The Cenozoic basalts exposed in Bo Phloi Gem Field, Kanchanaburi Province, western Thailand are a host to different gem materials (e.g., sapphire, black spinel, black pyroxene and zircon) as well as other xenocrysts and xenoliths from the deep-seated formations onto the earth surface. However, only felsic xenoliths have never been investigated and reported in detail though they are in fact significant evidence of ancient tectonic processes of this area. In this study, the felsic xenoliths were sampled and classified, on the basis of petrochemistry, into granite, syenogranite, and syenite. However, they contain similar mineral assemblages including essentials of quartz, K-feldspar, and plagioclase with different proportions and accessories of biotite, zircon, and opaque minerals. Moreover, large phenocrysts of K-feldspar and plagioclase commonly present as a primary texture which are frequently corroded and replaced by ‘sieved texture’ with secondary cumulative fringe of tiny feldspar and quartz. These secondary textures clearly indicate quenching after re-heating during transportation by basaltic magma. Geochemical analyses indicate that the alkaline and peraluminous magma show enrichment of Rb and depletion of Ba, Nb, Ta, Ti with steep slope of LREE/HREE enrichment patterns. These evidences suggest low-degree partial melting of crustal materials related to the collisional S-type granite magmatism. In addition, U-Pb dating of zircon from a felsic xenolith yields 211.6±1.3 Ma comparable to the Late Triassic magmatism of the central belt granite in this region which is resulted from the collision between Sibumasu and Indochina terranes.

泰国西部北碧府 Bo Phloi Gem Field 出露的新生代玄武岩含有不同的宝石材料（例如蓝宝石、黑色尖晶石、黑色辉石和锆石）以及来自深部地层的其他异种晶体和捕虏体地球表面。然而，只有长英质捕虏体从未被详细研究和报道过，尽管它们实际上是该地区古代构造过程的重要证据。在这项研究中，对长英质捕虏体进行了采样，并根据岩石化学将其分类为花岗岩、正长花岗岩和正长岩。然而，它们含有相似的矿物组合，包括石英、钾长石和斜长石的基本成分，以及不同比例的黑云母、锆石和不透明矿物的辅料。而且，钾长石和斜长石的大型斑晶通常作为主要结构存在，它们经常被腐蚀并被“筛状结构”取代，并带有微小的长石和石英的次生累积条纹。这些次生纹理清楚地表明玄武岩岩浆在运输过程中重新加热后淬火。地球化学分析表明，碱性和过铝质岩浆显示出Rb富集和Ba、Nb、Ta、Ti贫化，LREE/HREE富集模式斜率陡峭。这些证据表明与碰撞 S 型花岗岩岩浆作用有关的地壳物质发生了低度部分熔融。此外，长英质捕虏体中锆石的 U-Pb 定年结果为 211.6±1。