Diffuse gases in soil of Araro-Simirao geothermal system, Michoacan, Mexico

IF 0.9 4区地球科学 Q3 GEOLOGY

Andean Geology Pub Date : 2021-06-15 DOI:10.5027/ANDGEOV48N3-3327

I. Pérez-Martínez, R. Villanueva-Estrada, A. Rodríguez-Díaz, C. Canet, R. García, Alfredo Ramos-Leal, D. Garcia, Froylan Cambrón

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引用次数: 4

Abstract

The Araró-Simirao geothermal system is in the southeast part of the Cuitzeo Lake depression. Physiographically, it is located in the eastern portion of the central part of the TransMexican Volcanic Belt province (TMVB). It is a convective hydrothermal system of dominant liquid, with chlorinated sodium waters and high boron content. The principal gas emitted by the thermal springs is CO2 and, in lower concentrations, H2S, H2 and noble gases (He, Ne, Ar). The aim of this study was to delimit fluid ascent areas in the geothermal system by determining the relationships between diffuse gas emission concentrations in soils and the greatest permeability plausible zones (principal faults). Three sampling campaigns were carried out during 2018 (August and November) and 2019 (May), in which diffuse gas emission measurements (CO2, Rn and mercury vapors) across the soils and soil temperature measurements were carried out. For a sampling campaign, the CO2 flux ranged between 4.38 and 94.61 g m-2 d-1 and the gaseous elemental mercury (GEM) concentration ranged between 0.5 and 365 ng/m3. For the other sampling campaign, the CO2 flux ranged between 0.8 and 1,421 g m-2 d-1 and the GEM values ranged between 0.49 and 2,914ng/m3. In the last sampling campaign the222Rn and 220Rn were also measured, and these values oscillated between 1,060 and 124,100 Bq/m3 and from 0 to 7,511 Bq7m3, respectively. Several anomalous zones of CO2 fluxes, GEM and 222Rn concentrations were found, which match the greatest permeability zones (faults and lineaments). The zone with the highest values in these three parameters is located in the so-called «mud pool», at the crossing of the Araró-Simirao fault with a lineament NW-SE (south zone), which is associated with the upflow zone of the system. Other anomalous zones were also located in the fracture and/or lineaments zones in the central and north parts of the system, which are associated with the outflow zone. According to the data obtained, CO2 could be functioning as a carrier of Hg and 222Rn in the area of vertical rise of gases and, in the outflow zone this gas may be found dissolved in the groundwater.

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墨西哥米却肯Araro Simirao地热系统土壤中的扩散气体

Araró-Simirao地热系统位于Cuitzeo湖凹陷的东南部。从地理上看，它位于跨墨西哥火山带省（TMVB）中部的东部。它是一个以液体为主的对流热液系统，含有氯化钠水和高硼含量。温泉释放的主要气体是CO2，以及较低浓度的H2S、H2和稀有气体（He、Ne、Ar）。本研究的目的是通过确定土壤中扩散气体排放浓度与最大渗透率合理区域（主要断层）之间的关系，来界定地热系统中的流体上升区域。在2018年（8月和11月）和2019年（5月）期间进行了三次采样活动，其中对土壤中的扩散气体排放量（CO2、Rn和汞蒸气）进行了测量，并对土壤温度进行了测量。对于采样活动，CO2通量在4.38至94.61 g m-2 d-1之间，气态元素汞（GEM）浓度在0.5至365 ng/m3之间。对于其他采样活动，CO2通量在0.8至1421 g m-2 d-1之间，GEM值在0.49至2914ng/m3之间。在上一次采样活动中，还测量了22Rn和220Rn，这些值分别在1060至124100 Bq/m3和0至7511 Bq7m3之间波动。发现了几个CO2通量、GEM和222Rn浓度的异常带，这些异常带与最大渗透率带（断层和线性构造）相匹配。这三个参数值最高的区域位于所谓的“泥浆池”中，位于Araró-Simirao断层与NW-SE线性构造（南区）的交叉处，该线性构造与系统的上流区有关。其他异常带也位于系统中部和北部的断裂和/或线性构造带中，与流出带有关。根据获得的数据，在气体垂直上升的区域，二氧化碳可能是汞和222Rn的载体，在流出区，这种气体可能溶解在地下水中。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Andean Geology 地学-地质学

CiteScore

3.90

自引率

0.00%

发文量

审稿时长

>12 weeks

期刊介绍： This journal publishes original and review articles on geology and related sciences, in Spanish or English, in three issues a year (January, May and September). Articles or notes on major topics of broad interest in Earth Sciences dealing with the geology of South and Central America and Antarctica, and particularly of the Andes, are welcomed. The journal is interested in publishing thematic sets of papers and accepts articles dealing with systematic Paleontology only if their main focus is the chronostratigraphical, paleoecological and/or paleogeographical importance of the taxa described therein.