34-7 Characteristics of an Early Pleistocene Deep Sea Turbidite from the North Atlantic Ocean

Session: High latitude paleoceanographic discoveries from Scientific Ocean Drilling (IODP, ODP, DSDP). (Posters)

Presenting Author:

Authors:

Abstract:

IODP Hole U1563A, located in 1419 m of water on 5.23 Ma old ocean crust, about sixty-four km east of the Reykjanes Ridge at 60°12’N latitude in the North Atlantic recovered 335 m of sediment, 100% recovery.  Sediments above a hiatus at 300 m and 3.6 Ma are dominated by silty clay.  Below that they are dominantly carbonate oozes.  Four turbidites ranging in thickness from about 2 to 15 cm were recovered in Late Pliocene to Early Pleistocene silty clay.  All turbidites were CT and XRF scanned, although the unconsolidated nature of the sediment did not allow a good contact with the turbidites during XRF scanning.

In this study we chose a 14.5 cm long turbidite from Core 19, Section 5, roughly 2.2 Myr old to analyze in detail. Samples were taken every cm. Grain-size analysis shows an abrupt increase in the >63 um fraction from ~20% below to 60-85%, in the turbidite. There is a slightly more gradual decrease in >63 um size at the turbidite top. Outside of the turbidite, the coarse fraction consisted predominantly of planktonic foraminifera.  The components of the turbidite include coral and shell fragments and planktonic foraminifera with rare terrigenous and rock intervals.

In this presentation we will compare detailed counts and images of the components of the coarse fraction (150-500 um) with the CT scan images to determine how effective CT scans are at imaging coarse fraction components. We will also include grain size measurements of the >63 um fraction before during and after the turbidite deposition.  Crossing seismic lines from the site, show parallel layering, indicating that small turbidites in the deep ocean may be more common than presently thought, and can only be identified by recovering cores.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.