Variability of clay mineral assemblages in the Western Pacific Warm Pool(WPWP) over the past 370 ka shows the prominent glacial-interglacial cyclicity.Smectite(62%-91%) is the dominant clay mineral,with decreased cont...Variability of clay mineral assemblages in the Western Pacific Warm Pool(WPWP) over the past 370 ka shows the prominent glacial-interglacial cyclicity.Smectite(62%-91%) is the dominant clay mineral,with decreased contents during interglacials while increased in glacials.In contrast,variations in chlorite(4%-21%),illite(4%-12%),and kaolinite(2%-10%) share a similar pattern with higher contents during interglacials than glacials,mirroring to that of smectite.The results indicate that the smectite-dominated clay minerals derive mainly from the river detrital inputs of New Guinea.The glacial-interglacial cycle of clay mineral assemblages well correspond to the fluctuation of sea level.When the sea level was low,the river materials can travel more easily across the narrow shelf off the island of New Guinea,inject directly into the subsurface currents flowing westwards,then merge into the Equatorial Undercurrent(EUC),and eventually deposit on the central part of WPWP.Precessional periods of the smectite content indicate the intensity of mechanical erosion in its provenance of New Guinea,responding to the river runoff and precipitation,and this could also be linked to the meridional migration of the Intertropical Convergence Zone(ITCZ).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
The first attempt is made to evaluate quantitatively the changes of accumulation rates in the South China Sea during the last glaciation and Holocene, based on the data of 72 sediment cores taken from six areas deeper...The first attempt is made to evaluate quantitatively the changes of accumulation rates in the South China Sea during the last glaciation and Holocene, based on the data of 72 sediment cores taken from six areas deeper than 100 m. As shown from the calculations, the accumulation rate during the last glaciation is much higher than that during the Holocene. The southern and northern continental slopes are distinguished from other areas by the highest accumulation rates, with different features of sedimentation for aifferent stages: The Glacial-Holocene contrast in accumulation rate of terrigenous material is more distinct in the southern slope, while the contrast in biogenic sedimentation rate is more remarkable in the northern slope.展开更多
Since 40 kaBP, the current endorheism on the Tibetan Plateau had experienced at least four lake-expanding events, at 40-28 kaBP, 19-15 kaBP, 13-11 kaBP, 9.0-5.0 kaBP, respectively. The 40-28 kaBP and 9.0-5.0 kaBP lake...Since 40 kaBP, the current endorheism on the Tibetan Plateau had experienced at least four lake-expanding events, at 40-28 kaBP, 19-15 kaBP, 13-11 kaBP, 9.0-5.0 kaBP, respectively. The 40-28 kaBP and 9.0-5.0 kaBP lake-expanding events, corresponding to the global warming periods, were mainly determined by the abundant summer monsoon rainfall brought by strong Indian monsoon, aroused by enhanced solar radiation at earth orbital precessional cycle. The 40-28 kaBP lake-expanding event, also called the great lake period or the pan-lake period, for several great lake groups had come into being by the interconnection of the presently isolated and closed lake catchments. The total lake area over the Tibetan Plateau was estimated at least up to 150000 km2, 3.8 times of the present, and the lake supply coefficients were about 3-10. The 9.0-5.0 kaBP lake-expanding, with a total lake area of 68000 km2, less than the above mentioned reflected the Indian monsoon rainfall less than that of 40-28 kaBP. The expanded lakes at 19-15 kaBP and 13-11 kaBP, distributed in these basins with more or less existing glacial, indicated plenty of glacial meltwater discharged to balance evaporation on expansive lake surface. At the same time, the enhanced precipitation by the westerlies at 19-15 kaBP and by Indian monsoon at 13-11 kaBP plays an important role in maintaining the high lake level. Heinrich events greatly affected the evolution of climate system over the Tibetan Plateau, and thus gave a clear boundary of the high lake level change in the late Quaternary.展开更多
THE consequence of "nuclear winter" induced by nuclear war and climatic catastrophe induced by extraterrestrial impact were widely studied for fear of the potential danger of the basic nuclear war (the total...THE consequence of "nuclear winter" induced by nuclear war and climatic catastrophe induced by extraterrestrial impact were widely studied for fear of the potential danger of the basic nuclear war (the totalexplosive equivalent 5 000Mt TNT). Using zero-dimensional energy balance model authors reportedthe short-term climatic effect induced by six huge Cenozoic bolide-impact events (65, 34, 15, 2.4,1.1, 0.73 MaBP). However, only the direct climatic effect of dusts yielded by the impact was considered in the previous study. In this note, based on the previous simulation results the effect of variance ofglobal reflectance with temperature on the long-term climatic change was further taken into consideration.Combined with the strata records of palaeoclimatic change the relationship of impact energy with its in-展开更多
Today anthropogenic climate change is underway and predicted future global temperatures vary significantly. However, the drivers of current climate change and their links to Earth’s natural glacial cycle have yet to ...Today anthropogenic climate change is underway and predicted future global temperatures vary significantly. However, the drivers of current climate change and their links to Earth’s natural glacial cycle have yet to be fully resolved. Currently, many on a local level understand, and are exposed to, the heat energy generated by what’s referred to as the urban heat island effect (UHI), whereby natural flora with higher albedos </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> replaced by manmade urban areas with lower albedos. This heat effect is not constrained to these regions and all anthropogenic surfaces with lower albedos need to be studied and quantified as the accumulated additional heat energy (infrared energy) is trapped within Earth’s atmosphere and could affect the Earth on a planetary level. Deployed satellites have detected critical changes to Earth’s albedo to lower levels, however the cause and impact of these changes have yet to be fully understood and incorporated into Global Circulation models (GCMs). Here it’s shown that industrialization of anthropogenic landscape practices of the past century has displaced millions of square kilometres of naturally high albedo grasslands with lower albedo agricultural landscapes. Utilising a fundamental Energy Balance Model, (EBM) it’s demonstrated these specific changes have generated vast amounts of additional heat energy which is trapped by the atmosphere, transferred and stored within the oceans of the Earth as shown in <b></span></span></span><a href="file:///E:/360data/%E9%87%8D%E8%A6%81%E6%95%B0%E6%8D%AE/%E6%A1%8C%E9%9D%A2/%E7%A9%BA%E7%99%BD%E9%A1%B5.docx#F1"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><b><span style="font-family:Verdana;">Figure 1</span></b></span></span></a><span style="font-family:Verdana;"><span style展开更多
Based on the evidence available from both observations and model simulations, the author proposes a view that may provide a unified interpretation of the North Atlantic thermohaline variability. Because of the slow re...Based on the evidence available from both observations and model simulations, the author proposes a view that may provide a unified interpretation of the North Atlantic thermohaline variability. Because of the slow response time of the Southern Ocean （millennia） and the relatively faster response time of the North Atlantic （centuries）, the North Atlantic thermohaline circulation is controlled predominantly by the climate forcing over the Southern Ocean at the long glacial cycle timescales, but by the North Atlantic climate forcing at the short millennial timescaies.展开更多
The geochemical components of the leachate from loess-paleosol deposits can provide information about climaterelated post-depositional processes.For example,leachate lithium([Li]_(leachate))is a potential paleoclimate...The geochemical components of the leachate from loess-paleosol deposits can provide information about climaterelated post-depositional processes.For example,leachate lithium([Li]_(leachate))is a potential paleoclimate proxy because lithium is a typical lithophile element that is readily adsorbed by clay minerals during weathering and pedogenesis,and thus stratigraphic variations in[Li]leachatecan reflect these processes.We investigated the[Li]leachatevalues of two loess-paleosols profiles(the Luochuan and Weinan sections),on a north-south climatic gradient on the Chinese Loess Plateau.Independent paleoclimate information was provided by measurements of magnetic susceptibility,grain size,Rb/Sr ratios,and clay mineral content.During the last glacial-interglacial period,[Li]leachateincreased from 0.39 to 1.97μg/g at Luochuan and from 0.67 to 2.45μg/g at Weinan,mainly due to increasing pedogenesis.Based on these results we developed a conceptual model to explain the variations in[Li]leachate,Li^(+)within loess layers is mainly derived from dust input and the decomposition of primary minerals,influenced by the East Asian winter monsoon,while in paleosol layers Li is mainly derived from clay mineral adsorption during pedogenic processes,influenced by the East Asian summer monsoon.展开更多
基金supported by the National Natural Science Foundation of China (40925008 and 91128206)the National Basic Research Program of China(2007CB815906)
文摘Variability of clay mineral assemblages in the Western Pacific Warm Pool(WPWP) over the past 370 ka shows the prominent glacial-interglacial cyclicity.Smectite(62%-91%) is the dominant clay mineral,with decreased contents during interglacials while increased in glacials.In contrast,variations in chlorite(4%-21%),illite(4%-12%),and kaolinite(2%-10%) share a similar pattern with higher contents during interglacials than glacials,mirroring to that of smectite.The results indicate that the smectite-dominated clay minerals derive mainly from the river detrital inputs of New Guinea.The glacial-interglacial cycle of clay mineral assemblages well correspond to the fluctuation of sea level.When the sea level was low,the river materials can travel more easily across the narrow shelf off the island of New Guinea,inject directly into the subsurface currents flowing westwards,then merge into the Equatorial Undercurrent(EUC),and eventually deposit on the central part of WPWP.Precessional periods of the smectite content indicate the intensity of mechanical erosion in its provenance of New Guinea,responding to the river runoff and precipitation,and this could also be linked to the meridional migration of the Intertropical Convergence Zone(ITCZ).
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.
文摘The first attempt is made to evaluate quantitatively the changes of accumulation rates in the South China Sea during the last glaciation and Holocene, based on the data of 72 sediment cores taken from six areas deeper than 100 m. As shown from the calculations, the accumulation rate during the last glaciation is much higher than that during the Holocene. The southern and northern continental slopes are distinguished from other areas by the highest accumulation rates, with different features of sedimentation for aifferent stages: The Glacial-Holocene contrast in accumulation rate of terrigenous material is more distinct in the southern slope, while the contrast in biogenic sedimentation rate is more remarkable in the northern slope.
基金the National Key Project for Basic Research (Grant No.G1998040800).
文摘Since 40 kaBP, the current endorheism on the Tibetan Plateau had experienced at least four lake-expanding events, at 40-28 kaBP, 19-15 kaBP, 13-11 kaBP, 9.0-5.0 kaBP, respectively. The 40-28 kaBP and 9.0-5.0 kaBP lake-expanding events, corresponding to the global warming periods, were mainly determined by the abundant summer monsoon rainfall brought by strong Indian monsoon, aroused by enhanced solar radiation at earth orbital precessional cycle. The 40-28 kaBP lake-expanding event, also called the great lake period or the pan-lake period, for several great lake groups had come into being by the interconnection of the presently isolated and closed lake catchments. The total lake area over the Tibetan Plateau was estimated at least up to 150000 km2, 3.8 times of the present, and the lake supply coefficients were about 3-10. The 9.0-5.0 kaBP lake-expanding, with a total lake area of 68000 km2, less than the above mentioned reflected the Indian monsoon rainfall less than that of 40-28 kaBP. The expanded lakes at 19-15 kaBP and 13-11 kaBP, distributed in these basins with more or less existing glacial, indicated plenty of glacial meltwater discharged to balance evaporation on expansive lake surface. At the same time, the enhanced precipitation by the westerlies at 19-15 kaBP and by Indian monsoon at 13-11 kaBP plays an important role in maintaining the high lake level. Heinrich events greatly affected the evolution of climate system over the Tibetan Plateau, and thus gave a clear boundary of the high lake level change in the late Quaternary.
文摘THE consequence of "nuclear winter" induced by nuclear war and climatic catastrophe induced by extraterrestrial impact were widely studied for fear of the potential danger of the basic nuclear war (the totalexplosive equivalent 5 000Mt TNT). Using zero-dimensional energy balance model authors reportedthe short-term climatic effect induced by six huge Cenozoic bolide-impact events (65, 34, 15, 2.4,1.1, 0.73 MaBP). However, only the direct climatic effect of dusts yielded by the impact was considered in the previous study. In this note, based on the previous simulation results the effect of variance ofglobal reflectance with temperature on the long-term climatic change was further taken into consideration.Combined with the strata records of palaeoclimatic change the relationship of impact energy with its in-
文摘Today anthropogenic climate change is underway and predicted future global temperatures vary significantly. However, the drivers of current climate change and their links to Earth’s natural glacial cycle have yet to be fully resolved. Currently, many on a local level understand, and are exposed to, the heat energy generated by what’s referred to as the urban heat island effect (UHI), whereby natural flora with higher albedos </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> replaced by manmade urban areas with lower albedos. This heat effect is not constrained to these regions and all anthropogenic surfaces with lower albedos need to be studied and quantified as the accumulated additional heat energy (infrared energy) is trapped within Earth’s atmosphere and could affect the Earth on a planetary level. Deployed satellites have detected critical changes to Earth’s albedo to lower levels, however the cause and impact of these changes have yet to be fully understood and incorporated into Global Circulation models (GCMs). Here it’s shown that industrialization of anthropogenic landscape practices of the past century has displaced millions of square kilometres of naturally high albedo grasslands with lower albedo agricultural landscapes. Utilising a fundamental Energy Balance Model, (EBM) it’s demonstrated these specific changes have generated vast amounts of additional heat energy which is trapped by the atmosphere, transferred and stored within the oceans of the Earth as shown in <b></span></span></span><a href="file:///E:/360data/%E9%87%8D%E8%A6%81%E6%95%B0%E6%8D%AE/%E6%A1%8C%E9%9D%A2/%E7%A9%BA%E7%99%BD%E9%A1%B5.docx#F1"><span style="font-family:Verdana;"><span style="font-family:Verdana;"><b><span style="font-family:Verdana;">Figure 1</span></b></span></span></a><span style="font-family:Verdana;"><span style
文摘Based on the evidence available from both observations and model simulations, the author proposes a view that may provide a unified interpretation of the North Atlantic thermohaline variability. Because of the slow response time of the Southern Ocean （millennia） and the relatively faster response time of the North Atlantic （centuries）, the North Atlantic thermohaline circulation is controlled predominantly by the climate forcing over the Southern Ocean at the long glacial cycle timescales, but by the North Atlantic climate forcing at the short millennial timescaies.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.42272221,41930863)the Fundamental Research Funds for the Central Universities(Grant No.300102272901)+1 种基金the Foundation of the State Key Laboratory of Loess and Quaternary Geology(Institute of Earth and Environment,CAS)(SKLLQG1905,SKLLQGPY2006)the Second Tibet Plateau Scientific Expedition and Research Program(STEP)(2019QZKK0704,2019QZKK0101)。
文摘The geochemical components of the leachate from loess-paleosol deposits can provide information about climaterelated post-depositional processes.For example,leachate lithium([Li]_(leachate))is a potential paleoclimate proxy because lithium is a typical lithophile element that is readily adsorbed by clay minerals during weathering and pedogenesis,and thus stratigraphic variations in[Li]leachatecan reflect these processes.We investigated the[Li]leachatevalues of two loess-paleosols profiles(the Luochuan and Weinan sections),on a north-south climatic gradient on the Chinese Loess Plateau.Independent paleoclimate information was provided by measurements of magnetic susceptibility,grain size,Rb/Sr ratios,and clay mineral content.During the last glacial-interglacial period,[Li]leachateincreased from 0.39 to 1.97μg/g at Luochuan and from 0.67 to 2.45μg/g at Weinan,mainly due to increasing pedogenesis.Based on these results we developed a conceptual model to explain the variations in[Li]leachate,Li^(+)within loess layers is mainly derived from dust input and the decomposition of primary minerals,influenced by the East Asian winter monsoon,while in paleosol layers Li is mainly derived from clay mineral adsorption during pedogenic processes,influenced by the East Asian summer monsoon.
