摘要:
乐安江是德兴铜矿地区的主要水系,为查明乐安江德兴铜矿段河流阶地发育情况及其所产生的环境效应,对乐安江海口镇-泗州镇坑口段-乐平市洺口镇戴村村段及大坞河与浮溪河所发育的河流阶地进行划分,并运用光释光(OSL, Opically Stimulated Luminesecence)测年方法对此段乐安江低阶地的形成时代进行测定。得到以下认识:研究区乐安江至少发育五级阶地, T5拔河高度约50 m, T4拔河在28~40 m之间, T3拔河在20~30 m之间, T2拔河高度在12~22 m之间, T1拔河高度在6~15 m之间;另外研究区乐安江支流大坞河与浮溪河,也有3~5级阶地发育。该段乐安江三级阶地上沉积物的 OSL 年龄为(120.6±5.8)~(153.6±8.1) ka,二级阶地上沉积物 OSL 年龄为(43.0±1.8)~(109.9±4.6) ka,一级阶地上沉积物OSL 年龄为(0.9±0.1)~(1.2±0.1) ka。四级阶地可能形成于倒数第二次间冰期。以上认识填补了乐安江河流阶地研究的空白,为今后研究区第四纪地质的研究奠定了一定的基础。结合大坞河一、二级阶地上土壤、种植物中重金属含量分析,认为研究乐安江德兴铜矿段及其支流的河流阶地对确定德兴铜矿所排放出的酸性废水的影响范围及该地区的农业区划具有重要意义。
Abstract:
The Le’an River is the main stream in the Dexing copper orefield. The authors divided the terraces of the Le’an River and its branches and used OSL (Opically Stimulated Luminesecence) dating to confirm the formation age of low terraces so as to find out Le’an River terraces in the Dexing copper mine and its environmental effects. Some conclusions have been reached: There are five terraces of the Le’an River in the study area: T1 is between 6 to 15 m above the river level; T2 is between 12 to 22 m above the river level, T3 is between 28 to 40 m above the river level;T4 is between 20 to 30 m above the river level;T5 is 50 m above the river level. Besides, the Dawu River and the Fuxi River, two branches of the Le’an River, also have 3~5 terraces. OSL ages of T3 are (120.6±5.8)~(153.6±8.1) ka; OSL ages of T2 are (43.0±1.8)~(109.9±4.6) ka; OSL ages of T1 are (0.9±0.1)~(1.2±0.1) ka, T4 was probably formed in the period just before the last interglacial period. The above understandings fill the gap in the study of Le’an River terraces and lay a certain foundation for the future study of the Quaternary geology. In combination with plant and soil heavy metal content in T1 and T2 of the Dawu River, the authors hold that the study of terraces of the Le’an River and its branches in the Dexing copper mine have great significance for confirming the influence range of acidic waste water discharged by the Dexing copper mine and agricultural regionalization.
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