The Potential of Marine Ferromanganese Nodules From Eastern Pacific as Recorders of Earth's Magnetic Field Changes During the Past 4.7 Myr: A Geochronological Study by Magnetic Scanning and Authigenic ¹⁰Be/⁹Be Dating

Abstract

The Clarion and Clipperton Fracture Zones in the Eastern Pacific are well known as a manganese nodule belt, which developed since the late Oligocene. The slow growth rate of these marine ferromanganese nodules implies that they have potentially recorded long‐term environmental changes. To produce environmental records from these nodules, their chronology needs to be established first. In order to achieve this objective, many dating methods have been applied; however, due to relatively low‐resolution temporal constraint, high‐resolution environmental signals recorded in marine ferromanganese nodules have not been well documented yet. In this paper, we present a geochronological study based jointly on magnetic scanning and analyses of the authigenic beryllium isotopes (authigenic 10Be/9Be) and the cobalt (Co) flux of a marine ferromanganese nodule. Results lead to the following observations: (1) The growth of the studied nodule resulted from a combination of hydrogenetic and diagenetic processes, and (2) a total of 24 magnetozones is recognized for the studied nodule. Correlation to the geomagnetic polarity timescale suggests that chrons from C3n.2r to C1n were recorded in the nodule, implying that the growth of this nodule initiated ~4.70 Ma, which agrees well with the authigenic 10Be/9Be and Co chronometers. Furthermore, a consistent pattern of broad paleomagnetic field variations was observed between the nodule's magnetic signal and the ocean‐floor magnetic fields of the South Atlantic, confirming the validity of our growth model. Overall, our study highlights the potential of marine ferromanganese nodules from the Eastern Pacific as recorders of changes in Earth's magnetic field.

Plio-Pleistocene deep-sea ventilation in the eastern Pacific and potential linkages with Northern Hemisphere glaciation

“…4 Ma ago onward accompany NHG enhancement at ~3. 15 Ma ago (Fig. 3B), in agreement with prolonged surface water cooling around Antarctica since ~3.…”

“…These events are evident in all three time scales of this study (table S3). (E) Paleomagnetic (triangles) and 10 Be/ 9 Be (squares) age control points for the studied MFN (15) accompanied by Antarctic climate variability and shifts in AABW production.…”

Abyssal Manganese Nodule Recording of Global Cooling and Tibetan Plateau Uplift Impacts on Asian Aridification

“…There are several empirical equations that relate growth rate with Co contents. Although they share the same mathematical form, their coefficients are different, which could yield significantly distinct estimates for the same sample (Yi et al., 2020). In addition, the Co‐based method can only provide relative ages if additional constraints from absolute age points are lacking.…”

New Opportunities and Untapped Scientific Potential in the Abyssal Ocean

“…The long-term environmental stability of abyssal plains and seamounts contributes to the formation of ferro-manganese crusts and polymetallic nodules. These slowly depositing crusts precipitate from bottom waters, possibly mediated by microbial Mn oxidation (Blöthe et al, 2015;Shulse et al, 2017), and provide a long-term record of redox chemistry, ocean current dynamics, continental erosion (Koschinsky and Hein, 2017) and magnetic field patterns (Yi et al, 2020). In addition, they concentrate metals such as cobalt, copper, and nickel and have long been viewed as a potential source of raw materials for industrial use (Lusty and Murton, 2018;Miller et al, 2018).…”