Mangroves can deliver important socio-economic benefits and store significant volumes of carbon along tropical to temperate coastlines, but the distribution is controlled by complex geomorphologic, hydrodynamic and salinity conditions, as well as human-related pressures. In the Mekong delta, the interaction of tide, wave and riverine hydrodynamic processes clearly impacts sedimentation and mangrove distribution. Extensive mangroves presently occur along the northeastern delta margin (Can Gio, located 40 km southeast of Ho Chi Minh City), in an embayed, back-barrier environment subject to the highest tidal range (c. 4 m) and away from major fluvial distributary channels. However, the development of the Can Gio mangrove system during the Holocene evolution of the Mekong delta is not fully understood. This study aims to constrain the sedimentary evolution of the back-barrier mangrove in Can Gio based on stratigraphic, palynological and geochronological analyses of sediment cores. Two deep borehole cores (15 and 30 m deep) and four short auger cores (up to 4 m deep) were taken at the modern mangrove to characterize a 20-km-long shore-normal cross section dated with radiocarbon and optically-stimulated luminescence (OSL) ages. The cores consist of a thick (> 20 m) subtidal mud from the base of the Holocene unit to the level of 3–4 m deep below the ground level, overlain by carbonaceous, intertidal mud. Chronological data reveal major episode of subtidal mud aggradation from 6 to 3.5 ka, forming the topography for mangrove development. Radiocarbon ages in the overlying intertidal mud range from 4 ka to modern and show some inconsistencies with the stratigraphy, suggesting mangrove root penetration and sediment mixing. The beach-ridge structure and OSL ages of the Can Gio barrier indicate that barrier formation initiated just before 3.2 ka. The transition from subtidal to intertidal mud aggradation and initiation of barrier formation, are broadly correlated with the onset of the subaqueous delta progradation and shift to a wave-dominated regime in the central delta. However, after 3.5 ka, the Can Gio shoreline had negligible sediment accretion while the central delta prograded up to 50 km seawards. Reduced sediment supply to Can Gio is consistent with more asymmetric, southwestward-dominated longshore drift after 3.5 ka. The negligible progradation at Can Gio also indicates minor sediment supply from the nearby Dong Nai River, which prevented upper intertidal accretion and translation of mangroves into a flood plain.

红树林可以带来重要的社会经济效益，并且可以在热带到温带的海岸线上储存大量的碳，但分布受到复杂的地貌，水动力和盐度条件以及与人类相关的压力的控制。在湄公河三角洲，潮汐，波浪和河流水动力过程的相互作用明显影响着沉积和红树林的分布。目前在东北三角洲边缘（胡志明市东南40公里处的Can Gio）上有大量的红树林，处于一个受潮的背屏障环境中，潮汐范围最高（约4 m），并且远离主要的河流分布渠道。然而，人们对湄公河三角洲全新世演化过程中Can Gio红树林系统的发展还没有完全了解。本研究旨在通过对沉积物芯的地层学，孢粉学和年代学分析来限制Can Gio背屏障红树林的沉积演化。在现代红树林中采集了两个深孔岩心（深度分别为15和30 m）和四个短螺旋岩心（深度分别为4 m），以表征20公里长的沿岸法线横截面，其放射性碳和光激发发光（OSL）年龄。岩心由全新世单元底部至地表以下3–4 m的厚（> 20 m）潮间带泥浆组成，上面覆盖着含碳的潮间带泥浆。年代学数据显示，潮下带泥浆淤积主要发生在6到3.5 ka之间，形成了红树林发育的地形。上覆潮间带泥浆中的放射性碳年龄范围从4 ka到现代，并显示出与地层学的某些不一致之处，表明红树林的根部渗透和沉积物混合。Can Gio屏障的滩脊结构和OSL年龄表明，屏障的形成始于3.2 ka之前。从潮下到潮间泥质的转变和屏障形成的开始，与水下三角洲发育的开始和向中央三角洲的波浪主导型转变有广泛的关系。但是，在3.5 ka之后，Can Gio海岸线的沉积物积聚微不足道，而中央三角洲则向海扩展了50 km。向Can Gio输送的沉积物减少与3.5 ka之后更多的不对称，西南为主的长岸漂流相一致。