Petrogenesis of late Cenozoic high Mg andesites with high Nb/Ta ratios in Northern Songliao Basin, NE China
Petrogenesis of late Cenozoic high Mg andesites with high Nb/Ta ratios in Northern Songliao Basin, NE China
复制标题
松辽盆地北部晚新生代高铌/钽比高镁安山岩岩石成因
DOI：
10.1016/j.lithos.2022.106954
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发表时间：
2022
期刊：
影响因子：
3.5
通讯作者：
Ni Li
中科院分区：
文献类型：
--
作者：
Yongwei Zhao;Haibo Zou;Ni Li
松辽盆地北方新生代发育高镁安山岩和高钾玄武岩两类熔岩。本文通过对南岭地区门鲁河和逊克两个火山熔岩的K-Ar年代学、橄榄石斑晶成分、全岩主微量元素和Sr-Nd-Pb-Hf同位素组成的研究，探讨了两个火山熔岩高Nb/Ta特征的成因和地幔源区的不均一性。门鲁河和逊克的HMA爆发于0.20 ~ 1.72Ma之间。这些安山质熔岩显示出负εNd（−3.2 $> −10.4）和负εHf（−3.3 $> −19.3）、高87 Sr/86 Sr（0.7048-0.7061）和非放射成因Pb同位素（206 Pb/204 Pb = 16.50-17.10），与HMA气田附近的科罗-五大连池-二克山地区的高钾玄武岩（HKB）相似。在HMA中，橄榄石斑晶具有高Ni含量和升高的Fe/Mn（69.1-93.9，平均78.1）组成。岩石学指数FCKANTMS（Yang等人，2019年）的值范围为0.57至0.75。橄榄石成分和岩石学指标都支持辉石来源。安山岩中大离子亲石元素（Ba、K和Sr）的富集和高场强元素（Nb、Ta、Th和U）的亏损，以及异常高的Nb/Ta比值（18.9-22.6），与碳酸盐岩和硅酸盐熔体向岩石圈地幔的交代作用相一致。HMA倾向于出现在裂谷盆地中，而HKB倾向于出现在裂谷带外，表明岩浆-构造密切相关。交代作用（由碳酸盐岩和硅酸盐熔体）和裂谷作用可能形成正反馈机制，导致耦合的HMA，HKB和裂谷在NSB。
Two types of Cenozoic lavas composed of high magnesium andesites (HMAs) and high-K basalts (HKBs) occur in the northern Songliao Basin (NSB), Northeastern China. This study presents K-Ar geochronology, olivine phenocryst compositions, whole-rock major and trace element, and Sr-Nd-Pb-Hf isotopic compositions of HMAs from Menluhe and Xunke in NSB, and discuss the origin of high Nb/Ta signature and mantle source heterogeneity of these lavas. The HMAs from Menluhe and Xunke erupted between 0.20 and 1.72 Ma. These andesitic lavas display negative εNd(−3.2 ∼ −10.4) and εHf(−3.3 ∼ −19.3), elevated87Sr/86Sr (0.7048–0.7061), and unradiogenic Pb isotopes (206Pb/204Pb = 16.50–17.10), similar to those of the high potassium basalts (HKBs) in Keluo-Wudalianchi-Erkeshan near the HMA fields. Within the HMAs, the olivine phenocrysts have high Ni contents and elevated Fe/Mn (69.1–93.9, average 78.1) compositions. The petrology index FCKANTMS (Yang et al., 2019) values range from 0.57 to 0.75. Both the olivine compositions and the petrology index support a pyroxene source. Enrichments in large ion lithophile elements (Ba, K and Sr) and depletions in high field-strength elements (Nb, Ta, Th and U), with anomalously high Nb/Ta ratios (18.9–22.6) in the andesite, are consistent with a combined metasomatism of carbonatite and silicate melts to the lithospheric mantle. HMAs tend to occur in rift basins, while HKBs tend to occur in off-rift zones, suggesting a close magmatic-tectonic correlation. Metasomatism (by carbonatite and silicate melts) and rifting may form a positive feedback mechanism, resulting in coupled HMAs, HKBs and rifts in NSB.