河流碳输移与陆地侵蚀-沉积过程关系的研究进展

河流碳输移与陆地侵蚀-沉积过程紧密相关。首先就机械和化学风化两种不同的陆地侵蚀机制在提供河流碳源方面所发挥的不同作用作了详细论述,并比较了季风流域和非季风流域间河流碳输移在通量及性质上的差异。之后对陆地碳沉积机制进行了归纳,指出了包括大坝截留,河漫滩、河口-近岸带沉积及陆地碳沉降等几种可能的陆源碳踪迹。陆地环境的截留效应相对于侵蚀尚不太清楚,今后应加强对陆地碳沉积的研究,进一步明确各种碳沉积的作用机制及其对全球陆地碳汇的贡献量。此外,人类活动对陆地侵蚀-沉积过程及河流碳循环所产生的直接或间接的影响也有待于今后继续深入探索。

伸展背景下陆相地层发育的控制——以阜新盆地为例

陆相地层发育普遍认为是受构造控制的，然而在构造背景下，其它控制因素如水位或水量、沉积物供给量等是如何起作用的呢？根据Ｓｃｈｌｉｓｃｈｅ的伸展盆地定量充填模型，模拟阜新盆地沙海组和阜新组地层的形成，得出一些对陆相地层发育控制的一些认识。在陆相地层发育过程中，层序发育与沉积环境转化是受盆地的构造沉降与可容空间、沉积物供给与沉积物堆积速率、盆地供水量与气候以及沉积作用过程的影响和控制。

Isotopic compositional Characteristics of Terrigenous Natural Gases in China

The C and H isotopic compositions of the methane in more than 160 gas samples from 10 basins in China are presented in this paper.The natural gases are classified as four types: biogenic gas ,bio-thermocatalytic transitional gas, gas associated with condensate oil ,and coal-type gas. The isotopic compositions of these gases closely related to the depositional basins, the types of organic matter,the stages of thermal evolution and the genetic characteristics of different gas reservoirs.Studies of the C and H isotopic compositions of terrigenous natural gases will provide valua-ble information on the prospecting and development of natural gases of different genetic types.

Biomarker Compounds as Indicators of Paleoenvironments

In an attempt to assess the paleoenvironments of terrestrial sediments,some twenty-two representa-tive Chinese non-marine sediment samples were studied using the molecular organic geochemistry method.The sediment samples stuied include oilshale,shale,mudstone and glauber salt from Tertiary to Cretaceous in age.Judging from geological/geochemical data and paleosalinity data,the samples studied are of lacustrine sedimentary origin and can be divided into three different types:fresh water,brackish and saline/hypersaline lake sediments.The aliphatic fractions were separated from the extracts of the samples and analysed by means of GC and GC/MS instruments,giving a number of parameters such as relative abundances of alkanes and cycloalkanes as shown in the mass chromatograms.

黄土的万卷书——刘东生院士和他的黄土研究

中国科学院院士、中科院地质与地球物理研究所研究员刘东生于 2 0 0 4年 2月 2 0日获 2 0 0 3年度国家最高科学技术奖。刘东生院士还于 2 0 0 2年 4月获得世界环境科学最高荣誉、“环境科学的诺贝尔奖”———泰勒奖。本刊特刊载三思科学报道编辑碧声对刘院士和他的学生郭正堂教授的专访。

全球第一口陆相白垩纪科学钻井在我国大庆市开钻

全球第一口陆相白垩纪科学钻井——松科1井，不久前在我国大庆市开钻。据介绍。白垩纪是地球上典型的温室气候时代，虽然国际科学界已在深海和陆地实施了几十口针对白垩纪的海相科学钻探计划，但是针对陆地沉积的科学钻探仍是空白。松辽盆地是世界上最大的白垩纪含油气湖盆之一。松科1井将采用世界上最先进的钻井、测井技术，建立包括岩石地层、古生物、沉积相、古地磁、有机地化、旋回地层和地微生物在内的十大剖面系列；

“黄土之父”刘东生

刘东生是我国黄土研究方面的专家。在半个世纪的地学研究中,他建立的黄土“新风成说”,平息了170多年来黄土成因的风成与水成之争;通过对古土壤的序列研究,向四次冰期提出挑战,经过3年的时间,他总结出环境变化的多旋回理论,成为古环境研究史上的一次重大革命。刘东生完成了到现在为止,全球惟一完整的陆地沉积记录,使中国的黄土成为认识全球变化的一把“钥匙”,被称为“黄土之父”。

Episodic Orogeny Deduced from Coeval Sedimentary Sequences in the Foreland Basin and Its Implication for Uplift Process of Longmen Mountain,China

Longmen Mountain located at the boundary between the Sichuan Basin and Tibetan Plateau,representing the steepest gradient of any edges of the plateau.Three endmember models of uplift process and mechanism have been proposed,including crustal thickening,crustal flow,and crustal isostatic rebound.Here we use coeval sedimentary sequences in the foreland basin to restraint uplift process and mechanism in the Longmen Mountain.The more than 10,000 m thick Late TriassicQuaternary strata filled in this foreland basin and can be divided into six megasequences that are distinguished as two distinct types.The first type is the wedge-shaped megasequences which are sedimentary response of strong active thrust loading events,characterized by a high rate of subsidence and sediment accumulation,coarsening-upward succession and a dual-sourced sediment supply.This type includes Late Triassic,Late Jurassic to Early Cretaceous and Late Cretaceous to Paleogene megasequences.The second type is the tabular megasequences,characterized by the low rate of subsidence and sediment accumulation,finingupward succession,and a single-sourced sediment supply,which is sedimentary response of isostatic rebound and erosion unloading.This type includes the Early to Middle Jurassic,Middle Cretaceous and Neogene to Quaternary megasequences.Basing on sedimentary,active tectonic,geomorphic evidence,we infer that the direction has been reversed from SSWdirected sinistral strike-slip to NNE-directed dextral strike-slip during 40-3.6 Ma,and since 3.6 Ma,the Longmen Mountain thrust belt belong to times of isostatic rebound and erosional unloading with NNEdirected dextral strike-slip.This suggests that crustal isostatic rebound is a primary driver for uplift and topography of the present Longmen Mountain.The Wenchuan(Ms8.0) earthquake,which ruptured a large thrust fault with NNE-directed dextral strikeslip along the range front,is an active manifestation of this crustal isostatic rebound process with dextral strike-slipping and shortening.This process may be the cause for the Wenchuan Earthquake and the apparent paradox of high relief,little shortening,the relative dearth of historical seismicity in the region.

Sedimentological features and biostratigraphy of Jurassic/Cretaceous deposits in continental basins in Priamurie,Far East Russia

The paper describes the sedimentary features and biostratigraphy of the transitional Jurassic to Cretaceous deposits in the continental basins of Priamurie formed after the collision between the Siberian and North China blocks. In Upper Priamurie, the collision occurred in the late Early Jurassic as dated by the emplacement of the post-collisional granites （ 191 Ma）. While in Lower Priamurie and West Priokhotie it could take place in the late Middle Jurassic on the basis of fossil evidence from an aceretionary turbidite complex. This event reflected the environmental change from coastal-marine to alluvial plains, often boggy, where coals aecmnulated. The environinental change is in harmony with that of biota. Systematic study of floral and spores/pollen assemblages, particularly in the sections of interbedded marine and non-marine deposits, makes clear the chronostrati-graphic succession of floral associations and shows the possibility of their application for subdivision and correlation of the continental deposits of Priamurie. Tire coastal-marine environment of the residual post-collisional sublatitudinal basins in the uestern part of Priamurie （Upper Amur and Dep basins） was replaced by the continental in the late Middle Jurassic and in the eastern part in the Berriasian-Valanginian （Torom Basin）. Similar environmental change commenced in the submeridional rift basins： the Bureya Basin in the Callovian and the Partizansk Basin in the Hauterivian. Changes in ecosystems ocemTed frequently during the Middle Jurassic-Ne- ocomian, but the most substantial changes took place in the late Middle Jurassic and in the end of Late Jurassie.

Depositional Characteristics of Deltas and Their Relationship with Hydrocarbon Accumulation in the North Slope, Biyang Depression

Tectonic movements in the North Slope of Biyang Depression are comparatively mild and stable, thus generating two categories of deltas. Elementary reasons for the coexistence of deltas are the existence of the palaeodrainage pattern and the effect of palaeotopography. The sedimentary facies is the most elementary factor controlling the physical property of reservoirs. The layout and spatial combination model of the sand body and faults are the major influential factors on the occurrence of hydrocarbons. Comparative study on Houzhang and Yanglou Braided Deltas as well as Zhangchang and Gucheng Meandering Deltas suggests that the hydrocarbons distribute primarily in the mouth bar subfacies and secondarily in the distal bar subfacies of the braided delta, while the oil-water and aqueous layers are mainly found in the subaquatic distributary channel. Although the sand body of the meandering delta has excellent stratification and high porosity, the thickness is far less than that of the braided delta. Therefore, the yield of hydrocarbon is relatively low. The mudstone of the delta front subfacies is a kind of source rock with a high content of organic matter. The conducting system for oil/gas migration in the North Slope is a composite one comprising faults and sand- stone reservoirs. A large amount of oil/gas from the deep depression first migrated towards the slope along the sand body which stretches and connects with the source rocks, and then redistributed along the faults in the slope. After the movement reached a standstill, the faults formed the occlusion in the up-dip direction of the sand body, generating a great quantity of fault block hydrocarbon reservoirs in the Noah Slope.

Heavy mineral stratigraphy of sediments from the southern outer shelf of the East China Sea since the last glaciation using fuzzy C-means cluster method

Correspondence analysis and fuzzy C-means cluster methods were used to divide the stratigraphy of heavy mineral assemblages, and the sediment sources and depositional dynamics of the environment reconstructed. The assemblages were taken from marine sediments from the late Pleistocene to the Holocene in Core Q43 situated on the outer shelf of the East China Sea. Based on the variable boundaries of the mineral assemblage at 63 and 228 cmbsf （cm below sea floor）, the core might have previously been divided into three sediment strata marked with units Ⅰ, Ⅱ and Ⅲ, which would be consistent with the divided sediment stratum of the core using minor element geochemistry. The downcore distribution of heavy minerals divided the sedimentary sequence into three major units, which were further subdivided into four subunits. The interval between 0 and 63 cmbsf of the core （unit Ⅰ）, which spans the Holocene and the uppermost late Pleistocene, is characterized by a hornblende-epidote-pyroxene assemblage, and contains relatively a smaller amount of schistic mineral and authigenic pyrite. In comparison, the interval between 63 and 228 cmbsf （unit Ⅱ）, is representative of the Last Glacial Maximum （LGM）, and features a hornblende-epidote-magnetite-ilmenite assemblage containing the highest concentrations of heavy minerals and opaque minerals. However, the interval between 228 and 309 cmbsf （unit Ⅲ）, which spans the subinterglacial period, is characterized by a hornblende-authigenic-pyrite-mica assemblage. Relative ratios of some heavy minerals can be used as tracers of clastic sediment sources. The lower part of the sediment core shows the highest magnetite/ilmenite ratio and relatively high hornblende/augite and hornblende/epidote ratios. The middle core shows the highest hornblende/augite and hornblende/epidote ratios, and the lowest magnetite/ilmenite ratio. The upper part exhibits a slightly higher magnetite/ilmenite ratio, and also the lowest hornblende/augite and hornblende/epidote ratios. The distribution of the mineral ratio is consistent with stratigraphic division in heavy mineral data using correspondence analysis and fuzzy C-means clustering. Variations in heavy mineral association and mineral ratio in core Q43 revealed changes in provenance and depositional environment of the southern outer shelf of the East China Sea since the late Pleistocene, well corresponding to interglacial and glacial cycles.

Sequence associations of sedimentary facies in continental basins and their applications to palaeogeographic mapping

According to the characteristics of sedimentary facies and their vertical associations, sequence association of sedimentary facies can be divided into 2 types and 28 subtypes. The first type(type A)is a sedimentary sequence without volcanic rocks, including 18 subtypes. The second type(type B)is a volcanogenic succession including 10 subtypes. Each subtype may reflect certain filling condition under certain sedimentary environment. Time and space distribution of different types of sequence associations can reflect tectonics that controlled the basin evolution, sedimentary environments and palaeogeography.

Large excavations and their effect on displacement of land boundaries

A study to estimate land surface movement caused by large surface excavations in sedimentary strata is presented.In stratified or jointed strata the stress relief driven movement adjacent to large excavations can be significantly larger than expected.High lateral stresses measured in Australia and other places around the world indicate that the ratio of horizontal to vertical stress has been particularly high at shallow depths.The in situ strata is in compression and during excavation,stress is relieved towards the opening causing strata movement.Large excavations such as,open cut mines or highway cuttings,can initiate an extensive horizontal slide of surface layers towards the excavation.These ground movements can be damaging to surface structures such as water storage dams and large buildings.Based on stress measurements at shallow depths in Australian coal mines the study presented here calculates and models the extent of potential ground movement along the bedding surface adjacent to large excavations and provides a new prediction tool of land movement at the excavation boundary that can benefit the geotechnical practitioners in the mining industry.

HIGH-RESOLUTION SEQUENCE DIVISION AND TRANSGRESSIVE EVENTS COAL FORMATIONIN SOUTHEASTERN NORTH CHINA EPICONTINENTAL BASIN

The sea level changes in the Paleozoic epicontinental basin were of high frequency and the transgressive events were episodic.This kind of sea level changes controlled both the basin filling and the coal accumulation within the basin.Coal accumulation in the transgressive process is one of the typical features of the North China epicontinental basin.High resolution sequence analysis to the Permo carboniferous coal series based on the core observation indicates that the epicontintental coal bearing succession can be divided into 1 tectonic sequence (the original type of basin filling), 3 supersequences, 12 third order sequences and about 48 parasequences.The third order sequences are of dual configuration sequences that are composed of transgressive systems tract in the lower part and highstand systems tract in the upper part.The transgressive systems tracts are relatively thin in thickness and have fewer parasequences (commonly 1 to 2), while the highstand systems tracts are thick, generally consist of several parasequences.

Distinct distribution revealing multiple bacterial sources for 1-Omonoalkyl glycerol ethers in terrestrial and lake environments

The 1-O-monoalkyl glycerol ethers （MAGEs） were initially viewed as the biomarkers for sulfate-reducing bacteria （SRB） me- diating anaerobic oxidation of methane in the marine environments. However, limited information is known about their distri- bution in terrestrial and other aquatic settings including soils, fresh water lakes, and cave sediments, which may obscure our understanding of their biological sources. Here we found that MAGEs were ubiquitous but differed obviously in distributional pattern among those environments. The surface soils are dominated generally by iC15：0-MAGE, followed by nCI6：o-MAGE whereas the lake sediments show the opposite, resulting in significantly higher iC15：0/nC16：0 ratios in soils than in lake sedi- ments. The cave deposits are characterized by considerably higher proportions of branched MAGEs than the former two envi- ronments. The logarithm of iC15：0/aC15：0 ratio shows a significant negative correlation with soil pH, likely reflecting an adapta- tion of microbial cell membrane to change in the ambient proton concentration. The MAGE profiles in cultured bacteria cannot fully explain the MAGE distribution in all the samples analyzed. Therefore, MAGEs in soil, lake sediments, and cave deposits likely have additional biological source（s） other than SRB and cultured MAGE-producing bacteria. The difference in MAGE pattern among environments is likely to be attributed to change in microbial communities.

Soil pH impact on microbial tetraether lipids and terrestrial input index (BIT) in China

The distributions of microbial tetraether lipids i.e. glycerol dialkyl glycerol tetraethers (GDGTs) were investigated in a variety of Chinese soils featured by a wide range of pH values in different climate zones. The bacterial branched GDGTs and archaeal isoprenoid GDGTs were found to be widely distributed in Chinese soils and their relative abundance was controlled primarily by soil pH. The bacterial bGDGTs usually dominate over archaeal iGDGTs in abundance when the soil pH is below 8.0. However archaeal iGDGTs become dominant and the abundance of halophilic archaea characterized by GDGT V without cyclopentyl ring increases dramatically in the alkaline soil with pH greater than 8.0. The relative abundance of archaeal iGDGTs to bacterial bGDGTs was defined here as RAI index. The RAI index decreases with elevated soil pH and a linear correlation is found between them indicating that the relative abundance of archaeal iGDGTs to bacterial bGDGTs increases with increased pH. The RAI index thus could be a novel proxy of the pH values of paleosol. The terrestrial input index BIT (Branched and Isoprenoid Tetraethers Index) decreases with increased soil pH suggesting that soil pH should be taken into consideration when the terrestrial contribution to marine sediments is estimated by BIT index. Moreover the TEX86 index cannot be used to reconstruct sea surface temperature in the sediments featured by a large terrestrial input.

Biomarker evidence for changes in terrestrial organic matter input into the Yellow Sea mud area during the Holocene

We present lipid biomarker records of two cores （ZYI and ZY3） from the central South Yellow Sea mud area to investigate the changes in sources and transport processes of the sedimentary organic matter （OM） throughout the Holocene. Based on the analysis of marine biomarker content （EPB （Phytoplankton Biomarker, total content of brassicasterol, dinosterol and C37-alkenones） and crenarchaeol）, and terrestrial biomarkers （En-alkanols and brGDGTs） as well as TMBR＇ and BIT index values, the marine organic matter （MOM） and terrestrial organic matter （TOM） deposition history was reconstructed. Changes in TOM and MOM were related to variations in land vegetation density and marine productivity, as well as transport processes dominated by the oceanic circulation system. The marine biomarker contents from the South Yellow Sea have generally in- creased throughout the Holocene, indicating that the increased MOM contents were mainly controlled by the strengthening of the circulation system. The terrestrial biomarkers, on the other hand, were more variable, indicating more complex influence of TOM burial in the Yellow Sea. During the Early Holocene （7200-6000 cal yr BP）, the moderate TOM input revealed by the terrestrial proxy records may result from abundant land source supply by strong river transport despite the lack of transport via circulation system. The Mid-Holocene （6000-3000 cal yr BP） was characterized by decreased terrestrial biomarker contents. The balance between the decrease in land source supply and increase of transportation by the current system of the TOM resulted in the lower but stable contents of TOM. During the Late Holocene （3000 cal yr BP to present）, the TOM deposition in the South Yellow Sea increased as the current system was further enhanced and thus transported more TOM to the central South Yellow Sea, although the land supply of TOM was further reduced.

Decomposition of Different Litter Fractions in a Subtropical Bamboo Ecosystem as Affected by Experimental Nitrogen Deposition

As an important component of the global carbon （C） budget, litter decomposition in terrestrial ecosystems is greatly affected by the increasing nitrogen （N） deposition observed globally. We hypothesized that different litter fractions derived from a single tree species may respond to N deposition differently depending on the quality of the litter substrate. To test the hypothesis, a two-year field experiment was conducted using the litterbag method in a Pleioblastus amarus plantation in the rainy region of Southwest China. Four N treatment levels were applied： control （no N added）, low-N （50 kg N ha-1 year-1）, medium-N （150 kg N ha-a year-1）, and high-N （300 kg N ha-1 year-l）. We observed different patterns of mass loss for the three P. amarus litter fractions （leaves, sheaths, and twigs） of varying substrate quality in the control plots. There were two decomposition stages with different decay rates （fast rate in early stages and slow rate in the later stages） for leaves and sheaths, while we did not observe a slower phase for the decay of twigs during the 2-year study period. The annual decomposition rate （k） of twigs was significantly lower than that of leaves or sheaths. Addition of N slowed the decomposition of leaves and twigs in the later stages of decomposition by inhibiting the decay of lignin and cellulose, while addition of N did not affect the mass loss of sheaths during the study period. In the decomposition of all three litter fractions, experimental N deposition reduced the net N accumulation in the early stages and also decreased the net N release in the later stages. The results of this study suggest that litter substrate quality may be an important factor affecting litter decomposition in a bamboo ecosystem affected by N deposition.

Spatial distribution of marine chemicals along a transect from Zhongshan Station to the Grove Mountain area, Eastern Antarctica

This study investigates the regional distribution of marine aerosol originated species （Na＋, CI-, nss-SO42- and MSA） in the snow pits （or firn cores） collected along a transect between Zhongshan Station and the Grove Mountain area （450 km inland） on the eastern side of the Lambert Glacier Basin. Concentrations of Na＋ and Cl- decrease exponentially with distance from the coast to 100 km inland （i.e., 1500 m a.s.1.）. Statistical results demonstrate that distance from the coast inland and elevation af-fect the concentration of sea-salt originated ions in inland areas significantly. Increase of Cl-/Na＋ ratio and higher variability in its standard deviation suggest that there are other sources of ions in addition to sea-salt in inland areas of the Antarctic conti- nent. The concentrations of Na＋ and Cl- from nine sampling sites in the Grove Mountain area are relatively higher than those from sites along CHINARE transect, although all sites are at similar distance inland. This phenomenon indicates that the barri- er effect of the mountain may be the most important factor influencing ion deposition. In addition, nss-SO42- and MSA vary differently, with nss-SO42- decreasing with distance more significantly. This implies that sources and transporting pathways influence the deposition of the two sulfur compounds considerably, being supported by the spatial pattern of correlation coeffi- cients between the nss-SO42- and MSA.