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Provenance of the Phuquoc Basin fill, southern Indochina: Implication for Early Cretaceous drainage patterns and basin configuration in Southeast Asia
Gondwana Research ( IF 7.2 ) Pub Date : 2021-04-20 , DOI: 10.1016/j.gr.2021.03.014
Tu-Anh Nguyen , Michael B.W. Fyhn , Jeppe Ågård Kristensen , Lars Henrik Nielsen , Tonny B. Thomsen , Nynke Keulen , Sofie Lindström , Lars O. Bodreel

Cretaceous basins cover large parts of mainland SE Asia. Yet, the development during the Cretaceous is poorly understood including the establishment of the Cretaceous basin configuration. Based on detrital zircon and heavy mineral analysis, this study investigates the provenance of Lower Cretaceous deposits in the Phuquoc Basin, exposed in Cambodia and SW Vietnam and extending into the Gulf of Thailand. Our results document five major zircon populations with 130–145 Ma, 145–200 Ma, 200–270 Ma, 420–470 Ma, 1800–1900 Ma ages and two subordinate 2400–2700 Ma, 750–1000 Ma age clusters. These ages resemble those of the Qinling-Dabie and the Songpan-Ganzi orogenic belts and differ from other Asian terranes. These ages suggest that the Qinling-Dabie and Songpan-Ganzi orogenic belts were major sources of sediment for the Phuquoc Basin in the Early Cretaceous. Heavy mineral compositions including the presence of almandine, often co-occurring with silimanite and epidote, suggest metamorphic and granitic constituents in the hinterland, compatible with these orogenic belts being the source.

The detrital zircon age pattern of the Phuquoc Basin closely resembles the zircon ages in Khorat and the Sichuan basins, suggesting a common sediment source, and bears great similarities with mid-Cretaceous strata in the Lanping-Simao Basin. These basins share a remarkable lithostratigraphic similarity and are confined by erosion. Taken altogether, this supports that the Phuquoc, Khorat, Sichuan, and probably the Lanping-Simao basins, formed part of a Cretaceous basin covering much of central SE Asia segregated by Late Cretaceous and Cenozoic denudation and translation. The absence of 130–145 Ma and 145–200 Ma aged zircons in the Lanping-Simao Basin suggests that another drainage system sprang from the Songpan-Ganzi Orogenic Belt and fed into this basin before merging with the Qinling-Dabie Orogenic Belt drainage system south of the Sichuan Basin. The combined drainage system likely passed through the Khorat Basin before entering the Phuquoc Basin.



中文翻译:

印度支那南部 Phuquoc 盆地填充物的来源:对东南亚早白垩世流域模式和盆地构造的影响

白垩纪盆地覆盖了东南亚大陆的大部分地区。然而,人们对白垩纪期间的发展知之甚少,包括白垩纪盆地构造的建立。本研究基于碎屑锆石和重矿物分析,调查了 Phuquoc 盆地下白垩统矿床的物源,这些矿床位于柬埔寨和越南西南部,并延伸到泰国湾。我们的结果记录了 5 个主要的锆石种群,具有 130-145 Ma、145-200 Ma、200-270 Ma、420-470 Ma、1800-1900 Ma 年龄和两个从属 2400-2700 Ma、750-1000 Ma 年龄簇。这些时代类似于秦岭-大别和松潘-甘孜造山带的时代,与亚洲其他地体不同。这些年代表明秦岭-大别和松潘-甘孜造山带是早白垩世富国盆地沉积物的主要来源。重矿物成分包括铁铝榴石的存在,通常与硅线石和绿帘石同时出现,表明腹地有变质和花岗岩成分,与这些造山带是源相容。

富国盆地的碎屑锆石年龄模式与呵叻和四川盆地的锆石年龄非常相似,表明是一个共同的沉积源,与兰坪-思茅盆地中白垩世地层有很大的相似性。这些盆地具有显着的岩石地层相​​似性,并受到侵蚀的限制。总而言之,这支持了富国、呵叻、四川,可能还有兰坪-思茅盆地,形成了白垩纪盆地的一部分,该盆地覆盖了由晚白垩世和新生代剥蚀和平移分隔的大部分东南亚中部。兰坪-思茅盆地缺少 130-145 Ma 和 145-200 Ma 年龄的锆石表明松潘-甘孜造山带的另一个排水系统在与秦岭-大别造山带南部的排水系统汇合之前注入盆地四川盆地。

更新日期:2021-06-22
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