Coring disturbances in IODP piston cores with implications for offshore record of volcanic events and the Missoula megafloods

Abstract

Piston cores collected from IODP drilling platforms (and its predecessors) provide the best long-term geological and climatic record of marine sediments worldwide. Coring disturbances affecting the original sediment texture have been recognized since the early days of coring and include deformation resulting from shear of sediment against the core barrel, basal flow-in due to partial stroke, loss of stratigraphy, fall-in, sediment loss through core catchers, and structures formed during core recovery and on-deck transport. The most severe disturbances occur in noncohesive (sandy) facies, which are particularly common in volcanogenic environments and submarine fans. Although all of these types of coring disturbances have been recognized previously, our contribution is novel because it provides an easily accessible summary of methods for their identification. This contribution gives two specific examples on the importance of these coring disturbances. We show how suck-in of sediments during coring artificially created very thick volcaniclastic sand layers in cores offshore Montserrat and Martinique (Lesser Antilles). We then analyze very thick, structureless sand layers from the Escanaba Trough inferred to be a record of the Missoula megafloods. These sand layers tend to coincide with the base of core sections, and their facies suggest coring disturbance by basal flow-in, destroying the original structure and texture of the beds. We conclude by outlining and supporting IODP-led initiatives to further reduce and identify coring disturbances and acknowledge their recent successes in drilling challenging sand-rich settings, such as during IODP Expedition 340.

Anisotropy of Magnetic Susceptibility (AMS) of Sediments From Holes U1480E and U1480H, IODP Expedition 362: Sedimentary or Artificial Origin and Implications for Paleomagnetic Studies

“…The most likely explanation for the randomly distributed AMS axes is coring‐induced disturbance. Once decoupled from the host sediments, the core barrel containing the core liner and the cored sediments is retrieved to the rig floor with a high‐speed winch, which involves strong accelerations and decelerations (e.g., Jutzeler et al, ). During the long vertical transport distance (the water depth is 4148 m at Site U1480), it is likely that the sediments experienced vibration and fluidization, despite the great care taken by the highly experienced IODP crew.…”

Expedition 350 methods

“…Core disturbances are recorded in DESClogik. Core disturbances are diverse (Jutzeler et al, 2014), and some of them are only associated with specific coring techniques.…”

Contrasting styles of deep-marine pyroclastic eruptions revealed from Axial Seamount push core records

“…The presence of planar bedding contacts in the cores and general absence of core disruption structures (cf. Jutzeler et al, 2014) indicate that the clastic deposits in cores preserve primary depositional fabrics. Recovered clastic sequences compressed by ∼25% during core tube insertion, recovery, storage on the ROV and ship, and transport to the U.S. Geological Survey in Menlo Park, California, where they were split and photographed.…”