Diffuse He degassing monitoring of the Tenerife North-western Rift Zone (NWRZ) volcano, Canary Islands

2020 ◽  
Author(s):  
Guillermo Recio ◽  
Eleanor Dunn ◽  
Yasmin McInally ◽  
Nemesio M. Pérez ◽  
Cecilia Amonte ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Rift Zone ◽  
Soil Gas ◽  
Sequential Gaussian Simulation ◽  
Volcanic Complex ◽  
Concentration Data ◽  
Entire Area ◽  
North West ◽  
Geochemical Properties ◽  
Helium Emission

<p>Tenerife (2034 km<sup>2</sup>), the largest island of the Canarian archipelago, is characterized by three volcanic rifts oriented NW-SE, NE-SW and N-S with a central volcanic complex, Las Cañadas Caldera, hosting Teide-Pico Viejo volcanoes. The North West volcanic Rift Zone (NWRZ, 72 km<sup>2</sup>) of Tenerife is one of the youngest and most active volcanic systems of the island, where two historical eruptions have occurred: Arenas Negras in 1706 and Chinyero in 1909. Diffuse degassing studies has become an important volcanic surveillance tool at those volcanic areas where visible manifestations of volcanic gases are absent, as in the case of NWRZ. Mapping soil gas emission along volcanic structures can provide a better understanding of the processes occurring at depth and allows monitoring the spatial distribution, magnitude and temporal evolution of the surface gas emissions. The geochemical properties of He, minimize the interaction of this noble gas on its movement toward the earth’s surface, and make this gas an almost ideal geochemical indicator of changes occurring in the magmatic plumbing system of the volcano (Padrón et al., 2013, Geology 41(5):539–542). Since 2014, surface He emission surveys have been performed once a year as an additional geochemical tool to monitor the volcanic activity of NWRZ. At 345 sampling sites soil gas samples were collected at 40 cm depth and analyzed for He concentration within 24 hours by means of QMS, model Pfeiffer Omnistar 422. The soil helium concentration data were used to estimate the diffusive helium flux at each point, to construct spatial distribution maps by sequential Gaussian simulation and then to estimate the total helium emission in the NWRZ. Helium emission ranged between non-detected values up to 7.2 mgm<sup>-2</sup>d<sup>-1</sup>, and the emission rate of the entire area was in the range ~1 – 45 kg d<sup>-1</sup>. An increasing trend was observed in the period 2016-2018, showing a good temporal coincidence with a significant increase in seismic activity recorded in Tenerife. The promising results observed in the NWRZ and in other volcanic systems (Padrón et al., 2013) indicate that soil helium emission monitoring could be an excellent early warning geochemical precursory signal for future volcanic unrest.</p>

Monitoring of diffuse CO2 degassing at NERZ, NWRZ and NSRZ volcanic systems of Tenerife, Canary Islands

2021 ◽  
Author(s):  
Fátima Rodríguez ◽  
Eleazar Padrón ◽  
Gladys Melián ◽  
María Asensio-Ramos ◽  
Mar Alonso ◽  
...  
Keyword(s):  
Rift Zone ◽  
Emission Rate ◽  
Interpolation Method ◽  
Sampling Site ◽  
Sequential Gaussian Simulation ◽  
Rift System ◽  
Volcanic Complex ◽  
North East ◽  
The North ◽  
Volcanic Seismicity

<p>One of the main volcano-structural and geomorphological feature in Tenerife (2,034 km<sup>2</sup>) is the triple rift system, formed by aligned of hundreds of monogenetic eruptive products of shield basaltic volcanism. At the intersection of this triple rift system rises the Teide-Pico Viejo volcanic complex. These volcanic rifts are considered as active volcanic edifices. The North East volcanic Rift Zone (NERZ, 210 km<sup>2</sup>) form a main NE-SW structure. The North West volcanic Rift Zone (NWRZ, 72 km<sup>2</sup>) is oriented in NW-SE direction and the North South volcanic Rift Zone (NSRZ, 325 km<sup>2</sup>) comprises a more scattered area on the south of these monogenetic cones. The most recent eruptive activity of Tenerife has taken place in these rift systems. NERZ host the fissural eruption of Arafo-Fasnia-Siete Fuentes (1704-1705). NWRZ host two historical eruptions: Arenas Negras in 1706 and Chinyero in 1909. Recently the eruption of Boca Cangrejo (1492) has been added to the historical register through <sup>14</sup>C dating. NSRZ does not host historical volcanism, although it is recent, up to 10,000 years old.</p><p>In order to provide a multidisciplinary approach to monitor potential volcanic activity changes at the NERZ, NWRZ and NSRZ, diffuse CO<sub>2</sub> emission surveys have been undertaken since 2000, in general in a yearly basis, but with a higher frequency when seismic swarms have occurred in and around NWRZ volcano. Each study area for NERZ, NWRZ and NSRZ comprises hundreds of sampling sites homogenously distributed. Soil CO<sub>2</sub> efflux measurements at each sampling site were conducted at the surface environment by means of a portable non-dispersive infrared spectrophotometer (NDIR) LICOR Li820 following the accumulation chamber method. To quantify the CO<sub>2</sub> emission rate from the NERZ, NWRZ and NSRZ a sequential Gaussian simulation (sGs) was used as interpolation method.</p><p>The diffuse CO<sub>2</sub> emission rate for the NERZ ranged from 532 up to 2823 t d<sup>-1 </sup>between 2001 and 2020, with the highest value measured in 2020. In the case of NWRZ, the diffuse CO<sub>2</sub> emission rate ranged from 52 up to 867 t d<sup>-1 </sup>between 2000 and 2020, with the highest value measured in one of the surveys of 2005. Finally, and for NSRZ, the diffuse CO<sub>2</sub> emission rate ranged from 78 up to 819 t d<sup>-1 </sup>between 2002 and 2020, with the highest value measured in 2019. The temporal evolution of diffuse CO<sub>2</sub> emission at the NERZ, NWRZ and NSRZ shows a nice and clear relationship with the volcanic seismicity in and around Tenerife Island, which started to take place from the end of 2016. The good temporal correlation between the volcanic seismicity and the increase trend observed in the time series of diffuse CO<sub>2</sub> emission rates at NERZ, NWRZ and NSRZ is also coincident with the observed increase of diffuse CO<sub>2</sub> emission rate at the summit crater of Teide. This work demonstrates the importance of performing soil CO<sub>2</sub> efflux surveys at active rift systems in volcanic oceanic islands as an effective geochemical monitoring tool.</p>

Diffuse H2 and He degassing survey to study of hidden potential geothermal systems in La Palma, Canary Islands

2020 ◽  
Author(s):  
Fátima Rodríguez ◽  
Antonio Polo Sánchez ◽  
Katherine Dale ◽  
Chloe Codner ◽  
Alba Martín ◽  
...  
Keyword(s):  
Rift Zone ◽  
Average Distance ◽  
Hydrothermal Systems ◽  
Soil Gas ◽  
Geothermal Systems ◽  
Soil Matrix ◽  
North West ◽  
The North ◽  
La Palma ◽  
Cumbre Vieja

<p>La Palma is one of the eastern islands of the Canary Archipelago located off the West African continental margin. Volcanic activity in the last 123 ka has taken place exclusively at the southern part of the island, where Cumbre Vieja volcano has been formed. Cumbre Vieja, one of the most active basaltic volcano in the Canaries, host seven historical eruptions being Teneguía eruption (1971) the most recent one. Cumbre Vieja volcano, characterized by a main north–south rift zone 20 km long and covering an area of 220 km<sup>2</sup>, does not show any visible degassing that show the existence of active geothermal systems. For that reason, geochemical prospecting of soil gases and volatiles in the soil matrix itself of Cumbre Vieja can provide useful information to investigate the presence of permeable areas and potential upflow areas for the degassing of geothermal systems at depth.</p><p>We report herein the results of an intensive soil gas study, focused on non-reactive and/or highly mobile gases such as helium (He) and hydrogen (H<sub>2</sub>), in Cumbre Vieja, with geothermal exploration purposes. He has unique characteristics as a geochemical tracer: it is chemically inert and radioactively stable, non-biogenic, highly mobile and relatively insoluble in water. H<sub>2</sub> is one of the most abundant trace species in volcano-hydrothermal systems and is a key participant in many redox reactions occurring in the hydrothermal reservoir gas.</p><p>Soil gas samples were collected at 1,201 sites selected from June 2019 to September 2019, with an average distance between sites of ≈ 250 m, at ≈ 40 cm depth using a metallic probe. He content was analyzed by means of a quadrupole mass spectrometer (QMS; Pfeiffer Omnistar 422) and hydrogen concentrations by a micro-gas chromatograph (microGC; VARIAN CP490). Soil He concentration showed values up to 23.9 ppm with an average of 5.73 ppm. Soil H<sub>2</sub> concentrations measured ranged from typical atmospheric values (≈ 0.5 ppm) up to 19.8 ppm. The mean value measured for H<sub>2</sub> was 0.78 ppm. Although He concentration values showed high spatial variability, the highest values can be observed in the north–south rift zone of Cumbre Vieja and around the surface contact with Cumbre Nueva ridge. Spatial distribution of H<sub>2</sub> concentration showed the highest values in the north-west area of Cumbre Vieja volcano. The results showed here are useful to identify the possible existence of permeable portions of deep-seated actively degassing geothermal reservoirs. However, a multidisciplinary approach is essential to obtain additional information about possible geothermal systems underlying at Palma island with the last goal of the selection of appropriate locations for future exploratory wells.</p>

scholarly journals Spatial Distribution and Evaluation of Arsenic and Zinc Content in the Soil of a Karst Landscape

2021 ◽  
Vol 13 (12) ◽  
pp. 6976
Author(s):  
Dimitrios E. Alexakis ◽  
George D. Bathrellos ◽  
Hariklia D. Skilodimou ◽  
Dimitra E. Gamvroula
Keyword(s):  
Land Use ◽  
Spatial Distribution ◽  
Land Use Planning ◽  
Urban Soil ◽  
Agricultural Soil ◽  
Agricultural Land ◽  
Land Evaluation ◽  
Agricultural Activity ◽  
North West ◽  
Total Study Area

Karst features such as polje are highly vulnerable to natural and anthropogenic pollution. The main objectives of this study were to investigate the soil quality in the Ioannina polje (north-west Greece) concerning arsenic (As) and zinc (Zn), and delineate their origin as well as compare the As and Zn content in soil with criteria recorded in the literature. For this purpose, the geomorphological settings, the land use, and the soil physicochemical properties were mapped and evaluated, including soil texture and concentrations of aqua-regia extractable As and Zn. The concentration of elements was spatially correlated with the land use and the geology of the study area, while screening values were applied to assess land suitability. The results reveal that 72% of the total study area has a very gentle slope. This relief favors urban and agricultural activity. Thus, the urban and agricultural land used cover 92% of the total area. The spatial distribution for As and Zn in the soil of the study area is located on very gentle slopes and is strongly correlated with the geological parent materials and human-induced contamination sources. Arsenic and Zn can be considered enriched in the soil of the area studied. The median topsoil contents (in mg kg−1) for As (agricultural soil 16.0; urban soil 17.8) and Zn (agricultural soil 92.0; urban soil 95.0) are higher compared to the corresponding median values of European topsoils. Land evaluation suitability concerning criteria given from the literature is discussed. The proposed work may be helpful in the project of land use planning and the protection of the natural environment.

Integration of Chemofacies and Rock Mechanical Properties Using Machine Learning Algorithms: Implications for Geomechanics and Hydraulic Fracture Stimulations in Paleozoic Formations, Saudi Arabia

2021 ◽  
Author(s):  
Maaruf Hussain ◽  
Abduljamiu Amao ◽  
Khalid Al-Ramadan ◽  
Sunday Olatunji ◽  
Ardiansyah Negara
Keyword(s):  
Machine Learning ◽  
Mechanical Properties ◽  
Saudi Arabia ◽  
Spatial Distribution ◽  
Chemical Composition ◽  
Rock Strength ◽  
Machine Learning Algorithms ◽  
Unconventional Reservoirs ◽  
Geochemical Properties ◽  
Rock Mechanical Properties

Abstract The knowledge of rock mechanical properties is critical to reducing drilling risk and maximizing well and reservoir productivity. Rock chemical composition, their spatial distribution, and porosity significantly influenced these properties. However, low porosity characterized unconventional reservoirs as such, geochemical properties considerably control their mechanical behavior. In this study, we used chemostratigraphy as a correlation tool to separate strata in highly homogenous formations where other traditional stratigraphic methods failed. In addition, we integrated the chemofacies output and reduced Young's modulus to outline predictable associations between facies and mechanical properties. Thus, providing better understanding of lithofacies-controlled changes in rock strength that are useful inputs for geomechanical models and completions stimulations.

Spatial distribution of the extreme hydrological events in Xinjiang, north-west of China

2013 ◽  
Vol 67 (2) ◽  
pp. 483-495 ◽  
Author(s):  
Guili Sun ◽  
Yaning Chen ◽  
Weihong Li ◽  
Cunde Pan ◽  
Jiang Li ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
North West ◽  
Extreme Hydrological Events

Chemical Characterization of Environmental Samples after Oil Spill in Iguassu River, Parana, Brazil, July/2000

2003 ◽  
Vol 2003 (1) ◽  
pp. 579-588
Author(s):  
Maria de Fátima Guadalupe Meniconi ◽  
Irene Terezinha Gabardo ◽  
Silvana Maria Barbanti ◽  
Nelson Luna Caicedo
Keyword(s):  
Monitoring Program ◽  
Chemical Characterization ◽  
Hydrocarbon Contamination ◽  
Concentration Data ◽  
Entire Area ◽  
Monitoring Wells ◽  
South Of Brazil ◽  
One Year ◽  
The Impact ◽  
Spilled Oil

ABSTRACT On July 16, 2000, a rupture of a pipeline occurred in the Scraper area of the PETROBRAS refinery located in Araucaria, in the state of Parana, south of Brazil. This resulted in the spill of approximately 4,000m3 (1,060,000 gallons) of a crude oil (Cusiana − 41°API). The spilled oil spread over part of the refinery area, affecting the wetlands that are crossed by the Arroio Saldanha creek before discharging into the Barigui River, which is a tributary of Iguassu River. This entire area crossed by the creek is referred to as Point Zero (PO). This paper presents the chemical data of 2 monitoring programs: the Barigui, Iguassu and Arroio Saldanha Rivers, and the groundwater of Point Zero. The programs were carried out in 2 phases: for 3 months immediately after the spill and 1 year later. They included the analyses of BTEX, TPH, PAH, n-alkanes, UCM and biomarkers for the water and sediment samples. The rivers program encompassed 13 stations along Barigui and Iguassu Rivers and 1 station at Arroio Saldanha Creek. The results in water and sediments demonstrated the efficiency of the recovering of the spilled oil from the water. That suggested that the impact of the spill on the Barigui and Iguassu Rivers was of a short duration after the spill. On the other hand, the hydrocarbon concentration data for Arroio Saldanha Creek during the 3 months after the spill revealed high levels of hydrocarbon contamination, which corroborated the visual inspection. The groundwater monitoring program in the terrestrial area of Point Zero was initiated shortly after the spill. The groundwater program included about 80 monitoring wells (piezometers) installed, along the Arroio Saldanha Creek and in the wetlands crossed by the creek. It could be observed that BTEX and TPH groundwater concentrations decreased significantly after one year.

Soil gas physical-chemistry survey for geothermal exploration at Terceira Island, Azores.

2020 ◽  
Author(s):  
Claudia Rodríguez-Pérez ◽  
Alba Martín-Lorenzo ◽  
Fátima Rodríguez ◽  
Gladys V. Melián ◽  
María Asensio-Ramos ◽  
...  
Keyword(s):  
Hydrothermal Activity ◽  
Soil Gas ◽  
Volcanic Complex ◽  
Additional Information ◽  
Geothermal Potential ◽  
Potential Success ◽  
Exploratory Wells ◽  
To Receive ◽  
Selection Of

<p>Terceira Island is located in the Azores Archipelago and it lies at the intersection of four submarine volcanic ridges. Due to its characteristics the geothermal potential of Terceira Island has begun to receive some interest from researchers and decision makers from the 70s of last century, but only in 2000 an exploration license was granted in favour of GEOTERCEIRA (now EDA RENOVÁVEIS S.A.). The area of this license is located in the central part of the island in the Pico Alto Volcanic Complex, and includes the fumarolic field of Furnas do Enxofre.</p><p>The main aim of this study is to provide additional information about the presence of fluids upflow regions and areas of increased subsurface permeability related to high temperature hydrothermal activity at depth, as part of an study to expand the current geothermal plant of Terceira. To achieve this objective, a soil gas and diffuse CO<sub>2</sub> and H<sub>2</sub>S degassing survey, which included in situ CO<sub>2</sub> emission measurements and soil temperature at 15 and 40 cm deep and the collection of soil gas samples, was performed during September 2019. 122 sampling sites were selected spaced at ~100 meters at Pico Alto Volcanic Complex. Diffuse CO<sub>2</sub> and H<sub>2</sub>S measurements were performed according to the accumulation chamber method, using a non-dispersive infrared (NDIR) LICOR-830 CO<sub>2</sub> analyser and ALPHASENSE H<sub>2</sub>S-BH detectors, respectively. In addition, soil gas samples were collected to analyse the He, H<sub>2</sub>, O<sub>2</sub>, N<sub>2</sub>, CO<sub>2</sub>, CH<sub>4</sub> and CO contents and the isotopic composition of the CO<sub>2</sub>. Soil CO<sub>2</sub> efflux values ranged between non-detectable values and 56.2 g m<sup>2</sup> d<sup>-1</sup>, with an average of 21.7 g m<sup>2</sup> d<sup>-1</sup>. Soil H<sub>2</sub>S efflux values ranged between non-detectable values and 0.245 g m<sup>2</sup> d<sup>-1</sup>, with an average of 0.027 g m<sup>2</sup> d<sup>-1</sup>. The probability plot technique applied to the soil CO<sub>2</sub> efflux data allowed to distinguish three different geochemical populations: background, intermediate and peak represented by 36.9 %, 59.8 % and 3.3 % respectively, with geometric means of 10.8, 25.4 and 50.0 g m<sup>2</sup> d<sup>-1</sup> respectively. The spatial distribution of soil CO<sub>2</sub> efflux data, constructed by means of Sequential Gaussian simulations algorithm, depicted the most important emission anomalies at the western section of the study area. These results can help to identify the possible existence of additional actively degassing geothermal reservoirs to reduce the uncertainty inherent to the selection of the area with the highest potential success in the selection of new exploratory wells at Terceira.</p>

A Late Mesozoic island arc in the southern Andes, Chile

1979 ◽  
Vol 116 (3) ◽  
pp. 181-190 ◽  
Author(s):  
M. Suárez
Keyword(s):  
Continental Crust ◽  
Rift Zone ◽  
Volcanic Rocks ◽  
Upper Jurassic ◽  
Island Arc ◽  
Volcanic Complex ◽  
Late Mesozoic ◽  
Marginal Basin ◽  
The Pacific ◽  
Pacific Side

SummaryThe Hardy Formation, a sequence of Upper Mesozoic volcanic rocks exposed in Peninsula Hardy (Isla Hoste) in the southernmost archipelago of Chile represents, at least in part, the island-arc assemblage of an island-arc-marginal-basin system related to an eastward dipping subduction zone. This island arc was founded on South American continental crust and is also represented in the island of South Georgia 2000 km to the E. The island-arc assemblage includes pyroclastic rocks, characterized by a high proportion of vitric material, and lava intercalations ranging in composition from rhyolite to basalt. These rocks underwent zeolite and prehnite-pumpellyite facies metamorphism and are gently folded, in contrast with the intense folding exhibited by the rocks exposed to the north of Peninsula Hardy. Silicic volcanics assigned to this assemblage underlie pillow lavas, and are intruded by dolerites and gabbros probably related to a Late Jurassic-Early Cretaceous ophiolite magmatism associated with the generation of a quasioceanic marginal basin. Volcanic turbidites (Yahgan Formation) were deposited into the marginal basin.It is suggested that in pre-marginal basin times the Hardy Formation interfingered towards the Atlantic with the silicic volcanics of the Tobifera Formation. However, recent geochemical work on the Tobifera Formation suggest an origin by continental crust anatexis in a volcano-tectonic rift zone related to upper mantle diapirism, whereas an island arc origin is favoured for at least the andesitic and basaltic components of the Hardy Formation. Therefore, the geology of Peninsula Hardy as presented here, confirms early assumptions of the splitting apart of a Middle–Upper Jurassic volcanic terrain along the Pacific margin of South America during the generation of a marginal basin. The spreading axis of the latter seems to have been located at the boundary of two somewhat overlapping petrotectonic assemblages: and island arc on the Pacific side and a silicic volcano-tectonic rift zone towards the Atlantic. A probably Cenozoic volcanic complex discordantly overlies the Yahgan and Hardy formations.

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