Tracing Fluid Origin, Transport and Interaction in the Crust

Ballentine, C. J.; Burgess, R.; Marty, Bernard

doi:10.2138/rmg.2002.47.13

Cited by 319 publications

(230 citation statements)

References 131 publications

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“…Consistent with these observations, the CO 2 / 3 He range from 3.70 × 10 8 at Bilbo in a relatively low CO 2 sample, to 6.59 × 10 10 at Bilbo Red. Although there is considerable range in these values, which seem to straddle the typical MORB-like composition (~2 × 10 9 ), likely reflecting variable degrees of gas-water interactions, these observations are largely consistent with the range observed for mantle-derived CO 2 and 3 He (Ballentine et al, 2002).…”

Section: Diagrams (See Text)supporting

confidence: 76%

Geothermal potential and origin of natural thermal fluids in the northern Lake Abaya area, Main Ethiopian Rift, East Africa

Minissale

Corti

Tassi

et al. 2017

Journal of Volcanology and Geothermal Research

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In this study, the occurrence, chemical composition, origin and geothermal significance of thermal springs and fumaroles naturally discharging in the area located north of the Lake Abaya (western margin of the Main Ethiopian Rift, East Africa) are reviewed in relation with recent tectonics. All thermal springs showed a dominantly Na-HCO 3 composition, consistent with observations dating from at least 1972, and most of them displayed a narrow range of δD and δ 18 O isotopic compositions for water similar to regional meteoric origins. These observations suggest that water-rock interaction processes occur in all aquifers and dominate the contributions of water that actively circulate within thermal fluids, and also suggest a similar elevation of groundwater recharge throughout the study area. Most of the thermal springs are dominated by a CO 2 -rich gas phase and discharge along the active faults bordering the western edge of the Main Ethiopian Rift valley. The δ 13 C values of CO 2 and the 3 He/ 4 He isotopic ratios are consistent with the presence of mantle-derived fluids similar to what is observed in many other areas along the kinematically active African Rift, especially within Ethiopia. The application of geothermometric techniques in the liquid and the gas phases suggests the presence of a deep reservoir in which the fluids equilibrated at a maximum temperature of approximately 180°C. Additionally, the presence of fumaroles at boiling temperatures and water/mud boiling pools in several places suggests that the geothermal reservoir is positioned at a relatively shallow depth and likely located in the western side of the study area. The analysis of data collected throughout time reveals that the waters of Lake Abaya have experienced an increase in salinity of 20% paralleled contemporaneously with a decrease in pH and δ 18 O and δD of water in the last 40 years; these changes do not appear to be related to climate changeinduced increases in temperature or evaporation at the global scale.

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Section: Diagrams (See Text)supporting

confidence: 76%

Geothermal potential and origin of natural thermal fluids in the northern Lake Abaya area, Main Ethiopian Rift, East Africa

Minissale

Corti

Tassi

et al. 2017

Journal of Volcanology and Geothermal Research

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“…Helium is an inert noble gas with a radiogenic isotope, 4 He, that is a major component of thermogenic natural gas. Similar to hydrocarbon components, the abundance and isotopic composition of helium can help distinguish between potential sources and/or residence times of fluids in the crust, including natural gases (15,16,33). Across our dataset, the ratio of 4 He:CH 4 in most drinking water wells showed a typical range between ∼2 × 10 −3 and 1 × 10 −2 , independent of distance to natural gas wells (Fig.…”

Section: Resultsmentioning

confidence: 82%

Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction

Jackson

Vengosh²,

Darrah³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

505

475

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Horizontal drilling and hydraulic fracturing are transforming energy production, but their potential environmental effects remain controversial. We analyzed 141 drinking water wells across the Appalachian Plateaus physiographic province of northeastern Pennsylvania, examining natural gas concentrations and isotopic signatures with proximity to shale gas wells. Methane was detected in 82% of drinking water samples, with average concentrations six times higher for homes <1 km from natural gas wells (P = 0.0006). Ethane was 23 times higher in homes <1 km from gas wells (P = 0.0013); propane was detected in 10 water wells, all within approximately 1 km distance (P = 0.01). Of three factors previously proposed to influence gas concentrations in shallow groundwater (distances to gas wells, valley bottoms, and the Appalachian Structural Front, a proxy for tectonic deformation), distance to gas wells was highly significant for methane concentrations (P = 0.007; multiple regression), whereas distances to valley bottoms and the Appalachian Structural Front were not significant (P = 0.27 and P = 0.11, respectively). Distance to gas wells was also the most significant factor for Pearson and Spearman correlation analyses (P < 0.01). For ethane concentrations, distance to gas wells was the only statistically significant factor (P < 0.005). Isotopic signatures (δ 13 C-CH 4 , δ 13 C-C 2 H 6 , and δ 2 H-CH 4 ), hydrocarbon ratios (methane to ethane and propane), and the ratio of the noble gas 4 He to CH 4 in groundwater were characteristic of a thermally postmature Marcellus-like source in some cases. Overall, our data suggest that some homeowners living <1 km from gas wells have drinking water contaminated with stray gases.carbon, hydrogen, and helium isotopes | groundwater contamination | geochemical fingerprinting | fracking | hydrology and ecology

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“…Therefore, for this project, we cautiously operated under the canonical view that crushing primarily releases noble gases that were trapped in inclusions during mineral growth (e.g. Ballentine et al, 2002;Stuart et al, 1994). Purification and analyses of the released gases follow Dodson et al (1997).…”

Section: Noble Gases From Fluid Inclusions: Analytical Methods and Rementioning

confidence: 99%

Isotopic evidence for the infiltration of mantle and metamorphic CO2–H2O fluids from below in faulted rocks from the San Andreas Fault system

et al. 2011

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To characterize the origin of the fluids involved in the San Andreas Fault (SAF) system, we carried out an isotope study of exhumed faulted rocks from deformation zones, vein fillings and their hosts and the fluid inclusions associated with these materials. Samples were collected from segments along the SAF system selected to provide a depth profile from upper to lower crust. In all, 75 samples from various structures and lithologies from 13 localities were analyzed for noble gas, carbon, and oxygen isotope compositions. Fluid inclusions exhibit helium isotope ratios ( 3 He/ 4 He) of 0.1-2.5 times the ratio in air, indicating that past fluids percolating through the SAF system contained mantle helium contributions of at least 35%, similar to what has been measured in present-day ground waters associated with the fault . Calcite is the predominant vein mineral and is a common accessory mineral in deformation zones. A systematic variation of C-and O-isotope compositions of carbonates from veins, deformation zones and their hosts suggests percolation by external fluids of similar compositions and origin with the amount of fluid infiltration increasing from host rocks to vein to deformation zones. The isotopic trend observed for carbonates in veins and deformation zones follows that shown by carbonates in host limestones, marbles, and other host rocks, increasing with increasing contribution of deep metamorphic crustal volatiles. At each crustal level, the composition of the infiltrating fluids is thus buffered by deeper metamorphic sources. A negative correlation between calcite δ 13 C and fluid inclusion 3 He/ 4 He is consistent with a mantle origin for a fraction of the infiltrating CO 2 . Noble gas and stable isotope systematics show consistent evidence for the involvement of mantle-derived fluids combined with infiltration of deep metamorphic H 2 O and CO 2 in faulting, supporting the involvement of deep fluids percolating through and perhaps weakening the fault zone. There is no clear evidence for a significant contribution from meteoric water, except for overprinting related to late weathering.

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Tracing Fluid Origin, Transport and Interaction in the Crust

Cited by 319 publications

References 131 publications

Geothermal potential and origin of natural thermal fluids in the northern Lake Abaya area, Main Ethiopian Rift, East Africa

Geothermal potential and origin of natural thermal fluids in the northern Lake Abaya area, Main Ethiopian Rift, East Africa

Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction

Isotopic evidence for the infiltration of mantle and metamorphic CO2–H2O fluids from below in faulted rocks from the San Andreas Fault system

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