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Researches on biogeochemical processes and nutrient cycling in karstic ecological systems, southwest China: A review. LIU Cong-Jiang, LANG Bin-Chao, LI Sai-Liang, PIAO He-Chun, CHU Cheng-Long, LIU Chao-Ze, ZHANG Wei 2009, 16(6): 1-12.  Abstract ( 2565 )   PDF (1458KB) ( 2199 )    Karstic geological and ecological systems are the important components of the Earths surface system, and their changes will give impacts on other areas and even the Earth system. Biogeochemical cycling is the key subject of studies of global as well as local changes, since there is a strong linkage between change of an ecological system and biogeochemical cycling of water and nutrients. Accordingly, it is important to study the changes of karstic ecological system and its response to or impact on global change, based on a better understanding of biogeochemical cycling in a whole karstic ecological system. It is the base of further studies on plant adaptabilities and optimization of assemblage of plant species of an ecological system. Based on the previous studies, this review introduces our researches on biogeochemical processes and nutrient cycling occurring mainly at rock/soil and soil/plant interfaces in karstic ecological system by using chemical balance theory, stoichiometry and multiple isotope tracers (e.g., δ13C, δ15N, δ34S, 87Sr/86Sr). The achieved important understandings are that the biogeochemical cycling of nutrients in karstic ecological system is active, coupled to each other and closely related to ecoenvironmental change, that human activities are clearly impacting natural biogeochemical cycling in catchments and result in related ecological and environmental problems, and that the studies on areal change are important for studying global change. These findings or recognitions will be the main directions leading our further studies of biogeochemical cycling nutrients in karstic and other ecological systems. Related Articles | Metrics

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Morphological and migration characteristics of largescaled submarine, coastal and desert sand dunes. GAO Shu 2009, 16(6): 13-22.  Abstract ( 1816 )   PDF (1539KB) ( 1012 )   The migration of submarine, coastal and desert dunes is influenced by their morphological parameters. Analysis of the wave height and length of some representative largescaled dunes indicates that these parameters are highly different among the submarine, coastal and desert dunes, with the height being the smallest for the submarine dunes and the largest for the desert dunes for the same range of lengths. Such phenomena are mainly due to the difference in the thickness of the fluid over the bedforms and secondly due to the sediment supply. In shallow marine environments, the water depth represents a limiting factor for upward growth of the dunes, whilst on land the thick atmospheric layer provides the space for dune growth; in deserts, relatively abundant sand supply, as compared with the coastal environment, results in full growth of the dunes. There tends to be deviations of the heightlength data points from statistical HL curves; numerical experiments demonstrate that such deviations may be associated with the bedload transport rate. Along the transport pathways, if the transport rate increases or decreases, then the resultant HL data may systematically deviate from the standard curve; likewise, rapid decrease in the transport rate can reduce significantly the dune migration rate, which causes upward accretion of sand and may form extremely high dunes. This behavior  can be used to control the rate of dune migration, on the basis of a distanceduration curve and appropriate design of dune height. An example of deriving the distanceduration curve is provided in the present study. The designed height may be realized by artificial measures such as a fencing system, low walls and trenches in front of the dunes, and the deployment of armoring layers on the bed. Related Articles | Metrics

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A discussion on the westerlydominated climate model in midlatitude Asia during the modern interglacial period. CHEN Fa-Hu, CHEN Jian-Hui, HUANG Wei 2009, 16(6): 23-32.  Abstract ( 2288 )   PDF (1501KB) ( 2863 )    The midlatitude Asian continent can be roughly divided into two distinct climatic regions: the humid easternsouthern part of Asia mainly controlled by monsoon circulation and inland arid Asia (including the coldarid northern Tibetan Plateau) in the western part dominated by the midlatitude westerlies. Based on the extensive review of recently published literatures, we found that a dry early Holocene, a wettest midHolocene, and a moderately wet late Holocene dominated in arid central Asia (ACA), while a strong summer monsoon and humid climate characterized the early Holocene, and a weakened summer monsoon and drier climate prevailed during the late Holocene. During the past millennium, ACA experienced a dry Medieval Warm Period (MWP) and a humid Little Ice Age (LIA). In contrast, it is indicated by a speleothem proxy record from Wanxiang Cave that the monsoon precipitation was generally high during the MWP and generally low during the LIA. Over the last 100 or 50 years, moisture has increased in arid NW China, while climate in monsooninfluenced semiarid NW China and North China has become drier. In addition, antiphase relationship in precipitation changes between the northern Tibetan Plateau (climatically controlled by westerlies) and southern Tibetan Plateau (mainly influenced by Indian monsoon circulation) exists on decadal to centennial timescale. In summary, moisture variability in ACA and northern Tibetan Plateau has showed major difference from monsoon evolution on various timescales in the Holocene. It is thus proposed that there is a westerlydominated climate model in midlatitude Asia during the modern interglacial period. Related Articles | Metrics

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Variation in carbon and sulphur isotopes and environments during the critical geological transitions. HONG Jian-Guo, CHEN Dai-Zhao, YAN De-Tian 2009, 16(6): 33-47.  Abstract ( 1725 )   PDF (2118KB) ( 1983 )    Stable isotopes of carbon and sulphur are fractionated during cycling between surface reservoirs and geological reservoirs. The main processes that control the isotopic composition of various reservoirs are photosynthesis and equilibrium between oceanic dissolved inorganic carbon and atmospheric CO2 for carbon, and bacterial sulphate reduction for sulphur. CS cycling from surface reservoirs and stored in geological reservoirs provides a geological record of ancient isotopic compositions. These isotopic signals can be used to improve and refine our understanding of historical changes in global geochemical cycles through geological time, especially for some key transitional periods. A number of case studies with detailed applications of these principles have been discussed to illustrate the causes and effects of ancient global environmental change. Related Articles | Metrics

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Parameters and model analysis for the deepsea hydrothermal plume. JIA Jian-Xin, HAN Ning, LIN Hua-Tang 2009, 16(6): 48-54.  Abstract ( 1748 )   PDF (865KB) ( 783 )    According to the hydrothermal activity models developed in recent years, the rules of the rising height and heat flux of the thermal column were systematically considered. Results show that (1) the thermal rising height is related to the bottom horizontal flow and heat source characteristics, and the heat flux of the single hydrothermal vent and of the neutral buoyancy layer in the thermal column could reach to a magnitude of 109 W/m2; that (2) the hydrothermal plume could be affected by many factors such as shape, salinity, temperature and velocity, which changed with height; that (3) by considering the characteristics of the oceanic crust, the buoyancy flux and the max rising height of the thermal column would be changed, and the rising height would reach more than 1000 m, and the heat flux would reach to a magnitude of 108 W/m2. The values obtained above could be used for the further study of the mechanism of hydrothermal plume movement and the establishment of hydrothermal activity model. Related Articles | Metrics

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Ferromanganese metallogenic system and oreforming processes of seamounts in the Pacific.  DAN Hua-Fa, LIN Xiang-Wen, LIU Ji-Hua 2009, 16(6): 55-65.  Abstract ( 1741 )   PDF (3189KB) ( 782 )    The structure of metallogenic system and oreforming processes are studied preliminarily in this essay for Corich MnFe crusts on the seamounts in the Pacific. Orecontrolling factors of ferromanganese metallogenic system on seamounts mainly include geological and oceanographic factors. The major geological factors are composed of the formation, migration and drowning of seamounts, as well as opening and closure of seaways. The major oceanographic factors are composed of thermohaline circulation, oxygen minimum zone (OMZ), aragonite lysocline, carbonate compensation depth, and hydrodynamic conditions around seamounts. This essay focuses on the orecontrolling factors on Corich FeMn crusts, which could be the migration and drowning of seamounts, opening and closure of seaways, evolution of OMZ, variation of ocean circulation and climate change. Seamounts provide an oreholding space for the precipitation of Corich FeMn crusts. Longterm stability of an oreholding space is the precondition for the precipitation of crusts; the age of seamounts, migration of seamounts, and the opening and closure of seaways constrained the evolution of oreforming background of seamount metallogenic system for Corich FeMn crusts. OMZ is the predominant geochemical barrier zone for the mineralization of crusts, and a major source for manganese; internal tide and eddies mixed the OMZ seawater and oxygen and Ferich deep and bottom water, which resulted in the oxidation of metal ions, aggregation and then the precipitation of colloid, and the formation of Corich FeMn crusts. Taking the Magellan Seamount Cluster and Marcuswake Seamount Cluster as an example, the oreforming process of Corich FeMn crusts since the late Cretaceous is divided into five stages: (1) the Cretaceousthe Eocene; (2) the Late Eocenethe Late Oligocene; (3) the Late Oligocenethe early Middle Miocene; (4) the early Middle Miocenethe early Late Miocene; (5) the early Late Miocenethe present. Stage 2 and 3 are favorable for the formation of Corich FeMn crusts. Related Articles | Metrics

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Effects of hydrogeochemistry on δ13CDIC values of drip water in Qixing Cave, Guizhou, China and their implications. WANG Shi-Jie, LUO Wei-Jun, LIU Xiu-Meng, XIE Xin-Nai, ZHOU Yun-Chao, LI Ting-Yu, LIU Qi-Meng 2009, 16(6): 66-76.  Abstract ( 2792 )   PDF (1566KB) ( 1034 )    Monitoring and sampling of soil waters and cave drip waters during the periods from April 2003 to May 2004 were performed monthly at Qixing Cave, Duyun, Guizhou, southwest China, in order to understand the effects of hydrogeochemisty on δ13CDIC of cave drip waters and their implications for interpreting the potential paleoenvironmental signal preserved in speleothems. The results show that there exists remarkable difference (≤69‰) among δ13CDIC of cave drip waters at 9 sampling sites synchronously. Drip waters are obviously classified into two groups. Compared to Group Ⅱ (3#, 4#, 5# and 9#), Group Ⅰ (1#, 2#, 6#, 7# and 8#) is characterized by heavier δ13CDIC values, smaller Ca, Sr and HCO3 concentrations as well as electrical conductivity (EC) and saturation index for calcite (SIC), and larger Mg/Ca ratio. Good correlations between δ13CDIC of drip water and its corresponding contents of Ca, Sr and HCO3, EC, Mg/Ca, and SIC, respectively, have been found in drip waters. These characteristics imply that δ13CDIC of cave drip waters are controlled to some extend by hydrogeochemistry. In comparison with average δ13CDIC value -9.9‰ of soil waters, δ13CDIC values of drip waters in Group Ⅰ  are heavier up to 45‰57‰, which is caused by the contribution from amounts of bedrock dissolution and prior calcite precipitation (PCP); by contrast, those in Group Ⅱ are slightly heavier (06‰16‰), which is affected less by bedrock dissolution and PCP, especially for 9# drip water. Therefore, the accurate interpretation of δ13C recorded in speleothems can not be guaranteed if not considering the effects of the above mentioned hydrogeochemical processes. Related Articles | Metrics

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On the division of UpperLower Cretaceous boundary in Songliao Basin. HUANG Qing-Hua, ZHANG Wen-Jing, GU Qiong, DANG Yi-Min, WANG Beng, GAO Bao-Meng, XIE Lei 2009, 16(6): 77-84.  Abstract ( 2508 )   PDF (979KB) ( 804 )   The Songliao Basin was a big lake during the midCretaceous, where Jehol, Songhuajiang and Mingshui biotas were developed in the Cretaceous; the organic of the lake expressed the sequence, the explosion and the extinction of the three biotas. The Songhuajiang Biota consisted of ostracodes, conchostracans, bivalves, charophytes, dinoflagellates, palynoflora, angiospermae etc. with distinct regional features. The angiospermae fossils such as Trapa angulata, Platanus septentrionalis, and the angiospermae pollen such as Crenwellia, Xinjiangpollis, Quantonenpollenites, Lythraites, Gothanipollis have been obtained from the Quantou Formation, with the age of the Late Cretaceous. SHRIMP zircon UPb ages of nine volcanic rock samples from Yingchen range from (1151±12) Ma to (1111±09) Ma, falling into the Late Aptian to the Early Albian stage. The magnetostratigraphic research indicated that the polarity from the Denglouku to the Yaojia Formation is normal, but twice brief reversed polarity occurred in the Upper Part of the Denglouku Formation and the Lower Part of the Yaojia Formation. The dark shales and oilshales in the Lower Part of the Qingshankou Formation are of high organic carbon, and positive excursion of kerogen isotopes. It is suggested that the dark shales in the Lower Part of the Qingshankou Formation are the products of the lake anoxic period. Based on the study of biostratigraphy, chronostratigraphy, magnetostratigraphy and event stratigraphy, the Lower/Upper Cretaceous boundary in the Songliao Basin is, therefore, between the Quantou and the Denglouku Formation, instead of between the Quantou and the Qingshankou Formation. Related Articles | Metrics

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Uppermost Cretaceous sediments: Sedimentary microfacies and sedimentary environment evolution of Sifangtai Formation and Mingshui Formation in SKⅠ（n）. CHENG Ri-Hui, WANG Guo-Dong, WANG Pu-Jun, GAO Wei-Feng 2009, 16(6): 85-95.  Abstract ( 2217 )   PDF (2838KB) ( 850 )   Sifangtai formation and Mingshui formation developed on the uppermost Cretaceous, Songliao sag basin. The continuous rock core of both formations in SKⅠ(n)( the north hole of SK, China continental scientific drilling ) reveals their sedimentary facies and environments. Sifangtai Fm. composed of sediments of meandering river and shallow lake. The sediments of meandering river is an association of some microfacies including channel lag, point bar, natural levee, crevasse splay, crevasse channel, flooded plain and pond. The sediments of shallow lake is another microfacies association including nearshore bar and mudstone of still water. Mingshui Fm. composed of sediments of meandering river, shallow lake and lakeshore. The first member of Mingshui Fm. is dominated by the sediments of shallow lake and the second member is alternation of the sediments of both meandering river and shallow lake. The microfacies of sediments of meandering river in Mingshui Fm. includes channel lag, point bar, natural levee, crevasse splay, crevasse channel, flooded plain and pond, while shallow lake includes mudstone of still water, nearshore bar and tempestite, and lake shore includes sand beach and mud beach. Lake level had undergone variations several times. The lowest lake level occurred in Sifangtai Fm. and the highest lake level in the first member of Mingshui Fm. The lake level change with “lowhighlow” feature shows a cycle from Sifangtai Fm. to Mingshui Fm. The relationship between sediment colors and paleoclimates shows the climate of Sifangtai and Mingshui stages. Sifangtai Fm. presented aridsemiarid with high temperature. The lower part of the first member of Mingshui Fm. presented aridsemiarid with low temperature, and the upper part presented alternation of aridity and humidity with low temperature. The lower and middle part of the second member of Mingshui Fm. presented alternation of aridity and humidity with high temperature and the upper part presented arid and semiarid with high temperature. The vertical change of sedimentary facies from Sifangtai Fm. to Mingshui Fm. shows northwestward migration of sedimentary facies zones whose center was the area of sediments of shallow lake.  Related Articles | Metrics

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Organic geochemical characteristics of anoxic levels in the Cretaceous Qingshankou Formation of Songliao Basin. KONG Hui, HUANG Yong-Jian, HUANG Qing-Hua, ZHANG Wen-Jing, XIE Lei, LIU Hua-Gong, XIE Xiao-Yun 2009, 16(6): 96-103.  Abstract ( 2375 )   PDF (1246KB) ( 886 )    The Songliao Basin was a big lake during the midCretaceous, where dark mudstones and shales of the Qingshankou Formation were distributed in the basin. The dark mudstones and shales in the Member 1 of the Qingshankou Formation are of high organic carbon and low diasteranes contents. Organic geochemical characteristics are illustrated by biomarkers of 28, 30bisnorhopane and gammacerane, and positive excursion of kerogen isotopes. It is suggested that the dark mudstones and shales in the Member 1 of the Qingshankou Formation are the products of lake anoxic event in the extreme greenhouse climate period. Based on the study of biostratigraphy and anoxic eventstratigraphy, we propose that the Qingshankou Formation may correspond to the oceanic anoxic event at the CenomanianTuronian boundary in the Cretaceous, and the age of the Qingshankou Formation in the Songliao Basin is the Late Cenomanian to the Early Turonian. Related Articles | Metrics

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Well site selecting, core section characteristics and distribution of the special lithological layers in CCSDSKIn borehole, Songliao Basin. GAO Wei-Feng, WANG Cheng-Shan, WANG Pu-Jun, MO Xiao-Qiao, LIN Yan-An, CHENG Ri-Hui, WANG Guo-Dong 2009, 16(6): 104-112.  Abstract ( 2003 )   PDF (2049KB) ( 1204 )   CCSDSKIn borehole (China Cretaceous Continental Scientific DrillingSongkeⅠ—the north borehole) is the north one of the two drilling wells of the Cretaceous Scientific Drilling Project in Songliao Basin. It is located in Talaha syncline in Gulong sag of center depression, north Songliao Basin. Based on the detailed description of the cores from the Taikang Formation to the first member of the Nenjiang Formation in CCSDSKIn borehole, we have established the core section and identified five special lithological layers, including dolomite, volcanic ash, oil shale, lime mudstone and marl. The total number of special lithological layers is 73 with total thickness of 708 m. They distribute in the second to the fifth member of the Nenjiang Formation and the second member of the Mingshui Formation. The detailed description of the cores from CCSDSKIn borehole and the identification of special lithological layers will benefit the further studies. Related Articles | Metrics

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A study of the stability assessment and treatment of dangerous rock in Fengcheng town of the Three Gorges Reservoir area. ZHANG Ban, LI E-Ling, SHEN Ai-Ji, KANG Xiang-Yang, QIN Jie-Miao 2009, 16(6): 113-119.  Abstract ( 1557 )   PDF (1347KB) ( 757 )   The failure of dangerous rock is one of the geological disasters that occurs frequently in the Three Gorges Reservoir area. Based on the study  of geological background conditions and the factors inducing the failure of dangerous rocks, this paper explains the distribution and morphological characteristics of dangerous rocks in Fengcheng town, provides the classification of  the failure modes of the dangerous rocks in this area, and analyses the stabilities of six representative monomers of dangerous rocks qualitatively by stereographic projection method and quantitatively by limit equilibrium method. The results of the study show that all of the six dangerous rocks are instable or metastable, therefore, the control measures on them must be taken. The joint  controlling measures of smallscale earthwork, rockside support and anchorage, with surface drainage and closing fissures are put forward. Related Articles | Metrics

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The impact of middle to late Holocene environmental changes on human activities in the Qujialing region, Jingshan, Hubei Province. SHI Chen-Xi, MO Che-Wen, MAO Long-Jiang, LIU Hui 2009, 16(6): 120-128.  Abstract ( 2765 )   PDF (1682KB) ( 1638 )   The Qujialing site is a representative Neolithic archaeological site on the east of lower reaches of Hanjiang River, ~130 km from the Wuhan City, Hubei province, China. Synthetic analyses of grainsize, Rb/Sr ratio, magnetic susceptibility and pollen of sedimentary samples from Qujialing profile near the Qujialing site revealed the depositional process and characteristics, and climate changes since 52 ka BP in this area. The sediments were dominantly consisted of silt and clay of percentage over 95%, and that the <30 μm particle group was the “dominant group”. The grainsize probability cumulative curves were characterized by threesegment pattern except a small number of doublesegment pattern. The average ratio of Rb/Sr in the 5th layer was 13, which was generally higher than that in 14 layers (098). Magnetic susceptibility values were in the range of (5341499)×10-8 m3·kg-1. Three pollen zones were divided from bottom topwards. The depositional characteristics showed that there were some similarities between the sediments of Qujialing profile and loess, because many of the sediments were derived from the loessic materials in upper drainage area of the Qingmudang River. But the dominant sedimentary facies of Qujialing profile was fluvial facies based on the grain size analyses, field observation and the geomorphic place. By means of magnetic susceptibility, Rb/Sr ratio and pollen analyses, the climate changes were divided into three periods during the midlate Holocene: from 52 ka BP to 42 ka BP, the temperature and precipitation were higher than present in this area, but the climate turned into cool and arid with fluctuations at the end of that time; 4220 ka BP was a coolarid period; a relatively warmwet period occurred after 20 ka BP. Both of the climate and hydrological changes may have been the controlling factors of the collapse of the late Neolithic Culture in the Qujialing region. Related Articles | Metrics

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POSTTSUNAMI ASSESSMENT IN THE COASTAL REGION BETWEEN KANYAKUMARI AND OVARI, TAMIL NADU—A CASE STUDY S.Saravanan, N.Chandrasekar, C.Hentry, M.Rajamanickam, J.Loveson Immanuel 2009, 16(6): 129-137.  Abstract ( 1407 )   PDF (851KB) ( 2030 )    Coastal zones are dynamic areas that are constantly undergoing change in response to a multitude of factors including sea level rise, wave and current patterns, hurricanes and human influences. On 26th December 2004, huge waves smashed across the shore between Kanyakumari and Ovari. As they crossed the beach, the waves up to 30 feet tall. Many people are dead due to crush and pull to sea and drowned as the mighty waves withdraw. Many villages have been obliterated, the death tale could exceed 300 but the damage to the property is very high. The size of the tsunami is related to the area that moves on the ocean bottom and how far it moves. This region is manifested with marine terrace, sand dunes, beach ridges, estuaries, floodplains, beaches, mangroves, peneplains, uplands, sea cliff, etc. We have attempted the shoreline dynamics using beach profile survey, and coastal environment changes through online survey, governmental. records and coastal geomorphological studies using remote sensing technique. The major destructions are identified in this paper. Related Articles | Metrics

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Beach sediments from northern South China Sea suggest high and oscillating sea level during the late Holocene. TU Ke-Bi, CHEN Te-Gu 2009, 16(6): 138-145.  Abstract ( 1790 )   PDF (1695KB) ( 1125 )    Reconstruction of the late Holocene sealevel changing process is significant for understanding the current situation and the future trend of the present sea level. Leizhou Peninsula located in the northern coast of the South China Sea is an ideal site for studying the Holocene sealevel history because of its tectonic stability and its possession of numerous sealevel indicators. Beach sediment from this site suggests that from 1.712 Cal. ka BP (or 14C ages from 21 to 17 ka BP) it was an overall sea level rising period with a shortterm sealevel dropping punctuation occurred at ~15 Cal. ka BP. The sealevel at 12 Cal. ka BP was at least 128 cm higher than the present one, and then it started to decline some time later, which resulted in the retreat of the coastline by about 210 m and the formation of the present beachsand bank system. Associating with other evidences from coral reefs at this site, we believe that the sea level, just like climate, oscillated at millennial, centennial and interdecadalscale cycles over the Midlate Holocene. Related Articles | Metrics

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Direct evidence of Heinrich event 3: Desiccation crack in Zhoushan Islands, Zhejiang Province. GU Nan, SUN Li-An, YUAN Lin-Chi, XIE Zhou-Qing 2009, 16(6): 146-153.  Abstract ( 1546 )   PDF (1732KB) ( 713 )   The large desiccation cracks, which are up to 60 cm deep, were developed on the intertidal zone of the Guanyin Bay, Zhujiajian Island, Zhejiang Province. The results from chronological, palynological and mineralogical analysis show that the time of the formation of the desiccation crack is coincident with the period of the environmental change from warm and humid to cold and dry. The desiccation crack corresponds to an abrupt climate shift event during 312304 ka BP, with a decline in vegetation. It is most probable that this phenomenon demonstrates a direct landscape evidence for the worldwide abrupt climate event—the Heinrich event 3. The desiccation crack provides a new method for the research of Quaternary abrupt climate shift events. Related Articles | Metrics

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Cenozoic sedimentation in the southern Tarim Basin: Implications for the uplift of northern Tibet and evolution of the Taklimakan Desert. ZHENG Hong-Bei, GU Jun-Chao, WANG Ge 2009, 16(6): 154-161.  Abstract ( 2831 )   PDF (1902KB) ( 1033 )   塔里木盆地南缘新生代沉积地层厚达万米以上。研究的叶城和阿尔塔什两个剖面分别厚4 500 m和7 000 m,基本代表了塔里木南部的新生代沉积。叶城剖面的底界年龄根据磁性地层测定约为8 Ma。阿尔塔什剖面的底界年龄根据海相碳酸盐岩87Sr/86Sr的比值与全球Sr同位素曲线对比,约为30~35 Ma。从岩性地层分析,剖面的下部为中新统乌恰群,主要由泥岩和粉砂岩组成,沉积相为低能环境的辫状河和曲流河。剖面的中部是上新统阿图什组,由红色泥岩、砂岩夹薄层砾岩以及埋藏风成黄土构成,沉积环境为冲洪积扇的中远端。剖面的上部是上新统—下更新统西域组,由中粗砾岩夹块状粉砂岩透镜体(埋藏风成黄土)组成,主要是近源洪积扇沉积和风成沉积,以上地层层序可以进行很好的区域对比。塔里木盆地南缘新生代沉积由新近纪红层向上变化为逆粒序砾岩和碎屑流沉积,记录了青藏高原北缘隆升造成的沉积环境的变化,尤其是干旱化气候的阶段性演化。在约8 Ma时,叶城和阿尔塔什两个剖面都发育了风成沙丘沉积。而在阿尔塔什剖面,沙丘沉积之下还发育了一套厚层的膏盐沉积,指示了塔里木盆地南缘在此前后已经相当干旱,只是仅凭这些证据还难以判断沙漠发育的规模。而上新世—更新世阿图什组和西域组中发育的埋藏风成黄土沉积,则指示了塔克拉玛干沙漠在此时已经发育到了相当规模,极度干旱的气候条件(可能类似于现在)已经形成。 Related Articles | Metrics

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A preliminary study of the Holocene lake level changes and their causes derived from the sediment record of Zigetang Lake, Tibetan Plateau. LI Shi-Jie, Bernd Wünnemann, JIA Wei-Lan, XU Shou-Bing, CHEN De-Fu, JIANG Yong-Jian 2009, 16(6): 162-167.  Abstract ( 1891 )   PDF (912KB) ( 1784 )    The Zigetang Lake is an enclosed lake, located in the hinterland of the North Tibetan Plateau and within the marginal region of southwest monsoon. There is no distribution of glacier in the catchment, and the precipitation controlled by the southwest monsoon is the main water supply for the Zigetang Lake. Therefore, the expansion and contraction of lake water area reflects the changes of southwest monsoon directly. The carbonate concentration of enclosed lake sediments in semiarid region indicates the changes of the lake level sensitively. The carbonate concentration in the sediment core of Zigetang Lake has generally been in high value but there were several abrupt lowering stages during the Holocene period, which could reveal the evolution stages of the lake level better when associated with the changes of soluble salt (Cl- and SO2-4) concentration in the sediment core. The analysis results for a 740 cmlong core drilled in the central Zigetang Lake show that this core has completely covered the whole Holocene period and that the carbonate concentration decreased greatly during 9389 cal ka BP, 8378 cal ka BP, 5047 cal ka BP, 4038 cal ka BP, and 3127 cal ka BP, respectively, indicating the desalination of the lake and the rise of the lake level. The high value of carbonate and soluble salt (Cl- and SO2-4) content around 38 cal ka BP indicates the increase of salinity and the decline of the lake level. The content of carbonate and soluble salt decreased gradually since 1 cal ka BP, which indicates the gradual desalination of the lake and the slow rise of the lake level. However, the increase of soluble salt content in the past 100 years indicates the contraction of lake water area and the decline of the lake level, which is in accord with the warming and drying process of the climate. The fluctuations of southwest monsoon during the Holocene can be derived from the five extremely low value events of carbonate concentration in the sediment core from the Zigetang Lake. Related Articles | Metrics

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The oxygen and carbon isotopic signatures of laminations in lacustrine stromatolites and palaeoenvironmental significances of growth rhythmites. YI Hai-Sheng, SHI Zhi-Jiang, HUI Bo, JIA Guo-Qing 2009, 16(6): 168-176.  Abstract ( 2362 )   PDF (1528KB) ( 1426 )    The lacustrine stromatolites from the Oligocene Yaxicuo Formation of the northern Tibetan Plateau display regular growth rhythms of dark (organicrich layer) and light (sedimentrich layer) lamination alternations with millimeter scale. The lamination morphologies exhibit dome and columnar shapes in a vertical section. In order to understand the origin and time length scale of a couplet of laminae in stromatolites, the stable oxygen and carbon isotopic compositions of individual lamina were analyzed by using laser microsampling technique. The analysis results showed that the dark lamina in stromatolites commonly has relatively higher δ18O and δ13C values than the light lamina. The δ18O and δ13C values display positive covariance, i.e., simultaneous enrichment in dark laminae and coeval depletion in light laminae. We believe that the cyclic fluctuations of isotopic signals among couplets of laminae were caused by seasonal climatic variations. We suggest that the couplets of laminae in lacustrine stromatolites indicate the origin of annual lamination. This study demonstrates the lamination in lacustrine stromatolites can provide us a kind of geologic material with highresolution to reconstruct terrestrial palaeoclimate and palaeoenvironment changes during the geologic history. Related Articles | Metrics

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The characteristics of the Indian monsoon: Evidences from the sedimentary records of Tengchong and ShangriLa over the past 60 ka. FANG Nian-Jiao, BAO Dui, DING Xuan, YAN Yong, HE Feng-Fei, WEN Yan-Xing, NIE Gao-Gang 2009, 16(6): 177-185.  Abstract ( 1553 )   PDF (1623KB) ( 752 )    On the basis of correlating some significant proxies, such as TOC, δ13C, grainsize and pollen data, from the Napahai lake, Shangrila and the Beihai wetland, Tengchong, and referring the sedimentary rhythm and δ18O record since 60 ka BP from the Bay of Bengal, we found that all of them have been closely affected by the Indian monsoon system. Because of the difference in their latitudinal, longitudinal and sealand situations, however, the climatic records clearly show a differential affinity to the summer monsoon or to the winter one. The most impressive climatic shock over the past 60 ka was a great thermal and wet event that happened roughly from 37 ka BP to 32 ka BP and was evidently manifested within both the Beihais and the Napahais sedimentary sequences. Discordantly, that event cannot be recognized in the marine records. We deduced from the correlation between the continental deposit and marine deposit that the control of the regional climatic event originated from the land side rather than the sea side during the late MIS3. It is likely that an extreme warming up at that phase at the Tibetan Plateau, which resulted in the decline of the Indian winter monsoon and other changes of the atmospheric circulation, was responsible for the event. The geomorphologic configuration played an important role in the monsoonal precipitation as well.  Related Articles | Metrics

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A discussion on the layered landscape features and its origin in Tibetan Plateau. SHAO Zhao-Gang, MENG Xian-Gang, SHU Da-Gang, YANG Chao-Bin, LEI Wei-Zhi, WANG Jin, HAN Jian-En, TU Jia 2009, 16(6): 186-194.  Abstract ( 4836 )   PDF (4649KB) ( 6271 )    The QinghaiTibet Plateau is the highest, the latest and the most extensive plateau in the world. The layered landscape is a typical landform feature of the QinghaiTibet Plateau; the study of its formation is of great significance for understanding the process of QinghaiTibet Plateau uplifting and the evolution of the climate. This paper discusses the formation of the layered landscape on the QinghaiTibet Plateau based on the field investigation and the observed data analysis. We focus on the analysis of nowadays landform features of the QinghaiTibet Plateau and put forward that the main surface and the peak surface were formed in the plateau uplifting process. Under the intensive compression by the subduction and collision between the India plate and the Eurasian plate, the coactions of internal and external processes caused the uplift of the QinghaiTibet Plateau. The internal process had the characteristics of the differentially wholly uplifting. We hope this study could provide some new ideas and basis for the research on the uplifting of the QinghaiTibet Plateau. Related Articles | Metrics

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Isotopic evidences for provenances of loess of the Chinese Loess Plateau. YANG Jie-Dong, LI Gao-Jun, DAI Yun, RAO Wen-Bei, JI Jun-Feng 2009, 16(6): 195-206.  Abstract ( 2064 )   PDF (1540KB) ( 915 )    We have systematically collected the samples of the Malan loess in the Chinese Loess Plateau(CLP), the sand of ten deserts, the loess of the Hexi corridor, and the loess and sediments of riverbed and lake bottom on the northeast part of the QinghaiTibet Plateau. After removing calcites, the determined Nd and Sr isotopes of the Chinese Loess Plateau show that εNd(0) from -92 to -113 and 87Sr/86Sr from 071784 to 071944. They fall within the B region of NdSr isotope plot of provenances and are identical to those of the Badain Jaran Desert, the Tengger Desert and the northeast part of the QinghaiTibet Plateau. The determined C isotopes of dolomites of the Chinese Loess Plateau show that δ13C from 12‰ to 15‰. They are identical to those of the Qaidam Desert, the Hexi corridor and the northeastern part of the Tibetan Plateau. These imply that the northeastern part of the Tibetan Plateau, the Badain Jaran Desert and the Tengger Desert may be the source areas of loess materials of the Loess Plateau, and that the possibility of the other deserts and sandy lands being the provenances of the loess is excluded, among them including the Gurbantunggut Desert, the Hunlun Buir sandy land, the Onqin Daga sandy land, the Horqin sandy land, the Hobqi Desert, the Mu Us Desert and the Taklimakan Desert. The field surveys further reveal the possibility that the materials of the Chinese Loess Plateau, the Badain Jaran Desert and the Tengger Desert are derived ultimately from the northeast part of the QinghaiTibet Plateau. Related Articles | Metrics

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Debris flow induced by glaciallake break in Southeast Tibet. CHENG Zun-Lan, TIAN Jin-Chang, ZHANG Zheng-Bei, JIANG Ba 2009, 16(6): 207-214.  Abstract ( 1698 )   PDF (1592KB) ( 858 )    The debris flow caused by flood of glacierlake break is a major disaster to Southeast Tibet. Based on field investigation and data analysis, this paper discusses the influences of climate factors on the lake break. It is found that the break is likely to occur after the abnormal changes in climate, especially at the turn from coldwet weather to hotdry weather. Debris flows due to glaciers will be more active in the future decades. Related Articles | Metrics

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The Cenozoic tectonic evolution of the west Qinling: Constraints on the uplift and deformation of the Tibetan Plateau. GUO Jin-Jing, HAN Wen-Feng, LI Xue-Feng 2009, 16(6): 215-225.  Abstract ( 2136 )   PDF (1974KB) ( 1118 )   The Cenozoic tectonic and geomorphological processes of the west Qinling as a part of QinghaiTibetan plateau could provide some constraints on the uplift and deformation model of the QinghaiTibetan plateau. Based on the analysis of the Cenozoic sedimentary strata and its deformation features, regional fault framework and its kinematics, and geomorphological records, we could reach the following preliminary understanding. (1) Based on their rock composition, spatial distribution and tectonic deformation characteristics, we can divide the Late MesozoicCenozoic red bed sedimentary strata in the west Qinling into the Late JurassicEarly Cretaceous, the Late CretaceousPaleogene and the Neogene three tectonic strata units, which corresponds to three tectonic evolution stages. (2)The faultthrusting and foldshortening of K2E strata in the west Qinling occurred at the end of Eocene, synchronous with the crust shortening and thrusting in the QinghaiTibetan plateau, which may indicate that the compressive tectonic stress from the collisional convergence between the India plate and the Eurasia plate have been transmitted to the west Qinling. (3)The west Qinling had undergone a relatively tectonic stable period since the Neogene, in which extensive erosion and planation occurred, and finally main planation surface and associated Neogene sedimentary strata consisting of red conglomerate and red clay were formed before 36 Ma. This planation surface at presentday decreased gradually from 3200 m in the west to 1200 m in the east, which can be interpreted as continuous uplift in the eastward expansion of the QinghaiTibetan plateau. (4) The structural deformation transition from thrustingshortening to extensionstrike slip at 1314 Ma or 8 Ma in the south Tibet have not appeared widely in the west Qinling, whereas fault thrusting predominated the total Cenozoic tectonic history and leftlateral strikeslip only occurred in the northern boundary fault of the west Qinling, which may indicate that block slip and thrusting coexisted in the west Qinling. (5) The regional displacement field determined by the GPS observational data and tectonic stress directions deduced by earthquake mechanism solution showed eastward motion of the west Qinling block and Edirected tectonic stress, which may reflect that eastward creep of low crust drags upper crust movement and uplift. The gradient zone of the crust thickness of the west Qinling could be interpreted as the result of eastward expansion creep of the thickened lower crust, which controlled main landform features of the west Qinling. Related Articles | Metrics

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Modeling the East Asian climate during the Late Cretaceous (80 Ma). CHEN Jun-Meng, DIAO Beng, WANG Cheng-Shan, HUANG Yong-Jian 2009, 16(6): 226-239.  Abstract ( 1655 )   PDF (3725KB) ( 895 )   In this paper, the East Asian climate during the Late Cretaceous (80 Ma) is examined by using the Community Climate System Model Version 2 (CCSM2) from the National Center for Atmospheric Research (NCAR) and the reconstructed palaeogeographic data. The simulation results show that the largescale prevailing wind directions and pressure systems over East Asia showed a remarkable seasonal variation during 80 Ma, so that it can be inferred that there existed a monsoon circulation over East Asia at that time. Compared to the present climate, the atmospheric circulation systems over the Eurasian continent in the Late Cretaceous showed a stronger meridional feature, which possibly corresponded to a smaller zonal span of the continent. Moreover, under a warmer background in the Late Cretaceous, the winter and summer monsoons over East Asia showed a synchronous variation, with a stronger winter monsoon as well as a stronger summer monsoon. The pattern of annual mean precipitation is similar to that of the present climate, with the maximum precipitation appearing in the intertropical convergence zone (ITCZ) between 10°S and 10°N. There was also more precipitation over the eastern coasts of the continent adjacent to the western Pacific, with the central value exceeding 1200 mm, and there was less precipitation in the mid latitudes of the inland areas. Although a more precipitation belt also appeared near 30°N over the western Pacific, which is similar to the present climate, there was no precipitation belt over the land of East Asia. This feature implies that the uplift of the Tibetan Plateau plays an important role in the formation of the present baiu rain (plum rains). Moreover, the simulated climate over East Asia during 80 Ma was warmer relative to the present one and surface air temperature is 2 ℃ higher at the same latitudes compared to the present climate; the simulated temperature is close to the estimation from the geological evidence. Related Articles | Metrics

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SOUTHERN BARENTS SEA ANOMALOUS MAGNETIC FIELD AND ITS CORRELATION WITH BOTTOM GEOLOGICAL STRUCTURE AMA.M.Gorodnitskiy A.M.Filin Yu.D.Malyutin A.N.Ivanenko N.A.ShishkinaShirshov 2009, 16(6): 226-239.  Abstract ( 1158 )   PDF (1490KB) ( 848 )    Results of data processing of marine magnetic surveys in a southern part of Barents Sea, executed from 1986 to 2001 are considered. The geomagnetic investigation of Southern Barents Sea bottom points on its complicated manystage geologictectonic structures in which two disjunctive structures prevail: RipheanVendian inherited rift structures with northwest strike and orthogonal system of superposed faults transformed in  northeastern direction. Late Devonian alkaline intrusives with associated ore mineralization are confined to points of these systems intersection. Related Articles | Metrics

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A study of RS image landform frame and lithologic component decomposing algorithm and multifractal feature of rock types. BO Wei, NI Guo-Jiang, LI Han-Bei 2009, 16(6): 248-256.  Abstract ( 1920 )   PDF (2430KB) ( 935 )    Landform framelithologic component decomposing algorithm for remote sensing (RS) image is proposed according to the principle of optical imaging and fractal feature of landform. The algorithm is applied to decomposing the ETM image of rocks for the study of αf(α) multifractal spectrum. The original ETM image, decomposed landform frame subimage and lithologic component subimage are used to calculate the αf(α) multifractal spectra of adamellite and metamorphic sedimentary rocks in different area. With the original ETM image, the αf(α) multifractal spectra do not show any relation to rock types. However, with the decomposed image, the adamellite in different area have the same αf(α) spectra feature of lithologic component subimage and different αf(α) spectra feature of landform frame subimage. On the contrary, the adamellite and metamorphic sedimentary rocks in nearby area have similar αf(α) spectra of landform frame subimage and different αf(α) spectra of lithologic component subimage. This means the landform framelithologic component algorithm and αf(α) multifractal spectrum can provide a new validate method to improve the lithology recognition with RS image texture. Related Articles | Metrics

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Selforganizing abiogenic dissipative structures in the geologic history of the Earth. S.L.Shvartsev 2009, 16(6): 257-275.  Abstract ( 1751 )   PDF (799KB) ( 2074 )   It is shown that since the appearance of water on the Earth, a stationary disequilibriumequilibrium waterrock system came into existence.  This system is internally inconsistent, which determines its ability to develop continuously in a spontaneous manner for a long geologic time, leading to the formation of principally new mineral phases and geochemical types of water. Within the Earths crust, this system persistently develops in a nonlinear field of the thermodynamic branch under the conditions far from equilibrium; it is capable of accumulating the solar energy and forms abiogenic dissipative structures playing a special role in the progressive development of inert matter and then of living matter. The inclination of this system to the progressive selforganization defines it as one of the fundamental and basic system in the development of inorganic matter. From this system there was a set of others having inherited most of its properties. The evolution of the waterrock system led to the formation of  secondary mineral phases and new geochemical types of water, and as these increased, the system gradually became more complex in composition and structure and formed new geochemical media which, in turn, control the formation of new mineral phases having effect on the characteristics of the media. This process is geologically perpetual. This is the essence of selforganization in mineral kingdom, including initiation, growth and spatialtemporal dispersal of new structural forms, mineral and geochemical media formations, and finally, the origination of new organic substances and life. Related Articles | Metrics

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The estimation of aquifer parameters using tidal effect in a coastal aquifer: A case study in Beihai Peninsula, Guangxi China. JIA Yu-Jiang, LI Hai-Long 2009, 16(6): 276-281.  Abstract ( 2017 )   PDF (858KB) ( 1186 )    How to estimate aquifer parameters or to confirm the extending length of the aquifer under the sea or the existence of the aquifer submarine outletcapping via the analysis of the observed data of water level dynamic condition in observation well has attracted much attention from hydrogeologists. Based on the well acquaintance with the hydrogeological conditions in the Beihai Peninsula, Guangxi Autonomous Region, China, we can conceptualize the first confined aquifer in this area into a vertical threelayered nonstationary flow model with the aquifer submarine outletcapping and the leakage through the aquifers roof. The analytical solution to this model is applied to analyze the tidal and piezometer data in a coastal aquifer of the Beihai Peninsula in this paper. The aquifer parameters are estimated using leastsquares objective function with novel penalty functions incorporating known information. The solution prediction closely fits with the observation very well. Related Articles | Metrics

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Research on superimposed metallogenic systems and polygenetic mineral deposits. DI Yu-Sheng, WANG Jian-Beng, BANG Run-Min, LIU Jia-Jun 2009, 16(6): 282-290.  Abstract ( 4113 )   PDF (1165KB) ( 7515 )   The superimposition between different oreforming events usually induced the formation of superimposed metallogenic systems in the long and complex oreforming processes. It is the major  cause for  the generation of many complex and compound mineral deposits. The special tectonic situation and the specific fabric composition make the Chinese mainland a compound and active continent, so caused the development of superimposed metallogenic systems in China. It is one of the most important features of regional metallogeny of China. On the basis of a brief retrospect on the research history of metallogenic systems, superimposed metallogenic effects (generation of large and rich ore deposits, complex composition of ores, etc.), forming mechanisms and major controlling factors (stable geochemical fields, overlap of oreforming structural belts, repeated activities of contemporaneous faults, geochemical barriers of some early ore beds, etc.) of superimposed metallogenic systems are discussed in this paper. Also basic types of superimposed metallogenic systems and their temporalspatial distribution are summarized.  Among them the superimposition between earlier  sedimentary mineralization and later magmatic hydrothermal mineralization is the most common combination of superimposed metallogenic systems. Complexity of superimposed oreforming processes caused  the complexity of a superimposed metallogenic system. So only through much more detailed and thorough research can we understand better  the superimposed metallogenic systems, including their forming mechanisms and processes. Research on superimposed metallogenic systems is very important both in recognizing regional metallogeny of China and in guiding mineral exploration activities. Related Articles | Metrics

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Triassic magmatism in the southern Lancangjiang zone, southwestern China and its constraints on the tectonic evolution of PaleoTethys. FAN Wei-Ming, BANG Tou-Beng, WANG Yue-Jun 2009, 16(6): 291-302.  Abstract ( 1962 )   PDF (2150KB) ( 1606 )   Triassic magmatism widely developed in the southern Lancangjiang zone, southwestern China. The study of their precise UPb geochronology and characteristics of rock associations shows that (1) small amount of EarlyTriassic (~248 Ma) volcanic rocks were preserved and cropped out in the area, which consist mainly of thin bed of andesitic rocks intercalated with minor basaltic andesites; that (2) the MiddleTriassic magmatism was characterized by extensive felsic igneous rocks with minor basalts interbedded in the middle of volcanic sections in part of areas, and the late MiddleTriassic rhyolites and main body of Lincang granitic batholith have the same extrusive/intrusive time with the age of ~230 Ma; that (3) the LateTriassic volcanic sequences are principally composed of basalts with minor interlayered rhyolites, exhibiting typical characteristics of bimodal volcanics. In addition, the features of elemental geochemistry of all samples suggest that (1) the EarlyTriassic andesitic rocks, characterized by characteristic natures of island arc volcanics, likely erupted in the subduction setting; that (2) the generation of LateTriassic rhyolites with an affinity of Alike granite and synchronously main body granites in the Lincang batholith displaying similar geochemical features, is closely related with the postcollision or latecollision setting; that (3) although the LateTriassic basic rocks partly show island arc volcanics such as highAl contents and NbTa depletion, some of them possessing highMg contents and mostly having traceelement ratios similar to intraplate basalt, which indicates that they erupted in the postcollision rift environment. Integrated with previous data in the study area, we conclude that the subduction and closing of main PaleoTethys Ocean (ChangningMenglian Ocean) in the Sanjiang area of southwestern China probably had completed until the late EarlyTriassic, and the succeeding continentcontinent/arc collision and postcollision rifting developed in the MiddleTriassic and LateTriassic, respectively, and finally the evolution of PaleoTethys finished in the end of the LateTriassic. Related Articles | Metrics

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Do the Tianshan Carboniferous volcanic successions contain Nbenriched arc basalts? JIA Lin-Qi, JIA Jie-Chun, XU Hua-Xi, LI Xiang-Min, MA Zhong-Beng 2009, 16(6): 303-317.  Abstract ( 2359 )   PDF (3225KB) ( 905 )   The Tianshan CarboniferousEarly Permian riftrelated volcanism in northwestern China represents a newly recognized large igneous province. It has been deemed that an assemblage of Nbenriched arc basalt, adakite and highMg andesite occurred in the Tianshan Carboniferous volcanic successions. Divergent chemical and isotopic characteristics between this rock assemblage and the typical Nbenriched arc basalts, adakites and highMg andesites reveal that the former is not arc related. This postulated arcrelated assemblage is indeed an intracontinental volcanic assemblage that consists of crustally uncontaminated, lesscontaminated and strongly contaminated continental volcanic rocks. Related Articles | Metrics

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Comprehensive prospecting model for leadzinc deposit of HuanggangGanzhuermiao Metallogenic Belt, Inner Mongolia. WANG Miao, FAN Ji-Zhang, WANG Zhong-Wen, MA Yan-Yang 2009, 16(6): 318-324.  Abstract ( 1461 )   PDF (1722KB) ( 952 )    Taking the leadzinc deposit of HuanggangGanzhuermiao Metallogenic Belt as a predicted mine, this paper systematically analyzed the relationships between geological conditions including strata and magmatic rocks, etc. and leadzinc deposits, and found out the control action and manner of geological conditions on leadzinc deposit. The leadzinc mineralization has a close relationship with the Permian in spatial distribution and content compositions. Manganese calcium pyroxene skarn and volcanic sedimentary rocks provide material for leadzinc deposit. The beneficial rocks are Yanshanian acid intrusive bodies. In the metallogenic belt, the concentrated mineralization area is the intersection of multiple parts of fractures. The differently striking faults make deposits form a NE zone and an EW row, and the deposits distribute with equal intervals. Finally, we established a comprehensive prospecting model for leadzinc deposit, which consists of geological, geochemical and mineralization information and provides the theoretical basis for predicting the leadzinc deposit within the metallogenic belt. Related Articles | Metrics

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Trace element and REE geochemistry and its metallogenic significance for CuZn deposits in the Tongbai area, Henan. LI Li-Xin, LI Hou-Min, WANG De-Gong, ZHANG Chang-Jing 2009, 16(6): 325-336.  Abstract ( 2030 )   PDF (2478KB) ( 834 )    There are some CuZn polymetallic ore deposits  of volcanic hosted massive sulfide (VHMS) type  located in the Tongbai Region, Henan Province, China.  The trace element and rare earth element (REEs) abundance of ores of Liushanyan CuZn deposit, DalishuFanglaozhuang CuZn deposit and Yangjuan Cumineralizing spot were analyzed by using ICPMS method in order to discuss the genesis of these deposits. Four types have been identified on the  basis of study on trace elements and REEs geochemistry: ores of the first type show LREEenriched REE patterns, without Eu anomalies and weak negative Ce anomalies, but with a weak depleted HFSE and smaller anomalies at Zr and Ti relative to NMORB; ores of the second type show LREEenriched REE patterns having negative Eu anomalies and weak negative Ce anomalies; ores of the third type show LREEenriched REE patterns, having positive Eu anomalies and negative Ce anomalies, with a depleted HFSE and small negative anomalies at Zr and Ti relative to NMORB; ores of the fourth type show horizontal REE distribution patterns, having positive Eu anomalies and weak negative Ce anomalies, with a depleted HFSE and no anomalies at Zr and Ti relative to NMORB. The first type and the second type have similar characteristics to the basic volcanic rocks and acid volcanic rocks respectively. Characteristics of the third type indicate that the convective mixing of a small amount of sea water with high  temperature hydrothermal fluids had happened with a lot of minerals which are insoluble in the solvents in the residual phase. The fourth type has a depleted mantle source. These characteristics indicate that the mineralization material has the same source with its wall rocks of the Liushanyan Formation, which are the products of mantle partial melting that had undergone  multiple earlier melting events. Related Articles | Metrics

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Provenance sediments and its exploration significance—A case from Member 1 of Qingshuihe Formation of Lower Cretaceous in Junggar Basin. HOU Lian-Hua, WANG Jing-Gong, KUANG Li-Chun, KUANG Jun, ZHANG Guang-E, LIU Lei 2009, 16(6): 337-348.  Abstract ( 1924 )   PDF (4353KB) ( 770 )   In order to reveal the main control factor of the distribution of depositional system and sandstone as well as its affection for reservoir forming, we have restored the palaeogeomorphology of CheMo paleouplift through a multimethod research based on the investigation of the coring, seismic and well logging data. The results indicate that CheMo paleouplift was developed from the Middle Jurassic to the Early Cretaceous and reached its peak development in the Late Jurassic. Information from the core, seismic section, heavy minerals, and sandbody thickness can also give a reasonable explanation about the origin mechanism of the reservoirs in this area. The distribution of depositional system and sandstone around CheMo paleouplift was controlled by local provenance sediments. The formation of ancient reservoirs was also determined by the appearance of this uplift. Tectonic movement including two structural tilting periods, the distribution of local provenance sandstone, fault system and modern structures are the key controlling factors for oil and gas migration and the formation of secondary reservoirs. We concluded that the area showing good correlation between local provenance sandstone and modern structures is favorable for the development of lithologicstratigraphic reservoirs. The paleoslopes of CheMo paleouplift are the main regions for further exploration. This new understanding has brought a breakthrough in the exploration of CheMo paleouplift. Taking Shamen1 Well as an example, the exploration of lithologicstratigraphic reservoirs in the central Junggar basin will enter a new period. Related Articles | Metrics

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Differential hydrocarbon migration and entrapment in the karstified carbonate reservoir: A case study of Well TZ83 block of the central Tarim uplift zone. XIANG Cai-Fu, WANG Jian-Zhong, LONG Xiong-Ai, JIANG Zhen-Hua, LIU Luo-Fu, LI Su-Mei 2009, 16(6): 349-358.  Abstract ( 1974 )   PDF (2039KB) ( 925 )    The mechanism of hydrocarbon migration and entrapment occurring in complex carbonate porefissurefracture reservoirs is a key problem for effective hydrocarbon exploration and development of the lower part of an overlapped basin. The production, gas/oil ratio and the composition of crude oils and natural gas in the TZ83 Well block are high at the intersection point of the NE and NWstrike fault and decrease gradually along the ridge of the structure. A basic model of the porefissurefracture system is built based on the achievements in the research on carbonate karstification. The processes of the hydrocarbon migration and entrapment in this system are analyzed, which indicates that an understanding of the complexity of differential hydrocarbon migration is a key to interpreting this phenomenon. Hydrocarbon must charge the nearest compartment until it can migrate further away to charge other compartments on its pathway in the complex porefissurefracture system. As a result, gas is enriched near the hydrocarbon injection point and drives away the oil which is enriched in compartments farther from the injection point; and the complex gasoilwater relationship is controlled by the lateral connected networks. Thus, we indicate that the fault intersection point is the injection point of the oil and gas and that the main pathway system is distributed along the ridge of the structure. The theory of differential hydrocarbon migration in the porefissurefracture system suggests that (1) in hydrocarbon exploration, the structure of the fissurefractures system should be described first, then the special distribution of gasoilwater is predicted according to the main charging point and the main pathway system; and that (2) the exploration should be confined to the hydrocarbon charging point and the main pathway systems. An exploration area should not be abandoned merely due to the failure in some wells. Related Articles | Metrics

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A thermodynamic model based on ab initio intermolecular potential to predict the equilibrium condition of methane hydrate under the influence of temperature, pressure, salinity and capillary force. CHEN Ya-Li, DUAN Zhen-??, SUN Rui, MAO Shi-De, ZHANG Chi 2009, 16(6): 359-371.  Abstract ( 2041 )   PDF (2496KB) ( 653 )    A thermodynamic model is presented for predicting the multiphase equilibria of methane hydrate, liquid and vapor phases under conditions of different temperature, pressure, salinity and pore sizes. The model is based  on Van der WaalsPlatteeuw model, angledependent ab initio intermolecular potentials, DMW92 equation of state and Pitzer theory. Comparison with the experimental data shows that this model can  predict the equilibrium pT condition of CH4 hydrate in seawater and porous media with high accuracy. Online calculations of the pT condition for the formation of methane hydrate at a given salinity and pore sizes of sediments is available on: www.geochemmodel.org/models.htm. Related Articles | Metrics

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Compositional characteristics and geochemical significance of nalkanes in process of crude oil cracking. TANG Xiao-Jiang, HUANG Guang-Hui, ZHANG Min, HAN Jin-Beng, LI Bi 2009, 16(6): 372-378.  Abstract ( 2003 )   PDF (1337KB) ( 795 )    The simulation experiments with crude oil samples have been performed in laboratory by using high temperature simulative techniques, and the characteristics of change of compositions have also been analyzed by geochemical methods in the cracking process. The results indicate that before a large number of gaseous hydrocarbon being generated by cracking of crude oil, the nalkanes of high molecular weight from crude oil has already begun to be pyrolyzed, and C+15  hydrocarbon mainly cracked into C6C14. With increasing maturity, C6C14 is further transformed into C1C5, accompanied by the output of benzene, ultimately forming methane and cracking bitumen. In the pyrolysis of nalkanes process, abundance of benzene and its homologue show significantly increasing, which can be used as potential distinguishing marks of crude oil cracking. Besides, comparative simulation experiments on nhexadecane have been performed in laboratory by the same experimental condition, and it shows that the characteristics of change of compositions are basically the same as that of nalkanes in crude oil. Related Articles | Metrics

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A study of the incremental trend of the reserves in Daqing Oilfield and its controlling factors. LI Jia-Guang, GUO Shao-Bin, CHEN Chao-Yu 2009, 16(6): 379-383.  Abstract ( 1920 )   PDF (989KB) ( 1033 )    Daqing Oilfield, as the biggest petroleum production base in China, its total production of crude oil accounts for over 40％ of the total production of the mainland in the same period, and its development situation directly influences the supply of the national crude oil. In recent years, because the production of Daqing Oilfield gradually decreases and the domestic energy supply falls short, the increasing speed of oil and gas resources quantity draws the attention of the public. According to the situation and based on the collection of great quantities of original data in Daqing Oilfield and in combination with the characteristics of Daqing Oilfield, this article adopts the prediction method for the growth of reserves to make an estimate of the new recoverable reserves in Daqing Oilfield. The result shows that the new added resource quantity in Daqing Oilfield presents a downward trend, and the time of finally recoverable reserves will be 2028. The article also analyzes the main controlling factors in the changing of new added oil and gas resources from international and domestic respects, and draws a conclusion that the fluctuation of international crude oil price and the domestic policy guidelines and technology progress are the main causes that influence the new added oil and gas resources in Daqing Oilfield. Related Articles | Metrics