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USGS CMG Menlo Park Sediment Core Splitting and Description Lab--M1021

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Room Sediment Core Splitting and Description Laboratory
Location Rm. M1021, 1st floor, Bldg. 15 (McKelvey Bldg.)
Contact Mike Torresan
Cathy Frazee
Description Laboratory and staging area specializing in the splitting, describing, photographing, and subsampling of sediment cores and other marine samples. The laboratory also serves as the staging area for determining many simple physical-index properties such as color, sediment type, visual grain-size estimates, water content, and strength. Smear slides can also be produced and analyzed for sediment composition determinations. Laboratory also has a rotap and sieves that can be used for dry particle size analysis. This lab is adjacent to a refrigerated core archive facility (Room M1021A).
Core splitter, sieves, rotap sieve shaker, microscopes, digital camera (on order), osmotic knives, light table for viewing x-ray films) and refrigerated core storage locker (Room 1021A).
This laboratory, located immediately adjacent to the USGS Core and Sample Archive Facility is used to split, describe, photograph, and subsamplemarine sediment cores. The most specialized piece of equipment residing in the core laboratory is the core splitter; a device was designed to split 3"-diameter polybuterate or polycarbonate liners longitudinally into two halves. The working halves of each core or core section are then subsampled while the archive half is photographed and preserved intact. Typically; the archive half is x-rayed to identify fine-scale biogenic and physical structures. Many times whole cores will be x-radiographed prior to splitting to determine if there are any obstructions like pebbles or cobbles that will interfere with the splitting process. Many samples that were not collected as cylindrical cores (e.g., box cores, dredges, or grab samples) are also described, subsampled, and catalogued in this laboratory.

This laboratory serves as the staging area for many simple tests and standardized techniques that provide quick determinations of specific physical properties of the samples (color, sediment type, and visual grain size estimates, water content, strength). During the sample description and curation process; smear slides can be made from discrete sample intervals. The smear slides are placed under a microscope and used to identify and determine the relative abundance of minerals, microfauna, and microfossils that compose the sediment. Resin and epoxy peels of the cores can also be produced, but often this process requires the use of a fume hood owing to the vapors released by the epoxy or resins used.

The core splitting laboratory also houses sieves and a rotap machine (for mechanically shaking the set of stacked sieves). The sieves and rotap are used in conjunction for the particle size distribution of particles coarser than 0.063 mm. This includes sand (2.00 mm - 0.063 mm), gravel (2.00 mm - 4.00 mm), and pebbles (4.00 mm - 64.00 mm). Larger particles must be hand measured as described in various sedimentological texts. An alternate method for determining the distribution of the sand-size fraction is used in the Settling Laboratory. Brief reviews are given in the description of the particle size analysis laboratories.

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