Based on 14C dating and core sediments survey, phytolith records are employed to reconstruct paleovegetation and paleoclimate in the Jianghan Plain in the middle reach of the Yangtze River. Phytoliths identified are a...Based on 14C dating and core sediments survey, phytolith records are employed to reconstruct paleovegetation and paleoclimate in the Jianghan Plain in the middle reach of the Yangtze River. Phytoliths identified are assigned into 21 well-described morphotypes and divided into four groups （Poaceae, fern, coniferous and broad-leaved）. The phytolith assemblages together with warmth index （Iw） are divided into 18 ecological zones, which reflect a complete vegetation history related to climate change in the middle reach of the Yangtze River during the past 15000 years. On the basis of the correlation ofphytolith records with the paleoclimatic indicators from stalagmite, peatland, North Atlantic deep-sea sediments, Loess Plateau of Central China, and Arabic Sea sediments, eight climatic phases are identified included Last Glacial Maximum （LGM） （20- 14.8 cal kaBP）, Last Deglaciation （LDG） （14.8-11.9 cal kaBP）, low-temperature phase in the Early Holocene （11.9-8 cal kaBP）, Holocene Opti- mum （8-4.9cal kaBP）, Holocene Katathermal （4.9- 1.1 cal kaBP）, Medieval Warmth Period （MWP） （1.1- 0.7 cal kaBP）, Little Ice Age （LIA） （0.7-0.15 cal kaBP）, and Modem Warming （0.15 cal kaBP-present）. Climatic events such as Bolling-Allerod warm intervals, Older Dryas, Inter-Allerod Cold Period, and Younger Dryas, and eight Holocene Bond events （B1-8） have been identified since the LDG. Our results demonstrate that the evolution of the climate in the research area has a strong link with the Indian Summer Monsoon （SW Monsoon）, Asian Summer Monsoon （SE Monsoon）, and Holocene events in North Atlantic simultaneously, which might indicate that solar variability affects the Earth surface climate system at the centennial and millennial scales.展开更多
Paleoclimate changes during the last glacial in the arid central Asia are not as well understood as the monsoon-dominated areas of Asia. Here we report a 75-m-long sediment core over past 120 kyr based on astronomical...Paleoclimate changes during the last glacial in the arid central Asia are not as well understood as the monsoon-dominated areas of Asia. Here we report a 75-m-long sediment core over past 120 kyr based on astronomical tuning combined with the optically stimulated luminescence(OSL) dating in the Kashi depression of the western Tarim Basin, Northwest China. Analysis of grain size and highresolution gamma ray(GR) logs from the KT11 borehole across the last glacial period yields a climate history for the Tarim Basin which reflects the variations of its temperature and the hydrological cycles. Comparison of these records with north hemisphere summer insolation, the Greenland ice core temperature, stalagmites and the loess from the nearby region indicates that the deposits in the fluvio-lacustrine system of the Kashi depression responded to climate change at the Younger Dryas(YD), six Heinrich cooling events and the Dansgaard-Oeschger cycles. Our work indicates that the alternations between warm-humid and cold-dry climates were prevalent in the western Tarim Basin during the last glacial period, showing an in-phase pattern with the climate variations of the East Asian Monsoon, controlled ultimately by precession and North Atlantic Ocean climate variability on orbital-millennial time scales.展开更多
文摘Based on 14C dating and core sediments survey, phytolith records are employed to reconstruct paleovegetation and paleoclimate in the Jianghan Plain in the middle reach of the Yangtze River. Phytoliths identified are assigned into 21 well-described morphotypes and divided into four groups （Poaceae, fern, coniferous and broad-leaved）. The phytolith assemblages together with warmth index （Iw） are divided into 18 ecological zones, which reflect a complete vegetation history related to climate change in the middle reach of the Yangtze River during the past 15000 years. On the basis of the correlation ofphytolith records with the paleoclimatic indicators from stalagmite, peatland, North Atlantic deep-sea sediments, Loess Plateau of Central China, and Arabic Sea sediments, eight climatic phases are identified included Last Glacial Maximum （LGM） （20- 14.8 cal kaBP）, Last Deglaciation （LDG） （14.8-11.9 cal kaBP）, low-temperature phase in the Early Holocene （11.9-8 cal kaBP）, Holocene Opti- mum （8-4.9cal kaBP）, Holocene Katathermal （4.9- 1.1 cal kaBP）, Medieval Warmth Period （MWP） （1.1- 0.7 cal kaBP）, Little Ice Age （LIA） （0.7-0.15 cal kaBP）, and Modem Warming （0.15 cal kaBP-present）. Climatic events such as Bolling-Allerod warm intervals, Older Dryas, Inter-Allerod Cold Period, and Younger Dryas, and eight Holocene Bond events （B1-8） have been identified since the LDG. Our results demonstrate that the evolution of the climate in the research area has a strong link with the Indian Summer Monsoon （SW Monsoon）, Asian Summer Monsoon （SE Monsoon）, and Holocene events in North Atlantic simultaneously, which might indicate that solar variability affects the Earth surface climate system at the centennial and millennial scales.
基金supported by the National Natural Science Foundation of China (Nos. 41772029, 41322013)Natural Science Foundation for Distinguished Young Scholars of Hubei Province of China (No. 2016CFA051)+2 种基金the Program of Introducing Talents of Discipline to Universities (Nos. B14031, B08030)the Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) (Nos. CUGCJ1703, CUGQYZX1705)Hydrogeological Environmental Geological Survey of Kashi, Xinjiang (No. S15-2LQ1)。
文摘Paleoclimate changes during the last glacial in the arid central Asia are not as well understood as the monsoon-dominated areas of Asia. Here we report a 75-m-long sediment core over past 120 kyr based on astronomical tuning combined with the optically stimulated luminescence(OSL) dating in the Kashi depression of the western Tarim Basin, Northwest China. Analysis of grain size and highresolution gamma ray(GR) logs from the KT11 borehole across the last glacial period yields a climate history for the Tarim Basin which reflects the variations of its temperature and the hydrological cycles. Comparison of these records with north hemisphere summer insolation, the Greenland ice core temperature, stalagmites and the loess from the nearby region indicates that the deposits in the fluvio-lacustrine system of the Kashi depression responded to climate change at the Younger Dryas(YD), six Heinrich cooling events and the Dansgaard-Oeschger cycles. Our work indicates that the alternations between warm-humid and cold-dry climates were prevalent in the western Tarim Basin during the last glacial period, showing an in-phase pattern with the climate variations of the East Asian Monsoon, controlled ultimately by precession and North Atlantic Ocean climate variability on orbital-millennial time scales.
