Objective The East Mariana Basin of the West Pacific Ocean, which is located east of the Mariana Trench, south of the Magellan Seamounts, and north of the Caroline Seamounts, is an ideal area for the study of Asian aeolian dust deposits, but the sediment research of the East Mariana Basin is still weak. To reveal the sediment geochemical characteristics and provide background data for further sediment provenance, seabed mineral resource evaluation and climate-environment evolution research, the element geochemistry of surface sediments in the East Mariana Basin was studied. Methods Based on 28 pelagic clay surface sediment (0-10 cm) samples collected in the eastern section of the East Mariana Basin using the box and gravity samplers, contents of major, trace, and rare earth elements of the sediments were analyzed using inductively coupled plasma optical emission and mass spectroscopy methods. Then, elements geochemical characteristics were analyzed, and their influencing factors and indicative significance were discussed. Results The results show that the contents of major elements in the pelagic clay sediments in the study area are roughly the same as those in the neighboring sea areas of the West Pacific Ocean. The distribution pattern of major elements (oxides) in sediments follows SiO2> Al2O3 > Fe2O3> Na2O > MgO > K2O > CaO > MnO > TiO2 > P2O5. SiO2 has the highest content of all major elements, with an average of 49.14%, followed by Al2O3, with an average of 15.85%. The trace element with the highest content was Ba, with an average of 770×10-6, followed by Cu, with an average of 289×10-6. The average of total rare earth elements (∑REE) is 284×10-6, which is light rare earth-rich type, with the highest Ce, Nd, and La contents. Principal component analysis of elements shows that the composition of chemical elements can be divided into four categories: The first type is closely related to rare earth elements, including most rare earth elements (except Ce), P2O5, and TiO2, the second type is related to Fe-Mn micronodules, including Fe2O3, MnO, Cr, Co, Ni, Cu, and Ba, the third type is related to terrigenous debris, including Al2O3, MgO, SiO2, U, Hf, Th, and Ce, and the fourth type is related to biological sources, including Cd, CaO, and Mo. Conclusions The element combination indices (Si/Al, Fe/Al, La/Tb, Th/Sc, etc.) and projection diagrams (La-Th-Sc triangle diagram and La/Th-Hf bivariate diagram) further revealed that the sediments sources were dominated by terrigenous materials, particular terrestrial aeolian dust materials. Furthermore, the Chemical Index of Alteration (CIA) indicates that the parent rocks in the sediment source area are in low-medium chemical weathering conditions. The redox sensitive elemental (Cr, Ni, V, U, Th, etc.) combination reveals that the bottom sedimentary environment in the study area was oxidation-weak oxidation environment. This study has reference significance for understanding the influence of the Asian aeolian dust on the sediment provenance of the East Mariana Basin, revealing the sedimentary environment characteristics of the basin and the distribution of seabed mineral resources.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |