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 whol...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＋Mg O, 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.展开更多
位于越南西北部的奠边府(Dien Bien Phu)断裂,向北延伸入中国云南境内,向南进入老挝境内,走向由近N—S向向南逐渐过渡为NE—SW向,倾角陡立。沿断裂带发育3个具有不同运动学机制的第四纪盆地——婵讷(Chan Nua)盆地、莱州(Lai Chau)盆地...位于越南西北部的奠边府(Dien Bien Phu)断裂,向北延伸入中国云南境内,向南进入老挝境内,走向由近N—S向向南逐渐过渡为NE—SW向,倾角陡立。沿断裂带发育3个具有不同运动学机制的第四纪盆地——婵讷(Chan Nua)盆地、莱州(Lai Chau)盆地和奠边府盆地。根据对奠边府断裂带地区ETM遥感数据进行详细解译以及野外实地考察,得到奠边府断裂具有早期的右行走滑和后期的左行走滑特征的证据;并且根据断裂两侧水系受断裂影响发生左错的程度不同,认为奠边府断裂的西盘相对于东盘较为活动,即为主动盘。奠边府断裂北延进入越南境内,与金平地区的三家河断裂相连,并继续向北并入哀牢山剪切带中。奠边府断裂现今的左行走滑与红河断裂现今的右行走滑共同组成了一组共轭断裂系。展开更多
文摘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＋Mg O, 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.
文摘位于越南西北部的奠边府(Dien Bien Phu)断裂,向北延伸入中国云南境内,向南进入老挝境内,走向由近N—S向向南逐渐过渡为NE—SW向,倾角陡立。沿断裂带发育3个具有不同运动学机制的第四纪盆地——婵讷(Chan Nua)盆地、莱州(Lai Chau)盆地和奠边府盆地。根据对奠边府断裂带地区ETM遥感数据进行详细解译以及野外实地考察,得到奠边府断裂具有早期的右行走滑和后期的左行走滑特征的证据;并且根据断裂两侧水系受断裂影响发生左错的程度不同,认为奠边府断裂的西盘相对于东盘较为活动,即为主动盘。奠边府断裂北延进入越南境内,与金平地区的三家河断裂相连,并继续向北并入哀牢山剪切带中。奠边府断裂现今的左行走滑与红河断裂现今的右行走滑共同组成了一组共轭断裂系。
