The timing and behavioral markers of the Upper Paleolithic in different parts of the world are of great importance to research on modern human dispersals. The pattern of behavioral developments in the Upper Paleolithic in northern China differs in important ways from the patterns observed in West Eurasia, Africa, and South Asia. Shuidonggou (SDG), a cluster of Paleolithic sites in northern China, contains several of the most important Upper Paleolithic sites in the region. Various localities yield evidence of three major cultural components dated by 14C, uranium-series, and optically stimulated luminescence (OSL) methods to between roughly 46 ka and 10 ka. The oldest component, blade assemblages with western Eurasian early Upper Paleolithic characteristics, appears to be intrusive from Siberia and/or Mongolia, beginning at least 41 ka (e.g., SDG 1 and SDG 9). Advanced core and flake assemblages may mark the appearance of an indigenous Late Paleolithic of North China beginning at around 33 ka (e.g., SDG 2 and SDG 8). Finally, around 10.5 ka, microblade technology arrived in the area (SDG 12), although we are not sure of its origins at present. Other typical Upper Paleolithic cultural remains, such as bone tools and body decorations, have been found at various localities in the SDG area as well (e.g., ostrich eggshell beads from SDG 2, 7, and 8). Information from this cluster of occupations increases our understanding of cultural variability, adaptation, and demographic dynamics of modern humans in Late Pleistocene northern Asia.
The origin of large‐scale ancient dolomite is one of the most hotly debated topics in sedimentology. The Loushanguan group of the upper 3rd‐Furongian Cambrian series on the south‐eastern margin of the Sichuan Basin consists of numerous dolomites, and the origins of these dolomites have never been reported previously although they are probably good hydrocarbon reservoirs. Based on a systematic analysis of petrology, fluid inclusions, carbon and oxygen isotopes, trace elements and rare earth elements (REEs), this study provides some unique insights into the origins of the dolomites. Four dolomite types have been identified in the study area: dolomicrite, fabric‐retentive oolitic dolomite, fabric‐obliterative dolomite and saddle dolomite cement. In the dolomicrite and fabric‐retentive oolitic dolomite, high Sr contents (with respect to the fabric‐obliterative dolomite) and the lack of two‐phase aqueous inclusions suggest that they formed at shallow‐to‐intermediate burial depths at low temperatures (<50–60°C). Carbon and oxygen isotopes and seawater‐like REE+Y characteristics of the dolomicrite and fabric‐retentive oolitic dolomite indicate that the dolomitizing fluids were evaporated seawater or slightly modified seawater. The obliteration of the original sedimentary fabric and relatively low δ18O and Sr values compared to the fabric‐retentive dolomite indicate that fabric‐obliterative dolomite formed at intermediate‐to‐deep burial diagenesis. The chemical composition approaches pure dolomite and the REE+Y characteristics are similar to those of the fabric‐retentive dolomite, indicating that the fabric‐obliterative dolomite was formed due to the recrystallization of the previously formed fabric‐retentive dolomite at elevated burial depths and temperatures. High fluid inclusion homogenization temperatures (115–150°C), low δ18O values, nonplanar‐a crystals and seawater‐like REE+Y characteristics suggest that saddle dolomite cement formed by reprecipitation of dolomite that related to seawater‐driven and deep burial fluid. In the study area, dolomicrite and fabric‐retentive oolitic dolomite may have been formed by penecontemporaneous or seepage‐reflux dolomitization during early‐stage diagenesis. Subsequently, during progressive burial, most of the fabric‐retentive dolomite was converted into fabric‐obliterative dolomite by recrystallization. This study confirms that fabric‐obliterative dolomite was the main dolomite type, and although deeply buried, these Cambrian dolomites most likely have preserved coeval seawater geochemical signals. 相似文献