The Leaking Mantle

Hilton, David R.

doi:10.1126/science.1151983

Cited by 36 publications

(31 citation statements)

References 9 publications

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“…Further, our results suggest that earthquake swarms occurring in a current non‐volcanic region are induced by an active magmatic process in the lithospheric mantle. Our latest helium isotope results support the idea that the leaking mantle and the occurrence of earthquake swarms are coupled [see Hilton , 2007].…”

Section: Resultssupporting

confidence: 77%

Earthquake swarms in non‐volcanic regions: What fluids have to say

Bräuer

Kämpf

Strauch

2009

Geophysical Research Letters

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The detailed processes generating earthquake swarms are complex and not fully understood. Most earthquake swarms occur in volcanic regions and mid‐ocean rifts. Here, we report new 3He/4He data of free gases monitored at CO2‐rich degassing locations close to the Nový Kostel focal zone (NKFZ) located in the western Eger rift. The NKFZ is known for the recurrence of earthquake swarms at which the focal zone ranges between 6 and 12 km depth. At degassing locations neighboring to the NKFZ a progressive increase of mantle‐derived helium has been observed during the last 15 years – actually the highest 3He/4He ratios (>6 Ra) in Central Europe. The 3He/4He anomalies indicate hidden magmatic activity. We assume that the latest strong earthquake swarm in October 2008 was initiated by a hidden magma intrusion process from the upper mantle into the lower crust that has been indicated by a three month lasting increase of the 3He/4He ratios in spring 2006 at all degassing locations near the NKFZ.

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Section: Resultssupporting

confidence: 77%

Earthquake swarms in non‐volcanic regions: What fluids have to say

Bräuer

Kämpf

Strauch

2009

Geophysical Research Letters

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“…3 He is essentially primordial and retained in the Earth's interior, whereas 4 He is mainly produced in the crust by the decay of U and Th, so any 3 He/ 4 He ratio at the Earth's surface larger than the atmospheric helium indicates the relatively higher contribution of mantle helium [ Ozima and Podosek , 2002]. It is well known that mantle degassing does not occur homogeneously over the Earth's surface [e.g., Hilton , 2007]. In continental settings, the flux of radiogenic 4 He from the crust has been investigated and the distribution of mantle helium and its manifestation in tectonically active areas has been mapped [e.g., Marty et al , 1989].…”

Section: Introductionmentioning

confidence: 99%

Relationship between ³He/⁴He ratios and subduction of the Philippine Sea plate beneath southwest Japan

Umeda¹,

Kusano²,

Asamori³

et al. 2012

J. Geophys. Res.

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[1] Regional and local variations in mantle helium provide insight into the coupling of mantle-crust tectonics, and heat and/or mass transfer from the Earth's interior. In order to further elucidate the geographic distribution of 3 He/ 4 He ratios in southwest Japan, the data from a total of 924 sites were compiled and synthesized. These include data from 48 additional hot spring and drinking water well sites on the northern Kyushu Island and in the northern Chugoku region. There appears to be good correlation between variations in helium isotope ratios and the geophysical evidence used to determine the configuration of the subducting Philippine Sea plate (PHS). Seismological studies reveal that the leading edge of the aseismic slab does not extend to the northern Chugoku region nor to the Osaka Bay area, where gas samples with significantly elevated 3 He/ 4 He ratios occur. This is consistent with a mantle-derived helium in these areas, from melts and/or mantle fluids ascribed to upwelling asthenosphere without being hindered by the descending PHS slab. In contrast, gas samples in the regions where the overriding crust comes into direct contact with the subducting PHS are dominated by radiogenic helium derived from the crust because of the absence of a mantle wedge, the most plausible source of mantle helium. Owing to the abrupt changes in the seismicity and focal mechanisms of intraplate earthquakes, the PHS is considered to have slab tears beneath the Kii Channel and/or the eastern Kii Peninsula oriented in a NW-SE direction. However, the lenear alignment of anomalously high 3 He/ 4 He ratios does not appear to be NW-SE trending along the assumed slab tears but rather forms an broad, ENE-WSW trending zone between the tears where low-frequency events occur. The emanation of gas with elevated 3 He/ 4 He ratios in the central peninsula can be explained by the upward mobilization of mantle volatiles derived from the mantle wedge above the PHS and/or transferred from the hydrated slab mantle through the N-S trending fractured medium within the PHS. Accordingly, the helium isotopes observed on the Earth's surface may be efficient geochemical indicators of the configuration of a relatively younger, warm aseismic slab, and be especially useful in seismically inactive areas.

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“…In particular, fluid inclusions (FIs) may provide information on the presence of mantle‐derived fluids that reached the surface making a proof of possible relationship between tectonics and circulating fluids over the faulted zones. In addition, they can add data on the existence of deep‐rooted, lithospheric faults, which are able to drive mantle‐derived fluids toward the surface (Batista Cruz et al, ; Caracausi et al, ; Hilton, ; Kennedy et al, ; Kulongoski et al, ; Marty et al, ; O'Nions & Oxburgh, ; Pik & Marty, ; Smeraglia et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Faults are important pathways for fluid circulation within the crust and upwelling of hydrothermal or mantle fluids (Alçiçek et al, 2013;Brogi, 2004;Brogi & Capezzuoli, 2009;Faccenna et al, 2008;Hilton, 2007;Smeraglia et al, 2018;Uysal et al, 2007); contrastingly, they can locally act as impermeable barriers (e.g., Person, 2007). Faults opening can be triggered by earthquakes, fluid overpressures, or localized dissolution (Gratier & Gueydan, 2007).…”

Section: Introductionmentioning

confidence: 99%

Geochemistry of Fluid Inclusions in Travertines From Western and Northern Turkey: Inferences on the Role of Active Faults in Fluids Circulation

Rizzo

Uysal

Mutlu

et al. 2019

Geochem Geophys Geosyst

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The understanding of the relationship between the geochemistry of fluids circulating during travertine deposition and the presence of active faults is crucial for evaluating the seismogenetic potential of an area. Here we investigate travertines from Pamukkale and Reşadiye (Turkey), sited in seismic regions and next to thermal springs. These travertines formed ~24,500–50,000 (Pamukkale) and ~240–14,600 years (Reşadiye) BP. We characterize fluid inclusions (FIs) and studied concentration of H2O, CO2, O2 + N2, and 3He, 4He, 20Ne, and 40Ar, and bulk composition (trace elements and δ13C‐δ18O). FIs from both localities are mainly primary with low salinity and homogenization temperature around 136–140 °C. H2O is the major component followed by CO2, with the highest gas content measured in Pamukkale travertines. Concentrations of Ne‐Ar together with O2 + N2 indicate that travertines from both areas precipitated from atmosphere‐derived fluids. The 3He/4He is 0.5–1.3 Ra in Pamukkale and 0.9–4.4 Ra in Reşadiye. Samples with R/Ra > 1 are modified by cosmogenic 3He addition during exposure to cosmic rays. Excluding these data, FIs of Reşadiye are mostly atmosphere‐derived. This implies a shallow formation where the circulation was dominated by meteoric waters, which is consistent with their young age. Instead, FIs of Pamukkale show mixing of mantle‐, crustal‐, and atmosphere‐derived He, indicating that these travertines formed in lithospheric fractures. Based on the δ13CCO2 and δ18O of bulk rocks, we infer that travertines formed involving crustal‐ (mechanochemical rather than organic) and mantle‐derived CO2. Trace elements of Pamukkale and Reşadiye show comparable rare earth element patterns. We conclude that travertines formed in response of seismogenetic activity.

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The Leaking Mantle

Cited by 36 publications

References 9 publications

Earthquake swarms in non‐volcanic regions: What fluids have to say

Earthquake swarms in non‐volcanic regions: What fluids have to say

Relationship between ³He/⁴He ratios and subduction of the Philippine Sea plate beneath southwest Japan

Geochemistry of Fluid Inclusions in Travertines From Western and Northern Turkey: Inferences on the Role of Active Faults in Fluids Circulation

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The Leaking Mantle

Cited by 36 publications

References 9 publications

Earthquake swarms in non‐volcanic regions: What fluids have to say

Earthquake swarms in non‐volcanic regions: What fluids have to say

Relationship between 3He/4He ratios and subduction of the Philippine Sea plate beneath southwest Japan

Geochemistry of Fluid Inclusions in Travertines From Western and Northern Turkey: Inferences on the Role of Active Faults in Fluids Circulation

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Relationship between ³He/⁴He ratios and subduction of the Philippine Sea plate beneath southwest Japan