163 D6. Mélange Session (Posters)

Tuesday, 17 October 2023
8:00 AM - 5:30 PM
Hall B

ENVIRONMENTAL MAGNETIC RECORD AND RELATIVE GEOMAGNETIC PALEOINTENSITY OF IODP SITE U1389 (MEDITERRANEAN OVERFLOW WATER, GULF OF CADIZ)

Paper number: 163-7
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

We present a detailed paleomagnetic and rock magnetic analysis from the advanced piston-cored section of Integrated Ocean Drilling Program (IODP) Site U1389 (107 meters composite depth) located in the Gulf of Cadiz, on the Iberian Margin. The investigation forms part of the IODP Expedition 339's broader mission to explore climatic variations and their influence on the Mediterranean Overflow Water (MOW) to the North Atlantic over the past six million years. The focus of our study is Site U1389, with sediments being contourites from the Huelva sheeted drift that have seen rapid accumulation of a very uniform series of pelagic sediments (48 cm/ka). The uniform series of pelagic sediment provides an intriguing insight into paleoenvironmental variability. The chronology (from Sierro et al., 2020) spans the last 120 ka, derived by tuning G. Bulloides oxygen isotope data to the Greenland GICC05 ice core record. This chronology extends to older sediments of up to 200 ka via synchronization with Asian speleothem records. Rock magnetic and paleomagnetic measurements were conducted at 1-cm resolution on the entire 107-m of U-channel samples. The aim is to generate a comprehensive record of paleoenvironmental changes and MOW fluctuations while yielding data on paleosecular variation and relative geomagnetic paleointensity. Our investigation successfully removed secondary drilling-induced magnetization, revealing a robust primary magnetization carried by the sediment. The samples' behavior during isothermal remanent magnetization acquisition and alternating field demagnetization suggests magnetite as the dominant carrier of magnetic remanence. The study will present detailed rock magnetic data from low-temperature and FORC measurements in addition to time-frequency analyses of high-resolution paleomagnetic proxy data from the entire 107-m section of Site U1389. Our ultimate objective is to identify the factors driving the cyclic changes evident in the sediment archive and to extract a high-resolution record of relative geomagnetic paleointensity over the past 200 ka.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-394515

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