Previous   |    Next

doi:10.2204/iodp.proc.340.206.2016

Introduction

In specific types of sediments, Integrated Ocean Drilling Program (IODP) advanced piston corer (APC) technology can produce substantial coring disturbances. These disturbances are mostly present where thick intervals of loose, granular, unconsolidated sediment occur. Volcaniclastic deposits are the sediment type most prone to being affected because they are commonly very thick and well-sorted deposits with particles of low density and low cohesion. Coring disturbances can affect large parts of the core, up to total disruption of the original stratigraphy. More details of about specific types of coring disturbances are found in Jutzeler et al. (2014).

We consider here only two types of coring disturbances, the ones most likely to destroy the original stratigraphy: fall-in and flow-in. Fall-in refers to material that has fallen into the hole or did not get washed during drilling and hole cleaning and was then collected at the top of the next core. These disturbances are commonly easy to identify because of their position at the uppermost part of the core and their common coarse-grained textures. In contrast, flow-in disturbances can affect a few centimeters to the entire length of the core, and the resulting facies may be extremely similar to some natural normally graded facies. Basal flow-in is restricted to the lower part of the core, whereas midcore flow-in can occur at any position. Cores disturbed by flow-in may have been subsequently disturbed when put horizontally on deck (Jutzeler et al., 2014). We do not consider disturbance by core extension (Jutzeler et al., 2014) because it generally does not mix several intervals together.

Because of the intrinsic difficulties in determining where core disturbances are most likely to occur, we analyzed every high-resolution image of core sections from Expedition 340: 277 cores and 1818 core sections. This list of disturbed intervals does not include reconstruction of the stratigraphy between holes, which would in many cases require an extensive study including componentry, dating, and chemical analyses. The present exhaustive list will allow researchers to study and interpret Expedition 340 cores with much more confidence. Importantly, it will help researchers involved in future studies to avoid parts of the cores that are not representative of the original stratigraphy.

Top of page   |    Previous   |    Next