄榄岩，因此在较高温度下熔化程度的增加可能会导致“碳酸岩指纹”的稀释。虽然不能排除缺硅榴辉岩-辉石岩或角闪岩的贡献，但我们的观察表明碳化橄榄岩是山东新生代强碱性玄武岩的主要来源。
The genesis of intra-plate alkaline basalts remains controversial, and three sources have been proposed: silica-deficient eclogite–pyroxenite, hornblendite, and carbonated peridotite. Here, we assess these models by analyzing Cenozoic intra-continental alkaline basalts from Shandong province, North China. The Cenozoic basalts of Shandong province consist of an early sequence of weakly alkaline rocks (alkali olivine basalts) and a late sequence of strongly alkaline rocks (basanites and nephelinites). In comparison with the weakly alkaline rocks, the strongly alkaline rocks have lower concentrations of SiO2(39.2–45.1wt.%) and Al2O3(10.3–13.8wt.%), higher alkalis (Na2O+K2O=4.3–8.6wt.%) and CaO (8.0–12.6wt.%), higher concentrations of most incompatible elements, and higher values of Ca/Al (0.7–1.3), La/Yb (39.4–65.7), and Sm/Yb (6.1–9.9). On the whole, primitive-mantle normalized spidergrams reveal that the strongly alkaline rocks have stronger negative K, Zr, Hf, and Ti anomalies (Hf/Hf*=0.59–0.77, Ti/Ti*=0.46–0.71) than do the weakly alkaline rocks. All these rocks have superchondritic Zr/Hf ratios (>44). Inverse rare earth element (REE) modeling suggests that the strongly and weakly alkaline rocks represent melting amounts of <3% and 3–10%, respectively. Neither silica-deficient eclogite–pyroxenite melts nor hornblendite melts can satisfy all the features mentioned above. Here we prefer a carbonated mantle source because the main characteristics of the strongly alkaline rocks resemble those of carbonatites (e.g., enrichment of most incompatible elements, high Ca/Al ratios, superchondritic Zr/Hf ratios, and negative K, Zr, Hf, and Ti anomalies). Since dry peridotite has a higher solidus temperature than does carbonated peridotite in the mantle, an increased degree of melting under higher temperatures may result in the dilution of “carbonatitic fingerprints.” Although contributions from silica-deficient eclogite–pyroxenite or hornblendite cannot be ruled out, our observations suggest that carbonated peridotite is the main source for the Cenozoic strongly alkaline basalts of Shandong.
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影响因子：
3.9
作者：
Dasgupta, Rajdeep;Hirschmann, Marc M.;Withers, Anthony C.
通讯作者：
Withers, Anthony C.
DOI：
10.1016/0168-9622(86)90054-0
发表时间：
1986
期刊：
Chemical Geology: Isotope Geoscience Section
影响因子：
--
作者：
Z. Peng;R. Zartman;K. Futa;D. G. Chen
通讯作者：
Z. Peng;R. Zartman;K. Futa;D. G. Chen
影响因子：
3.9
作者：
H. Zou;A. Zindler;Xi‐sheng Xu;Q. Qi
通讯作者：
H. Zou;A. Zindler;Xi‐sheng Xu;Q. Qi
影响因子：
3.5
作者：
P. Wyllie;Wuu-Liang Huang
通讯作者：
P. Wyllie;Wuu-Liang Huang
影响因子：
3.8
作者：
Guochun Zhao;S. Wilde;Peter A. Cawood;M. Sun
通讯作者：
Guochun Zhao;S. Wilde;Peter A. Cawood;M. Sun