The Quaternary aggradation red earth(QARE)deposit in the middle reaches of the Yangtze River(MRYR)in southern China provides important evidence for understanding the paleoenvironment.However,its provenance remains con...The Quaternary aggradation red earth(QARE)deposit in the middle reaches of the Yangtze River(MRYR)in southern China provides important evidence for understanding the paleoenvironment.However,its provenance remains controversial.In this study,the surface microtextures of grains from the QARE were observed,and compared with those of grains from the loess deposit on the Loess Plateau in northern China.The results show that the surface microtextures and morphologies of the quartz grains in the QARE are distinctly different from those in the northern loess,indicating that the deposits in the two regions have different provenances.The Gobi and deserts in inland northwestern China are not considered as the primary provenance for the QARE in southern China.It is suggested that the large areas of dry and bare river and lake beds and floodplains in the MRYR,which became exposed during glacial periods,provided the dominant source for materials in the QARE.We suggest that against the background of the middle-Pleistocene climate transition(MPT),regional aridification and a strengthened east Asian winter monsoon(driven by global cooling and the rapid uplift of the Tibetan Plateau)were primary drivers for the initiation of the QARE deposit in the MRYR region in southern China.The development of large areas of aeolian red earth deposit is direct evidence of environmental deterioration in the MRYR,indicating a cold and dry environment with frequent aeolian activity,in an area that now experiences a warm and humid subtropical monsoon climate.The results are also evidence of a regional response in the mid-subtropics of southern China to the MPT global cooling event around 1.2 Ma.展开更多
A thin layer of yellow-brown-colored earth was generally found on Quaternary red clay in Jiujiang,Jiangxi Province. A typical profile was established. Both particle size distribution and REE (rare earthelements) chara...A thin layer of yellow-brown-colored earth was generally found on Quaternary red clay in Jiujiang,Jiangxi Province. A typical profile was established. Both particle size distribution and REE (rare earthelements) characteristics of the yellow-brown-colored earth of the profile fully suggested its aeolian origin andclose similarity to Naming Xiashu loess. The study also implied aeolian origin of the underlying Quaternaryred clap Compared with the red clay, the yellow- brown- colored earth was less weathered because of its lowercontent of free iron and higher mole ratios of SiO2/A12O3 and SiO2/(Fe2O3+A12O3 ) as well as its lessdeveloped chemical microtextures of quartz grains.In order to study the aged of the two deposits comparatively, the thermoluminescent dating method wasused. As a result, the bottom of the yellow-brown-colored esrth was dated to 6015 ka B. P. and the upperpart of the red clay 38854 ka B. P. It was suggested that the yellow- browm- colored earth was formed inthe Late Pleistocene and was probably the aeolian deposit of the Last Glacial, which corresponded with theMalan loess in the Loess Plateau of the northwestern part of China; while the underlying red clay was formedin the Middle Pleistocene.A "yellow cap" on Quaternary red clay in Jiujiang implied a great climatic and environmental varistionin the beginning of the Late Pleistocene in the southern pot of China, especially in the middle and lowerreaches of the Yangtze River. The eveal not only halted the rubification, once dominating the region, butalso produced a widespread covering of aeolian deposit, as only occurred in the cold and dry environment.展开更多
The particle size distribution, heavy mineral constituents and rare earth elements (REE) characteristics of the Quaternary red clay of southern Anhui Province were studied to explore the origin of the clay. The resul...The particle size distribution, heavy mineral constituents and rare earth elements (REE) characteristics of the Quaternary red clay of southern Anhui Province were studied to explore the origin of the clay. The results showed that the clay had some properties of areolian deposits, which could be compared with those of the loess in North China; and its chondrite normalized curves of REE were similar to those of the Xiashu loess, implying that they shared the same origin. It was concluded in combination with the results reported by other researchers that the Quaternary red clay of southern Anhui Province originated from aeolian deposits, and this could reveal the cycles of warm and cold climates in the area during the Quaternary period.展开更多
Mineral magnetic measurements have been made on Quaternary Red Earth profilesfrom Zhejiang Province, Eastern China. Three distinctive magnetic stratigraphic horizons havebeen identified on the basis of magnetic suscep...Mineral magnetic measurements have been made on Quaternary Red Earth profilesfrom Zhejiang Province, Eastern China. Three distinctive magnetic stratigraphic horizons havebeen identified on the basis of magnetic susceptibility, anhysteretic remanent magnetization,saturation isothermal remanent magnetization and magnetization parameters measurements.Magnetic measurements revealed that there were great variations in ferrimagnetic mineralconcentration, mineralogy assemblages and grain size in Quaternary Red Earth profiles, suggestingthat these variations reflect pedogenic processes fluctuation and environmental changes. Thepreliminary results indicate that mineral magnetic measurement of Quaternary Red Earth is usefulfor studying the Quaternary environmental changes recorded in paleosols.展开更多
基金supported by“The National Key R&D of China”(2016 YFC0500909).
文摘The Quaternary aggradation red earth(QARE)deposit in the middle reaches of the Yangtze River(MRYR)in southern China provides important evidence for understanding the paleoenvironment.However,its provenance remains controversial.In this study,the surface microtextures of grains from the QARE were observed,and compared with those of grains from the loess deposit on the Loess Plateau in northern China.The results show that the surface microtextures and morphologies of the quartz grains in the QARE are distinctly different from those in the northern loess,indicating that the deposits in the two regions have different provenances.The Gobi and deserts in inland northwestern China are not considered as the primary provenance for the QARE in southern China.It is suggested that the large areas of dry and bare river and lake beds and floodplains in the MRYR,which became exposed during glacial periods,provided the dominant source for materials in the QARE.We suggest that against the background of the middle-Pleistocene climate transition(MPT),regional aridification and a strengthened east Asian winter monsoon(driven by global cooling and the rapid uplift of the Tibetan Plateau)were primary drivers for the initiation of the QARE deposit in the MRYR region in southern China.The development of large areas of aeolian red earth deposit is direct evidence of environmental deterioration in the MRYR,indicating a cold and dry environment with frequent aeolian activity,in an area that now experiences a warm and humid subtropical monsoon climate.The results are also evidence of a regional response in the mid-subtropics of southern China to the MPT global cooling event around 1.2 Ma.
文摘A thin layer of yellow-brown-colored earth was generally found on Quaternary red clay in Jiujiang,Jiangxi Province. A typical profile was established. Both particle size distribution and REE (rare earthelements) characteristics of the yellow-brown-colored earth of the profile fully suggested its aeolian origin andclose similarity to Naming Xiashu loess. The study also implied aeolian origin of the underlying Quaternaryred clap Compared with the red clay, the yellow- brown- colored earth was less weathered because of its lowercontent of free iron and higher mole ratios of SiO2/A12O3 and SiO2/(Fe2O3+A12O3 ) as well as its lessdeveloped chemical microtextures of quartz grains.In order to study the aged of the two deposits comparatively, the thermoluminescent dating method wasused. As a result, the bottom of the yellow-brown-colored esrth was dated to 6015 ka B. P. and the upperpart of the red clay 38854 ka B. P. It was suggested that the yellow- browm- colored earth was formed inthe Late Pleistocene and was probably the aeolian deposit of the Last Glacial, which corresponded with theMalan loess in the Loess Plateau of the northwestern part of China; while the underlying red clay was formedin the Middle Pleistocene.A "yellow cap" on Quaternary red clay in Jiujiang implied a great climatic and environmental varistionin the beginning of the Late Pleistocene in the southern pot of China, especially in the middle and lowerreaches of the Yangtze River. The eveal not only halted the rubification, once dominating the region, butalso produced a widespread covering of aeolian deposit, as only occurred in the cold and dry environment.
文摘The particle size distribution, heavy mineral constituents and rare earth elements (REE) characteristics of the Quaternary red clay of southern Anhui Province were studied to explore the origin of the clay. The results showed that the clay had some properties of areolian deposits, which could be compared with those of the loess in North China; and its chondrite normalized curves of REE were similar to those of the Xiashu loess, implying that they shared the same origin. It was concluded in combination with the results reported by other researchers that the Quaternary red clay of southern Anhui Province originated from aeolian deposits, and this could reveal the cycles of warm and cold climates in the area during the Quaternary period.
文摘Mineral magnetic measurements have been made on Quaternary Red Earth profilesfrom Zhejiang Province, Eastern China. Three distinctive magnetic stratigraphic horizons havebeen identified on the basis of magnetic susceptibility, anhysteretic remanent magnetization,saturation isothermal remanent magnetization and magnetization parameters measurements.Magnetic measurements revealed that there were great variations in ferrimagnetic mineralconcentration, mineralogy assemblages and grain size in Quaternary Red Earth profiles, suggestingthat these variations reflect pedogenic processes fluctuation and environmental changes. Thepreliminary results indicate that mineral magnetic measurement of Quaternary Red Earth is usefulfor studying the Quaternary environmental changes recorded in paleosols.
