全新世以来辽河三角洲地区的化学风化及其对气候变化的响应

Chemical weathering and its implications regarding climate changes in the Liaohe Delta since the Holocene

以辽河三角洲ZK2孔为研究对象,对其57件沉积物样品进行常量元素测试和分析。研究表明,该地区总体遭受的化学风化作用较弱,基本处于化学风化的初期阶段,与所处纬度整体化学风化特征类似。将该区全新世以来的气候变化过程分为如下5个阶段:全新世早期(11.0—8.8 cal ka BP):化学风化程度逐渐增强,气候逐步向温湿方向发展;全新世早中期(8.8—6.9cal ka BP):化学风化程度最强,气候暖湿;全新世中期(6.9—4.6cal ka BP):风化强度较强,但有减弱的趋势,气候温湿;全新世中晚期(4.6—1.3 cal ka BP):化学风化程度在该时期属于最弱阶段,气候冷干;全新世晚期(1.3 cal ka BP—至今):气候温干,风化程度有所增强。总体来说,该区常量元素反映的气候变化过程与石笋δ^(18)O曲线基本一致,揭示了常量元素在反演气候变化过程中有一定的作用。

In this study, we analyzed a total of 57 samples with respect to the major elements in core ZK2 in the Liaohe Delta. The results of the research reveal that the chemical weathering of the region has been generally weak and remains in the early stage, which is similar to the overall chemical weathering characteristics observed at this latitude. We categorized the paleoclimate changes of this area into five stages since the Holocene as follows:(1) the Early Holocene (11.0-8.8 cal ka BP) during which the in tensity of the chemical weathering was gradually enhanced and the climate gradually transformed into warm-wet conditions;(2) the Early and Mid-Holocene (8.8-6.9 cal ka BP) during which the intensity of the chemical weathering was strongest and the climate was hot and wet;(3) the Mid-Holocene (6.9-4.6 cal ka BP) during which the intensity of the chemical weathering was strong but exhibited a weakening trend, and the climate was warm and wet;(4) the Middle and Late Holocene (4.6-1.3 cal ka BP) during which the intensity of the chemical weathering was weakest and the climate turned cold and dry;and (5) the Late Holocene (1.3 cal ka BP-present) during which the climate was warm and dry with an enhancing intensity of the chemical weathering. In general, the climate change process reflected by the major elements in this area is consistent with the stalagmite δ18O curve, which indicates that the major elements have a certain role in the inversion process of climate change.