CO2 discharge in an active, non-volcanic continental rift area (Czech Republic): Characterisation (δ13C, 3He/4He) and quantification of diffuse and vent CO2 emissions
CO2 discharge in an active, non-volcanic continental rift area (Czech Republic): Characterisation (δ13C, 3He/4He) and quantification of diffuse and vent CO2 emissions
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DOI：
10.1016/j.chemgeo.2012.08.005
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发表时间：
2013-02
期刊：
影响因子：
3.9
通讯作者：
H. Kämpf;K. Bräuer;J. Schumann;K. Hahne;G. Strauch
中科院分区：
文献类型：
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作者：
H. Kämpf;K. Bräuer;J. Schumann;K. Hahne;G. Strauch
在沿波察基-普莱斯纳断层带 (PPZ) 的埃格尔裂谷 (ER) 地区西部，二氧化碳脱气主要发生在 Bublák 和 Hartoušov 两个莫费特油田内。我们在2007年至2009年间反复研究了属于这些mofette气田的27个湿mofettes的气体排放率，并选择了mofettes的气体成分和同位素比（δ13C，3He/4He）。沿 PPZ 的详细地面测绘还提供了 Hartoušov 和 Bublák 莫菲特油田内两个独立的扩散脱气结构 (DDS)。通过测量 682 个 CO2 土壤气体浓度、762 个 CO2 土壤气体通量（最大 10 个网格间距）以及部分土壤气体同位素比（13C/12C、3He/4He）分析，对 DDS Hartoušov 进行了详细研究。在 DDS Hartoušov，2009 年春季，总 CO2 土壤通量产生了 1.559tm−2d−1，Hartoušov mofette 田湿 mofette 的 CO2 排放率产生了 0.62td−1。 27 个湿莫菲特的 CO2 排放总量为 3.75t d−1。在CO2土壤通量较高的地区，地幔源氦的比例与湿气释放的范围相同；两者都涵盖了次大陆地幔的特征。此外，湿莫菲特释放的气体中分析的 δ13C 值与土壤气体中分析的 δ13C 值几乎相同。考虑到生物土壤 CO2 通量为 25gm−2d−1 作为背景，地幔来源的 CO2 通量产生约 1566tm−2d−1。 DDS Hartoušov 的 CO2 通量测绘结果可以证明，97.4% 的土壤 CO2 释放量（1.518tm−2d−1）来自于 CO2 通量高于 500gm−2d−1 的地点，这表明主要与断层相关的 CO2 释放。在中央 mofette Bublák (B2)，气体排放率于 1993 年首次测定。2007 年至 2009 年期间重复的测量表明，气体排放率明显增加了 40% 以上，与 1993 年至 2008 年期间 3He/4He 比率从 5Ra 增加到大约 6Ra 密切相关（Bräuer 等人， 2009）。 Bublák mofette 气田的特点是 PPZ 沿线的 CO2 排放率最高，结合欧洲次大陆地幔的氦同位素特征，该区域被确定为深部流体注入区。
In the western Eger Rift (ER) area along the Počatky–Plesná fault zone (PPZ) CO2degassing occurs predominantly within two mofette fields Bublák and Hartoušov. We studied 27 wet mofettes belonging to these mofette fields for gas emission rates repeatedly between 2007 and 2009 and selected mofettes for gas composition and isotope ratios (δ13C,3He/4He). Detailed ground mapping along the PPZ provided further two separated diffuse degassing structures (DDS) within the mofette fields Hartoušov and Bublák. The DDS Hartoušov was studied in detail by measurements of 682 CO2soil gas concentrations, 762 CO2soil gas fluxes (max. 10 grid spacing) and partly by analyses of isotope ratios (13C/12C,3He/4He) of soil gas. At the DDS Hartoušov the total CO2soil flux yielded 1.559tm−2d−1in spring 2009 and the CO2emission rate at the wet mofettes of Hartoušov mofette field yielded 0.62td−1. The total CO2discharge of the 27 wet mofettes was 3.75t d−1. At sites with high CO2soil flux, the portion of mantle-derived helium is in the same range as the releasing at wet mofettes; both cover the signature of the subcontinental mantle. Also, the δ13C values analysed in the gas releasing from wet mofettes and those analysed in soil gas are nearly the same. Taking in account a biogenic soil CO2flux of 25gm−2d−1as background, the mantle-derived CO2flux yielded approximately 1566tm−2d−1. As a result of the CO2flux mapping of the DDS Hartoušov, it could be proved that 97.4% of the released soil CO2(1.518tm−2d−1) stems from sites with CO2fluxes higher than 500gm−2d−1‐pointing to dominantly fault-related CO2release. At the central mofette Bublák (B2), the gas emission rate was determined for the first time in 1993. Measurements repeated between 2007 and 2009 showed a clear increase in the gas emission rate of more than 40%, correlating well with the increase of the3He/4He ratios from 5Ra to approximately 6Ra between 1993 and 2008 at this location (Bräuer et al., 2009). The Bublák mofette field is characterised by the highest CO2emission rate along the PPZ, and in combination with the helium isotope signature of the European subcontinental mantle, this area was identified as a deep-reaching fluid injection zone.