Mineral Phase-Element Associations Based on Sequential Leaching of Ferromanganese Crusts, Amerasia Basin Arctic Ocean

Abstract

Ferromanganese (FeMn) crusts from Mendeleev Ridge, Chukchi Borderland, and Alpha Ridge, in the Amerasia Basin, Arctic Ocean, are similar based on morphology and chemical composition. The crusts are characterized by a two- to four-layered stratigraphy. The chemical composition of the Arctic crusts differs significantly from hydrogenetic crusts from elsewhere of global ocean by high mean Fe/Mn ratios, high As, Li, V, Sc, and Th concentrations, and high detrital contents. Here, we present element distributions through crust stratigraphic sections and element phase association using several complementary techniques such as SEM-EDS, LA-ICP-MS, and sequential leaching, a widely employed method of element phase association that dissolves mineral phases of different stability step-by-step: Exchangeable cations and Ca carbonates, Mn-oxides, Fe-hydroxides, and residual fraction. Sequential leaching shows that the Arctic crusts have higher contents of most elements characteristic of the aluminosilicate phase than do Pacific crusts. Elements have similar distributions between the hydrogenetic Mn and Fe phases in all the Arctic and Pacific crusts. The main host phases for the elements enriched in the Arctic crusts over Pacific crusts (Li, As, Th, and V) are the Mn-phase for Li and Fe-phase for As, Th, and V; those elements also have higher contents in the residual aluminosilicate phase. Thus, higher concentrations of Li, As, Th, and V likely occur in the dissolved and particulate phases in bottom waters where the Arctic crusts grow, which has been shown to be true for Sc, also highly enriched in the crusts. The phase distributions of elements within the crust layers is mostly consistent among the Arctic crusts, being somewhat different in element concentrations in the residual phase.

The influence of hydrothermal activity during the origin of Co-rich manganese crusts of the N-W Pacific

“…High V and Cd in Mn fraction of CMC imply a lower oxidation potential of the fluid during precipitation of the crust. More reduced fluids can reflect higher productivity in surface waters, or circulation of reduced fluids in the seamounts that reflect hydrothermal circulation created during a rejuvenation stage volcanism, or release of pressurized fluids during tectonic events [14]. Consequently, concentration of V in Mn phase of CMC from Govorov and Zubov Guyots may reflect involvement endogenic source for formation bulk chemical composition of the deposits.…”

Distribution of Rare Earth Elements plus Yttrium among Major Mineral Phases of Marine Fe–Mn Crusts from the South China Sea and Western Pacific Ocean: A Comparative Study

“…LA-ICP-MS mapping is an "only slightly" destructive technique and was previously applied to Fe-Mn crusts and Fe-Mn nodules [14,35]. The accuracy of the LA-ICP-MS is mainly influenced by a few critical factors.…”

“…The Pacific holds significant reserves of Fe-Mn crust deposits, and there is a famous prime crust zone (PCZ) in the north-equatorial Pacific Ocean [1,7,10]. In addition, a number of mining areas with the potential for exploitation were also found in the Atlantic Ocean [8,11], Indian Ocean [12,13], and Arctic Ocean [14]. In addition to the open oceans, some Fe-Mn crust deposits were also discovered near the continental margin, such as the Baltic Sea [15], the California continental margin [2,16,17], and the South China Sea (SCS) [18][19][20][21].…”

“…The samples were examined using in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) mapping in order to observe the occurrence phase of REY in the layer structure. Furthermore, major mineral phases (i.e., easily exchangeable and carbonate, Mn-oxide, amorphous FeOOH, and residual aluminosilicates phases) of these Fe-Mn crusts were separated using a sequential leaching experiment which was proven to be an effective method for understanding the incorporation of elements in mineral phases of Fe-Mn crusts [8,14,[24][25][26][27]. These results are expected to provide better information on the process of REY incorporation into Fe-Mn crusts in a marginal sea.…”

The Arctic Ocean Manganese Cycle, an Overlooked Mechanism in the Anomalous Palaeomagnetic Sedimentary Record

“…Mn and Fe cycling in the sediments has received little to no attention with respect to palaeo-and rock magnetic data, even though ferromagnetic manganese minerals exist, such as jacobsite (MnFe 2 O 4 ). Fe/Mn ratios in Arctic ferromanganese nodules are considerably higher than deposits in other ocean basins Konstantinova et al, 2017Konstantinova et al, , 2018 and there is a known connection between Mn and Fe redox reactions (e.g., Schulz and Zabel, 2006).…”