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1.
This paper presents the study on two continuous glacio-lacustrine sedimentary deposits, Laotanfang (3 597 m) and Shibantang (3 689 m) located on the southern and northern sides of Hulifang peak in Yunan, China. Environmental change indexes are constructed for each deposit, based on grain size, geochemical and pollen analysis, environmental magnetic susceptibility, and 14C dating. The study of climatic environmental change since the Holocene epoch in this region shows that the climate fluctuated at different stages during the early Holocene, that is, the climate was cool and wet during 8 4-7 7 ka, cold and wet during 7 7-6 5 ka, cold and dry during 6 5-4 7 ka, cool and wet during 4 7-2 1 ka, warm and wet during 2 1-1 0 ka, and warmer and wet since 1 ka. These findings reflect the overlapping influences of the southwest and southeast monsoons in different times during the Holocene in the north part of southwestern China are in accord with other Holocene climate change models in this part of China. 相似文献
2.
To reconstruct the productivity changes for the last 10 500 a in the northeastern East China Sea (ECS), biogenic compounds (such as carbonate, organic carbon and opal), marine micropaleontological fossils (planktonic foraminifera, benthic foraminifera, radiolarian and silicoflagellate) and the compositional characters of benthic foraminifera fauna analyses were carried out on a sediment core DOC082 obtained from the western slope of Okinawa Trough (29°13.93′N, 128°08.53′E; 1 128 m water depth). The long-term changes of biogenic and micropaleontological proxies display some similarities through the last 10 500 a, which show three different phases: lower values are recorded during the early and middle Holocene (before about 4 000 a BP), followed by an abrupt and remarkable increase at about 4 000 a BP, the late Holocene (after about 3 000 a BP) is characterized by continuously high values. The multi-proxy data of paleoproductivity and percents of benthic foraminifera genera (Uvigerina and Bulimina) show that during the early and middle Holocene (10 500–4 000 a BP) productivity was relatively low with a sudden and distinct increase at about 4 000 a BP, and the late Holocene (3 400–0 a BP) is marked by significantly higher productivity. Also, the radiolarian-based sea surface temperature (SST) records reveal a distinct decline in SST in the late Holocene after 3 200 a BP, very different from the early and middle Holocene. For the last 3 000 a, the enhanced biological productivity and distinctly lower SST indicate a major change of oceanographic conditions in the northeastern ECS. These marine environmental anomalies are consistent with other paleoclimatic records for the late Holocene in the Chinese continent and its surrounding regions. After analyzing the mechanisms of modern productivity and SST changes in the northeastern ECS, and based on the climatic anomalies in the Chinese continent and variations in the Kuroshio Current during modern El Niño periods, we suggest that the anomalous environmental conditions in the northeastern ECS may imply intensified El Niño activity during the late Holocene. 相似文献
3.
Wei ZHANG Chuanchuan LI Zhijiu CUI Jinliang FENG . College of Urban Environmental Sciences Liaoning Normal University Dalian Liaoning China. College of Environmental Sciences Peking University Beijing China 《东北亚地学研究》2008,11(3):156-167
This paper presents the study on two continuous glacio-lacustrine sedimentary deposits, Laotanfang （3 597 m） and Shibantang （3 689 m） located on the southern and northern sides of Hulifang peak in Yunan, China. Environmental change indexes are constructed for each deposit, based on grain size, geochemical and pollen analysis, environmental magnetic susceptibility, and 14C dating. The study of climatic environmental change since the Holocene epoch in this region shows that the climate fluctuated at different stages during the early Holocene, that is, the climate was cool and wet during 8.4-7. 7r ka, cold and wet during 7.7-6. 5 ka, cold and dry during 6. 5-4.7 ka, cool and wet during 4.7-2. 1 ka, warm and wet during 2. 1-1.0 ka, and warmer and wet since 1 ka. These findings reflect the overlapping influences of the southwest and southeast monsoons in different times during the Holocene in the north part of southwestern China are in accord with other Holocene climate change models in this part of China. 相似文献
4.
榆林长城沿线处于环境变化敏感带,其风沙滩区沉积剖面的磁化率和粒度分析结果显示,该区全新世早期11 500~10 000 a BP随着全球气候的逐渐转暖,磁化率、黏粒和粉沙含量逐渐增高;全新世中期的10 000~4 500 a BP气候相对比较湿润,植被覆盖度增大,风沙活动减弱,地表沉积物当中粉沙和黏土成分含量显著增大,风化成壤作用增强,地表发育沙质弱古土壤;全新世中期后段的4 500~3 000 a BP期间,气候以比较温和湿润为主,但在4 200~4 000 a BP出现一个气候干旱事件,风沙活动强烈;近3 000 a以来,气候显著干旱化,波动频繁,地表风沙沉积物显著变粗,表现出有5次沙漠扩张。该区生态环境演化、人文历史变迁基本上是自然因素与人为活动综合作用的结果,以自然演化为主,近代人为因素对环境变化起着加强和放大作用。 相似文献
5.
The relationship between the East Asian winter monsoon (EAWM) and East Asian summer monsoon (EASM) during the Holocene is complicated and remains controversial. In this study, analysis of grain size and benthic foraminiferal oxygen isotope, as well as accelerator mass spectrometry 14C dating was performed on a sediment core retrieved from the newly revealed muddy deposit on the northern South China Sea continental shelf. The history of the EAWM and EASM were reconstructed for the last 8200 a BP. Further analysis in conjunction with previously published paleo-climate proxies revealed that the relationship between the EAWM and EASM during the Holocene is more complex than a simple and strict anti-phase one-both negative and positive correlations were identified. The EAWM and EASM are negatively correlated around 7500, 4800, 4200, 3200, and 300 a BP (cooling periods), while positively correlated around 7100, 3700, and 2100 a BP (warm periods). In particular, both the EAWM and EASM intensified during the three positive correlation periods. However, we also found that the relationship between these two sub-monsoons is anti-phase during the final phase of particularly hot periods like Holocene Optimum and Medieval warm period. The possible impact from variations of solar irradiance on the relationship between the EAWM and EASM was also discussed. 相似文献
6.
Zhang Hucai 《中国地理科学(英文版)》1997,8(4):377-382
Chronology establishment and dating data analyses on lacustrine deposits in northeastern Sahara show that vast fresh lakes
existed over there between 9900–2400 a B. P. Especially, great continuous lakes developed and got their maximum extent during
the period from 9800 a B. P. to 6450 a B. P. From 6000 a B. P. to 3600 a B. P., the evolution of the lakes experienced a new
stage with a property of drastic fluctuations and a periodicity of 600 years, which was the response to the climatic environment
changes. On the aspect of the relation between natural environment and the human, the warm-humid period in the Holocene was
not only a very important time for human development and evolution, but also was a moment for human reproduction and division.
On the other hand, this warm-humid period was also a distinguished time to natural environment changes, the accumulation of
the strong weathered debris and fine materials formed the basements for the formation of the Sahara Desert.
Supported by the National Natural Science Foundation of China, German Research Foundation and Gansu Provincial Natural Science
Foundation. 相似文献
7.
A great number of geologic records has shown that the climatic environment in Xinjiang in the Holocene was mainly characterized
by warm-dry, although alternated with sub-fluctuations, several important boundaries of environmental changes can also be
determined as follows: 12,000 a B.P., 9000 a B. P., 3000 a B.P., 1500 a B.P. and 400 a B.P.. Since the Holocene, Xinjiang
has undergone the influence of two kinds of environmental development patterns (the westerly type and the monsoon type), so
the hydro-thermal disposal here was much more complicated. Generally speaking, the neoglacials of Xinjiang are characteristics
of cold (cool)-humid and in the Climatic Optimal, it is dominated by warm-humid conditions in spite of being intercalated
several sub-fluctuations of warm-dry intervals. 相似文献
8.
1 INTRODUCTION δ13C in organic matters from lacustrine sedi- ments varies with several factors including aquatic plants, vegetation type in the catchment, atmos- pheric CO2 concentration, climate (temperature and precipitation), and properties of water, … 相似文献
9.
Phase evolution of Holocene paleoenvironmental changes in the southern Yellow Sea: Benthic foraminiferal evidence from core C02 总被引：1，自引：1，他引：0
Li Fang Rong Xiang Meixun Zhao Liping Zhou Jianguo Liu Lanlan Zhang 《中国海洋大学学报(英文版)》2013,12(4):629-638
Assemblages of benthic foraminifera in a sediment core (C02) near the western margin of the southern Yellow Sea Mud were studied to decipher the phase evolution of Holocene paleoenvironmental changes associated with the Holocene marine transgression. It appears that during the early Holocene (11.2–10.1 kyr BP), the faunal was dominated by low salinity and shallow water species Cribrononion subincertum, Buccella frigida and Ammonia beccarii, reflecting a near coast depositional environment. A rapid increase of the relative abundance of Ammonia compressiuscula between 10.1–9.3 kyr BP indicates that the sea level rose rapidly during that time period. From 9.3–7.7 kyr BP, the benthic foraminiferal assemblage was dominated by high percentage of A. compressiscula, suggesting that the sea level was relatively stable. An obvious transition of benthic foraminifera, from the A. compressiuscula-dominated assemblage to an Ammonia ketienziensis-dominated assemblage, occurred between 7.7–6.2 kyr BP, possibly corresponding to a second sea level rapid rise period in the Yellow Sea during the Holocene. This transition may correspond to the gradually strengthened Yellow Sea warm current (YSWC) and finally is established the modern-type circulation in the Yellow Sea. It may also mark the formation of the Yellow Sea cold bottom water (YSCBW) during that period. Since then, the benthic foraminiferal assemblage based on core C02 was dominated by typical YSCBW species, A. ketienziensis, Astrononion italicum and Hanzawaia nipponica, at 6.2–4 kyr BP. A non-deposition period occurred since ～4 kyr BP, which possibly related to the hydrology changes caused by the East Asia monsoon. The two obvious benthic foraminiferal transitions recorded in core C02 during the early and middle Holocene provide evidence that the Yellow Sea has undergone a two-phase rapid sea level rise during the Holocene marine transgression. 相似文献
10.
ＰＲＥＬＩＭＩＮＡＲＹ ＳＴＵＤＹ ＯＮ ＴＨＥ ＨＯＬＯＣＥＮＥ ＥＮＶＩＲＯＮＭＥＮＴ ＣＨＡＮＧＥＳ ＩＮ ＸＩＮＪＩＡＮＧ──ＧＥＯＬＯＧＩＣ ＲＥＣＯＲＤＳ ＡＮＤ ＳＥＱＵＥＮＣＥ ＺｈｏｎｇＷｅｉ（钟巍）（ＤｅｐａｒｔｍｅｎｔｏｆＧｅｏ... 相似文献
11.
CHENG Jie ZHANG Xujiao TIAN Mingzhong YU Wenyang and YU Jiangkuan China University of Geosciences Beijing China TANG Dexiang Institute of Process Engineering Chinese Academy of Sciences Beijing China YUE Jianwei Institute of Geographic Sciences Natural Resources Research Chinese Academy of Sciences Beijing China 《山地科学学报》2005,2(3):193-201
Introduction The Tibetan Plateau, located in west China, was uplifted during the Cenozoic and became the most youthful plateau in the world. Some researches have also shown that it started to develop into the cryosphere in the beginning of the Middle Pleistocene and became one of the three global cryospheres (two other cryospheres being the Artic and the Antarctic) (SHI et al. 1996). Because of the cryosphere development in the Tibetan Plateau, many periglacial and permafrost geomorpholog… 相似文献
12.
黄土作为典型的多物源沉积物，粒度分布常呈现多峰分布。端元分析可以从复杂的沉积物粒度中分离出代表不同沉积物源和沉积动力的端元组分，在黄土研究中得到了广泛应用。利用Paterson参数化端元模型对处于毛乌素沙漠东南缘的靖边三道沟剖面粒度进行端元分离与解释，并讨论其代表的环境意义。靖边三道沟黄土可分为4个端元:EM1（众数粒径8.93 μm）为背景粉尘；EM2（众数粒径25.18 μm）为与季风环流有关的组分；EM3（众数粒径39.91 μm）和EM4（众数粒径56.37 μm）都是与冬季风有关的组分，其中EM3为黄土高原黄土主要组分，EM4与现代沙尘暴的粒级大致相同。通过对各端元组分随年龄变化的曲线进行分析，得到以下结论:该剖面记录了靖边地区自MIS 3以来经历了MIS 3（32.8~29.8 ka BP）、LGM（29.8~22.8 ka BP）、冰消期（22.8~11.3 ka BP）和全新世（8.7~1.7 ka BP）共4个气候时期。端元组分还记录了冰消期H 1事件（16.2~13.8 ka BP）、B/A事件（13.8~12.8 ka BP）、YD事件（12.8~11.3 ka BP）共3次气候快速变化事件和D-O旋回。该剖面还记录了毛乌素沙漠末次冰期经历的3次主要的扩张-收缩旋回以及全新世8.7~8.2，6.0~5.0，3.5~2.5 ka共3次干旱沙进事件。 相似文献
13.
ＰＡＬＥＯＳＯＬＳＯＦＳＡＮＤＹＬＡＮＤＳＡＮＤＥＮＶＩＲＯＮＭＥＮＴＡＬＣＨＡＮＧＥＳＩＮＴＨＥＷＥＳＴＥＲＮＰＡＲＴＯＦＮＯＲＴＨＥＡＳＴＰＬＡＩＮＯＦＣＨＩＮＡＷＥＳＴＥＲＮＤＵＲＩＮＧＨＯＬＯＣＥＮＥ￥ＱｉｕＳｈａｎｗｅｎ（裘善文）ＬｉＱｕｓ... 相似文献
14.
１ ＳＴＵＤＩＥＤＲＥＧＩＯＮＡＮＤＡＮＡＬＹＳＩＳＭＥＴＨＯＤＬｏｃａｔｅｄａｔｎｏｒｔｈｗｅｓｔｅｒｎｍａｒｇｉｎｏｆＴｅｎｇｇｅｒＤｅｓｅｒｔａｎｄ７０ｋｍｎｏｒｔｈｅａｓｔｏｆＭｉｎｑｉｎＣｏｕｎｔｙｉｎＧａｎｓｕＰｒｏｖｉｎｃｅ,ＱｉｎｇｔｕＬａｋｅｂｅｌｏｎｇｓｔｏｔｈｅＳｈｉｙａｎｇＲｉｖｅｒＤｒｙＤｅｌｔａ,ａｎｄｔｈｅａｌｔｉｔｕｄｅｉｓ１２９２－１３１０ｍ．Ｔｈｅｒｅｇｉｏｎｈａｓｔｈｅｃｈａｒａｃｔｅｒｏｆｔｅｍｐｅｒａｔｅｃｏｎｔｉｎｅｎｔａｌａｒｉｄｄｅｓｅｒｔｃｌｉ… 相似文献
15.
According to loess and palaeosol climatic record, field observation, analysis data and14C dating, we discuss the climatic changes and the water level fluctuations of Qinghai Lake. It is pointed out that there were
four relatively warm and moist stages in Qinghai Lake basin during the Holocene. They formed in the periods from 10,300 yr.B.P.
to 8,500 yr.B.P., 7,000 yr.B.P. to 3,500 yr.B.P., 2,800 yr.B.P. to 2,000 yr.B.P. and from 1,300 yr.B.P. up to now. the climate
in the Holocene optimum period, from 7,000 yr.B.P. to 3,500 yr.B.P., was much warmer and moister than that today. Polypodium
plant grew luxuriantly around Qinghai Lake. The annual temperature was 2.5°C higher than that today, but there was no forest
at Qinghai Lake shore. It is found that there was a good relationship between precipitation and water level fluctuation. In
warm and moist period water level was high and in the cold and dry period it was low in the Holocene. There were four high
water level periods for Qinghai Lake in the Holocene, but the highest level was less than 30m above present water level.
This research is supported by Youth Foundation of Natural Science Foundation of China (No. 49101015). 相似文献
16.
A synthesis of Holocene pollen records from the Tibetan Plateau shows the history of vegetation and climatic changes during the Holocene. Palynological evidences from 24 cores/sections have been compiled and show that the vegetation shifted from subalpine/alpine conifer forest to subalpine/alpine evergreen sclerophyllous forest in the southeastern part of the plateau; from alpine steppe to alpine desert in the central, western and northern part; and from alpine meadow to alpine steppe in the eastern and southern plateau regions during the Holocene. These records show that increases in precipitation began about 9 ka from the southeast, and a wide ranging level of increased humidity developed over the entire of the plateau around 8-7 ka, followed by aridity from 6 ka and a continuous drying over the plateau after 4-3 ka. The changes in Holocene climates of the plateau can be interpreted qualitatively as a response to orbital forcing and its secondary effects on the Indian Monsoon which expanded northwards 相似文献
17.
Study on the organic compounds and stable isotope composition of a sediment section in Dabusu Lake revealed that the organic materials in the sediments came mainly from terrestrial plants brought into the lake by rtmoff.The δ^13 C of the organic materials had high values during warm-dry climatic stages and decreased in cold-wet stages.Analysis of data on carbonate content and ^14C age showed that the lake basin had experienced several wet-cold and warm-dry climatic cycles since 15000 a BP. Since 6700 a BP, the climate reached a relatively stable warm-dry stage,so that the lake water was gradually condensed and finally a saline lake was formed. 相似文献
18.
Isotopic evidence for holocene climatic changes in Bosten Lake, Southern Xinjiang, China 总被引：2，自引：0，他引：2
ＩＳＯＴＯＰＩＣＥＶＩＤＥＮＣＥＦＯＲＨＯＬＯＣＥＮＥＣＬＩＭＡＴＩＣＣＨＡＮＧＥＳＩＮＢＯＳＴＥＮＬＡＫＥ,ＳＯＵＴＨＥＲＮＸＩＮＪＩＡＮＧ,ＣＨＩＮＡＺｈｏｎｇＷｅｉ（钟巍）ＸｉｏｎｇＨｅｉｇａｎｇ（熊黑钢）ＤｅｐａｒｔｍｅｎｔｏｆＧｅｏｇｒａｐ... 相似文献
19.
研究剖面位于洛川源北部的富县县城东郊。剖面由第一层古土壤(S_1)、马兰黄土(L_1)和全新世古土壤(S_0)组成。孢粉分析结果表明,黄土地层中孢粉非常丰富,为恢复古植被与古气候提供了可靠依据。S_1的植被是以榛、菊、蒿为主的疏林草原,有亚热带树种出现,反映了末次冰期的温湿气候。L_1时主要为菊、蒿干草原,气候冷干,其间有四次乔木增多期,反映了末次间冰期中有四次间冰阶的相对温湿气候波动。近代耕土中为以松、藜、中华卷柏为主的森林草原,反映了全新世某个时期比较温凉干旱的气候。 相似文献
20.
Sedimentary evolution of the Holocene subaqueous clinoform off the southern Shandong Peninsula in the Western South Yellow Sea 总被引：1，自引：0，他引：1
Jiandong Qiu Jian Liu Yoshiki Saito Zigeng Yang Baojing Yue Hong Wang Xianghuai Kong 《中国海洋大学学报(英文版)》2014,13(5):747-760
Based on the stratigraphic sequence formed since the last glaciation and revealed by 3000 km long high-resolution shallow seismic profiles and the core QDZ03 acquired recently off the southern Shandong Peninsula, we addressed the sedimentary characteristics of a Holocene subaqueous clinoform in this paper. Integrated analyses were made on the core QDZ03, including sedimentary facies, sediment grain sizes, clay minerals, geochemistry, micro paleontology, and AMS 14 C dating. The result indicates that there exists a Holocene subaqueous clinoform, whose bottom boundary generally lies at 15–40 m below the present sea level with its depth contours roughly parallel to the coast and getting deeper seawards. The maximum thickness of the clinoform is up to 22.5 m on the coast side, and the thickness contours generally spread in a banded way along the coastline and becomes thinner towards the sea. At the mouths of some bays along the coast, the clinoform stretches in the shape of a fan and its thickness is evidently larger than that of the surrounding sediments. This clinoform came into being in the early Holocene(about 11.2 cal kyr BP) and can be divided into the lower and upper depositional units(DU 2 and DU 1, respectively). The unit DU 2, being usually less than 3 m in thickness and formed under a low sedimentation rate, is located between the bottom boundary and the Holocene maximum flooding surface(MFS), and represents the sediment of a post-glacial transgressive systems tract; whereas the unit DU 1, the main body of the clinoform, sits on the MFS, belonging to the sediment of a highstand systems tract from middle Holocene(about 7–6 cal kyr BP) to the present. The provenance of the clinoform differs from that of the typical sediments of the Yellow River and can be considered as the results of the joint contribution from both the Yellow River and the proximal coastal sediments of the Shandong Peninsula, as evidenced by the sediment geochemistry of the core. As is controlled mainly by coactions of multiple factors such as the Holocene sea-level changes, sediment supplies and coastal dynamic conditions, the development of the clinoform is genetically related with the synchronous clinoform or subaqueous deltas around the northeastern Shandong Peninsula and in the northern South Yellow Sea in the spatial distribution and sediment provenance, as previously reported, with all of them being formed from the initial stage of the Holocene up to the present. 相似文献