Petrography, geochemistry and U-Pb detrital zircon dating of the clastic Phu Khat Formation in the Nakhon Thai region, Thailand: Implications for provenance and geotectonic setting
Petrography, geochemistry and U-Pb detrital zircon dating of the clastic Phu Khat Formation in the Nakhon Thai region, Thailand: Implications for provenance and geotectonic setting
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DOI：
10.1007/s12583-016-0667-7
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发表时间：
2016-06
影响因子：
3.3
通讯作者：
P. Nulay;C. Chonglakmani;Q. Feng
中科院分区：
文献类型：
--
作者：
P. Nulay;C. Chonglakmani;Q. Feng
本文的目的是利用岩相学和全岩地球化学结合 U-Pb 碎屑锆石测年技术，确定 Phu Khat 组的物源和构造环境，更好地了解那空泰地区的构造演化。晚白垩世至早第三纪Phu Khat组砂岩的主要特点是结构不分选和高度不稳定的火山岩碎片。该地层不整合地覆盖在晚白垩世 Khao Ya Puk 地层的高结构和矿物成熟度的碎屑砂岩之上。地球化学上，构造环境判别（K2O/Na2O-SiO2、Al2O3/SiO2-Fe2O3+MgO、Th-Sc-Zr/10）和岩相学表明，Phu Khat组形成于被动边缘构造环境，与Khao Ya Puk组相同，但沉积环境不同。地球化学物源判别图（La/Th-Hf、Th/Sc-Zr/Sc、Eu 异常 Eu/Eu* 0.42 至 0.74）和岩相学显示，Khao Ya Puk 组的物源主要是再生沉积岩，而 Phu Khat 组主要由与古老的少量长英质火山岩相关的再生沉积岩组成。 西部或东部大陆地体或两者隆起的大陆岛弧。然而，U-Pb碎屑锆石测年表明，Phu Khat组的独特来源来自那空泰地区以西的地体，那里的火山大陆弧主要活跃于中三叠世到晚三叠世。结果表明，虽然 Phu Khat 组在 Nakhon Thai 地区堆积，但西部地体由于先前存在的结构的重新激活而被抬升，可能自马斯特里赫特时期以来成为沉积物的源区。与此同时，东部地体（主要是黎府-碧差汶褶皱带）可能直到 Phu Khat 组的堆积结束才被抬升。随后，自伊普勒斯时期大印度与欧亚大陆碰撞以来，整个地区开始隆起，形成高山地区。
The purpose of this paper is to determine the provenance and tectonic setting of the Phu Khat Formation and get a better understanding of the tectonic evolution of the Nakhon Thai region using the petrography and whole-rock geochemistry integrated with the U-Pb detrital zircon dating. The sandstone of the Late Cretaceous to Early Tertiary Phu Khat Formation is chiefly characterized by unsorted texture and highly unstable volcanic lithic fragments. The formation overlies unconformably on a high textural and mineral maturity of clastic sandstone of the Late Cretaceous Khao Ya Puk Formation. Geochemically, the tectonic setting discrimination (K2O/Na2O-SiO2, Al2O3/SiO2-Fe2O3+MgO, and Th-Sc-Zr/10) and the petrography indicate that the Phu Khat Formation was accumulated in a passive margin tectonic setting which is the same as the Khao Ya Puk Formation but with a different depositional environment. The plots of geochemical provenance discrimination (La/Th-Hf, Th/Sc-Zr/Sc, Eu anomaly Eu/Eu* 0.42 to 0.74) and the petrography reveal that the provenance of the Khao Ya Puk Formation is mainly recycled sedimentary rocks while the Phu Khat Formation consists primarily of recycled sedimentary rocks associated with minor felsic volcanic rocks from the old continental island arc of the uplifted either western or eastern continental terranes or both. However, the U-Pb detrital zircon dating indicates a unique provenance of the Phu Khat Formation from the terrane west of the Nakhon Thai region where the volcanic continental arc is active predominantly in the Middle to Late Triassic. The results indicate that while the Phu Khat Formation was accumulated in Nakhon Thai region, the western terrane was uplifted by reactivation of the preexisting structure probably since the Maastrichtian time to be the source area of sediments. Meanwhile, the eastern terrane (mainly Loei-Phetchabun fold belt) had not been uplifted probably until, the accumulation of the Phu Khat Formation terminated. Subsequently, the whole region began to uplift forming a high mountainous area since the Ypresian time when the Greater India collided with the Eurasia.