|U.S. Geological Survey Data Series 344|
The vibracore is a sediment coring system that consists of a vibrating pneumatic head that shakes the core barrel into the sediment. The vibracore head, manufactured by Bradford, is connected to an aluminum pipe 3.5 inches wide and 20 feet in length. A tripod-like quadratic base supports this system. The whole system is lifted from the boat deck and lowered to the seafloor by a hydraulic crane. At the seafloor, the vibrating head is activated. The vibration propagates through the aluminum barrel to the seafloor. This vibration agitates the sediment around the outside of the core barrel, allowing the barrel to slide into the sediment column. Once resistance is reached, the vibration is shut off and the crane pulls the aluminum pipe out of the sediments column and onto the deck of the boat. The barrel is removed from the rig and cut to the level of sediment that has filled the pipe. Both ends are capped and taped to prevent leakage of the sediment out of the pipe. All cores are labeled and stored until processing. Detailed information can be found on the Methods page.
In the lab, vibracores were cut lengthwise, and in some cases a sonicating knife was used to obtain a clean, undisturbed surface on one-half length of the vibracore. This section was used to describe the core's contents on a Vibracore Description Sheet. Description includes, but is not limited to, sediment grain-size content, color, and characteristics such as bedding types, bioturbation, shells and shell fragments, and any other qualitative descriptions. Most of the cores were photographed. The description sheets are available as PDF files accessible in the directory for vibracore description sheets or through vibraprofiles.html in this archive. The other half length of the vibracore was used for sampling for various sediment analysis, most commonly sampled for grain-size. Detailed information can be found on the Methods page.
Grain-size data for 00SCC cruise and 00bss cores were obtained by using the Beckman Coulter LS 32 Laser counter variable-speed fluid module plus. A small amount (less than a teaspoon) of sample was used for analysis of grain size. Laser diffraction is correlated to the standard mesh size of each of the sediment sample grains, the distribution, and the volume of each grain mesh size. The data can be extracted in phi, mesh size, and in statistical formats of mean, standard deviation, kurtosis, cumulative size fractions, and percent. Although other extraction methods of data information are available using this machine, those previously mentioned were the most frequently used for this archive. The grain sizes presented for the P86 cruise were found in Suter and others (1991). The sand percents reported were both observed and analyzed. Grain-size analyses for these cores were conducted randomly. Overall, the percent sand, silt, and clay variations for the cores are presented in the folder Grain_Size and on the grain.html page of this archive. Detailed information can be found on the Methods and Grain-Size and Penetrometer Data pages.
The Photograph section includes core photographs for a few CR83 and most P86 and 00SCC cores.
The Study Area Map and the EUSTIS map were created by GIS software, modified by Adobe Illustrator software, and made available as JPEG or GIF files.
The printable profiles, digitized data, grain-size data, maps, and photographs are provided here as PDF, XLS, and JPEG or GIF images. The Study Area Map and the EUSTIS map are interactive maps that allow the user to obtain information about a core from its geographic location. The user navigates through the "sub-maps" to a core, which is linked to a table that contains Vibracore Description Sheets, Interpreted Core Classification Profiles, Grain-Size and Penetrometer Data, and vibracore Photographs.
Note: All sediment core data are linked to the cores on the Study Area Map for all vibracores (00SCC, CR83, and P86) and the cores on the USACE EUSTIS map for all borehole cores. Clicking on a core or core ID on the Study Area Map pages will bring forth a Core Data Table that contains all sediment core data and displays the specific core's information. The back button returns the user to the Study Area Map section. The Core Data Table (includes data from all cruises: USACE EUSTIS borehole cores (B-#), 00SCC (bss cores), CR83, and P86) contains core ID and five other columns containing previews and downloadable files for vibracore description sheets, interpreted core classification profiles, grain-size data, penetrometer data, and photographs.
A list of missing data for each cruise is as follows.
The digitizing process: A digitizing tablet by Wacom Co., Ltd., and Golden Software's Didger_3 digitizing programs were used for the physical digitizing process of the vibracore description sheets. A macro program created by James G. Flocks (USGS) was used to process the digitized description sheet profile information into interpreted core classification profiles or spreadsheets of information, accessible as Excel files (XLS). These interpreted core classification profiles are provided in this report and available for individual interpretation of the data. More information about the macro programs created by James G. Flocks (this volume) can be found in the Software folder and on the page software.html within this archive.