Methane hydrate in the global organic carbon cycle

K.A. Kvenvolden

doi:10.1046/j.1365-3121.2002.00414.x

Home/Archive/USGS

USGS · 70024211

Methane hydrate in the global organic carbon cycle

K.A. Kvenvolden

View original source ↗Export metadata ↓

Abstract

The global occurrence of methane hydrate in outer continental margins and in polar regions, and the magnitude of the amount of methane sequestered in methane hydrate suggest that methane hydrate is an important component in the global organic carbon cycle. Various versions of this cycle have emphasized the importance of methane hydrate, and in the latest version the role of methane hydrate is considered to be analogous to the workings of an electrical circuit. In this circuit the methane hydrate is a condenser and the consequences of methane hydrate dissociation are depicted as a resistor and inductor, reflecting temperature change and changes in earth surface history. These consequences may have implications for global change including global climate change.

Explore related subjects

Terra Nova Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

K.A. Kvenvolden. 2002-10-21. Methane hydrate in the global organic carbon cycle. https://doi.org/10.1046/j.1365-3121.2002.00414.x

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2025

Finding the hidden orogeny – The Proterozoic polymetamorphic history of northern New Mexico

Pressure–temperature–time-deformation histories provide key constraints on orogenic processes but can be affected by later overprinting. This is exemplified in the Proterozoic orogenic belts of southwestern Laurentia where competing tectonic models involve either a single progressive Mesoproterozoic event, the Picuris orogeny, or a polyorogenic history that also includes the ~1.65 Ga Mazatzal orogeny. We address this controversy with structural analysis and petrochronology in the type locality of the Picuris orogeny. Xenotime and monazite domains associated with the greenschist-facies axial planar fabric of early F 1 folds yield 1644 ± 11 Ma (xenotime) and 1641 ± 15 Ma (monazite) ages and 450°C–482°C temperatures recording metamorphism and shortening associated with the Mazatzal orogeny. This Palaeoproterozoic greenschist-facies assemblage was overprinted by higher grade, protracted (1470–1350 Ma) tectonism that included the Picuris orogeny. Our results document the complex polyphase crustal assembly of Laurentia and highlight how petrochronology can effectively see through higher grade overprints to identify a more complete orogenic evolution.

New Mexico↗

USGS2024

Lead isotopes constrain Precambrian crustal architecture, thermal history, and lithospheric foundering in Laurentia

Laurentia (ancestral North America) records nearly 4 billion years of crustal evolution. Here, a newly compiled continental-scale Pb isotopic database is used to evaluate the Precambrian crustal evolution of Laurentia. Pb model ages yield a 2.7 Ga peak, a 2.5–1.8 Ga minimum and 1.8–0.9 Ga continuum. Pb model ages yield thermochronometric data and track crustal growth via arc-related magmatism and accretionary orogenesis. Model 232 Th/ 204 Pb and 238 U/ 204 Pb broadly correlate with mapped crustal domains. More homogeneous and less radiogenic 238 U/ 204 Pb and 232 Th/ 238 U after 2.7 Ga suggests a shift to more juvenile sources, loss of early isotopic reservoirs and greater crustal reworking. U and Th are fractionated from Pb in Proterozoic orogens with abundant ferroan and anorthosite–mangerite–charnockite–granite(AMCG)-suite magmatism. This fractionation suggests the removal of Pb-rich lower crust, supporting petrogenetic models involving lithospheric foundering and magmatic underplating. Lithospheric thinning and associated magmatism may have contributed to high middle Proterozoic geothermal gradients.

Terra Nova↗

USGS2013

Caveats on tomographic images

Geological and geodynamic models of the mantle often rely on joint interpretations of published seismic tomography images and petrological/geochemical data. This approach tends to neglect the fundamental limitations of, and uncertainties in, seismic tomography results. These limitations and uncertainties involve theory, correcting for the crust, the lack of rays throughout much of the mantle, the difficulty in obtaining the true strength of anomalies, choice of what background model to subtract to reveal anomalies, and what cross-sections to select for publication. The aim of this review is to provide a relatively non-technical summary of the most important of these problems, collected together in a single paper, and presented in a form accessible to non-seismologists. Appreciation of these issues is essential if final geodynamic models are to be robust, and required by the scientific observations.

Terra Nova↗