A cold seep triggered by a hot ridge subduction

AbstractThe Chile Triple Junction, where the hot active spreading centre of the Chile Rise system subducts beneath the South American plate, offers a unique opportunity to understand the influence of the anomalous thermal regime on an otherwise cold continental margin. Integrated analysis of various geophysical and geological datasets, such as bathymetry, heat flow measured directly by thermal probes and calculated from gas hydrate distribution limits, thermal conductivities, and piston cores, have improved the knowledge about the hydrogeological system. In addition, rock dredging has evidenced the volcanism associated with ridge subduction. Here, we argue that the localized high heat flow over the toe of the accretionary prism results from fluid advection promoted by pressure-driven discharge (i.e., dewatering/discharge caused by horizontal compression of accreted sediments) as reported previously. However, by computing the new heat flow values with legacy data in the study area, we raise the assumption that these anomalous heat flow values are also promoted by the eastern flank of the currently subducting Chile Rise. Part of the rift axis is located just below the toe of the wedge, where active deformation and vigorous fluid advection are most intense, enhanced by the proximity of the young volcanic chain. Our results provide valuable information to current and future studies related to hydrothermal circulation, seismicity, volcanism, gas hydrate stability, and fluid venting in this natural laboratory.

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Roles of Hydrothermal Circulations on Heat Flow in the Fore-arc, Northeast Japan Subduction Zone, A Numerical Modeling Study.

10.5194/egusphere-egu21-1958 ◽

2021 ◽

Author(s):

Dongwoo Han ◽

Changyeol Lee

Keyword(s):

Heat Transfer ◽

Heat Flow ◽

Oceanic Crust ◽

Numerical Models ◽

Accretionary Prism ◽

High Heat ◽

Pacific Plate ◽

Model Calculations ◽

The Pacific ◽

Japan Subduction Zone

Heat flow in the fore-arc, Northeast Japan shows characteristic highs and lows in the seaward and landward regions of the trench axis, respectively, compared to 50 mW/m2 that is constrained from the corresponding half-space cooling model (135 Ma). For example, the high average of 70 mW/m2 at the 150-km seaward region from the trench was observed while the low average of 30 mW/m2 at the 50-km landward region was. To explain the differences between the constraints and observations of the heat flow, previous studies suggested that the high heat flow in the seaward region results from the reactivated hydrothermal circulations in the oceanic crust of the Pacific plate along the developed fractures by the flexural bending prior to subduction. The low heat flow is thought to result from thermal blanket effect of the accretionary prism that overlies the cooled subducting slab by the hydrothermal circulations. To understand heat transfer in the landward region of the trench, a series of two-dimensional numerical models are constructed by considering hydrothermal circulations in the kinematically thickening accretionary prism that overlies the converging oceanic crust of the Pacific plate where hydrothermal circulations developed prior to subduction. The model calculations demonstrate no meaningful hydrothermal circulations when the reasonable bulk permeability of the accretionary prism(<10-14m2) is used; the thermal blanket effect significantly hinders the heat transfer, yielding only the heat flow of 10 mW/m2 in the landward region, much lower than the average of 30 mW/m2. This indicates that other mechanisms such as the expelled pore fluid by compaction of the accretionary prism play important roles in the heat transfer across the accretionary prism.

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Thermal regime around the Chile Triple Junction based on JAMSTEC MR18-06 cruise 'EPIC'

10.5194/egusphere-egu2020-6414 ◽

2020 ◽

Author(s):

Masataka Kinoshita ◽

Ryo Anma ◽

Yuka Yokoyama ◽

Kosuke Ohta ◽

Yusuke Yokoyama ◽

...

Keyword(s):

Heat Flow ◽

Sedimentation Rate ◽

Thermal Regime ◽

Triple Junction ◽

Accretionary Prism ◽

Age Dating ◽

Spreading Center ◽

Ridge Axis ◽

Ridge Subduction ◽

Chile Triple Junction

The Chile triple junction (CTJ) is a unique place where a spreading center of mid-ocean ridge is subducting near the Taitao peninsula. Around CTJ, presence of high heat flow on the continental slope and near-trench young granitic rocks on the Taitao peninsula suggests the thermal and petrological impact of subducting ridge on the continental side. The tectonic history of the southeast Pacific since early Cenozoic to the present suggests that ridge subduction continuously occurred along the Chile trench, which migrated northward.In January 2019, the MR18-06 cruise Leg 2 was conducted at CTJ, as a part of 'EPIC' expedition by using R.V Mirai of JAMSTEC. During the leg, we completed 4 SCS lines, 6 piston coring with heat flow measurements, 2 dredges, and underway geophysics observations, as well as deployment of 13 OBSs. Coring/heatflow sites were located across the ridge axis, HP5 on the seaward plateau of axial graben, HP1/HP2/HP6 on the axis, and HP3/HP7 on the forearc slope near the trench axis. The primary object of heat flow measurement at CTJ is to better constrain the thermal regime around CTJ by adding new data right above CTJ. The key question is whether CTJ is thermally dominated by ridge activity (magmatic, tectonic, and/or hydrothermal) or by subduction initiation (tectonic thickening, accretion, and/or erosion). The ultimate goal is to model the temperature at the plate interface from the heat flow and other data, and to infer how the thermal regime at CTJ contributes the seismogenic behavior at the M~9 megathrust zone. Onboard and post-cruise measurements include; bulk density, porosity, Vp, resistivity, CT imags, iTracks element scan, age dating, etc. Core saples seaward of ridge axis (HP5) has few turbidites with higher density (~2 g/cc) and low sedimentation rate (SR; 0.2 m/ky), whereas cores on the axis the density are turbidite dominant with lower (1.6~1.8 g/cc) and very high SR (1~3 m/ky). The accretionary prism (landward of trench) cores have the density of 1.6~1.7 g/cc and SR=0.5~1 m/ky. They suggest that the turbidite covers only the axial graben. Heat flow in the axial graben range 140-210 mW/m^2, which is lower than on the seaward plateau (370 mW/m^2). This apparent controversy may be due to lower magmatic activity and/or high sedimentation rate on the axis. The lower spreading rate (2.6 cm/yr one side) and the rapid convergent rate at the trench (7.2 cm/yr) may suppress sufficient magma supply or hydrothermal circulation. Heat flow on the accretionary prism (230 mW/m^2) is higher than borehole or BSR-derived heat flow (~<100 mW/m^2). It is suggestive of fluid upwelling along the decollement as proposed in the previous study. Some numerical thermal models will be presented to show the effect of ridge subduction.

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Localized High Heat Flow Anomaly at the Frontal Thrust in the Nankai Trough off Muroto: Relationship between Pressure and Permeability in a Deep Part of the Accretionary Prism

Journal of Geography (Chigaku Zasshi) ◽

10.5026/jgeography.120.224 ◽

2011 ◽

Vol 120 (1) ◽

pp. 224-236 ◽

Cited By ~ 2

Author(s):

Keiko FUJINO ◽

Masataka KINOSHITA

Keyword(s):

Heat Flow ◽

Nankai Trough ◽

Accretionary Prism ◽

High Heat ◽

Deep Part ◽

High Heat Flow

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Gas Hydrate Estimate in an Area of Deformation and High Heat Flow at the Chile Triple Junction

10.20944/preprints201810.0619.v1 ◽

2018 ◽

Author(s):

Lucía Villar-Muñoz ◽

Iván Vargas-Cordero ◽

Joaquim P. Bento ◽

Umberta Tinivella ◽

Francisco Fernandoy ◽

...

Keyword(s):

Heat Flow ◽

Marine Sediments ◽

Gas Hydrate ◽

Triple Junction ◽

High Heat ◽

Spreading Ridge ◽

High Heat Flow ◽

Geothermal Gradients ◽

Free Gas ◽

Chile Triple Junction

Large amounts of gas hydrate are present in marine sediments offshore Taitao Peninsula, near the Chile Triple Junction. Here, marine sediments on the forearc contain carbon that is converted to methane in a zone of very high heat flow and intense rock deformation above the downgoing oceanic spreading ridge separating the Nazca and Antarctic plates. This regime enables vigorous fluid migration. Here we present an analysis of the spatial distribution, concentration, estimate of gas phases (gas hydrate and free gas) and geothermal gradients in the accretionary prism and forearc sediments offshore Taitao (45.5° - 47° S). Velocity analysis of Seismic Profile RC2901-751 indicates gas hydrate concentration values <10% of the total rock volume, and extremely high geothermal gradients (<190 °Ckm-1). Gas hydrates are located in shallow sediments (90-280 meters below the seafloor). The large amount of hydrate and free gas estimated (7.21x1011 m3 and 4.1x1010 m3, respectively), the high seismicity, the mechanically unstable nature of the sediments, and the anomalous geothermal conditions, set the stage for potential massive releases of methane to the ocean mainly through hydrate dissociation and/or migration directly to the seabed through faults. We conclude that the Chile Triple Junction is an important methane seepage area and should be the focus of novel geological and ecological research.

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Gas Hydrate Estimate in an Area of Deformation and High Heat Flow at the Chile Triple Junction

Geosciences ◽

10.3390/geosciences9010028 ◽

2019 ◽

Vol 9 (1) ◽

pp. 28 ◽

Cited By ~ 2

Author(s):

Lucía Villar-Muñoz ◽

Iván Vargas-Cordero ◽

Joaquim Bento ◽

Umberta Tinivella ◽

Francisco Fernandoy ◽

...

Keyword(s):

Heat Flow ◽

Marine Sediments ◽

Gas Hydrate ◽

Triple Junction ◽

High Heat ◽

Spreading Ridge ◽

High Heat Flow ◽

Geothermal Gradients ◽

Free Gas ◽

Chile Triple Junction

Large amounts of gas hydrate are present in marine sediments offshore Taitao Peninsula, near the Chile Triple Junction. Here, marine sediments on the forearc contain carbon that is converted to methane in a regime of very high heat flow and intense rock deformation above the downgoing oceanic spreading ridge separating the Nazca and Antarctic plates. This regime enables vigorous fluid migration. Here, we present an analysis of the spatial distribution, concentration, estimate of gas-phases (gas hydrate and free gas) and geothermal gradients in the accretionary prism, and forearc sediments offshore Taitao (45.5°–47° S). Velocity analysis of Seismic Profile RC2901-751 indicates gas hydrate concentration values <10% of the total rock volume and extremely high geothermal gradients (<190 °C·km−1). Gas hydrates are located in shallow sediments (90–280 m below the seafloor). The large amount of hydrate and free gas estimated (7.21 × 1011 m3 and 4.1 × 1010 m3; respectively), the high seismicity, the mechanically unstable nature of the sediments, and the anomalous conditions of the geothermal gradient set the stage for potentially massive releases of methane to the ocean, mainly through hydrate dissociation and/or migration directly to the seabed through faults. We conclude that the Chile Triple Junction is an important methane seepage area and should be the focus of novel geological, oceanographic, and ecological research.

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High heat flow under Deccan Traps causes uplift of Western India

Nature India ◽

10.1038/nindia.2009.87 ◽

2009 ◽

Keyword(s):

Heat Flow ◽

High Heat ◽

Deccan Traps ◽

Western India ◽

High Heat Flow

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THE DISCOVERY OF COLD SEEP CARBONATE IN SHUANGHU REGION, QIANGTANG BASIN AND ITS IMPLICATIONS FOR GAS HYDRATE ACCUMULATION

Marine Geology & Quaternary Geology ◽

10.3724/sp.j.1140.2013.02105 ◽

2014 ◽

Vol 33 (2) ◽

pp. 105-110

Author(s):

Yanju LI ◽

Jiannan SHI ◽

Lidong ZHU ◽

Xiugen FU ◽

Wenguang YANG ◽

...

Keyword(s):

Gas Hydrate ◽

Cold Seep ◽

Qiangtang Basin ◽

Seep Carbonate

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High heat flow at the SW passive margin of the Gulf of California

Terra Nova ◽

10.1111/ter.12569 ◽

2021 ◽

Author(s):

Rosa Maria Prol‐Ledesma ◽

Juan Luis Carrillo De La Cruz ◽

Marco‐Antonio Torres‐Vera ◽

Alejandro Estradas‐Romero

Keyword(s):

Heat Flow ◽

Gulf Of California ◽

High Heat ◽

Passive Margin ◽

High Heat Flow

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A heat-flow reconnaissance of southeastern Alaska

Canadian Journal of Earth Sciences ◽

10.1139/e85-040 ◽

1985 ◽

Vol 22 (3) ◽

pp. 416-421 ◽

Cited By ~ 8

Author(s):

J. H. Sass ◽

L. A. Lawver ◽

R. J. Munroe

Keyword(s):

Heat Flow ◽

Plate Boundary ◽

Thermal Spring ◽

High Heat ◽

Transform Fault ◽

High Heat Flow ◽

Queen Charlotte Islands ◽

Late Tertiary ◽

The Mean ◽

Strain Heating

Heat flow was measured at nine sites in crystalline and sedimentary rocks of southeastern Alaska. Seven of the sites, located between 115 and 155 km landward of the Queen Charlotte – Fairweather transform fault, have an average heat flow of 59 ± 6 mW m−2. This value is significantly higher than the mean of 42 mW m−2 in the coastal provinces between Cape Mendocino and the Queen Charlotte Islands, to the south, and is lower than the mean of 72 ± 2 mW m−2 for 81 values within 100 km of the San Andreas transform fault, even farther south. This intermediate value suggests the absence of significant heat sinks associated with Cenozoic subduction and of heat sources related to either late Cenozoic tectono-magmatic events or significant shear-strain heating. At Warm Springs Bay, 75 km from the plate boundary, an anomalously high heat flow of 150 mW m−2 can most plausibly be ascribed to the thermal spring activity from which its name is derived. At Quartz Hill, 240 km landward of the plate boundary, a value of 115 mW m−2 might indicate a transition to a province of high heat flow resulting from late Tertiary and Quaternary extension and volcanism.

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