Minerals and rocks have distinct 87Sr/86Sr and 143Nd/144Nd ratios, depending on their geological origin and ages, and these isotope ratios are less altered than elemental composition during transport in the atmosphere...Minerals and rocks have distinct 87Sr/86Sr and 143Nd/144Nd ratios, depending on their geological origin and ages, and these isotope ratios are less altered than elemental composition during transport in the atmosphere or after deposition as sediments, thus stable isotopes of Sr and Nd have great potential as tracers for provenance and trans- port of materials. During the hypergene process, Sr isotope ratios of sediments are controlled by their parent rocks, particle sizes and chemical weathering. In general, the higher the Sr isotope ratios of parent rocks, and/or the more the fine-grained fractions, and/or the stronger the chemical weathering, thus the higher the Sr isotope ratios of sediments. On the contrary, there are lower Sr isotope ratios of sedi- ments. Nd isotope ratios of sediments, independent of their particle sizes and chemical weathering, are only associated with parent rocks. For the prove- nance of the Chinese Loess Plateau, different re- seachers drew discordant and even contradictory conclusions by using the method of Sr-Nd isotopic tracing. From the previous Nd isotope data, it is con- sidered that the Tarim Basin, deserts in the central and west parts of Inner Mongolia and the Tibetan Plateau are the main sources of the Chinese Loess Plateau, and are also manufacturers for eolian dust of the Far East regions, together with the Chinese Loess Plateau. Sr isotope ratios of eolian dust are solely affected by wind sorting and weather- ing-pedogenesis due to its homogeneous composi- tion in the Chinese Loess Plateau. Wind sorting isrelated to the East Asian winter monsoon but weath- ering-pedogenesis is mainly associated with the East Asian summer monsoon. Studies on Sr isotopic compositions of the loess-paleosol sequence suggest that 87Sr/86Sr ratios in acid-soluble materials are an index for chemical weathering intensity of the Chi- nese Loess Plateau, indicating the East Asian sum- mer monsoon variations, whereas 87Sr/86Sr ratios in acid-insoluble materials are significantly controlled by particl展开更多
273 samples from Ocean Drilling Program (ODP) Site 1146 in the northern South China Sea (SCS) were analyzed for grain-size distributions using grain-size class vs. standard deviation method and end-member modeling alg...273 samples from Ocean Drilling Program (ODP) Site 1146 in the northern South China Sea (SCS) were analyzed for grain-size distributions using grain-size class vs. standard deviation method and end-member modeling algorithm (EMMA) in order to investigate the evolution of the East Asian monsoon since about 20 Ma. 10–19 μm/1.3–2.4 μm, the ratio of two grain-size populations with the highest variability through time was used to indicate East Asian winter monsoon intensity relative to summer monsoon. The mass accumulation rate of the coarsest end member EM1 (eolian), resulting from EMMA, can be used as a proxy of winter monsoon strength and Asian inland aridity, and the ratio of EM1/(EM2+EM3) as a proxy of winter monsoon intensity relative to summer monsoon. The combined proxies show that a profound enhancement of East Asian winter monsoon strength and winter monsoon intensity relative to summer monsoon occurred at about 8 Ma, and it is possible that the summer monsoon simultaneously intensified with winter monsoon at 3 Ma. Our results are well consistent with the previous studies in loess, eolian deposion in the Pacifc, radiolarians and planktonic foraminifera in the SCS. The phased uplift of the Himalaya-Tibetan Plateau may have played a significant role in strengthening the Asian monsoon at 8 Ma and 3 Ma.展开更多
Mineral dust released from the desert is one of the important components of atmospheric aerosols. Arid and semi-arid deserts, sandy lands in northern China and their adjacent Gobi Desert lands in northern China and ne...Mineral dust released from the desert is one of the important components of atmospheric aerosols. Arid and semi-arid deserts, sandy lands in northern China and their adjacent Gobi Desert lands in northern China and neighboring Mongolia(hereinafter referred to as Gobi) are potential sources of mineral dust in Asia. However, there is currently a lack of systematic studies on the characteristics of major elements in the potential mineral dust source area. This study investigates the major elements of 310 surficial sand samples in the stabilized and semi-stabilized dune fields from 12 deserts/sandy land and Gobi in northern China and southern Mongolian Gobi and compiles published data. We identify four regions with distinct geochemical characteristics:(1) Taklimakan, Kumtag and Qaidam deserts in western China;(2) Badain Jaran, Tengger, Hobq, and Mu Us deserts in the central and western regions of northern China;(3) Hulun Buir, Onqin Daga and Horqin sandy lands in northeast China;and(4) Gobi and Gurbantunggut deserts. The spatial distributions of the SiO2 and CaO contents in Chinese deserts are highly variable. The average content of SiO2 generally reflects an increasing trend from west to east, while the average content of CaO shows a decreasing trend from west to east. We demonstrate that the spatial variation of major elements is likely controlled by two key scenarios: the composition of source rocks and the mineral maturity caused by the supply of fresh materials. The SiO2/(Al2O3+K2O+Na2O) ratio of desert sediments is relatively lower in western China and may be caused by high ferricmagnesia and high carbonate minerals;this ratio is relatively higher in the northeast sandy lands and may be linked to a lack of fresh material supply and the presence of high K-feldspar minerals in source rocks. The deserts can be further distinguished by ternary diagrams with SiO2/10-CaO-Al2O3,(K2O+Na2O)-CaO-Fe2O3 and CaO-Na2O-K2O. The comparison of major elements between desert sediments and loess suggests that the western and/or ce展开更多
Based on a δ180 chronology, rare earth elements （REE） and other typical elements in sediments from core MD06-3047 in the western Philippine Sea were analyzed to constrain the provenances of the sediments and invest...Based on a δ180 chronology, rare earth elements （REE） and other typical elements in sediments from core MD06-3047 in the western Philippine Sea were analyzed to constrain the provenances of the sediments and investigate quantitative changes in the Asian eolian input to the study area over the last 700 ka. Among the competing processes that might affect REE compositions, sediment provenance is the most important one. Provenance analysis suggests that the study sediments have two provenance end-members; local volcanic sources are dominant, and eolian dust from the Asian continent has a smaller contribution. During glacial periods, eolian input to the western Philippine Sea was enhanced. In contrast, material supply from local volcanics in- creased during interglacial periods. Changes in eolian input to the study area were probably related to the strength of the East Asian winter monsoon （EAWM） as well as aridity in the Asian continent on an orbital time scale, and were partly influenced by local control factors on shorter time scales. Therefore, we propose that the present study expands the application of the REE-based method for quantitatively estimating the eolian component from the mid-latitude northern Pacific to the low-latitude western Pacific. Additionally, the study preliminarily confirms the influence of EAWM-transported eolian materi- al on sedimentation in the western Philippine Sea since 700 ka.展开更多
To synthetically realize the character of major-element compositions as well as its significance for provenance and paleoenvironment recorded in core sediments of the West Philippine Sea over the last 700 ka,grain siz...To synthetically realize the character of major-element compositions as well as its significance for provenance and paleoenvironment recorded in core sediments of the West Philippine Sea over the last 700 ka,grain size and major elements of 221 bulk sediments,together with major-element compositions in the detrital phase of 16 typical samples,in core MD06-3047 collected from the Benham Rise were analyzed.Both discrimination plot and R-mode factor analysis indicate that vertical changes of major elements are mainly controlled by the sedimentation of nearby volcanic matter and the eolian dust input,whereas influences from marine biologic deposition and hydrothermal activity are minor.In particular,Al2O3 and K2O are representative of an eolian dust factor.The variation in the eolian dust factor score is characterized by the obviously glacial-interglacial periodicity and can be well compared with the paleotemperature record of the Antarctic ice core and the evolution of the East Asian winter monsoon(EAWM) recorded in the Chinese loess sequence,and then offers a new proxy for the evolution history of eolian dust input into the study area that is controlled by the EAWM intensity and aridity in the continental source regions of atmospheric dust.展开更多
To understand the provenance and evolution of eolian input in the last 1.95 Ma in the Parece Vela Basin in the eastern Philippine Sea, the clay mineral assemblage of a gravity core PV090510 from the basin was investig...To understand the provenance and evolution of eolian input in the last 1.95 Ma in the Parece Vela Basin in the eastern Philippine Sea, the clay mineral assemblage of a gravity core PV090510 from the basin was investigated using paleogeomagnetic dating and X-ray diffraction. The assemblage of the core mainly consisted of smectite （-46%） and illite （-40%）, with some chlorite （-10%） and kaolinite （-4%）. Analysis of the provenance of these minerals suggested that smectite was mainly derived from volcanic rocks of the Mariana Arc, while illite, chlorite, and kaolinite were mainly transported as eolian dust by the East Asian monsoon from central Asia. We used the ratio of （illite＋chlorite＋kaolinite）/smectite as a proxy for Asian eolian input to the Parece Vela Basin since 1.95 Ma. This ratio followed glacial and interglacial cycles and was consistent with the intensity of the East Asian monsoon and aridity of central Asia since 1.95 Ma. The changes of the ratio reflected three different stages of the East Asian monsoon and provenance climate.展开更多
As the second largest dust source on the globe,the tectonic and climatic evolution of continental Asia has an important impact on regional and global climate change.The West Pacific is the main sediment sink for eolia...As the second largest dust source on the globe,the tectonic and climatic evolution of continental Asia has an important impact on regional and global climate change.The West Pacific is the main sediment sink for eolian dust transported eastward from the Asian interior.Clay minerals,as the major fine-grained weathering products of continental rocks,can be readily transported by wind or currents over long distances and thus have been widely used in the reconstruction of paleoclimate and weathering history.However,the overall evolutionary tendency and response mechanism of clay mineral records over large spatial and long timescales across Asia remain unclear.Here,two continuous and high-resolution clay mineral records since 30 Ma were reconstructed from sediments at Deep Sea Drilling Program(DSDP)Sites 292 and 296 in the Philippine Sea.Clay minerals and Sr-Nd isotope compositions were used to constrain provenance and reconstruct the drying history of the dust source region since the Oligocene.The results show that the clay-sized detrital sediments in the Philippine Sea are a mixture of Asian eolian dust and volcanic materials from the West Pacific arcs.Based on the clay mineral compositions and eolian flux,we reveal that the Asian interior has been continuously drying since the late Oligocene and that stepwise enhanced aridification occurred at approximately 20,14,7,and 3 Ma.Compared with other regions of the world,the relative contents of illite and chlorite increased more dramatically in Asia during the late Cenozoic,and the inconsistency became more obvious at approximately 20 Ma.Since 3 Ma,illite and chlorite have increased consistently across the globe.Combined with the Asian tectonic and climatic history,we suggest that the increase in illite and chlorite from Asia between 20 and 3 Ma was mainly in response to the uplift of the Himalayan-Tibetan Plateau,whereas after 3 Ma,it was primarily controlled by global cooling driven by the expansion of the Arctic ice sheet.展开更多
A compartment model of dynamic deposition processes has been developed and testedin the Potou loess section of China. There are four components in the model : carbonate input ofeolian dust, carbonate output of erosion...A compartment model of dynamic deposition processes has been developed and testedin the Potou loess section of China. There are four components in the model : carbonate input ofeolian dust, carbonate output of erosion, carbonate chemical equilibrium and soil water balance. Aclimate stochastic model software (CLIMAK) generates the daily weather data. The processes ofeolian dust deposition, erosion, and pedogenesis simulate the complex process of carbonatedeposition in a loess-paleosol sequence. We consider both climatic change and soil-forming factors.The results indicate that since the Late Pleistocene in Potou section, the mean carbonate fluxesfrom precipitation, eolian dust and erosion are 0.14g/cm^2/kg, 1.45g/cm^2/ka and 0.23g/cm^2/karespectively. Of this, 91.2% of the carbonate input is from eolian dust.展开更多
Aeolian dust, a primary terrigenous component of ocean sediments, has been widely used to reconstruct the paleoclimatic evolution because its transported distance, grain size and concentration are sensitive to climate...Aeolian dust, a primary terrigenous component of ocean sediments, has been widely used to reconstruct the paleoclimatic evolution because its transported distance, grain size and concentration are sensitive to climate changes. To further characterize the aeolian dust, the deposits at site Ocean Drilling Program (ODP) 882A in northwestern Pacific Ocean are divided into four grain-size fractions (<8, 8-16, 16-64, >64 μm) using the gravitative differentiation method. Detailed rock magnetism results show that magnetite and hematite are dominant magnetic minerals for the dust components. In addition, the aeolian dust (<8 μm) represented by the concentration of magnetic minerals increases sharply at 2.73 Ma, which corresponds to the onset of major glaciation in the Northern Hemisphere. In contrast, the ice-rafted detritus (IRD) (>64 μm) contributes little to the magnetic enhancement of the sediments at 2.73 Ma. These new results greatly improve our understanding of paleoenvironmental evolution during late Pliocene-early Pleistocene in this area.展开更多
Eolian dust is an important material source of marine sediment and heavy metals influencing marine environment and primary productivity. Although the eastern China Seas and their adjacent regions are downwind of East ...Eolian dust is an important material source of marine sediment and heavy metals influencing marine environment and primary productivity. Although the eastern China Seas and their adjacent regions are downwind of East Asian dust sources and have potentially high atmospheric input, study on the eolian dust in these regions is limited. This study on the compositions of eolian dust indicated that dust concentration and particle sizes varied with seasons and meteorologic conditions, that mineral and chemical compositions have significant regional variation, and that high Fe content is one of the characteristics of eolian dust which was found to be a mixture of natural loess and/or soil and anthropogenic matter that contained fairly high S and heavy metals.展开更多
文摘Minerals and rocks have distinct 87Sr/86Sr and 143Nd/144Nd ratios, depending on their geological origin and ages, and these isotope ratios are less altered than elemental composition during transport in the atmosphere or after deposition as sediments, thus stable isotopes of Sr and Nd have great potential as tracers for provenance and trans- port of materials. During the hypergene process, Sr isotope ratios of sediments are controlled by their parent rocks, particle sizes and chemical weathering. In general, the higher the Sr isotope ratios of parent rocks, and/or the more the fine-grained fractions, and/or the stronger the chemical weathering, thus the higher the Sr isotope ratios of sediments. On the contrary, there are lower Sr isotope ratios of sedi- ments. Nd isotope ratios of sediments, independent of their particle sizes and chemical weathering, are only associated with parent rocks. For the prove- nance of the Chinese Loess Plateau, different re- seachers drew discordant and even contradictory conclusions by using the method of Sr-Nd isotopic tracing. From the previous Nd isotope data, it is con- sidered that the Tarim Basin, deserts in the central and west parts of Inner Mongolia and the Tibetan Plateau are the main sources of the Chinese Loess Plateau, and are also manufacturers for eolian dust of the Far East regions, together with the Chinese Loess Plateau. Sr isotope ratios of eolian dust are solely affected by wind sorting and weather- ing-pedogenesis due to its homogeneous composi- tion in the Chinese Loess Plateau. Wind sorting isrelated to the East Asian winter monsoon but weath- ering-pedogenesis is mainly associated with the East Asian summer monsoon. Studies on Sr isotopic compositions of the loess-paleosol sequence suggest that 87Sr/86Sr ratios in acid-soluble materials are an index for chemical weathering intensity of the Chi- nese Loess Plateau, indicating the East Asian sum- mer monsoon variations, whereas 87Sr/86Sr ratios in acid-insoluble materials are significantly controlled by particl
基金National Natural Science Foundation of China (Grant Nos. 90411014 and 40576032)
文摘273 samples from Ocean Drilling Program (ODP) Site 1146 in the northern South China Sea (SCS) were analyzed for grain-size distributions using grain-size class vs. standard deviation method and end-member modeling algorithm (EMMA) in order to investigate the evolution of the East Asian monsoon since about 20 Ma. 10–19 μm/1.3–2.4 μm, the ratio of two grain-size populations with the highest variability through time was used to indicate East Asian winter monsoon intensity relative to summer monsoon. The mass accumulation rate of the coarsest end member EM1 (eolian), resulting from EMMA, can be used as a proxy of winter monsoon strength and Asian inland aridity, and the ratio of EM1/(EM2+EM3) as a proxy of winter monsoon intensity relative to summer monsoon. The combined proxies show that a profound enhancement of East Asian winter monsoon strength and winter monsoon intensity relative to summer monsoon occurred at about 8 Ma, and it is possible that the summer monsoon simultaneously intensified with winter monsoon at 3 Ma. Our results are well consistent with the previous studies in loess, eolian deposion in the Pacifc, radiolarians and planktonic foraminifera in the SCS. The phased uplift of the Himalaya-Tibetan Plateau may have played a significant role in strengthening the Asian monsoon at 8 Ma and 3 Ma.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41673095, 41230526, 41690111 & 41877369)the Fundamental Research Funds for the Central Universities (Grant No. Swu118203)
文摘Mineral dust released from the desert is one of the important components of atmospheric aerosols. Arid and semi-arid deserts, sandy lands in northern China and their adjacent Gobi Desert lands in northern China and neighboring Mongolia(hereinafter referred to as Gobi) are potential sources of mineral dust in Asia. However, there is currently a lack of systematic studies on the characteristics of major elements in the potential mineral dust source area. This study investigates the major elements of 310 surficial sand samples in the stabilized and semi-stabilized dune fields from 12 deserts/sandy land and Gobi in northern China and southern Mongolian Gobi and compiles published data. We identify four regions with distinct geochemical characteristics:(1) Taklimakan, Kumtag and Qaidam deserts in western China;(2) Badain Jaran, Tengger, Hobq, and Mu Us deserts in the central and western regions of northern China;(3) Hulun Buir, Onqin Daga and Horqin sandy lands in northeast China;and(4) Gobi and Gurbantunggut deserts. The spatial distributions of the SiO2 and CaO contents in Chinese deserts are highly variable. The average content of SiO2 generally reflects an increasing trend from west to east, while the average content of CaO shows a decreasing trend from west to east. We demonstrate that the spatial variation of major elements is likely controlled by two key scenarios: the composition of source rocks and the mineral maturity caused by the supply of fresh materials. The SiO2/(Al2O3+K2O+Na2O) ratio of desert sediments is relatively lower in western China and may be caused by high ferricmagnesia and high carbonate minerals;this ratio is relatively higher in the northeast sandy lands and may be linked to a lack of fresh material supply and the presence of high K-feldspar minerals in source rocks. The deserts can be further distinguished by ternary diagrams with SiO2/10-CaO-Al2O3,(K2O+Na2O)-CaO-Fe2O3 and CaO-Na2O-K2O. The comparison of major elements between desert sediments and loess suggests that the western and/or ce
基金supported by the Public Science and Technology Research Funds Projects of the OceanState Oceanic Administration of the People’s Republic of China(Grant No.201005003)+1 种基金the National Natural Science Foundation of China(Grant Nos.41376064,41230959,41106043,and 41076033)the National Basic Research Program of China(Grant No.2007CB815903)
文摘Based on a δ180 chronology, rare earth elements （REE） and other typical elements in sediments from core MD06-3047 in the western Philippine Sea were analyzed to constrain the provenances of the sediments and investigate quantitative changes in the Asian eolian input to the study area over the last 700 ka. Among the competing processes that might affect REE compositions, sediment provenance is the most important one. Provenance analysis suggests that the study sediments have two provenance end-members; local volcanic sources are dominant, and eolian dust from the Asian continent has a smaller contribution. During glacial periods, eolian input to the western Philippine Sea was enhanced. In contrast, material supply from local volcanics in- creased during interglacial periods. Changes in eolian input to the study area were probably related to the strength of the East Asian winter monsoon （EAWM） as well as aridity in the Asian continent on an orbital time scale, and were partly influenced by local control factors on shorter time scales. Therefore, we propose that the present study expands the application of the REE-based method for quantitatively estimating the eolian component from the mid-latitude northern Pacific to the low-latitude western Pacific. Additionally, the study preliminarily confirms the influence of EAWM-transported eolian materi- al on sedimentation in the western Philippine Sea since 700 ka.
基金supported by the Public Science and Technology Research Funds Projects of Ocean,State Oceanic Administration of the People's Republic of China(201005003)the Open Fund of the KLMGE,IO,CAS,the National Natural Science Foundation of China(41106043 and 41230959)+1 种基金the National Basic Research Program of China(2007CB815903)the Innovative Program of the Chinese Academy of Sciences(KZCX2-YW-221)
文摘To synthetically realize the character of major-element compositions as well as its significance for provenance and paleoenvironment recorded in core sediments of the West Philippine Sea over the last 700 ka,grain size and major elements of 221 bulk sediments,together with major-element compositions in the detrital phase of 16 typical samples,in core MD06-3047 collected from the Benham Rise were analyzed.Both discrimination plot and R-mode factor analysis indicate that vertical changes of major elements are mainly controlled by the sedimentation of nearby volcanic matter and the eolian dust input,whereas influences from marine biologic deposition and hydrothermal activity are minor.In particular,Al2O3 and K2O are representative of an eolian dust factor.The variation in the eolian dust factor score is characterized by the obviously glacial-interglacial periodicity and can be well compared with the paleotemperature record of the Antarctic ice core and the evolution of the East Asian winter monsoon(EAWM) recorded in the Chinese loess sequence,and then offers a new proxy for the evolution history of eolian dust input into the study area that is controlled by the EAWM intensity and aridity in the continental source regions of atmospheric dust.
基金Supported by the National Basic Research Program of China(973 Program)(No.2007CB411703)the National Natural Science Foundation of China(No.40976026)
文摘To understand the provenance and evolution of eolian input in the last 1.95 Ma in the Parece Vela Basin in the eastern Philippine Sea, the clay mineral assemblage of a gravity core PV090510 from the basin was investigated using paleogeomagnetic dating and X-ray diffraction. The assemblage of the core mainly consisted of smectite （-46%） and illite （-40%）, with some chlorite （-10%） and kaolinite （-4%）. Analysis of the provenance of these minerals suggested that smectite was mainly derived from volcanic rocks of the Mariana Arc, while illite, chlorite, and kaolinite were mainly transported as eolian dust by the East Asian monsoon from central Asia. We used the ratio of （illite＋chlorite＋kaolinite）/smectite as a proxy for Asian eolian input to the Parece Vela Basin since 1.95 Ma. This ratio followed glacial and interglacial cycles and was consistent with the intensity of the East Asian monsoon and aridity of central Asia since 1.95 Ma. The changes of the ratio reflected three different stages of the East Asian monsoon and provenance climate.
基金supported by the National Natural Science Foundation of China(Grant Nos.42125602,42076052)the National Key Research and Development Program of China(Grant No.2022YFF0800503)+3 种基金the Strategic Priority Research Program of CAS(Grant No.XDB40010100)the Marine S&T Fund of Shandong Province for QNLM(Grant No.2022QNLM050203)the Innovation Project of QNLM(Grant No.MGQNLM-KF202001)the Taishan and Aoshan Talents Program(Grant No.2017ASTCP-ES01).
文摘As the second largest dust source on the globe,the tectonic and climatic evolution of continental Asia has an important impact on regional and global climate change.The West Pacific is the main sediment sink for eolian dust transported eastward from the Asian interior.Clay minerals,as the major fine-grained weathering products of continental rocks,can be readily transported by wind or currents over long distances and thus have been widely used in the reconstruction of paleoclimate and weathering history.However,the overall evolutionary tendency and response mechanism of clay mineral records over large spatial and long timescales across Asia remain unclear.Here,two continuous and high-resolution clay mineral records since 30 Ma were reconstructed from sediments at Deep Sea Drilling Program(DSDP)Sites 292 and 296 in the Philippine Sea.Clay minerals and Sr-Nd isotope compositions were used to constrain provenance and reconstruct the drying history of the dust source region since the Oligocene.The results show that the clay-sized detrital sediments in the Philippine Sea are a mixture of Asian eolian dust and volcanic materials from the West Pacific arcs.Based on the clay mineral compositions and eolian flux,we reveal that the Asian interior has been continuously drying since the late Oligocene and that stepwise enhanced aridification occurred at approximately 20,14,7,and 3 Ma.Compared with other regions of the world,the relative contents of illite and chlorite increased more dramatically in Asia during the late Cenozoic,and the inconsistency became more obvious at approximately 20 Ma.Since 3 Ma,illite and chlorite have increased consistently across the globe.Combined with the Asian tectonic and climatic history,we suggest that the increase in illite and chlorite from Asia between 20 and 3 Ma was mainly in response to the uplift of the Himalayan-Tibetan Plateau,whereas after 3 Ma,it was primarily controlled by global cooling driven by the expansion of the Arctic ice sheet.
文摘A compartment model of dynamic deposition processes has been developed and testedin the Potou loess section of China. There are four components in the model : carbonate input ofeolian dust, carbonate output of erosion, carbonate chemical equilibrium and soil water balance. Aclimate stochastic model software (CLIMAK) generates the daily weather data. The processes ofeolian dust deposition, erosion, and pedogenesis simulate the complex process of carbonatedeposition in a loess-paleosol sequence. We consider both climatic change and soil-forming factors.The results indicate that since the Late Pleistocene in Potou section, the mean carbonate fluxesfrom precipitation, eolian dust and erosion are 0.14g/cm^2/kg, 1.45g/cm^2/ka and 0.23g/cm^2/karespectively. Of this, 91.2% of the carbonate input is from eolian dust.
基金supported by National Natural Science Foundation of China (Grants Nos. 40974036, 41025013 and 40821091)the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘Aeolian dust, a primary terrigenous component of ocean sediments, has been widely used to reconstruct the paleoclimatic evolution because its transported distance, grain size and concentration are sensitive to climate changes. To further characterize the aeolian dust, the deposits at site Ocean Drilling Program (ODP) 882A in northwestern Pacific Ocean are divided into four grain-size fractions (<8, 8-16, 16-64, >64 μm) using the gravitative differentiation method. Detailed rock magnetism results show that magnetite and hematite are dominant magnetic minerals for the dust components. In addition, the aeolian dust (<8 μm) represented by the concentration of magnetic minerals increases sharply at 2.73 Ma, which corresponds to the onset of major glaciation in the Northern Hemisphere. In contrast, the ice-rafted detritus (IRD) (>64 μm) contributes little to the magnetic enhancement of the sediments at 2.73 Ma. These new results greatly improve our understanding of paleoenvironmental evolution during late Pliocene-early Pleistocene in this area.
文摘Eolian dust is an important material source of marine sediment and heavy metals influencing marine environment and primary productivity. Although the eastern China Seas and their adjacent regions are downwind of East Asian dust sources and have potentially high atmospheric input, study on the eolian dust in these regions is limited. This study on the compositions of eolian dust indicated that dust concentration and particle sizes varied with seasons and meteorologic conditions, that mineral and chemical compositions have significant regional variation, and that high Fe content is one of the characteristics of eolian dust which was found to be a mixture of natural loess and/or soil and anthropogenic matter that contained fairly high S and heavy metals.
