Redai dili (Sep 2021)
End-Member Analysis of Sedimentary Dynamics Indicated by the Grain-Size of Surface Sediments in the Quanzhou Bay
Abstract
Quanzhou Bay, the main port on the southeast coast of China, is the origin of the Maritime Silk Road. The landform is a semi-closed shelf bay. Two rivers, the Jinjiang and Luoyang, carry sediments to the bay and are connected to the Taiwan Strait. Sediment is also introduced to the bay from the open sea. Human activities have a strong influence on the bay, as does the occasional typhoon. Quanzhou Bay is characterized as a complex hydrodynamic environment with multi-source deposits. Grain size is an important indicator of the sedimentological characteristics of loose sediments, and it can reflect mixed sedimentary dynamics, sedimentary environment, and provenance. The End-Member Analysis method has the advantage of separating the mixed sedimentary dynamic components and has been widely used in sedimentology research. Many researchers have studied the sedimentological characteristics of Quanzhou Bay. However, further work on the identification of the dynamic components using End-Member Analysis methods is necessary to supplement previous work. In view of this, the present study adopts the particle size End-Member Analysis method, combined with sediment grain size parameters, water depth, and hydrodynamic forces, to analyze the sedimentation dynamics of 65 surface sediment samples collected in Quanzhou Bay of Fujian Province. Based on this analysis, we concluded that: (1) Owing to the continuous progress of sedimentary dynamics, separation, and sedimentation, provenance cannot be determined from grain size analyses, and only sedimentary kinetic characteristics can be defined; (2) Quanzhou Bay sediments are superimposed with at least four different dynamic end-member components. The distribution of the fine-grained End-Member components represented by EM 1 on the Quanzhou Bay area plane is generally corresponds to the weaker tidal hydrodynamics area. Therefore, we infer that this may represent a stagnant sedimentary environment with weak hydrodynamics. The EM 2 components, are somewhat high in the southern part of the bay mouth, and are relatively stable and with uniform distribution elsewhere in the bay. Considering the effect of tidal currents and the attenuation of tidal action in some areas, EM 2 components may represent the sedimentary dynamic environment of reworking under the action of typhoon storms. EM 3 and EM 1 components show an anti-correlation trend, which often occurs in areas with strong hydrodynamic forces. Therefore, EM 3 may be associated with a strong sedimentary dynamic environment under the action of tidal currents. The EM 4 component is generally higher in the northern part of the bay and in the estuary, but lower around the islands. This spatial distribution is likely to be caused by comprehensive human activities. There are many artificial sand-piling areas near Xiutu, and many cross-sea projects in the sea area north of Shihu, such as the wharf on the north bank east of Xiutu and the Cross-sea Bridge of Quanzhou Bay. The area affected by these projects coincides with high values of EM 4. The research in this paper is of progressive significance for a quantitative understanding of the complex sedimentary dynamics of Quanzhou Bay. Concurrently, by analyzing the dynamics and processes of sediment accumulation in the bay, a reference can be provided for channel dredging, utilization, and management for coastal zone development.
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