Elemental carbon was extracted from sediments by chemical oxidation and identified by Raman spectroscopy. The experimental results indicate that elemental carbon, defined by processing, is a continuum ranging from single crystal graphite to amorphous carbon. Chemical oxidation is a feasible method to extract elemental carbon from sediments, and when experimental condition and time are properly controlled, it can remove organic carbon without any loss of elemental carbon. However, due to the differences in experimental conditions and methods, different results have been obtained. Therefore, we believe that the determination of standard sample and its concentration as well as the unification of the experimental method are of great importance. Also, the unification and definition of all these carbon particulates can facilitate transect comparison and further research in related fields. In profile research, elemental carbon was extracted and determined by using the same method. The elemental carbon curve tends to change with other climatic proxies, indicating elemental carbon can provide another new proxy for climatic and environmental changes. Based on the analysis, we deduce that the elemental carbon record has different implications for climate and environmental changes on different timescales.

A significant change in composition was recorded in late Oligocene sediments from the northern South China Sea. This abrupt event coincided with the seafloor spreading axis jump across the Oligocene/Miocene boundary, leading to sedimentation breaks and slumps as well as obvious changes in sediment geochemical composition, and representing the greatest tectonic activity in the South China Sea region since the Oligocene. Through this tectonic event, the sedimentary environment in the Baiyun sag area transformed from a continental shelf in the late Oligocene to a continental slope since the early Miocene, the provenance of the sediments changed from neighboring areas to the hinterland of the South China block, and the sea level rose since the early Miocene in the area. Therefore, this abrupt change event has a profound influence on the evolution of petroleum offshore in the northern South China Sea.

In northern Jiangsu coastal zone area, Guanhe River is the biggest river and has the best navigation conditions among rivers which flow into the Yellow Sea. The grain sizes show gradual increase from the high intertidal zone to lower intertidal zone. The heavy metal values have slight changes along both sides of the river mouth, but show an evident change perpendicular to the tidal flat. In the latter case, they show a good correlation with grain size fluctuation, that is, the heavy metal values gradually decline when the grain size increases from the high intertidal zone to the lower intra-tidal zone. Analyses of the heavy metal elements show that on the Guanhe estuary surface sediment, the content of the elements Hg, As and Cu is above background values; Pb and Zn contents are rather close to the background values; and Cd content is less than the background values. The element Hg comes out to be harmful in a medium level to ecological environment, while the elements of Cr, As, Cu, Pb, Zn and Cd fall in a safe range of MPL. On the whole, Guanhe estuary tidal flat is not very harmful to the ecology in terms of the heavy metals.

Based on the high-resolution sporopollen and algae research of the sediments from core B106 in the northern South China Sea, three sporopollen assemblage zones have been distinguished in ascending order: Zone 1 (294–194 cm): Pinus-Quercus (evergreen)-Gramineae-Polypodiaceae- Pterdium-Dicranopteris. Zone 2 (194–94 cm): Pinus-Quercus (evergreen)-Polypodiaceae-Pteridium- Dicranopteris. Zone 3 (94–4 cm): Pinus-Polypodiaceae-Pteridium-Quercus (evergreen)-Dicranopteris. The three sporopollen zones correspond to three stages of vegetation, climate and paleoenvironment evolution of the northern part of the South China Sea since 11 000 years ago. Combined with AMS ¹⁴C dating, the sporopollen and algae data can be a scientific basis for stratigraphic division and reconstruction of paleoclimate and paleoenvironment in the South China Sea.

This paper presents pelagic records of planktic foraminifera, as well as data of stable isotope stratigraphy and carbonate stratigraphy since 3.5 Ma B.P. from site ODP758 in the Ninetyeast Ridge of the Indian Ocean. Based on these data, manifestations and related mechanisms of major tectonic and environmental events such as the rapid uplift of the Himalaya Mountains, “middle Pleistocene climatic transition” and “mid-Brunhes dissolution event” in the region are discussed. According to the analysis and comparison of various indices and changes in terms of foraminifera assemblage, paleotemperature, paleosalinity and themocline from site ODP758, the authors deduce that the paleoclimatic changes might correlate with the mid-Pleistocene transition at 1.4–1.7 Ma B.P. The changes of CaCO₃, mass accumulation rates (MAR) of CaCO₃ and non- CaCO₃ MAR indicate that the loaded terrigenous sediments increased at 1.7 Ma, which is in agreement with the uplift history of the Qinghai-Tibet plateau as shown by the available data. The last two changes coincide with the uplift of the Qinghai-Tibet plateau, hence they are called “Qinghai-Tibet movement” (1.7 Ma), and the “Kunlun-Yellow River movement” (1.2-0.6 Ma). The changes of the CaCO₃ content, coarse fraction (> 150 ?m) content and planktonic foraminifera biostratigraphy show that strong dissolution of abyssal CaCO₃ occurred in the study region during 0.5-0.4 Ma. The event was consistent with the “mid-Brunhes dissolution event” in the sedimentary records of the Atlantic Ocean, Pacific Ocean, Indian Ocean and Nansha sea area of the South China Sea.

Sediments with high sedimentation rate at site MD05-2905 in the Northeastern slope of the South China Sea provide unique materials for a high-resolution study on the paleoenvironment. Based on precise dating of AMS ¹⁴C, grain size analysis of terrigenous debris at core MD05-2905 was conducted after organic matter, biological carbonate and biogenic opal were removed. The results show that 15.5–63.5 ?m coarse grain size ingredients may indicate East Asian winter monsoon changes and that 2–9 ?m fine grain size ingredients may be used as a proxy of evolution of the East Asian summer monsoon. The results of grain size analysis, which suggest East Asian monsoon intensity, reveal that a winter monsoon dominated the glacial regime and a summer monsoon dominated the Holocene regime. It was also shown that the summer monsoon increased gradually,experienced several abrupt changes and reached a culmination in the early Holocene (11200–8500 a B.P.) since 36 ka. Controlled by precession periodicity, it may be related with the amount of solar radiation at the highest stage, which needs further study.

Earthquake, as disastrous events in geological history, can be recorded as soft-sediment deformation. In the Palaeogene of the East China Sea shelf, the soft-sediment deformation related to earthquake event is recognized as seismic micro-fractures, micro-corrugated laminations, liquefied veins, ‘vibrated liquefied layers’, deformed cross laminations and convolute laminations, load structures, flame structures, brecciation, slump structures and seismodisconformity. There exists a lateral continuum, the wide spatial distribution and the local vertical continuous sequences of seismites including slump, liquefaction and brecciation. In the Palaeogene of East China Sea shelf, where typical soft-sediment deformation structures were developed, clastic deposits of tidal-flat, delta and river facies are the main background deposits of Middle-Upper Eocene Pinghu Formation and Oligocene Huagang Formation. This succession also records diagnostic marks of event deposits and basinal tectonic activities in the form of seismites.

Rapid climate change at millennial and centennial scales is one of the most important aspects in paleoclimate study. It has been found that rapid climate change at millennial and centennial scales is a global phenomenon during both the glacial age and the Holocene with amplitudes typical of geological or astronomical time-scales. Simulations of glacial and Holocene climate changes have demonstrated the response of the climate system to the changes of earth orbital parameter and the importance of variations in feedbacks of ocean, vegetation, icecap and greenhouse gases. Modeling experiments suggest that the Atlantic thermohaline circulation was sensitive to the freshwater input into the North Atlantic and was closely related to the rapid climate changes during the last glacial age and the Holocene. Adopting the Earth-system models of intermediate complexity (EMICs), CLIMBER-2, the response of East Asian climate change to Dansgaard/Oeschger and Heinrich events during the typical last glacial period (60 ka B.P.–20 ka B.P.) and impacts of ice on the Tibetan plateau on Holocene climate change were stimulated, studied and revealed. Further progress of paleoclimate modeling depends on developing finer-grid models and reconstructing more reliable boundary conditions. More attention should be paid on the study of mechanisms of abrupt climatic changes as well as regional climate changes in the background of global climate change.

The ancient Zhuyeze Lake lies in the east Hexi corridor of Northwest China and it is the interacting belt of the East Asian summer monsoon and the westerly line. The research on paleoclimate of the lake facilitates the understanding of the processes and mechanism of climate change in Northwest China since the Last Deglaciation. Related researches of this area started in the 1960s, and the research on environment changes has become the “hotspot” during the last 10 years. This paper focuses on four sections (Qingtuhu Section, Xiqu Section, Shakengjing Section, Jiutuoliang Section) in ancient Zhuyeze Lake. Much work was done in spot investigation, section strata comparison, geophysical analyses, geochemical analyses and dependable ¹⁴C dating in order to retrieve the dry-wet history of climate changes in ancient Zhuyeze Lake since the Last Deglaciation. The main conclusions are as follows: (1) the highest terminal lake level was 1313–1315 m. In Holocene, the highest lake level was 1308–1309 m occurring between 6700–5800 a B.P.. (2) After geophysical and geochemical analyses, high-resolution records of the climate change since the Last Deglaciation were revealed as follows: cold and dry during 15800–13000 a B.P.; cool and wet during 13000–9500 a B.P.; warm and dry during 9500–6700 a B.P.; warm and wet during 6700–4300 a B.P.; cool and wet during 4300–2700 a B.P.; and at last dry during 2700–0 a B.P..

The eastern edge of the Qinghai-Tibetan plateau developed an integrated series of late Cenozoic lacustrine, loess, red and moraines deposits. Various genetic sediments recorded rich information of Quaternary palaeoenvironment changes. Xigeda Pliocene lacustrine deposits, formed during 4.2 Ma B.P.-2.6 Ma B.P., experienced nine periodic warm-cold stages. Eolian deposition in western Sichuan began at 1.15 Ma B.P., and the loess-soil sequences successively record fourteen palaeomonsoon change cycles. Red clay in the Chengdu plain record five stages of paleoclimatic change stages since 1.13 Ma B.P.. There was an old glacial period of 4.3 Ma B.P. in the eastern Qinghai-Tibetan plateau. During the Quaternary, there were five extreme paleoclimatic events corresponding to five glaciations.

High resolution research of rock magnetic records and quartz sands from the Maogou Section in the Linxia basin reveals that after a relatively stable environment between 13.07 Ma and 8.6 Ma, the basin was gradually influxed by eolian dusts at about 8.6 Ma, with two rapid increases at about 6.4 Ma and 5.3 Ma, respectively. The study suggests that drying of northwest China began at 8.6 Ma and strengthened rapidly at about 6.4 Ma and 5.3 Ma.

Shell bar, composed of abundant fossil shells of Corbicula fluminea müller and Corbicula largillierti philippi and located at the southeastern end (36°30′N, 96°12′E) of the paleolake Qarhan, is one of the most prominent features in the Qaidam basin. It is the highest site where such species of fossil shells have been found in the Late Pleistocene age. A 2.6-m-thick fresh profile was manually excavated to determine the formation ages and the scope of the high paleolake levels. Accelerator mass spectrometry (AMS), conventional radiocarbon dating, and sector inductively coupled plasma-mass spectroscopy ²³⁰Th methods were used to investigate the reliability and accuracy of dating results in different laboratories. Ages of various components (e.g. acid residual and acid soluble fraction of the organic matter) from the same sample were determined. Age differences of a variety of materials (e.g. organic matter, fossil shells, and salt crystals), and age differences at the same sampling position were evaluated. Dating shows that the AMS ages given by alkali residue and acid soluble fractions vary greatly, e.g., from 124.5 cm upwards. The dates given by the acid soluble fraction were normal. Down the column, the dates show a reverse pattern and those of alkali residues, especially the lower part of the section, show an unstable pattern. These imply that organic matter had been influenced by two separate processes. One possible explanation is that the alkali residual fraction most likely had been contaminated by dead carbon-bearing reworked material because the study section is located near the edge of the paleolake and could have been easily influenced by old eroded deposits. Another is that the acid soluble fraction could have been contaminated by upward-flowing groundwater containing soluble organic matter. The amount of this soluble organic material should be very small because the strongest age reversal is in the lower part, where the TOC content remains low, meaning that the change of soluble organic fraction alters neither TOC content nor the ?¹³C dramatically. It is concluded that a uniform mega-paleolake developed in the Qaidam basin in the northeastern Tibetan plateau between 39.7 and 17.5 ¹⁴C kaB.P. During the period when the high paleolake level of Qarhan was formed, the huge paleolake covered a vast area with dramatic lake level fluctuations. It is found that the ages determined may be influenced by either radioactive ¹⁴C variations of repeated deposition or content variations in the atmosphere. The ages given by fossil shells are 15–18 ka older than those given by organic matter. The large differences between the ages of fossil shells and organic matter might have resulted from the large water areas and huge water volume and the special location of the high-elevation Qaidam basin. This study also shows the reliability and accuracy of the ²³⁰Th dating method on the salt crystals but further study is needed to determine whether this method could be applied to the study area.

An extensive test program was conducted on East China deep clay to investigate mechanical behavior in the process of axial compression and triaxial compression. In addition, the effect of negative temperature and confining pressure on the strength of frozen clay was analyzed. It is concluded that the stress-strain curves at high confining pressure belong to the strain hardening type and its strength almost corresponds to confining pressure in the range of tested confined stress. With respect to temperature, the strength increases when the temperature decreases.

At present, researches on climate change of the Heihe River basin mainly focus on the relationship between basin climate change and regional water resources, regional desertification and dynamic climatic seasons of sandstorm, but less on climate change of oasis region, where there are more intense and frequent human activities. Based on data of precipitation, temperature, strong wind and dust events frequencies obtained from the six meteorological stations of Zhangye region in Heihe River basin, the features of climate change during 1968–2005 were carefully studied. Results show that the regional temperature rise rate exceeded the average level of China. The annual precipitation changed a little, but the precipitation had a slowly increasing trend in spring and winter. Frequencies of strong wind and sandstorm days show obviously descending trends, which had a close correlation with the regional temperature rise and the precipitation increase in spring and winter. Meanwhile, further human economic activities and exploitations to the oasis in the inland valley of arid regions also affected the climate change of this region, which has a sensitive and fragile eco-environment.