Dependence of sedimentation behavior on pore-fluid chemistry for sediment collected offshore South Korea during the Second Ulleung Basin Gas Hydrate Expedition, UBGH2

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Frequently anticipated questions:

What does this data set describe?

Title:
Dependence of sedimentation behavior on pore-fluid chemistry for sediment collected offshore South Korea during the Second Ulleung Basin Gas Hydrate Expedition, UBGH2
Abstract:
One goal of Korea’s Second Ulleung Basin Gas Hydrate Expedition, UBGH2, is to examine geotechnical properties of the marine sediment associated with methane gas hydrate occurrences found offshore eastern Korea in the Ulleung Basin, East Sea. Methane gas hydrate is a naturally occurring crystalline solid that sequesters methane in individual molecular cages formed by a lattice of water molecules. Offshore Korea, gas hydrate is found in thin, coarse-grained sediment layers that are interbedded with fine-grained sediment. Methane gas hydrate is a potential energy resource, but whether extracting methane from gas hydrate in these layered marine environments is technically and economically viable remains an open research topic as of 2019. This data release provides insight about a poorly quantified aspect of this process: the reaction of fine-grained sediment particles (fines) to the change in pore water chemistry that occurs when methane is extracted from gas hydrate. Fines are an issue for production because they can get resuspended in the flow of fluid and gas toward an extraction well. As fines move, they can cluster and subsequently clog pore throats in the sediment, reducing permeability (which controls how easily methane can flow toward the extraction well). The type of fine-grained particle and the chemistry of the surrounding pore water are the two main factors in determining the cluster structure (the size and fabric of the cluster) and the cluster formation and settling rates. Data in this study provide insight into both factors.
Fine particles interact with each other primarily in response to electrical forces, and changes in pore water chemistry can significantly alter how those forces are communicated between particles. In marine systems, in situ pore water is an electrically conductive brine. As gas hydrate dissociates, however, fresh water is released along with the methane, making the pore water less conductive. Depending on the type of fine-grained particles involved, the pore water chemistry change enhances or diminishes the clustering and changes the rates at which the clusters form and settle.
For this data release, specimens from the UBGH2 expedition were observed during sedimentation (settling) tests in pore fluids of differing chemistry. The results included in this data release can (1) provide insight into the types of fines present, which can be difficult to quantify if using the more standard x-ray diffraction method for identifying fines and (2) indicate whether the in situ fines are likely to increase or decrease their capacity to clog pore throats as the pore water transitions from higher to lower salinity during gas hydrate dissociation.
Supplemental_Information:
In addition to funding from the U.S. Geological Survey Gas Hydrate Project, this work is sponsored in part by the Department of Energy (DOE) through interagency agreements (DE-FE0026166 and DE-FE0023495) and a DOE grant awarded to Louisiana State University (DE-FE0028966). More information about the project can be found at: https://www.netl.doe.gov/research/oil-and-gas/project-summaries/methane-hydrate/fe0028966-lsu-fe0026166-usgs. This work is also part of ongoing work related to the UBGH2 Expedition, offshore Korea. Links to related data and publications within the UBGH2 project are collected in the USGS Energy Program website: https://energy.usgs.gov/GeneralInfo/EnergyNewsroomAll/TabId/770/ArtMID/3941/ArticleID/810/Korean-National-Gas-Hydrate-Program-Second-Ulleung-Basin-Gas-Hydrate-Drilling-Expedition-.aspx, and published papers from the 2013 special volume of the Journal of Marine and Petroleum Geology dedicated to the UBGH2 Expedition are listed at the journal website: https://www.sciencedirect.com/journal/marine-and-petroleum-geology/vol/47/suppl/C.
  1. How might this data set be cited?
    Jang, Junbong, Stern, Laura A., Waite, William F., Cao, Shuang C., Jung, Jongwon, and Lee, Joo Yong, 20200116, Dependence of sedimentation behavior on pore-fluid chemistry for sediment collected offshore South Korea during the Second Ulleung Basin Gas Hydrate Expedition, UBGH2: data release DOI:10.5066/P9UJOYVR, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Jang, J., Stern, L.A., Waite, W.F., Cao, S.C., Jung, J., and Lee, J.Y., 2020, Dependence of sedimentation behavior on pore-fluid chemistry for sediment collected offshore South Korea during the Second Ulleung Basin Gas Hydrate Expedition, UBGH2: U.S. Geological Survey data release, https://doi.org/10.5066/P9UJOYVR.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: 130.2664
    East_Bounding_Coordinate: 130.8952
    North_Bounding_Coordinate: 37.0160
    South_Bounding_Coordinate: 36.7118
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5d52d182e4b01d82ce8e26f1?name=UBGH2_Sedimentation_BrowseGraphic.png (PNG)
    Four sediment settling tubes, imaged at the end of the sedimentation test for UBGH2-6C-6P. From left to right, the settling fluid is: freshened pore water (DWF), dissolved salt water (DSW), 2-Molar brine and sodium hexametaphosphate ((NaPO3)6). The accumulation and depositional interfaces tracked in this data release are defined as follows: accumulation interface (blue arrows at the far left and right) separates the settled particles from the overlying particles that have yet to settle; the depositional interface (red arrows) separates the cloudy, particle-filled fluid from the overlying clear fluid out of which the particles have already settled.
    https://www.sciencebase.gov/catalog/file/get/5d52d182e4b01d82ce8e26f1?name=UBGH2_Sedimentation_ExamplePlot.png (PNG)
    Sedimentation dependence on pore fluid chemistry for UBGH2-6C-6P (Depositional interface, open symbols; Accumulation interface, solid symbols).
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 09-Jul-2010
    Ending_Date: 30-Sep-2010
    Currentness_Reference:
    ground condition of the field activity when the samples were collected
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set.
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.00001. Longitudes are given to the nearest 0.00001. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Meters below sea floor
      Depth_Resolution: 1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    UBGH2_Sedimentation_Data
    Depositional and accumulated sediment interface heights of UBGH2 (Ulleung Basin, offshore Korea) sediment specimens allowed to settle in various fluids. (Source: U.S. Geological Survey)
    Site
    Site: UBGH2 site name designation. Format is: Expedition Name (UBGH2)-Site Number (2-2_2 or 2-6) and Hole Designation Letter (B or C) within that site. (Source: Korea Institute of Geoscience and Mineral Resources (KIGAM)) Character set (text).
    Core
    CoreID: Unique identifier given to each collected sediment core at the designated site. (Source: Shipboard science party, D/V Fugro Synergy) Character set (text).
    Latitude (degrees, minutes, seconds)
    Latitude_DMS: Latitude coordinate, in degrees (°) minutes (’) decimal seconds (”), of the sample’s location. North latitude recorded as positive values. (Source: Shipboard science party, D/V Fugro Synergy)
    Range of values
    Minimum:36°42'42.4"
    Maximum:37°00'57.6"
    Units:degrees (°) minutes (’) decimal seconds (”)
    Longitude (degrees, minutes, seconds)
    Longitude_DMS: Longitude coordinate, in degrees (°) minutes (’) decimal seconds (”), of the sample’s location. East longitude is recorded as positive values. (Source: Shipboard science party, D/V Fugro Synergy)
    Range of values
    Minimum:130°15'59.0"
    Maximum:130°53'42.6"
    Units:degrees (°) minutes (’) decimal seconds (”)
    Latitude (decimal degrees)
    Lat_DD: Latitude coordinate, in decimal-degrees, of sample’s location. North latitude recorded as positive values. (Source: Shipboard science party, D/V Fugro Synergy)
    Range of values
    Minimum:36.71180
    Maximum:37.01600
    Units:decimal degrees
    Longitude (decimal degrees)
    Long_DD: Longitude coordinate, in decimal degrees, of the sample’s location. East longitude is recorded as positive values. (Source: Shipboard science party, D/V Fugro Synergy)
    Range of values
    Minimum:130.26639
    Maximum:130.89520
    Units:decimal degrees
    Average Depth, mbsf
    Average_Depth_mbsf: Depth of sample in meters below the sea floor (mbsf). (Source: Shipboard science party, D/V Fugro Synergy)
    Range of values
    Minimum:131.0
    Maximum:152.4
    Units:meters
    Sieve Number
    SieveNumber: Standard identification of the sieve size (sieve number) used to remove the coarsest grains from the specimens. (Source: ASTM E11-17, Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves, ASTM International, West Conshohocken, PA, 2017, www.astm.org/Standards/E11)
    Range of values
    Minimum:40
    Maximum:50
    Units:sieve number
    Sieve Mesh Size, micrometers
    MeshSize_micrometers: Standard identification of the sieve size (in micrometers) used to remove the coarsest grains from the specimens. (Source: ASTM E11-17, Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves, ASTM International, West Conshohocken, PA, 2017, www.astm.org/Standards/E11)
    Range of values
    Minimum:300
    Maximum:425
    Units:micrometers
    Elapsed Time [min]
    Time_min: Time elapsed since well-mixed specimen was allowed to begin settling. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.0833
    Maximum:1440
    Units:minutes
    Depositional Interface, Freshened Water, mm
    DWF_DepInt_mm: Each entry is the height of the interface between the settling sediment and the overlying fluid. Overlying fluid could be clear or it could be cloudy if sediment particles formed a colloidal suspension in the fluid. Blank entries indicate no measurement was made at the given time for that row. Explanation of "Freshened Water" is as follows: sediment is mixed with deionized water to obtain these data. As described in the process steps, the original specimen is dried, then saturated with deionized water to create the DWS specimen. That specimen is tested, then approximately 80% of the supernatant fluid in the cylinder is removed after the initial sedimentation test. The cylinder is refilled with deionized water, so the mixture contains freshened water and is identified as a “deionized water, freshened” sample (DWF). Thus, the DWF specimen is considered to have the freshest (lowest salt content) water. (Source: U.S. Geological Survey)
    Range of values
    Minimum:137.16
    Maximum:152.4
    Units:millimeters
    Accumulation Interface, Freshened Water, mm
    DWF_AccInt_mm: Each entry is the height of the interface between the accumulated sediment at the base of the specimen and the overlying mixture of sediment and fluid that is still settling. Entries that are equal to the corresponding Depositional Interface Height indicate specimens exhibiting uniform sedimentation (all particles or particle clusters falling at the same rate). Entries that are less than the corresponding Depositional Interface Height indicate specimens exhibiting Segregated Sedimentation (larger particles or particle clusters falling faster than smaller particles or particle clusters). Blank entries indicate no measurement was made at the given time for that row. As noted above, the DWF specimen is considered to have the freshest (lowest salt concentration) water. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:28.575
    Units:millimeters
    Depositional Interface, Dissolved Salt Water, mm
    DWS_DepInt_mm: Each entry is the height of the interface between the settling sediment and the overlying fluid. Overlying fluid could be clear or it could be cloudy if sediment particles formed a colloidal suspension in the fluid. Blank entries indicate no measurement was made at the given time for that row. Explanation of "Dissolved Salt Water" is as follows: sediment is mixed with deionized water to obtain these data. As described in the process steps, the original specimen is dried, then saturated with deionized water to create the DWS specimen. Because the salts in the original specimen remain in the specimen for this test, this specimen has a higher salt content than the DWF specimen. Because of the amount of fluid used for the settling test compared to the amount of sediment, the DWS fluid has a salinity that is less than the in situ salinity, however. (Source: U.S. Geological Survey)
    Range of values
    Minimum:22.606
    Maximum:152.4
    Units:millimeters
    Accumulation Interface, Dissolved Salt Water, mm
    DWS_AccInt_mm: Each entry is the height of the interface between the accumulated sediment at the base of the specimen and the overlying mixture of sediment and fluid that is still settling. Entries that are equal to the corresponding Depositional Interface Height indicate specimens exhibiting uniform sedimentation (all particles or particle clusters falling at the same rate). Entries that are less than the corresponding Depositional Interface Height indicate specimens exhibiting Segregated Sedimentation (larger particles or particle clusters falling faster than smaller particles or particle clusters). Blank entries indicate no measurement was made at the given time for that row. As noted above, the DWS specimen is considered to have a higher salt content (salinity) than the DWF specimen, but less than the in situ salinity. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:14.986
    Units:millimeters
    Depositional Interface, 2M Brine, mm
    2M_DepInt_mm: Each entry is the height of the interface between the settling sediment and the overlying fluid. Overlying fluid could be clear or it could be cloudy if sediment particles formed a colloidal suspension in the fluid. Blank entries indicate no measurement was made at the given time for that row. Explanation of "2M Brine" is as follows: sediment is mixed with brine (2M NaCl) to obtain these data. Because this test is run on the original sediment after drying, the specimen still contains the salt from the in situ environment. This salt is then dissolved in the 2M brine, so the final salinity is higher than 2M. The 2M Brine specimen has the highest salinity of any of the specimens tested here. (Source: U.S. Geological Survey)
    Range of values
    Minimum:23.495
    Maximum:152.4
    Units:millimeters
    Accumulation Interface, 2M Brine, mm
    2M_AccInt_mm: Each entry is the height of the interface between the accumulated sediment at the base of the specimen and the overlying mixture of sediment and fluid that is still settling. Entries that are equal to the corresponding Depositional Interface Height indicate specimens exhibiting uniform sedimentation (all particles or particle clusters falling at the same rate). Entries that are less than the corresponding Depositional Interface Height indicate specimens exhibiting Segregated Sedimentation (larger particles or particle clusters falling faster than smaller particles or particle clusters). Blank entries indicate no measurement was made at the given time for that row. Sediment is mixed with brine (2M NaCl) to obtain these data. As noted above, the 2M Brine specimen has the highest salinity of any of the specimens tested here. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:10.795
    Units:millimeters
    Depositional Interface, Sodium Hexametaphosphate, mm
    NaPO3_DepInt_mm: Each entry is the height of the interface between the settling sediment and the overlying fluid. Overlying fluid could be clear or it could be cloudy if sediment particles formed a colloidal suspension in the fluid. Blank entries indicate no measurement was made at the given time for that row. Explanation of "Sodium Hexametaphosphate" is as follows: sediment is mixed with the dispersant Sodium Hexametaphosphate ((NaPO3)6) to obtain these data. Unlike the ions of salt (NaCl), which remain as a dissolved phase in the water, the ions from (NaPO3)6 adsorb onto the sediment particles, meaning the particles all have the same type of surface electrical charge. Like charges repel, so the particles experience electrical repulsion that can help to keep the sediment particles separate (dispersed), hindering sedimentation. (Source: U.S. Geological Survey)
    Range of values
    Minimum:26.924
    Maximum:152.4
    Units:millimeters
    Accumulation Interface, Sodium Hexametaphosphate, mm
    NaPO3_AccInt_mm: Each entry is the height of the interface between the accumulated sediment at the base of the specimen and the overlying mixture of sediment and fluid that is still settling. Entries that are equal to the corresponding Depositional Interface Height indicate specimens exhibiting uniform sedimentation (all particles or particle clusters falling at the same rate). Entries that are less than the corresponding Depositional Interface Height indicate specimens exhibiting Segregated Sedimentation (larger particles or particle clusters falling faster than smaller particles or particle clusters). Blank entries indicate no measurement was made at the given time for that row. Sediment is mixed with the dispersant Sodium Hexametaphosphate ((NaPO3)6) to obtain these data. As noted above, (NaPO3)6 tends to disperse the particles, hindering sedimentation. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:17.526
    Units:millimeters
    Entity_and_Attribute_Overview:
    These data are available in a Microsoft Excel XLSX as well as a CSV format. The first two rows in the XLSX file are header rows, where the second row is an abbreviated column label intended for software packages that are unable to cope with longer labels available in the first row of the XLSX file. The first part of the attribute definition (before the colon) indicates the abbreviated column label. The first row of the CSV file is a header line and is the same as the abbreviated column label on the second row of the XLSX file.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Junbong Jang
    • Laura A. Stern
    • William F. Waite
    • Shuang C. Cao
    • Jongwon Jung
    • Joo Yong Lee
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Junbong Jang
    Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2278 (voice)
    508-457-2310 (FAX)
    jjang@usgs.gov

Why was the data set created?

As sediment settles in fluid, one or more fluid-sediment interfaces tend to form and move over time. Tracking the position of the accumulated and depositional interfaces (defined in the attribute labels below and in the browse graphic) over time in different fluids yield insights into the dependence of interparticle interactions on fluid chemistry. Sedimentation data contained in this report include UBGH2 sediment specimens collected from fine-grained intervals interbedded within coarser-grained, gas hydrate-bearing layers, as well as from the underlying fine-grained seal sediment. Additionally, pore fluid chemistry is varied to reveal sediment behavior trends, particularly with regard to the pore-fluid freshening that will occur if methane is extracted as an energy resource from gas hydrates hosted by these reservoir sediments in situ.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 30-Sep-2010 (process 1 of 7)
    Deployment sample collection: All specimens were collected from the working half of split cores collected from 20100709 – 20100930. After sampling, the specimens were oven-dried and packed in airtight specimen bags. Person who carried out this activity:
    Korea Institute of Geoscience and Mineral Resources
    Attn: Joo Yong Lee
    Research Geophysicist
    124, Gwahak-ro Yuseong-gu
    Daejeon, South Chungcheong
    Korea

    +82-042-868-3219 (voice)
    jyl@kigam.re.kr
    Date: 2018 (process 2 of 7)
    Laboratory sampling: After the shipboard specimen collection, the dry specimens were shipped at ambient temperatures to the Woods Hole Coastal and Marine Science Center (WHCMSC), where they were subsampled for the sediment settling tests. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Junbong Jang
    Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2278 (voice)
    508-457-2310 (FAX)
    jjang@usgs.gov
    Date: 2019 (process 3 of 7)
    Specimen set-up: After oven-drying a sediment specimen, sediment was spooned into a 25.4 mm diameter acrylic settling tube (settling tube pictured in the landing page browse graphic). Gentle pluviation of the sediment into the settling tube using the spoon created a loose-packed (maximum void ratio) fabric with a sediment height of 25.4 mm. The sediment was then mixed with a one of the test fluids to a final height of 152.4 mm to obtain a ratio of one to six in the diameter to height of the fluid column. The mixture was allowed to stabilize for more than twelve hours before the cylinder was evacuated in order to remove gas from the fluid. After degassing the fluid, the headspace was reopened to the atmosphere momentarily before a new stopper was inserted into the cylinder top to seal the specimen and water for the duration of the test. The sealed cylinder was shaken for one minute before being left to settle undisturbed. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Junbong Jang
    Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2278 (voice)
    508-457-2310 (FAX)
    jjang@usgs.gov
    Date: 2019 (process 4 of 7)
    Measurement: Heights of the depositional interface and the accumulated sediment interface were measured as functions of time until the interface locations stabilized (one to four days, see browse graphic for example of sedimentation behavior). Measurement intervals increased with time in an approximately logarithmic fashion over the course of a complete test to capture time-varying behavior of the sedimentation. Time measurements were made with a stopwatch, and had a precision of ± 0.2 min. Height measurements were made with a ruler affixed to the cylinder, and had a precision of ± 0.1 mm. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Junbong Jang
    Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2278 (voice)
    508-457-2310 (FAX)
    jjang@usgs.gov
    Date: 2019 (process 5 of 7)
    Fluid preparation: Each specimen was tested in more than one fluid. When the original marine sediment was dried, salt from the in situ pore-fluid precipitated as a solid material. Thus, the initial laboratory mixture of dry sediment with deionized water contained dissolved salt from the in situ pore water, and was identified as a “deionized water with salt” sample (DWS). In order to reduce the effect of salt, approximately 80% of the supernatant fluid in the cylinder was removed after the initial sedimentation test. The cylinder was refilled with deionized water, so the mixture contained freshened water and was identified as a “deionized water, freshened” sample (DWF). The sedimentation test was repeated with the freshened water mixture. Separately, subsamples of the original marine sediment were dried and tested with their in situ salts, using a 2M-brine solution (2M-brine = 2 Molar brine = 2 moles of NaCl in 1 liter of water) and also in a dispersant, sodium hexametaphosphate ((NaPO3)6). Sediment mixtures with 2M-brine and sodium hexametaphosphate were not recycled in the sedimentation tests. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Junbong Jang
    Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2278 (voice)
    508-457-2310 (FAX)
    jjang@usgs.gov
    Date: 2019 (process 6 of 7)
    Data archiving: Microsoft Excel version 16.16.11 was used to consolidate all data in a spreadsheet. Measured interface heights and elapsed times were arranged by sediment and pore fluid type. Results were then exported to a comma-separated values (csv) file format. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Junbong Jang
    Geophysicist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    USA

    508-548-8700 x2278 (voice)
    508-457-2310 (FAX)
    jjang@usgs.gov
    Date: 06-Aug-2020 (process 7 of 7)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    Fugro Survey Pte Ltd (FSPL) of Singapore provided surface positioning for navigation onboard the D/V Fugro Synergy. Their position utilized the Starfix Series and a Kongsberg HiPAP 500 Ultra Short Baseline (USBL) system for determining the drill string position at each location in local datum. A transponder mounted on the ship's remotely-operated vehicle, and a Compatt beacon mounted on the Seacalf seabed frame, were used for determining the subsurface-positioning. A calibration of the vessel’s HiPAP 500 USBL system was carried out at approximately 2,200 meters below sea surface near one site. The results of this calibration were entered into the Starfix USBL software for use in the subsequent UBGH2 operations. Horizontal position accuracy is considered to be within 15 meters radius.
  3. How accurate are the heights or depths?
    The depth of each sample was estimated by using the length of the drill string in conjunction with a direct observation by an ROV of when the drill bit made contact with the sea floor. This overall depth is then combined with the depth within the recovered core. The D/V Fugro Synergy approach to establishing the specimen depth is follow the same general principles as the International Ocean Drilling Program (http://www.iodp.org/policies-and-guidelines/142-iodp-depth-scales-terminology-april-2011/file), with an overall depth resolution ranging from 0.01 to 1 meter.
  4. Where are the gaps in the data? What is missing?
    The accumulation interfaces were not always observable for the entirety of each settling test. In general, as sediment settles, the sediment suspended above the accumulation interface becomes more concentrated and can become concentrated enough to obscure the accumulation interface. Blank interface height entries within a column of measured data occur because the accumulation interface height in question could not be resolved at the stated measurement time.
  5. How consistent are the relationships among the observations, including topology?
    The settlement tubes used in this work were all cut from the same acrylic tube, and thus are all nominally the same diameter. Equal heights of sediment and liquid were used in each test, each specimen was tested in the same set of liquids, and agitation times prior to allowing the system to settle were equivalent. This dataset covers the point-by point measurements of the sediment interfaces over time.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints None.
Use_Constraints Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? This dataset contains five files: UBGH2_Sedimentation_Data.xlsx (data in an Excel spreadsheet), UBGH2_Sedimentation_Data.csv (same data in a comma-separated text file), UBGH2_Sedimentation_BrowseGraphic.png (browse graphic), UBGH2_Sedimentation_ExamplePlot.png (example of how the data can be visualized) and FGDC CSDGM metadata in XML format.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    These data are available in XLSX and CSV formats, and a browse graphic in PNG format. The user must have software capable of reading the data formats.

Who wrote the metadata?

Dates:
Last modified: 19-Mar-2024
Metadata author:
U.S. Geological Survey
Attn: William F. Waite
Geophysicist
384 Woods Hole Rd.
Woods Hole, MA

508-548-8700 x2346 (voice)
508-457-2310 (FAX)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with USGS. (updated on 20240319)
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P9UJOYVR/UBGH2_SedimentationRate_Metadata.faq.html>
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