Deglacial and Holocene evolution of the Vietnam shelf: stratigraphy, sediments and sea-level change
Deglacial and Holocene evolution of the Vietnam shelf: stratigraphy, sediments and sea-level change
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DOI：
10.1016/j.margeo.2004.11.001
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发表时间：
2005-02
期刊：
影响因子：
2.9
通讯作者：
A. Schimanski;K. Stattegger
中科院分区：
文献类型：
--
作者：
A. Schimanski;K. Stattegger
在越南大陆架上，对超过 1000 英里的浅层高分辨率地震进行了分析，以揭示热带硅质碎屑环境中的冰川后演化，并分析了 21 至 169 m 水深的 25 个沉积岩芯，以确定地层、分布和沉积类型。使用 AMS-14C 技术对 47 个样品进行了年代测定。陆架分为三个区域：南部、中部和北部。在广阔的南部陆架上，沉积作用受到湄公河的影响，湄公河在该地区流入南海。这里有丰富的切谷填土，这些填土是在海平面低位时期被古湄公河切入晚更新世陆地表面的。这些山谷充满了海侵沉积物。在这个低梯度住宿主导的沉积系统中，在不受水流遮挡的位置，全新世沉积速率在 5-10 和 25-40 cm/ky 的范围内。中央陆架狭窄，沉积地层整合。在这里，众多的山区小河流到达南海，并将大量碎屑沉积物输送到陆架上。因此，在这个以供给为主的沉积系统中，全新世沉积速率很高，可达 50-100 cm/ky。红河三角洲附近广阔的北陆架与南陆架一样，显示出由古河道切入更新世陆地表面的切谷。在这个以住宿为主的陆架区域，沉降速率较低，为 5-10 cm/ky。在适用的情况下，我们将采样的矿床分配到不同的古相。后者与其沉积时的某些水深区间有关。与海平面曲线的比较 [Hanebuth, T.J.J., Stattegger, K., Grootes, P., 2000。 巽他陆架快速洪水；晚冰期海平面记录。 Science，288：1033–1035.]表明中央陆架出现沉降，这与该地区的高沉积速率相一致。相比之下，来自北陆架的数据表明构造隆起可能与哀牢山-红河断裂带近期的构造运动有关。南陆架数据与上述海平面曲线基本一致。
On the Vietnam Shelf more than 1000 miles of shallow high-resolution seismics were analyzed to unravel post-glacial evolution in a tropical, siliciclastic environment together with 25 sediment cores from water depths between 21 and 169 m to determine stratigraphy, distribution and style of sedimentation. Fourty-seven samples were dated with the AMS-14C technique. The shelf was grouped into three regions: a southern part, a central part, and a northern part. On the broad Southern Shelf, sedimentation is influenced by the Mekong River, which drains into the SCS in this area. Here, incised valley fills are abundant that were cut into the late Pleistocene land surface by the Paleo-Mekong River during times of sea level lowstand. Those valleys are filled with transgressive deposits. The Holocene sedimentation rate in this low gradient accommodation-dominated depositional system is in the range of 5–10 and 25–40 cm/ky at locations sheltered from currents. The Central Shelf is narrow and the sedimentary strata are conformable. Here, numerous small mountainous rivers reach the SCS and transport large amounts of detrital sediment onto the shelf. Therefore, the Holocene sedimentation rate is high with values of 50–100 cm/ky in this supply-dominated depositional system. The broad Northern Shelf in the vicinity of the Red River Delta shows, as on the Southern Shelf, incised valleys cut into the Pleistocene land surface by paleo river channels. In this accommodation-dominated shelf area, the sedimentation rate is low with values of 5–10 cm/ky. Where applicable, we assigned the sampled deposits to different paleo-facies. The latter are related to certain intervals of water depths at their time of deposition. Comparison with the sea-level curve of [Hanebuth, T.J.J., Stattegger, K., Grootes, P., 2000. Rapid flooding of the Sunda Shelf; a lateglacial sea-level record. Science, 288: 1033–1035.] indicates subsidence on the Central Shelf, which is in agreement with the high sedimentation rates in this area. In contrast, data from the Northern Shelf suggest tectonic uplift that might be related to recent tectonic movements along the Ailao Shan–Red River Fault zone. Data from the Southern Shelf are generally in agreement with the sea-level curve mentioned above.