| Grant number: | 17/04821-0 |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |
| Effective date (Start): | October 01, 2017 |
| Effective date (End): | April 26, 2023 |
| Field of knowledge: | Physical Sciences and Mathematics - Oceanography - Geological Oceanography |
| Principal Investigator: | Luigi Jovane |
| Grantee: | Muhammad Bin Hassan |
| Host Institution: | Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
| Associated research grant: | 14/50820-7 - Marine ferromanganese deposits: a major resource of E-tech elements, AP.TEM |
| Associated scholarship(s): | 21/06941-8 - A comparative geochemical analysis of Fe-Mn crusts from Atlantic Ocean, BE.EP.DD |
Abstract Hydrogenetic ferromanganese deposits are iron-oxyhydroxides and manganese oxide. These are chemical precipitates on the seafloor that grow over periods of tens of millions of years. Their secular records of chemical, mineralogical, and textural variations are archives of deep-sea environmental changes. However environmental reconstruction requires reliable high-resolution age dating. Earlier chronological methods, such as radiochemical and stable isotopes provided age models for ferromanganese crusts, but these methods have certain limitations on the millimeter scale. To overcome these, we will use a high-resolution magnetometry technique known as electronic paramagnetic resonance scanning microscopy. Correlating the boundaries of the magnetic stripes with known geomagnetic reversals, we will provide chronological constraints with the accuracy attained by the astronomically calibrated magnetostratigraphic time scale of 1-40 k.y. (Oda et al., 2011). It has been demonstrated that ferromanganese crusts record paleomagnetic reversals. For the Nishi-Shichito Ridge sample, Oda et al. (2011) successfully constructed a sub-millimeter scale magnetostratigraphy using a scanning SQUID (Superconducting Quantum Interference Device) microscope, and provided a high-fidelity age model giving a growth rate of 5.1 ± 0.2 mm/Ma, which is consistent with that obtained by 10Be/9Be dating method (6.0 ± 0.2 mm/Ma). However, as for the northwest Pacific, the crust from the Nishi-Shichito Ridge has only been demonstrated (Joshima and Usui, 1998; Oda et al., 2011) and the potential does not seem to be systematically investigated. In order to investigate a universal applicability of the 'magnetostratigraphic' method, We will conduct paleomagnetic measurements on the crust samples recovered from Clarion Clipperton Zone (Pacific Ocean) and Indian ocean, Tropic Seamount in the North East subtropic Atlantic and Rio Grande Rise in the South West subtropic Atlantic. We aim to use same techniques as done by Noguchi et al., (2016) for Atlantic Ocean. We will provide stepwise alternating field (AF) demagnetization as well as simultaneous remanence measurements to our thinly cut ferromanganese samples to find their Characteristic Remanent Magnetizations (ChRMs). Their remanences will be measured using a DC SQUID magnetometer. Ultrafine-scale magnetostratigraphy using SQUID microscopy is a powerful new chronological tool for estimating ages and growth rates for hydrogenetic ferromanganese crusts. It provides chronological constraints with the accuracy promised by the astronomically calibrated magnetostratigraphic time scale (1-40 k.y.). We will report and discuss the measurement results, and estimate a growth rate for each sample based on a reversal pattern deduced from the results. We aim to use different paleomagnetic techniques to understand the formation, distribution, and age of the ferromanganese crusts. The detailed study of these deposits will help to know the plaeomagnetic history and environmental conditions of ferromanganese deposits. (AU) | |
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