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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Application of combined Kr-81 and He-4 chronometers to the dating of old groundwater in a tectonically active region of the North China Plain
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Application of combined Kr-81 and He-4 chronometers to the dating of old groundwater in a tectonically active region of the North China Plain

机译：将KR-81和HE-4 Charonometer合并在华北平原构造活动区旧地下水约会中的应用

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摘要

Groundwater dating by radio-krypton ( Kr-81; half-life of about 229,000 years) was applied to the sedimentary basin aquifer of the North China Plain (NCP). Krypton gas extracted from deep groundwater in the Coastal Plain was analyzed for Kr-81/Kr ratios by Atom Trap Trace Analysis, which yielded normalized ratios of 0.05 to 0.20, corresponding to groundwater residence times of 0.5-1 million years. Helium isotope compositions were determined on groundwater samples collected from the Central Plain and the Coastal Plain along a flow path of about 200 km. Helium dissolved in the groundwater samples are a mixture of atmospheric, crustal radiogenic and mantle derived sources. Mantle derived He-3 contributes up to 30% of the total, and the area of occurrence coincides with zones of previous magmatic/tectonic activities. By contrast, 90% of He-4 is derived from crustal reservoirs and correlates with Kr-81 ages. The absolute groundwater ages (Kr-81) and radiogenic He-4 concentrations permit us to calibrate the He-4 flux into the aquifer as well as the vertical diffusion rate of He-4 to utilize the radiogenic He-4 in groundwater as a quantitative age tracer. Previously, groundwater showed C-14 activities near the limit of detection (30-40 k yr), in contrast Kr and radiogenic He-4 data reveal progressively older ages from the recharge area to the Coastal Plain, from 20,000 yr to 0.5 to 1 Ma along the flow path of the NCP aquifers. (C) 2018 Elsevier B.V. All rights reserved.
机译：广播氪（KR-81;约229,000年半衰期的地下水适用于华北平原（NCP）的沉积盆地含水层。通过原子捕集痕量分析分析了从沿海平原中深水中汲取的克里普隆汽油，以kr-81 / kr比率分析，其产生的标准化比为0.05至0.20，对应于地下水停留时间为0.5-1万年。在从中央平原和沿海平原收集的地下水样品上测定氦同位素组合物沿着约200公里的流动路径。溶解在地下水样品中的氦是大气，地壳辐射和搭腔衍生来源的混合物。地幔衍生的HE-3占总数的30％，并且发生的面积与以前的岩石/构造活动的区域一致。相比之下，＆ 90％的HE-4来自地壳储层，与KR-81年龄相关。绝对地下水（KR-81）和辐射性HE-4浓度允许我们将HE-4通量校准到含水层中以及HE-4的垂直扩散速率，以利用地下水中的辐射性HE-4作为定量年龄跟踪器。以前，地下水显示了靠近检测极限（30-40k YR）的C-14活性，相比之下KR和辐射性HE-4数据从充电区域向沿海平原逐渐呈现逐渐老年，从20,000 YR到0.5沿着NCP含水层的流动路径为1 mA。 （c）2018年elestvier b.v.保留所有权利。

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