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自始新世以来，西菲律宾海盆经历了复杂的地质演化过程，在西菲律宾海盆形成过程中伴随有大量的板内火山活动，形成大量的板内火山岩。西菲律宾海盆内板内火山岩主要出现在洋底高原。西菲律宾海盆内洋底高原板内火山岩在成因上是否存在相互联系一直是菲律宾海板块研究关注的重点。

在西菲律宾海盆内，发育有本哈姆隆起，乌尔达内塔高原，冲大东隆起等洋底高原，其中本哈姆隆起和乌尔达内塔高原两个洋底高原的构造位置较为特殊，两个高原在构造位置上几乎以中央盆地断裂为轴呈对称分布，因两高原特殊的构造位置使他们成为研究西菲律宾海盆内板内火山岩形成之间相互关系的良好切入点。

本文主要围绕研究程度较低的乌尔达内塔高原板内火山岩展开讨论，对在乌尔达内塔高原S1-TVG站位获得的10个玄武岩样品进行了矿物显微观察和电子探针元素分析，全岩主量元素、全岩微量元素以及同位素分析。地球化学分析结果表明我们获得的S1-TVG站位火山岩为碱性玄武岩，其地幔归一化微量元素模式具有典型洋岛玄武岩特征；具有较高的(Sm/Yb)_N值（1.89-3.92），指示源区可能存在石榴子石。结合前人研究获得的西菲律宾海盆板内火山岩数据，我们发现乌尔达内塔高原碱性玄武岩具有与本哈姆隆起拉斑玄武岩相似的Sr-Nd-Hf同位素组成，但具有明显低的²⁰⁶Pb/²⁰⁴Pb同位素组成；西菲律宾海盆内碱性洋岛玄武岩与拉斑洋岛玄武岩的Sr-Nd-Hf同位素组成范围几乎相同，但铅同位素组成存在明显差异，碱性洋岛玄武岩的铅同位素比值范围更大。

西菲律宾海盆形成环境复杂，板内火山岩形成时可能受到盆地扩张作用和地幔柱的影响，我们利用同位素数据模拟了地幔柱与扩张中心相互作用对板内碱性玄武岩的影响，模拟结果表明碱性火山岩的低²⁰⁶Pb/²⁰⁴Pb值不能通过与地幔柱有关的富集组分和与海盆扩张作用有关的亏损组分混合实现，表明乌尔达内塔高原碱性火山岩具有一个相对独立的地幔源区，形成时已远离扩张中心，不受扩张作用影响。

综上所述，我们认为：1）S1-TVG站位获得的乌尔达内塔高原的碱性玄武岩具有与洋岛玄武岩相似的地球化学特征，其形成与地幔柱有关，源区可能存在石榴子石；2）乌尔达内塔高原的碱性玄武岩形成时已经远离中央盆地断裂，此时形成的碱性玄武岩受地幔柱作用影响但不受扩张作用影响。

Since the Eocene, the West Philippine Basin has undergone a complex geological evolution process, accompanied by a large amount of intraplate volcanic activity during its formation, forming a large amount of intraplate volcanic rocks. The intraplate volcanic rocks in the basin mainly appear on the ocean floor plateau.The formation of intra plate volcanic rocks in the western Philippine Basin has always been a focus of research on the Philippine Sea Plate, with a focus on whether they are interconnected.

In the Western Philippine Basin, there is the development of the Benham Uplift; The Urdaneta Plateau, the Chongda East Uplift, and other ocean floor plateaus, among which the Benham Uplift and the Urdaneta Plateau have special structural positions. The two plateaus are almost symmetrically distributed along the central basin fault axis in their structural positions. Due to the special structural positions of the two plateaus, they have become good entry points for studying the relationship between the formation of intra plate volcanic rocks in the West Philippine Basin.

This article mainly discusses the volcanic rocks in the Urdaneta Plateau, which have a relatively low level of research. Mineral microscopy observation and electron probe element analysis were conducted on 10 volcanic rock samples obtained in the Urdaneta Plateau, including major and trace elements, as well as isotopic analysis. The geochemical analysis results indicate that the volcanic rocks at the S1-TVG site we obtained are alkaline basalts, and their mantle normalized trace element patterns exhibit typical characteristics of oceanic island basaltd; Has a high (Sm/Yb) _N value (1.89-3.92), indicating the possible presence of garnet in the source area. Based on the volcanic rocks data obtained from previous studies in the West Philippine Basin, we found that the alkaline basalt from the Urdaneta Plateau has similar Sr Nd Hf isotopic compositions to the tholeiitic basalt from the Benham Uplift, but with significantly lower ²⁰⁶Pb/²⁰⁴Pb isotopic compositions; The Sr-Nd-Hf isotope composition range of alkaline island basalt and Laban island basalt in the West Philippine Basin is almost the same, but there is a significant difference in lead isotope composition, with alkaline island basalt having a larger range of lead isotope ratios.

The formation environment of the West Philippine Basin is complex, and the formation of intraplate volcanic rocks may be influenced by basin expansion and mantle plumes. We used isotopic data to simulate the effect of the interaction between mantle plumes and expansion centers on intraplate alkaline basalt. The simulation results showed that the low ²⁰⁶Pb/²⁰⁴Pb values of alkaline volcanic rocks cannot be achieved by mixing enriched components related to mantle plumes with depleted components related to basin expansion. This indicates that the alkaline volcanic rocks in the Urdaneta Plateau have a relatively independent mantle source area, which is far away from the expansion center and not affected by expansion during formation.

In summary, we believe that: 1) The alkaline basalt obtained from the S1-TVG station in the Urdaneta Plateau has geochemical characteristics similar to those of oceanic island basalt, and its formation is related to mantle plumes. There may be garnet in the source area; 2) The alkaline basalt in the Urdaneta Plateau was formed far away from the central basin fault, and the alkaline basalt formed at this time was influenced by mantle plumes but not by expansion.

目  录

第1章 绪论 1

1.1 选题背景及意义 1

1.1.1 研究区地质背景 1

1.1.2 研究目的和意义 1

1.2 研究现状 3

1.2.1 板内火山岩研究现状 3

1.2.2 西菲律宾海盆构造演化历史研究现状 5

1.2.3 西菲律宾海盆内火山岩研究现状 9

1.3 存在问题 12

1.4 采样与研究思路 13

1.4.1 采样 13

1.4.2 研究内容 14

1.4.3 分析测试方法 14

1.4.4 预期成果 15

1.5 已完成工作量 15

第2章 区域概况 17

2.1区域构造概述 17

2.2区域地貌特征 17

2.3区域大洋钻探成果 18

2.4区域地磁条带特征 19

第3章 样品处理及研究方法 24

3.1 样品前处理 24

3.2 电子探针分析 24

3.3 主量元素分析 24

3.4 微量元素分析 26

3.5 同位素分析 26

3.5.1 Sr-Pb同位素分析 26

3.5.2 Nd-Hf同位素分析 28

第4章 分析结果 29

4.1 电子探针分析结果 29

4.2 全岩主量元素 31

4.3 全岩微量元素 35

4.4 同位素分析 37

第5章 分析讨论 40

5.1 海底蚀变 40

5.2 地幔源区特征 40

5.3 WPB板内火山岩之间的联系 43

第6章 结论 45

参考文献 46

附 录 54

致 谢 79

作者简历及攻读学位期间发表的学术论文及研究成果 81