## 1 Introduction  
The Yangtze River and Yellow River play significant roles in the formation and evolution of the eastern coastal zone and continental shelf of China [1]. The identification of their river sediments represents a basic problem in provenance research [2]. The Subei littoral plain area is representative of the East China continental shelf. Sediment mixing and diffusion of the Yangtze River and Yellow River, especially their material contributions, still remain to be further studied and explained [3]. Thus, based on theories of genetic mineralogy and marine geology, numerous studies on sediment identification in these two large rivers, as well as provenance tracing across the Subei littoral plain area have been performed by evaluating the provenance significance of typomorphic minerals and their assemblage, as well as the typomorphic characteristics of minerals, and these studies have yielded numerous and substantial achievements [1; 2; 4; 5; 6]. For instance, the results demonstrated that differences between the sediments in these two large rivers could be found in terms of clay mineral contents [6; 7; 8], ratios [9], crystallinity [7; 9], chemical indices [9], crystal shapes [10], geochemical characteristics [10], etc., including indicators of detritus identification [7; 8]. Previous results also revealed differences in carbonate mineral contents [11; 12; 13; 14], crystal shapes [12], grain size effects [12], abrasion and dissolution characteristics [15], etc., which could be used as tracing indices of the Yangtze River and Yellow River [11] to indicate the provenance of sediments on the continental shelf [12]. Other studies have suggested that indicators such as the crystal shape [16], light and/or heavy mineral assemblages [4; 11; 17; 18], geochemical composition [5; 6; 19; 20], magnetite content and other magnetic parameters [2; 21; 22] could also be applied to distinguish these two large rivers and the sediment provenance [4; 5; 17; 23] of the Yellow Sea and East Sea. In addition, previous results indicated that Yellow River sediments were characterized by high mica mineral contents [24; 25]. This finding could be considered for source identification, material diffusion, coastline changes and paleogeographic environment evolution [25]. Moreover, research has revealed that the heavy mineral assemblage of fine-grained (0.063-0.125 mm) sediments was basically characterized by a high content of schistose mica minerals (up to 60%) in the Yangtze River Estuary [26]. Compared with granular minerals, such as quartz and feldspar, schistose mica minerals, they exhibit different behaviors during migration and deposition [27; 28; 29]. Moreover, results show that mica \({}^{40}\)Ar/\({}^{39}\)Ar-dating has important implications for future provenance studies [30; 31]. Thus, mica could theoretically be employed as an indicator for sediment transport and diffusion [32]. The mica content difference could be applied to distinguish between Yangtze River and Yellow River pronounces [33]. However, relevant research on this topic is largely lacking. Certain questions still require further study. For example, what are the specific differences in detrital mica minerals in sediments between the Yangtze River and Yellow River? Could these differences be employed as specific diagnostic indices? Could these indices be applied to analyze detritus mixing and diffusion along the coast of the Subei littoral plain area? Based on the above information, this study compares the differences in the contents and ratios of detrital mica in sediments between the Yangtze River Estuary and the ancient Yellow River Estuary. The possible causes of these differences were also analyzed. Consequently, reliable specific diagnostic indices of detrital mica were examined and distinguished for detritus identification between these two rivers. Then, the mixed area of detrital mica along the coast of the Subei littoral plain area was analyzed. In addition, the ranges of influence of these two large rivers were preliminarily evaluated.