李通藝Lee, Tung-YiPHAM THI THANH MINHPHAM THI THANH MINH2023-12-082025-08-302023-12-082022https://etds.lib.ntnu.edu.tw/thesis/detail/05f2b4606725d0255eacc077cdff26b9/http://rportal.lib.ntnu.edu.tw/handle/20.500.12235/121054紅河發源於中國雲南省，流經揚子地塊西南緣，最後匯入南海。它被認為是從青藏高原東部和中國南部輸送沉積物進入東京灣(南海)的重要通道。由於紅河水系與構造、氣候，尤其是青藏高原的隆升關係密切，學者長期以來對其起源和演化進行了研究。然而，以前的研究主要集中在紅河河道的演化上，因為以前可能存在大陸尺度的水系系統，其中東亞的主要大河(即雅魯藏布江、湄公河、薩爾溫江、長江上游和中游)都曾經可能是古紅河的主要支流。然而，由於構造抬升、河道被捕獲，大規模的古紅河失去了源頭。儘管進行了許多研究，但尚未就紅河的演變情形達成一致共識，這意味著該系統的演變非常複雜。儘管紅河中下游位於越南北部領土，直接流經紅河剪切帶；相比之下，紅河的起源研究很少被探討，紅河在越南流域的可用數據仍然有限。因此，本研究收集了越南盆地的沉積物，這些盆地保存了近乎完整的新生代古紅河紀錄，包括來自安沛盆地(紅河中游)的5個礫岩層樣本、1個安沛的現代河沙和2個河內盆地(紅河下游)的鑽井岩心樣本。具體而言，安沛礫岩有4個晚中新統礫岩基質樣本，1個晚中新統之前的礫石樣本。兩口鑽井岩心被分成4個樣品，其中3個在中新統晚期沉積，1個在上新統-第四系沉積。在這項研究中，本研究利用雷射剝蝕感應耦合電漿質譜儀(LA-ICP-MS)碎屑鋯石的鈾-鉛年定年，結合一系列可用的鋯石鈾-鉛年代學數據，試圖了解紅河水系的起源和發展。總體而言，鋯石顆粒產生的年齡範圍從太古宙到新生代(3171±17到24.9±0.6 Ma)，表明沉積物輸入來自多個來源。鋯石年齡的統計分析顯示，南揚子地塊可能是晚中新世以來安沛和河內盆地最重要的源區。相比之下，松潘-甘孜和蘭坪-思茅地塊是晚中新世之前沉積的礫岩的主要物源來源。此外，這項研究提出了現代紅河的主要支流瀘江(Lo river)和李仙江(Da river)分別在晚中新世和上新世-第四紀時期與紅河主河道相連接的可能性。本研究還建議任何大陸尺度的古水系系統應可能存在於晚中新世之前，任何大規模的紅河捕獲至少應該在晚中新世之前發生。此外，在多維尺度(MDS)圖上，安沛盆地上中新統前樣品的年代頻譜與劍川盆地和貢覺盆地始新世地層的年代頻譜具有很強的相似性，此二盆地位於長江上游擬定捕獲點下方和上方。這意味著在始新世時期發生了古長江和古紅河連接。有趣的是，MDS圖上安沛上中新統前樣品與劍川盆地的始新世最後期(即劍川組)的樣品相差甚遠。這一結果表明，古紅河的捕獲很可能發生在始新世晚期，並且可能一直持續到早漸新世，正如安沛上中新統前樣品的最大沉積年代(大約 29 Ma)所顯示的那樣；且現代長江很可能誕生於漸新世早期。最後，本研究在晚中新統樣品中發現了在紅河平移斷層的前、同剪切過程中產生的大量鋯石；這可能表明在此期間有強烈的侵蝕作用，因此這些鋯石可以有如此大的數量。此外，變質鋯石鈾-鉛年代峰值約在30.6 Ma，可能表明紅河斷層系統從前剪切到同剪切期間發生強烈的變質作用。The Red River descends from the Yunnan Province in China and flows across the southwest edge of the Yangtze block before discharging into the South China Sea. It was considered as an important pathway for transporting sediments from the eastern Tibetan Plateau and southern China into the Tonkin Gulf (South China Sea). The provenance and evolution of the Red River drainage system have long been investigated due to its close relationship to the tectonics, climate, and especially the uplift of the Tibetan Plateau. However, previous studies have mainly focused on the evolution of the Red River due to the implication that a continental-scale drainage network formerly existed, in which large rivers in East Asia (i.e., Yarlung, Mekong, Salween, Upper-, and Middle Yangtze Rivers) once served as a major tributary of the paleo-Red River. Nevertheless, the large-scale paleo-Red River lost its headwater as a result of river capture in response to the tectonic uplift. Regardless of many studies that have been conducted, no agreement on the evolutionary history of the Red River has been reached, implying a relatively complex evolutionary history of this system. In contrast, provenance studies of the Red River are poorly explored, and available data from the Vietnamese basins are still limited. Even though the middle reaches and lower reaches of the Red River stretch in northern Vietnam territory, directly drain along the Red River Shear Zone.This study collected samples along the Red River Fault system, which preserved a near-complete Cenozoic paleo-Red River record. Samples includes four matrixes of conglomerates, one conglomerate cobble from the Yen Bai Basin (middle reaches of the Red River), one modern Red River sand at Yen Bai, and two boreholes from the Hanoi Basin (lower reaches of the Red River). Specifically, four conglomerate matrixes were deposited during the Late Miocene, and one conglomerate cobble was formed before the Late Miocene. The two boreholes were separated into four samples, three of which were deposited during the Late Miocene, and one was deposited during the Pliocene-Quaternary. This study applied U-Pb dating of detrital zircons by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and coupled with a large volume of published zircon U-Pb data in an attempt to constrain the provenance and evolution of the Red River drainage system.Overall, zircon grains yield ages ranging from the Archean to Cenozoic (3171±17 to 24.9±0.6 Ma), suggesting sediment was derived from multiple sources. Statistical analysis of the zircon ages implies that the southern Yangtze Block was likely the most important source area for the Yen Bai and Hanoi Basins since the Late Miocene. In contrast, the Songpan-Ganzi Block and Lanping-Simao Terrain were contributed as the major sources for the conglomerate cobble that was formed before the Late Miocene time. Additionally, this study proposes the possibility that the Lo and Da Rivers, major tributaries of the modern Red River, connected to the mainstream of the Red River during the Late Miocene and Pliocene time, respectively. This study also suggests that any continental-scale paleo-drainage network of the Red River must have existed prior to the Late Miocene, and any large-scale Red River capture should have occurred before at least the Late Miocene. Moreover, this study applied statistic comparison (multidimensional scaling-MDS) to test the differences and similarities between the age distributions. On the multidimensional scaling (MDS) plot, the pre-Upper Miocene sample from Yen Bai Basin showed a strong affinity to the Paleocene-Eocene formations from the Jianchuan and Gonjo Basins, located beneath and above the proposed capturing point of the Upper Yangtze River, respectively. This would imply that a paleo-Yangtze and paleo-Red River connection took place during the Paleogene. Interestingly, the pre-Upper Miocene sample was far from the latest Eocene formation (Jianchuan Formation) from the Jianchuan Basin on the MDS plot. This result indicates that the paleo-Red River’s capture was likely to take place since the latest Eocene time and probably continued until the Early Oligocene, as revealed by the maximum depositional age of the pre-Upper Miocene sample (ca. 29 Ma). As a result, the modern Yangtze River was likely formed since the Early Oligocene as well. Finally, this study found a significant number of zircon ages likely to record the pre-, syn-shearing of the Red River strike-slip fault in the Upper Miocene samples. Furthermore, the metamorphic zircon U-Pb age peaked at ca. 30.6 Ma which may indicate metamorphic activity before the onset of the Red River fault system.碎屑鋯石鈾-鉛定年紅河物源研究水系重組水系捕獲detrital zircon U-Pb datingRed Riverprovenance studydrainage reorganizationdrainage captureetd