Characteristics of and corrections for core shortening in unconsolidated sediments

Journal of Coastal Research
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Abstract

Thinning, bypassing, and compaction of shallow unconsolidated sediments during manual coring or vibracoring operations probably cause more sediment deformation and greater stratigraphic displacement than is commonly reported in the wetland literature. We measured core shortening in open-barrel cores from fluvial wetlands, lagoonal flats, and marshes to document the magnitude and characteristics of shortening where sediments may be stiff and require extra mechanical effort to recover a sufficient length of sample for analysis. Results of those measurements indicate that thinning or non- recovery of discrete sediment intervals can range from 0 to 67 percent and cumulative core shortening can be as much as 30 percent even for cores less than one meter long. Detailed open-barrel measurements also show that core shortening is not uniformly distributed throughout the depth of penetration as is often assumed. Analytical data derived from shortened cores can only be properly interpreted if patterns of shortening are established and incorporated into the analysis. Minor artificial displacement of sediment depths can alter plots of physico-chemical parameters and can significantly influence calculated rates of sedimentation and other depth-dependent statistical relationships. This study (1) demonstrates how plots of interval shortening and cumulative shortening can be used to characterize the distribution of shortening at depth and (2) presents a simple equation for stratigraphic restoration so that core observations and analyses are corrected to their original depths.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Characteristics of and corrections for core shortening in unconsolidated sediments
Series title Journal of Coastal Research
Volume 13
Issue 3
Year Published 1997
Language English
Publisher Coastal Education and Research Foundation
Contributing office(s) Coastal and Marine Geology Program
Description 9 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Journal of Coastal Research
First page 761
Last page 769