|Range of values|
|Range of values|
|known||locations where gas hydrate has been confirmed|
|inferred||location where gas hydrate indicators are recognized, but no visual confirmation has been made|
|BSR||bottom simulating reflections defined based on single or multichannel seismic data|
|carbonate indicators||presence of authigenic carbonate and carbonate formations inferred by reference authors to indicate hydrate|
|chlorinity||refers to chloride anomalies associated with freshening of pore waters, which occurs when gas hydrate dissociates in sediments and dilutes the pore waters|
|compliance||indicates that the analysis of seismic compliance contributed to the inference of subseafloor gas hydrates|
|deepwater seepage||describes a seafloor methane seep within the pressure and temperature conditions for gas hydrate stability, meaning that gas hydrate is inferred to be present beneath the sea floor near the seep|
|Directly observed||for known gas hydrates, the hydrate has been observed at the seafloor or recovered in cores|
|electromagnetic||refer to controlled source electromagnetic (EM) surveys or similar areal surveys using other EM technologies|
|gas concentrations||refer to characteristics of recovered sediments, which may include large amounts of gas upon recovery or may generate large volumes of gas as gas hydrate dissociation evolves|
|gas escape features||indicate indirect seafloor evidence (pockmarks) for gas escape in areas where gas hydrate should be stable|
|gravity||refers to the use of gravity anomalies to constrain gas hydrate locations|
|IR anomalies||indicates thermal infrared imaging of recovered cores to highlight cold spots associated with the presence or dissociation of gas hydrate in sediments|
|resistivity||Elevated resistivity values are the most commonly used well log indicator to infer gas hydrates in this database, and "resistivity" is used when this was the key measurement that contributed to the inference of gas hydrate|
|seafloor morphology||indicates the low hummocks sometimes associated with hydrate-cored seafloor mounds|
|sediment texture||denotes observations of the characteristic moussey texture of recovered sediment cores following gas hydrate dissociation|
|sediment structures||denotes sedimentary structures interpreted in the reference as being typical of gas hydrate provinces|
|seismic||seismic analyses other than bottom simulating reflections (BSRs); analyses may include seismic attributes, amplitude versus offset, analysis of frequency characteristics indicating gassy sediments, velocity analyses, or P-wave measurements on recovered cores|
|other||not fitting into any of the other defined categories|
|well logs||inference based on the analysis of conventional wireline logging records or those obtained via logging while drilling|
The database has been compiled and maintained since approximately 1990 by scientists in the USGS Gas Hydrates Project. The database was initiated at the predecessor to the Pacific Coastal and Marine Science Center in the earliest 1990s. The database has been maintained by numerous personnel at the Woods Hole Coastal and Marine Science Center since ~2010.
To provide information (both textual and geographic coordinates) about the locations of known (visually verified) gas hydrates and inferred gas hydrates in permafrost and marine settings based on compilation of data from the English-language scientific literature published since the 1970s.
Are there legal restrictions on access or use of the data?
Access_Constraints: None. Please see 'Distribution Info' for details.
Use_Constraints:Not to be used for planning exact location of gas hydrate studies. Users are advised to consult the original studies cited here to verify locations and learn more details about the gas hydrate discoveries. Users are also advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations.
Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
|Data format:||The dataset contains the XLSX format of the data, a browse graphic, and associated FGDC CSDGM metadata. in format XLXS (version Microsoft Excel Office 365) Size: 1|
To utilize these data, the user must have software capable of reading Excel files and displaying a JPEG file.