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norskBlar i forfatter "Vadakkepuliyambatta, Sunil"
Viser treff 1-20 av 28
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Abiotic methane from ultraslow-spreading ridges can charge Arctic gas hydrates
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-05)Biotic gas generation from the degradation of organic carbon in marine sediments supplies and maintains gas hydrates throughout the world’s oceans. In nascent, ultraslow-spreading ocean basins, methane generation can also be abiotic, occurring during the high-temperature (>200 °C) serpentinization of ultramafic rocks. Here, we report on the evolution of a growing Arctic gas- and gas hydrate–charged ... -
Bottom-simulating reflector dynamics at Arctic thermogenic gas provinces: An example from Vestnesa Ridge, offshore west Svalbard
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06) -
Constraints on oceanic methane emissions west of Svalbard from atmospheric in situ measurements and Lagrangian transport modeling
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-10) -
Controls on gas hydrate system evolution in a region of active fluid flow in the SW Barents Sea
(Journal article; Tidsskriftartikkel, 2015-09)The location and stability of gas hydrates in the SW Barents Sea is poorly constrained due to complex geological, geochemical, and geophysical conditions, including poor controls on regional heat flow and gas chemistry. Understanding the stability of gas hydrates in this region is important, as recent studies suggest destabilizing hydrates may lead to methane discharge into the ocean and possibly ... -
Crustal processes sustain Arctic abiotic gas hydrate and fluid flow systems
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-30)The Svyatogor Ridge and surroundings, located on the sediment-covered western flank of the Northern Knipovich Ridge, host extensive gas hydrate and related fluid flow systems. The fluid flow system here manifests in the upper sedimentary sequence as gas hydrates and free gas, indicated by bottom simulating reflections (BSRs) and amplitude anomalies. Using 2D seismic lines and bathymetric data, we ... -
Deglacial bottom water warming intensified Arctic methane seepage in the NW Barents Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-09)Changes in the Arctic climate-ocean system can rapidly impact carbon cycling and cryosphere. Methane release from the seafloor has been widespread in the Barents Sea since the last deglaciation, being closely linked to changes in pressure and bottom water temperature. Here, we present a post-glacial bottom water temperature record (18,000–0 years before present) based on Mg/Ca in benthic foraminifera ... -
Diverse gas composition controls the Moby-Dick gas hydrate system in the Gulf of Mexico
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-12)In marine basins, gas hydrate systems are usually identified by a bottom simulating reflection (BSR) that parallels the seafloor and coincides with the base of the gas hydrate stability zone (GHSZ). We present a newly discovered gas hydrate system, Moby-Dick, located in the Ship Basin in the northern Gulf of Mexico. In the seismic data, we observe a channel-levee complex with a consistent phase ... -
Dynamic and history of methane seepage in the SW Barents Sea: new insights from Leirdjupet Fault Complex
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-23)Methane emissions from Arctic continental margins are increasing due to the negative effect of global warming on ice sheet and permafrost stability, but dynamics and timescales of seafloor seepage still remain poorly constrained. Here, we examine sediment cores collected from an active seepage area located between 295 and 353 m water depth in the SW Barents Sea, at Leirdjupet Fault Complex. The ... -
Evidence of Arctic methane emissions across the mid-Pleistocene
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-08)During the Pleistocene, Earth’s climate changed dramatically. The mid-Pleistocene transition (MPT; ~1.3–0.7 million years (Ma)) featured an important ice volume increase at both poles. The evolution of large Arctic ice sheets caused the sequestration of methane as free gas and hydrates in subseabed sediments. Ice volume changes, associated with variable pressures and temperatures, perturbed those ... -
Evidences of accelerating the increase in the concentration of methane in the atmosphere after 2014: satellite data for the Arctic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017)Проанализированы результаты спутникового зондирования с помощью европейского орбитального интерферометра IASI/MetOP-A и алгоритма обработки данных, разработанного в NOAA. Спутниковые измерения для умеренных и высоких широт Северного полушария дают рост скорости концентрации метана от 4–9 ppbv/год (частей на миллиард по объему) в 2010–2013 гг. до 12–17 ppbv/год в 2015–2016 гг. Глобальные оценки на ... -
Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-07)We find that summer methane (CH4) release from seabed sediments west of Svalbard substantially increases CH4 concentrations in the ocean but has limited influence on the atmospheric CH4 levels. Our conclusion stems from complementary measurements at the seafloor, in the ocean, and in the atmosphere from land-based, ship and aircraft platforms during a summer campaign in 2014. We detected high ... -
Geological controls on fluid flow and gas hydrate pingo development on the Barents Sea margin
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-16)In 2014, the discovery of seafloor mounds leaking methane gas into the water column in the northwestern Barents Sea became the first to document the existence of non‐permafrost related gas hydrate pingos (GHP) on the Eurasian Arctic shelf. The discovered site is given attention because the gas hydrates occur close to the upper limit of the gas hydrate stability, thus may be vulnerable to climatic ... -
Handwritten letters and photo albums linking geoscientists with school classes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-14)Was something lost as society moved away from “traditional” media such as handwritten letters and photography and into the digital age? Some of the authors remember this age fondly, and we wanted to see if this fondness could be translated into a science dialogue project with school classes. We designed and carried out a communication process with four classes at different schools across Europe. ... -
The history and future trends of ocean warming-induced gas hydrate dissociation in the SW Barents Sea
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-01-13)The Barents Sea is a major part of the Arctic where the Gulf Stream mixes with the cold Arctic waters. Late Cenozoic uplift and glacial erosion have resulted in hydrocarbon leakage from reservoirs, evolution of fluid flow systems, shallow gas accumulations, and hydrate formation throughout the Barents Sea. Here we integrate seismic data observations of gas hydrate accumulations along with gas hydrate ... -
Hydrate occurrence in Europe: A review of available evidence
(Journal article; Tidsskriftartikkel, 2019-08-16)Large national programs in the United States and several Asian countries have defined and characterised their marine methane hydrate occurrences in some detail, but European hydrate occurrence has received less attention. The European Union-funded project “Marine gas hydrate – an indigenous resource of natural gas for Europe” (MIGRATE) aimed to determine the European potential inventory of exploitable ... -
Hydrocarbon leakage driven by quaternary glaciations in the Barents Sea based on 2D basin and petroleum system modeling
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-25)The Barents Sea has experienced intense erosion throughout the Cenozoic due to uplift and repeated episodes of glaciation. This, in turn, has driven large pressure and temperature fluctuations in the sediment substrate along with rearrangement of thermogenic oil and gas accumulations. As a result, some hydrocarbon fields have relatively shallow depths, and natural gas release is widespread. This ... -
Ice-sheet-driven methane storage and release in the Arctic
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-07)It is established that late-twentieth and twenty-first century ocean warming has forced dissociation of gas hydrates with concomitant seabed methane release. However, recent dating of methane expulsion sites suggests that gas release has been ongoing over many millennia. Here we synthesize observations of B1,900 fluid escape features—pockmarks and active gas flares—across a previously glaciated ... -
Impact of tides and sea-level on deep-sea Arctic methane emissions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-09)Sub-sea Arctic methane and gas hydrate reservoirs are expected to be severely impacted by ocean temperature increase and sea-level rise. Our understanding of the gas emission phenomenon in the Arctic is however partial, especially in deep environments where the access is difficult and hydro-acoustic surveys are sporadic. Here, we report on the first continuous pore-pressure and temperature measurements ... -
Lack of detectable chemosynthesis at a sponge dominated subarctic methane seep
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-20)We used high-resolution imagery within a Geographic Information System (GIS), free gas and porewater analyses and animal bulk stable isotope measurements to characterize the biotic and abiotic aspects of the newly discovered Vestbrona Carbonate Field (VCF) seep site on the Norwegian shelf (63°28′N, 6° 31′E, ∿270 m water depth). Free gas was mainly composed of microbial methane. Sediment porewater ... -
Methane at Svalbard and over the European Arctic Ocean
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-05)Methane (CH<sub>4</sub>) is a powerful greenhouse gas. Its atmospheric mixing ratios have been increasing since 2005. Therefore, quantification of CH<sub>4</sub> sources is essential for effective climate change mitigation. Here we report observations of the CH<sub>4</sub> mixing ratios measured at the Zeppelin Observatory (Svalbard) in the Arctic and aboard the research vessel (RV) Helmer Hanssen ...
