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珠江三角洲四会市和高要市两地埋藏古森林在发育历史时期形成了一层或多层腐殖质层。其中,四会埋藏古森林腐殖质层发育起止年代大致为4218±91 cal.aB.P.～3291±24cal.aB.P.;高要埋藏古森林腐殖质层发育有3期,它们的年代大致为49l0±64～1966±42cal.aB.P.,但在4347±63～4017±35cal.aB.P.和3658±45～3539±19cal.aB.P.之间发育中断,形成两层灰白色粘土层,3期腐殖质层(从上至下)发育持续的时间分别为1500a,400a和500a,约1000±500a。在四会埋藏古森林腐殖质层中,有机碳含量在26.2%～48.9%之间变化,δ~(13)C值波动介于-29.8‰～-25.6‰之间,其中,粘土层与腐殖质层边界点的有机碳含量为26.2%,δ~(13)C值为-25.6‰,对应的年代为3291±24cal.aB.P.;在高要埋藏古森林腐殖质层中,有机碳含量在20.3%～64.0%之间变化,δ~(13)C值波动介于-30.9‰～-29.0‰之间,而在腐殖质层之间的粘土层的中心位置,有机碳含量从上至下分别为1.0%和8.8%,对应的δ~(13)C值分别为-28.2‰和-27.8‰,较相邻腐殖质层平均δ~(13)C值偏正约2.0‰至2.5‰。腐殖质层有机碳含量与δ~(13)C值显示,埋藏古森林腐殖质层形成于湿地环境,而粘土层中有机碳含量和δ~(13)C值与腐殖质层中的显著差异及粘土层的沉积特征则说明粘土层很可能形成旱地环境。沉积环境干湿变化的周期与腐殖质层持续的时间一致,大致为1000±500a,这种变化可能与中全新世以来气候在千百年尺度上的波动相关,而四会和高要两地古森林湿地发育的起止时间不一致则主要与两地的地理位置及地形不同相关。
The ancient forests buried in Sihui City and Gaoyao City in the Pearl River Delta formed one or more layers of humus during the developmental history. Among them, four will be buried ancient forest humus layer from the start to the end of the age of roughly 4218 ± 91 cal.aB.P. ~ 3291 ± 24cal.aB.P .; high to buried ancient forest humus layer development of three, their age is roughly 49l0 ± 64-1966 ± 42cal.aB.P., but discontinuously developed between 4347 ± 63-4017 ± 35 cal.aB.P. and 3658 ± 45-3539 ± 19 cal.aB.P., forming two layers of off-white clay Layer, three humus layer (from top to bottom) for the duration of development were 1500a, 400a and 500a, about 1000 ± 500a. The content of organic carbon in the four ancient humus layers buried in the forest varied from 26.2% to 48.9%, and the δ ~ (13) C value ranged from -29.8 ‰ to -25.6 ‰, among which, the contents of clay and humus The organic carbon content of the boundary point is 26.2%, the δ ~ (13) C value is -25.6 ‰, and the corresponding age is 3291 ± 24cal.aB.P .; in the high-buried ancient forest humus layer, the organic carbon content is 20.3 % ~ 64.0%, δ ~ (13) C fluctuated between -30.9 ‰ ~ -29.0 ‰, while in the middle of the clay layer between humus layers, the contents of organic carbon from top to bottom were 1.0% and 8.8% respectively. The corresponding δ ~ (13) C values were -28.2 ‰ and -27.8 ‰, respectively, which were about 2.0 ‰ to 2.5 ‰ higher than the average δ 13 C values of the adjacent humus layers. The contents of organic carbon and δ ~ (13) C in the humus layer show that the humus layer of the buried ancient forest is formed in the wetland environment, while the organic carbon content and δ ~ (13) C value in the clay layer are significantly different from that in the humus layer and the clay layer The sedimentary characteristics indicate that the clay layer is likely to form a dry land environment. The period of variation of wet and dry depositional environment is consistent with the duration of humus layer, which is about 1000 ± 500a, which may be related to the climate fluctuation in the centennial since the middle Holocene. However, Inconsistent with the starting and ending time of the development of forest wetlands, mainly related to the geographical location and topography of the two places.