Crustal and Thermal Heterogeneities Across the Fram Strait and the Svalbard Margin

Dumais, Marie-Andrée; Gernigon, Laurent; Olesen, Odleiv; Lim, Anna; Johansen, Ståle Emil; Brönner, Marco

doi:10.1029/2022tc007302

Cited by 7 publications

(5 citation statements)

References 129 publications

(316 reference statements)

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“…The Molloy Ridge and the Molloy Transform Fault and Fracture Zone System was formed well after the opening of the Norwegian-Greenland Sea ∼56 Ma ago (Talwani and Eldholm, 1977). Engen et al (2008) suggest an early age of ∼19.6 Ma for the start of seafloor spreading at the present Molloy Ridge, which coincides with the recent modelling results suggesting 20 Ma for the opening of the Arctic-Atlantic Gateway (Dumais et al, 2021). In this region, the oceanic crust is thin, and the Moho is shallow (<5 km below seafloor) (Czuba et al, 2005).…”

Section: Introductionsupporting

confidence: 89%

“…Based on various palaeo-reconstruction models for the region, the Molloy Ridge was established after 20 Ma (Dumais et al, 2021) and therefore the oldest post rift sediments belong to this age. Indeed, the oldest age for the sediments lying right above the syn-rift rotated blocks and extending all the way to the STF can be assigned to be approximately ∼17-18 Ma using similar sedimentation rates and shelf progradation observations as proposed by Hustoft et al (2009) and Mattingsdal et al (2014).…”

Section: The Origin Of the Seeping Gas In Molloy Ridgementioning

confidence: 99%

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Acoustic evidence of hydrocarbon release associated with the Spitsbergen Transform Fault, north of the Molloy Ridge, Fram Strait

Chand,

Knies,

Geissler

et al. 2024

Front. Earth Sci.

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Hydrocarbon gases formed from biotic and abiotic processes are released through the seafloor at different locations around the world. They have been widely observed directly in video and photo data, and indirectly on echosounder data. Even though biotic gas generation is a very common process, abiotic gas generation is limited to regions where serpentinization of ultramafic rocks occur. Indications of abiotic gas occurrences are therefore sparse and much speculated upon. Here, we investigated the Spitsbergen Transform Fault, the Molloy Ridge, the Molloy Deep, and the Molloy Transform Fault/Fracture Zone, (a transform fault-bounded pull-a-part region offshore western Svalbard) where both processes may be active. Multiple acoustic gas flares, ∼1,770 and ∼3355 m high above the seafloor (tallest ever recorded), were observed indicating active migration and seepage of hydrocarbons. The proximity to the mid oceanic ridge and the documented high heat flow suggests the influence of high temperatures on organic-rich sedimentary deposits. Deep seismic data and other geological information available indicate that the main source of gas could be from thermal cracking of either pre- or syn-rift source rock organic material, potentially mixed with methane from serpentinization of mantle rocks (peridotites). Correlation with seismic stratigraphy from Ocean Drilling Program (ODP) Sites 910 and 912 on the adjacent Yermak Plateau suggests that the sedimentary source rocks may be present at the northern flank of the Molloy Ridge and within the deep graben along the Spitsbergen Transform Fault. The ∼3 km thick sedimentary succession in high heat flow zones within the transform fault and the active bounding faults allow generation and migration of hydrocarbons to the seafloor and sustains present day seepage.

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Section: Introductionsupporting

confidence: 89%

Section: The Origin Of the Seeping Gas In Molloy Ridgementioning

confidence: 99%

Acoustic evidence of hydrocarbon release associated with the Spitsbergen Transform Fault, north of the Molloy Ridge, Fram Strait

Chand,

Knies,

Geissler

et al. 2024

Front. Earth Sci.

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“…This interpretation is supported by the available focal mechanism solutions provided by the ISC bulletin (Bondár & Storchak, 2011), showing a gradual change from the strike‐slip pattern along the MTF all the way to normal faulting in the outside corner (Figures 6 and 8b). Additionally, a strong low‐gravity free‐air anomaly is visible in this corner (Figure 8b), which can correspond either to the spreading center as seen along the MR, MTF and along the KR to the south, but also reflect the sedimentary infill (Dumais et al., 2022; gravity data from Sandwell et al., 2014). The earthquake activity ceases roughly at the newly revised continental‐oceanic margin boundary (Dumais, et al., 2022; COB line in Figures 6 and 8b) and is most likely limited to the oceanic portion of the crust.…”

Section: Discussionmentioning

confidence: 99%

“…Additionally, a strong low‐gravity free‐air anomaly is visible in this corner (Figure 8b), which can correspond either to the spreading center as seen along the MR, MTF and along the KR to the south, but also reflect the sedimentary infill (Dumais et al., 2022; gravity data from Sandwell et al., 2014). The earthquake activity ceases roughly at the newly revised continental‐oceanic margin boundary (Dumais, et al., 2022; COB line in Figures 6 and 8b) and is most likely limited to the oceanic portion of the crust.…”

Section: Discussionmentioning

confidence: 99%

Local Seismicity and Sediment Deformation in the West Svalbard Margin: Implications of Neotectonics for Seafloor Seepage

Domel,

Plaza‐Faverola,

Schlindwein

et al. 2023

Geochem Geophys Geosyst

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In the Fram Strait, mid‐ocean ridge spreading is represented by the ultra‐slow system of the Molloy Ridge, the Molloy Transform Fault and the Knipovich Ridge. Sediments on oceanic and continental crust are gas charged and there are several locations with documented seafloor seepage. Sedimentary faulting shows recent stress release in the sub‐surface, but the drivers of stress change and its influence on fluid flow are not entirely understood. We present here the results of an 11‐month‐long ocean bottom seismometer survey conducted over the highly faulted sediment drift northwards from the Knipovich Ridge to monitor seismicity and infer the regional state of stress. We obtain a detailed earthquake catalog that improves the spatial resolution of mid‐ocean ridge seismicity compared with published data. Seismicity at the Molloy Transform Fault is occurring southwards from the bathymetric imprint of the fault, as supported by a seismic profile. Earthquakes in the northern termination of the Knipovich Ridge extend eastwards from the ridge valley, which together with syn‐rift faulting identified in seismic reflection data, suggests that a portion of the currently active spreading center is buried under sediments away from the bathymetric expression of the rift valley. This hints at the direct link between crustal rifting processes and faulting in shallow sediments. Two earthquakes occur close to the seepage system of the Vestnesa Ridge further north from the network. We suggest that deeper rift structures, reactivated by gravity and/or post‐glacial subsidence, may lead to accommodation of stress through shallow extensional faults, therefore impacting seepage dynamics.

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“…The Woodfjorden area is located about 200 km east of the NE Atlantic-Arctic Mid Ocean Ridge system and part of the European-Eurasian continent-ocean boundary system. The Cenozoic evolution of the area has been debated for decades with various interpretations put forward by, for instance, Vågnes and Amundsen (1993), Dörr et al (2013), Minakov (2018), Farnsworth et al (2020) and Dumais et al (2022).…”

Section: Geological Setting Of the Woodfjorden Areamentioning

confidence: 99%

Multi-disciplinary geoscientific expedition to Woodfjorden, NW Svalbard: Field sites, methods, and preliminary results

Senger,

Betlem,

Helland-Hansen

et al. 2024

Czech Polar Rep.

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The Woodfjorden area of northern Spitsbergen (NW Svalbard) offers access to the world’s northernmost onshore thermal springs, extinct Pleistocene alkali basaltic volcanoes and Miocene flood basalts including extensive hyaloclastites. In July 2023, we undertook a 14-day international multi-disciplinary geoscientific expedition to Woodfjorden-Bockfjorden to investigate the Cenozoic geological evolution of the area. The expedition objectives spanned a wide range of scientific topics from sampling of fluids and gas in the thermal springs to constraining the lithosphere by acquiring magnetotelluric data and sampling volcanic rocks. More specifically, we have 1) conducted gas, fluid and travertine sampling at the thermal springs of Gygrekjelda, Jotunkjeldene and Trollkjeldene, 2) mapped and sampled the Quaternary volcanic centers at Sverrefjellet and Halvdanpiggen, 3) sampled the Miocene basalts of the Seidfjellet Formation along seven profiles plus the underlying Devonian sedimentary rocks, 4) acquired magnetotelluric data at 12 stations along both coasts of Woodfjorden and Bockfjorden and 5) collected extensive digital geological data (digital outcrop models and photospheres) using unmanned aerial vehicles (UAVs; also known as drones). The collected samples are currently being analyzed for, amongst others, petrology, geochemistry and geochronology. In this contribution, we report on the expedition’s background, scientific objectives and present selected preliminary results such as field parameters from the thermal springs (temperature, pH, electrical conductivity), magnetic susceptibility of volcanic rocks and digital outcrop models plus photospheres.

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Crustal and Thermal Heterogeneities Across the Fram Strait and the Svalbard Margin

Cited by 7 publications

References 129 publications

Acoustic evidence of hydrocarbon release associated with the Spitsbergen Transform Fault, north of the Molloy Ridge, Fram Strait

Acoustic evidence of hydrocarbon release associated with the Spitsbergen Transform Fault, north of the Molloy Ridge, Fram Strait

Local Seismicity and Sediment Deformation in the West Svalbard Margin: Implications of Neotectonics for Seafloor Seepage

Multi-disciplinary geoscientific expedition to Woodfjorden, NW Svalbard: Field sites, methods, and preliminary results

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