Characteristics of heavy minerals in rivers entering the sea from the south bank of Laizhou Bay and their provenance significance

While focusing on identifying and tracing the sources of large rivers, the source-sink system of "short-source river flow – instantaneous large flux – rapid material transformation" deserves attention. The sediment sources of small- and medium-sized rivers entering the sea on the south bank of Laizhou Bay have clear sources, and low complexity in parent rocks, climate, and hydrodynamic conditions, which makes it easy to analyze the characteristics of material end-members under limited boundary conditions. We studied the differences in the characteristics of detrital heavy minerals from small- and medium-sized rivers, including Xiaoqing River, Mihe River, Bailang River, Yuhe River, Dihe River, Weihe River, and Jiaolai River on the south bank of Laizhou Bay, by which the sources of different river sources were analyzed and discriminated. Results show that a total of 31 heavy minerals were identified, mainly amphibole and epidote. The sediments of Xiaoqing River and Weihe River had a high heavy mineral content (＞5.5%) typical of abundant limonite, while those of other rivers had a low heavy mineral content (＜1.5%) typical of ample biotite. The characteristic mineral assemblages composed of garnet-sphene-apatite and standard minerals (wollastonite, sillimanite, corundum, staurolite, and andalusite, and so on) reflect different rock types such as acidic granites, regional metamorphic rocks, and contact metamorphic rocks exposed in the source area, which are the main controlling factors for the differences in the characteristic assemblages of different riverine minerals. In addition, the biplot and heatmap show that the spectra of heavy minerals from Huanghe River and the southern coastal waters of Laizhou Bay are quite different. The sediments in the offshore area of the southern coast of Laizhou Bay mainly come from nearby river materials, and the impact of Huanghe River materials weakens from west to east. Therefore, analyzing the characteristics of heavy minerals in short-source river sediments can provide a basis for identifying the sources of detrital sediments in the Shandong Peninsula, which is of great significance for a deeper understanding of the material supply process at the continental margin.