{"title":"Geological and oceanographic constrains on the deposit of ferromanganese nodules on the archipelagic aprons of seamounts","authors":"","doi":"10.1016/j.margeo.2024.107400","DOIUrl":null,"url":null,"abstract":"<div><p>The archipelagic aprons of the large deep-sea seamounts of the northwestern Pacific Ocean (NWPO) show potential areas for significant reserves of ferromanganese nodules (FMNs). This study used datasets such as depth, backscatter intensity (BI), and optical coverage in conjunction with mineralogical, element geochemical, Sr-Nd-Pb isotopic, and chronological analyses of FMNs of the Suda Guyot (SG), which was located on the central area of the Marcus-Wake seamounts, in the NWPO. The results indicated a Y-shaped distribution of the deposit on the northern apron of the SG. Landslides predated the mineralization processes of the FMN deposit, and the ubiquitous channels in the apron had largely minimal influence on the distribution of nodules. Current mineralization of the deposit has been ongoing for ∼10 Myrs. Continuous weakening of the Antarctic Bottom Water (AABW) resulted in a gradual decrease in bottom water oxygen contents around the SG. This in turn resulted in a decrease in cryptocrystalline Fe-vernadite (δ-MnO<sub>2</sub>) and elemental contents associated with δ-MnO<sub>2</sub> of FMNs, such as Mo, Te, and Tl. Meanwhile, the contribution of Asian dust to the study area increased, leading to increased Fe, which in turn increased amorphous ferrihydrite (FeOOH), and FeOOH-associated elements such as Ti, Pb, and Th. Productivity gradually increased to its peak value around 4–5 Myrs ago, leading to similar trends in REY, Ba, and U. REY contents exhibited a certain correlation with water depth around the SG. The results of this study suggest that the Carbonate Compensation Depth (CCD) variation resulted in higher content of REY of the FMNs in the shallower apron.</p></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":null,"pages":null},"PeriodicalIF":2.6000,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Marine Geology","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0025322724001841","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The archipelagic aprons of the large deep-sea seamounts of the northwestern Pacific Ocean (NWPO) show potential areas for significant reserves of ferromanganese nodules (FMNs). This study used datasets such as depth, backscatter intensity (BI), and optical coverage in conjunction with mineralogical, element geochemical, Sr-Nd-Pb isotopic, and chronological analyses of FMNs of the Suda Guyot (SG), which was located on the central area of the Marcus-Wake seamounts, in the NWPO. The results indicated a Y-shaped distribution of the deposit on the northern apron of the SG. Landslides predated the mineralization processes of the FMN deposit, and the ubiquitous channels in the apron had largely minimal influence on the distribution of nodules. Current mineralization of the deposit has been ongoing for ∼10 Myrs. Continuous weakening of the Antarctic Bottom Water (AABW) resulted in a gradual decrease in bottom water oxygen contents around the SG. This in turn resulted in a decrease in cryptocrystalline Fe-vernadite (δ-MnO2) and elemental contents associated with δ-MnO2 of FMNs, such as Mo, Te, and Tl. Meanwhile, the contribution of Asian dust to the study area increased, leading to increased Fe, which in turn increased amorphous ferrihydrite (FeOOH), and FeOOH-associated elements such as Ti, Pb, and Th. Productivity gradually increased to its peak value around 4–5 Myrs ago, leading to similar trends in REY, Ba, and U. REY contents exhibited a certain correlation with water depth around the SG. The results of this study suggest that the Carbonate Compensation Depth (CCD) variation resulted in higher content of REY of the FMNs in the shallower apron.
期刊介绍:
Marine Geology is the premier international journal on marine geological processes in the broadest sense. We seek papers that are comprehensive, interdisciplinary and synthetic that will be lasting contributions to the field. Although most papers are based on regional studies, they must demonstrate new findings of international significance. We accept papers on subjects as diverse as seafloor hydrothermal systems, beach dynamics, early diagenesis, microbiological studies in sediments, palaeoclimate studies and geophysical studies of the seabed. We encourage papers that address emerging new fields, for example the influence of anthropogenic processes on coastal/marine geology and coastal/marine geoarchaeology. We insist that the papers are concerned with the marine realm and that they deal with geology: with rocks, sediments, and physical and chemical processes affecting them. Papers should address scientific hypotheses: highly descriptive data compilations or papers that deal only with marine management and risk assessment should be submitted to other journals. Papers on laboratory or modelling studies must demonstrate direct relevance to marine processes or deposits. The primary criteria for acceptance of papers is that the science is of high quality, novel, significant, and of broad international interest.