• Volume 84,Issue 1,2010 Table of Contents
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    • Gas Hydrates in the Qilian Mountain Permafrost, Qinghai, Northwest China

      2010, 84(1):1-10.

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      Abstract:Abstract: Qilian Mountain permafrost, with area about 10×104 km2, locates in the north of Qinghai-Tibet plateau. It equips with perfect conditions and has great prospecting potential for gas hydrate. The Scientific Drilling Project of Gas Hydrate in Qilian Mountain permafrost, which locates in Juhugeng of Muri Coalfield, Tianjun County, Qinghai Province, has been implemented by China Geological Survey in 2008–2009. Four scientific drilling wells have been completed with a total footage of 2059.13 m. Samples of gas hydrate are collected separately from holes DK-1, DK-2 and DK-3. Gas hydrate is hosted under permafrost zone in the 133–396 m interval. The sample is white crystal and easily burning. Anomaly low temperature has been identified by the infrared camera. The gas hydrate-bearing cores strongly bubble in the water. Gas-bubble and water-drop are emitted from the hydrate-bearing cores and then characteristic of honeycombed structure is left. The typical spectrum curve of gas hydrate is detected using Raman spectrometry. Furthermore, the logging profile also indicates high electrical resistivity and sonic velocity. Gas hydrate in Qilian Mountain is characterized by a thinner permafrost zone, shallower buried depth, more complex gas component and coal-bed methane origin etc.

    • A New Juvenile Specimen of Lufengosaurus Huenei Young, 1941 (Dinosauria: Prosauropoda) from the Lower Jurassic Lower Lufeng Formation of Yunnan, Southwest China

      2010, 84(1):11-21.

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      Abstract:Abstract: A skull and a series of associated cervical vertebrae (ZLJ0112) discovered from the Lower Lufeng Formation (Lower Jurassic) are determined as a juvenile specimen of Lufengosaurus huenei Young 1941 based on amended autapomorphies. Differences between ZLJ0112 and the holotype (sub-adult specimen) are considered as ontogenetic characteristic changes of L. huenei. Since some of these differences are present in other prosauropod dinosaurs (i.e., forms of the maxillary vascular foramen are irregular; the frontal contribution to the dorsal margin of the orbit is substantial; the frontal contribution to the supratemporal fossa is absent; the supratemporal fenestra is visible in lateral view; the supraoccipital inclined at 75 degrees; the parasphenoid rostrum lies level with the occipital condyle; the retroarticular process is short; the axial postzygapophysis project caudally beyond the end of the centrum) they may be common ontogenetic changes in prosauropod dinosaurs.

    • New Jurassic Pseudopolycentropodids from China (Insecta: Mecoptera)

      2010, 84(1):22-30.

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      Abstract:Abstract: In this paper two new species of fossil Pseudopolycentropus Handlirsch, 1906 are described: Pseudopolycentropus janeannae sp. nov. and P. novokshonovi, sp. nov. All of them were recovered from the Middle Jurassic non-marine sedimentary strata of northeastern China. The new material from China reveals that the early diversification of pseudopolycentropodids was well underway by the Middle Jurassic.

    • Paleogeographical Distribution of Mesozoic Palaeontinidae (Insecta, Hemiptera) in China with Description of New Taxa

      2010, 84(1):31-37.

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      Abstract:Abstract: Until now, all Chinese palaeontinids have come from northern China and are more diverse than any other hemipterous insects in the Mesozoic. Most palaeontinids have been discovered from the area encompassing northern Hebei, the Ningcheng area of Inner Mongolia and western Liaoning. The difference in ubiquity of fossil records between northern and southern China is probably related to taphonomical and collecting bias. Records of Early and Late Jurassic palaeontinids are very scarce. The highest diversity of palaeontinid species occurs in the Middle Jurassic of Daohugou Lagerst?tte. Early Cretaceous palaeontinids of China are restricted to the typical distribution of Jehol Biota. Palaeontinodes sp. is described from the Lower Cretaceous Yixian Formation of Yangshuwanzi, Inner Mongolia and is the only Palaeontinodes specimen from the Cretaceous. Plachutella exculpta Zhang, 1997 from the Lower Jurassic Badaowan Formation of Karamai, Xinjiang is re-described and some previously reported species of this genus are discussed.

    • Late Mesozoic Chresmodids with Forewing from Inner Mongolia, China (Polyneoptera: Archaeorthoptera)

      2010, 84(1):38-46.

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      Abstract:Abstract: Three new species of Chresmodidae are described. They belong to two different genera: Chresmoda multinervis sp. nov., Chresmoda shihi sp. nov. and Jurachresmoda sanyica sp. nov.. A study of the forewing venation is provided. Longitudinal veins are mostly parallel; costal area is broad at the basal and narrowing distally; ScP is probably extending close to the wing apex; R is parallel at length to ScP; MA is running close to R, with two long parallel branches; MA branched-off basally; while MP is not branched until the middle of the wing. However, the important basal part of MP and CuP is poorly preserved. In addition, unique fringing hairs on the mid legs of C. shihi sp. nov. and J. sanyica sp. nov. are described and compared with Jurachresmoda gaskelli Zhang, Ren and Shih, 2008.

    • Xingxueanthus: An Enigmatic Jurassic Seed Plant and Its Implications for the Origin of Angiospermy

      2010, 84(1):47-55.

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      Abstract:Abstract: The origin of angiosperms has been tantalizing botanists for centuries. Despite the efforts of palaeobotanists, most of the pre-Cretaceous angiosperms are regarded either non-convincing or misdated. The applications of SEM and LM (light microscope) enable us to recognize a coalified fossil plant, Xingxueanthus sinensis gen. et sp. nov., from the Haifanggou Formation (Middle Jurassic, >160 Ma) in western Liaoning, China. Xingxueanthus is an “inflorescence” with more than 20 female units spirally arranged. Each female unit is situated in the axil of a bract. The female unit is composed of an ovule-container and a style-like projection at the top. There is a vertical column bearing several ovules in the ovule-container. The general morphology and the internal structure of Xingxueanthus distinguish itself from any known fossil and extant gymnosperms, and its structures are more comparable to those of angiosperms. Xingxueanthus, if taken as a gymnosperm, would represent a new class, demonstrate an evolutionarily advanced status of ovule-protection in gymnosperms never seen before, and provide new insights into the origin of angiospermy. Alternatively, if taken as an angiosperm, together with Schmeissneria, it would increase the diversity of Jurassic angiosperms, which has been underestimated for a long time, and suggest a much earlier origin of angiospermy than currently accepted.

    • New Bradoriid Arthropods from the Early Cambrian Balang Formation of Eastern Guizhou, South China

      2010, 84(1):56-68.

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      Abstract:Abstract: The Early Cambrian Balang Formation is comprised of mudrock and shale, which was deposited in a shelf environment in the eastern part of Guizhou, south China. The Balang Fauna, which consists of seven phyla, occurs in the middle and upper parts of the Balang Formation. Arthropods are important constituents of the Balang Fauna and include a great number of trilobites, large bivalved arthropods, and newly-discovered well-preserved bradoriid fossils. The bradoriids present include three genera and four species : Comptaluta inflata (Cheng, 1974) emend Hou et al., 2002; Comptaluta kailiensis sp. nov., and Alutella elongeta sp. nov., Aluta sp. This faunal assemblage in the Balang Formation is distinguished from the Tsunyiella Chang, 1964, Songlinella Yin, 1978 and Kunmingella Hou, 1956 assemblage which occurs in the Niutitang and Mingxinsi formations of the Yangtze Platform in middle region of Guizhou and which is earlier than the Balang Formation in age. However, this assemblage resembles the Comptaluta ?pik, 1968 assemblage from the Early Cambrian Heilinpu Formation in Wuding County, Yuanan Province and from the Ordian Stage of the Cambrian of Australia. The great abundance of Comptaluta ?pik, 1968 and overall taxonomic diversity of the Comptaluta ?pik, 1968 assemblage set it distinctly apart from the Alutella Kobayashi et Kato, 1951 and Aluta Hou, 1956 assemblages of the Balang Formation. Alutella Kobayashi et Kato, 1951 and Aluta Hou, 1956 also occur in the Early Cambrian Niutitang Formation of the Yangtze Platform of Guizhou. Individual Bradoriids from the Balang Formation are characterized by large size (>3 mm). The discovery of new Bradoriid assemblages not only expands the group’s geographical range and assemblage affinities, but also indicates that Bradoriids migrated eastward from shallow-water to deeper-water environments during the Early Cambrian, indicating that they were capable of life in deeper-water, and adaptation to a new ecological setting.

    • Holocene Floral and Faunal Remains Revealed Concealed Neotectonic Disturbance (Saria Tal, Kumaun Himalaya, India)

      2010, 84(1):69-76.

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      Abstract:Abstract: Palynological and paleontological investigations supported by the radiocarbon dates of the lacustrine sediments of two profiles from the temperate lake Saria Tal, in Naini Tal District, Kumaun Himalaya, have revealed the presence of a concealed fold at the region. The profile from bore cores represents the upper part of the Late Holocene and the profile from exposed sections from the Middle Holocene to the over middle part of the Late Holocene. The data generated from different investigations have uniformly indicated that the former profile represents normal superposition, while the latter represents the reverse order. The contemporary pollen as well as molluscan zones of both profiles are situated at different elevations but consist of similar bioremains – indicating continuation of the same strata in two profiles. The presence of reverse order of superposition, continuation of the same strata in two profiles at different elevations, and the orientation of biozones, have indicated that the revealed folding is of syncline type. The present study has also given an idea about the origin of this lake.

    • Mesozoic-Cenozoic Tectonics of the Yellow Sea and Oil-Gas Exploration

      2010, 84(1):77-90.

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      Abstract:Abstract: The purpose of the present study was to study the tectonics of the Yellow Sea. Although oil-gas exploration has been undertaken for more than 30 years in the southern Yellow Sea, the exploration progress has achieved little. There are three tectonic periods with near N–S trending shortening and compression (260–200?Ma, 135–52?Ma and 23–0.78?Ma) and three tectonic periods with near E–W trending shortening and compression (200–135?Ma, 52–23?Ma and 0.78?Ma) at the Yellow Sea and adjacent areas during the Mesozoic and Cenozoic. The Indosinian tectonic period is the collision period between the Sino-Korean and Yangtze Plates, which formed the basic tectonic framework for the Yellow Sea area. There were strong intraplate deformations during the Yanshanian (200–135?Ma) and Sichuanian (135–52?Ma) periods with different tectonic models, which are also the main formation periods for endogenic metallic mineral deposits around the Yellow Sea. The three tectonic periods during the Cenozoic affect important influences for forming oil-gas reservoirs. The Eocene–Oligocene (52–23?Ma) is the main forming period for oil-gas sources. The Miocene–Early Pleistocene (23–0.78 Ma) was a period of favorable passage for oil-gas migration along NNE trending faults. Since the Middle Pleistocene (0.78?Ma) the NNE trending faults are closed and make good conditions for the reservation of oil-gas. The authors suggest that we pay more attention to the oil-gas exploration at the intersections between the NNE trending existing faults and Paleogene–Neogene systems in the southern Yellow Sea area.

    • Archean Basement and a Paleoproterozoic Collision Orogen in the Huoqiu Area at the Southeastern Margin of North China Craton: Evidence from Sensitive High Resolution Ion Micro-Probe U-Pb Zircon Geochronology

      2010, 84(1):91-104.

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      Abstract:Abstract: This paper reports sensitive high resolution ion micro-probe U-Pb zircon ages for the “Huoqiu Group” and granitoids of the Early Precambrian basement in the Huoqiu area, southeastern margin of the North China Craton. The “Huoqiu Group” is similar in rock association and metamorphism to the khondalite series, apart from it containing considerable amounts of banded iron formation. All detrital zircons from the “Huoqiu Group” meta-sedimentary rocks are 3.0 Ga and 2.75 Ga, without any 2.5 Ga and younger ones, as is commonly found in Paleoproterozoic khondalite series in other areas of the North China Craton. In the Huoqiu area, 2.75 Ga and 2.56 Ga granitoids have also been identified. This basement assemblage underwent strong metamorphism during the late Paleoproterozoic (~1.84 Ga) tectonothermal event that is widely developed in the North China Craton. Thus the formation time of the “Huoqiu Group” can be constrained between 2.75 and 1.84 Ga in terms of detrital and metamorphic zircon ages. It is considered, combined with regional data, that there may be a Paleoproterozoic collision orogen extending in a NWW–SEE direction to the southern margin of the North China Craton.

    • Temporal-Spatial Structure of Intraplate Uplift in the Qinghai-Tibet Plateau

      2010, 84(1):105-134.

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      Abstract:Abstract: The intraplate uplift of the Qinghai-Tibet Plateau took place on the basis of breakup and assembly of the Precambrian supercontinent, and southward ocean-continent transition of the Proto-, Paleo-, Meso- and Neo-Tethys during the Caledonian, Indosinian, Yanshanian and Early Himalayan movements. The intraplate tectonic evolution of the Qinghai-Tibet Plateau underwent the early stage of intraplate orogeny characterized by migrational tectonic uplift, horizontal movement and geological processes during 180-7 Ma, and the late stage of isostatic mountain building characterized by pulsative rapid uplift, vertical movement and geographical processes since 3.6 Ma. The spatial-temporal evolution of the intraplate orogeny within the Qinghai-Tibet Plateau shows a regular transition from the northern part through the central part to the southern part during 180-120 Ma, 65-35 Ma, and 25-7 Ma respectively, with extensive intraplate faulting, folding, block movement, magmatism and metallogenesis. Simultaneous intraplate orogeny and basin formation resulted from crustal rheological stratification and basin-orogen coupling that was induced by lateral viscous flow in the lower crust. This continental dynamic process was controlled by lateral flow of hot and soft materials within the lower crust because of slab dehydration and melted mantle upwelling above the subducted plates during the southward Tethyan ocean-continent transition processes or asthenosphere diapirism. Intraplate orogeny and basin formation were irrelevant to plate collision. The Qinghai-Tibet Plateau as a whole was actually formed by the isostatic mountain building processes since 3.6 Ma that were characterized by crust-scale vertical movement, and integral rapid uplift of the plateau, accompanied by isostatic subsidence of peripheral basins and depressions, and great changes in topography and environment. A series of pulsative mountain building events, associated with gravity equilibrium and isostatic adjustment of crustal materials, at 3.6 Ma, 2.5 Ma, 1.8-1.2 Ma, 0.9-0.8 Ma and 0.15-0.12 Ma led to the formation of a composite orogenic belt by unifying the originally relatively independent Himalayas, Gangdisê, Tanghla, Longmenshan, Kunlun, Altyn Tagh, and Qilian mountains, and the formation of the complete Qinghai-Tibet Plateau with a unified mountain root after Miocene uplift of the plateau as a whole.

    • Normal Faulting Type Earthquake Activities in the Tibetan Plateau and Its Tectonic Implication

      2010, 84(1):135-144.

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      Abstract:Abstract: This paper analyzes various earthquake fault types, mechanism solutions, stress field as well as other geophysical data to study the crust movement in the Tibetan plateau and its tectonic implications. The results show that a lot of normal faulting type earthquakes concentrate in the central Tibetan plateau. Many of them are nearly perfect normal fault events. The strikes of the fault planes of the normal faulting earthquakes are almost in the N-S direction based on the analyses of the equal area projection diagrams of fault plane solutions. It implies that the dislocation slip vectors of the normal faulting type events have quite great components in the E-W direction. The extension is probably an eastward extensional motion, mainly a tectonic active regime in the altitudes of the plateau. The tensional stress in the E-W or WNW-ESE direction predominates the earthquake occurrence in the normal event region of the central plateau. A number of thrust fault and strike-slip fault type earthquakes with strong compressive stress nearly in the NNE-SSW direction occurred on the edges of the plateau. The eastward extensional motion in the Tibetan plateau is attributable to the eastward movement of materials in the upper mantle based on seismo-tomographic results. The eastward extensional motion in the Tibetan plateau may be related to the eastward extrusion of hotter mantle materials beneath the east boundary of the plateau. The northward motion of the Tibetan plateau shortened in the N-S direction probably encounters strong obstructions at the western and northern margins. Extensional motions from the relaxation of the topography and/or gravitational collapse in the altitudes of the plateau occur hardly in the N-S direction. The obstruction for the plateau to move eastward is rather weak.

    • Geochemical Signatures of Early Paleogene Source Rocks in the Sanshui Basin, South China

      2010, 84(1):145-154.

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      Abstract:Abstract: The Honggang member of the early Paleogene Buxin Formation is the main source rock in the Sanshui Basin, characterized by organic-rich black shales with the cyclic recurrence of organic-poor sediments. The geochemical characteristics of the Honggang member have been documented to determine the organic matter types and depositional environments in this paper. The organic matter of the black shales mainly consists of a mixture of land plant-derived and phytoplankton-derived organic matter. Total organic carbon content (TOC)–sulfur–iron (Fe) ?relationships suggest that the organic-rich black shales were deposited under dysoxic-to-euxinic water conditions. The time that iron minerals remained in contact with H2S? in anoxic waters possibly influenced the formation of syngenetic pyrite, and organic carbon controlled the formation of diagenetic pyrite. Organic-poor intervals usually show pyrite sulfur enrichment and higher degree of pyritization values relative to low organic carbon contents. This resulted from HS– diffusing downward from overlying organic-rich sediments and formed Fe sulfides through reactions with sufficient Fe. Trace elements generally exhibit low concentrations and little TOC dependence, suggesting some degree of depletion in these elements in the early Paleogene sediments of the Sanshui Basin. This probably resulted from cyclic recurrences of oxic benthic conditions, which promoted the remobilization of trace elements and caused the low concentration of trace elements.

    • Mineral Geochemical Compositions of Tourmalines and Their Significance in the Gejiu Tin Polymetallic Deposits, Yunnan, China

      2010, 84(1):155-166.

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      Abstract:Abstract: The Gejiu tin polymetallic deposits are located in the southeastern part of Yunnan Province in China. A detailed electronic microprobe study has been carried out to document geochemical compositions of tourmalines from the deposits. The results indicate a systematic change of mineral geochemical compositions, which might be used as a mineral geochemical tracer for post-magmatic hydrothermal fluid, basin fluid and their mixture. The tourmalines from granite are schorl with Fe/(Fe+Mg) ratios of 0.912-1.00 and Na/(Na+Ca) ratios of 0.892-0.981. Tourmalines as an inclusion in quartz from the ore bodies are dravite with Fe/(Fe+Mg) ratios of 0.212-0.519 and Na/ (Na+Ca) ratios of 0.786-0.997. Tourmalines from the country rocks are dravite with Fe/(Fe+Mg) ratios of 0.313-0.337 and Na/(Na+Ca) ratio of 0.599-0.723. Tourmalines from cassiterite-tourmaline veins that occur in crannies within the country rocks show distinct optical zoning with alternate occurrence of dravite and schorl, Fe/(Fe+Mg)=0.374-0.843, Na/(Na+Ca)=0.538-0.987. It suggests that schorl in granite and dravite in carbonatite are related to magmatic fluid and basin fluid respectively. When magmatic fluid rose up and entered into crannies of the country rocks, consisting mainly of carbonatite, basin fluid would be constantly added to the magmatic fluid. The two types of fluid were mixed in structural crannies of the sedimentary basin accompanied with periodic geochemical oscillations to form material records in chemical composition zonings of tourmalines.

    • Macrocrystal Garnet and Its Inclusions in Kimberlite Pipes from the Mengyin Area, Shandong Province, China

      2010, 84(1):167-177.

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      Abstract:Abstract: Based on previous studies of kimberlite xenoliths and diamond inclusions in this region, macrocrystal garnet was analyzed with the electric microprobe technique (EPMA). The garnet is collected from the Shengli No.1 kimberlite pipe in the Mengyin area of Shandong Province, China. The results indicate that the garnet contains two kinds of multiphase inclusions: one is K-, B-, and Cl-bearing oxygen-free phase, K- and Cl-bearing oxygen-free phase, and volatile-bearing garnet inclusions (in1 and in3); and the other is chlorite, phlogopite, apatite and calcite (in2). It is suggested that the formation of garnet and its inclusions is associated with strongly reduced mantle fluid. Such a fluid was transformed from ultra-deep high-reduction oxygen-free fluid into low-reduction alkaline fluid, and finally into oxidized fluid with low oxygen fugacity. This result confirms that the Mengyin area underwent metamorphism of slightly active deep fluid, and provides evidence for searching diamond by means of indicative minerals.

    • Crustal Composition of China Continent Constrained from Heat Flow Data and Helium Isotope Ratio of Underground Fluid

      2010, 84(1):178-184.

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      Abstract:Abstract: Based on conservation of energy principle and heat flow data in China continent, the upper limit of 1.3 μW/m3 heat production is obtained for continental crust in China. Furthermore, using the data of heat flow and helium isotope ratio of underground fluid, the heat productions of different tectonic units in China continent are estimated in range of 0.58–1.12 μW/m3 with a median of 0.85 μW/m3. Accordingly, the contents of U, Th and K2O in China crust are in ranges of 0.83–1.76 μg/g, 3.16–6.69 μg/g, and 1.0%–2.12%, respectively. These results indicate that the abundance of radioactive elements in the crust of China continent is much higher than that of Archean crust; and this fact implies China’s continental crust is much evolved in chemical composition. Meanwhile, significant lateral variation of crustal composition is also exhibited among different tectonic units in China continent. The crust of eastern China is much enriched in incompatible elements such as U, Th and K than that of western China; and the crust of orogenic belts is more enriched than that of platform regions. It can also be inferred that the crusts of eastern China and orogenic belts are much felsic than those of western China and platform regions, respectively, derived from the positive correlation between the heat production and SiO2 content of bulk crust. This deduction is consistent with the results derived from the crustal seismic velocity data in China. According to the facts of the lower seismic velocity of China than the average value of global crust, and the higher heat production of China continent compared with global crust composition models published by previous studies, it is deduced that the average composition models of global continent crust by Rudnick and Fountain (1995), Rudnick and Gao (2003), Weaver and Tarney (1984), Shaw et al. (1986), and Wedepohl (1995) overestimate the abundance of incompatible elements such as U, Th and K of continental crust.

    • A Quantitative Study of Fault Zone Sealing

      2010, 84(1):185-193.

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      Abstract:Abstract: A fault is not simply a plane, but a zone consisting of a series of broken planes or lower faults. The greater the scale of faults, the wider and more complex the fault zone is. Fault-sealing properties are influenced by the fault zone itself, whose fault displacement, depth, net-to-gross-ratio of mudstone, fault plane angle, and fault mechanical properties play important controlling roles. The sealing of hydrocarbon by the fault zone depends on whether the fault zone can form a continuous sealing zone and if the pore throats connecting those fault zones are small enough. The concept of fault zone-sealing potential is proposed here, and a quantitative formula is established by using a great amount of practical statistical data as well as the fuzzy comprehensive evaluation method, which is a comprehensive characterization parameter to judge whether or not fault zones could seal oil hydrocarbon. The greater the value of the fault zone-sealing potential, the better sealed the fault is. For example, with increasing depth, the sealing degree of the Xin 68 Fault in the Dongxin 1 oilfield changes greatly, reflecting the complexity of fault-sealing properties.

    • Geologic Characteristics of Volcanic Hydrocarbon Reservoirs and Exploration Directions in China

      2010, 84(1):194-205.

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      Abstract:Abstract: Volcanic rocks are distributed widely in China, which are important exploration targets. By analyzing many discovered volcanic hydrocarbon reservoirs all over the world, the authors summarized the geologic characteristics of the formation of volcanic hydrocarbon reservoirs in China, and gave further exploration directions and advices. (1) There are mainly Carboniferous-Permian, Jurassic-Cretaceous, Paleogene-Neogene volcanic rocks in oil- and gas-bearing basins in China, which are mainly distributed in the Junggar Basin, Songliao Basin, Bohai Bay Basin, etc. There are mainly intermediate rocks and acidic rocks in east China, and intermediate rocks and basic rocks in west China. They primarily develop in intracontinental rift settings and island arc environments. (2) Pore-fissure reservoirs are distributed widely in basins, which are volcanic rocks mainly in explosive and effusive facies. (3) Volcanic hydrocarbon reservoirs are chiefly near-source lithostratigraphic hydrocarbon reservoirs, and the oil and gas accumulation is predominantly controlled by lithotypes, faults and structural positions. (4) Deep-seated oil and gas reservoirs in the Songliao Basin and Carboniferous volcanic hydrocarbon reservoirs in the Junggar Basin are potential giant volcanic gas provinces, the volcanic hydrocarbon reservoirs in the Bohai Bay Basin and Santanghu Basin are favorable for oil and gas reserves increase, and volcanic rocks in the Turpan Basin, Sichuan Basin, Tarim Basin have exploration potentiality. (5) The technology series of oil and gas exploration in volcanic rocks have been preliminarily formed.

    • Characteristics of Underground Water Flow at Different Water Levels in Tianshengan Karst Area, Yunnan, China

      2010, 84(1):206-212.

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      Abstract:Abstract: Three tracing tests from the same injection point executed at low, medium, and high water levels in the karst aquifer near Tianshengan village, Lunan Stone Forest, Yunnan Province, China, have revealed the basic properties of underground water flow. They showed the general directions of water flows; tracer concentrations were observed at six successive points allowing for the calculation of apparent dominant flow velocities at these sections towards the Dalongtan karst spring. For the high water level, the discharge between single sections was between two and 10 times greater than that at low water level. For the medium water level, the flow velocity at different sections was between 1.4 and 3.7 times faster than that at low water level; and for high water level, it was between 1.3 and 2.7 times faster than that at medium water level. The fastest water flow appeared at the first section (23 cm/s at medium water level); and the slowest (0.6 cm/s at low water level) appeared where water flow must cross the Tianshengan fault (north–south direction), and later, a layer of 20–30 m thickness of quartz sandstone and shale clay-stones. It was also possible to calculate the recovery of the tracer for point 4, Dakenyan, where discharge was measured. At the medium water level, 50% of the injected tracer was detected a half-day after its first appearance and at low water level after more than 3 days. The previously published research illustrates the transport velocities of possible contaminants and their solubilities in water at different hydrological conditions.

    • Hydrogeochemistry and Water Quality Evaluation along the Flow Path in the Unconfined Aquifer of the Düzce Plain, North-western Turkey

      2010, 84(1):213-222.

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      Abstract:Abstract: The Düzce Plain has a multi-aquifer system, which consists of a near surface unconfined aquifer, along with first and second deeper confined aquifers. Hydrochemical evolution and water quality are related to infiltration of the precipitation, recharge from the formations surrounding the plain, flow path of groundwater and the relationship between surface and groundwater. The groundwater in the unconfined aquifer flows towards the Efteni Lake and the Büyük Melen River. Surface waters are divided into two main hydrochemical facies in the study area: (a) Ca2+–HCO3?; and (b) Ca2+, Mg2+–HCO3?, SO42?. The groundwater has generally three main hydrochemical facies: (a) Ca2+–HCO3?; (b) Ca2+, Mg2+–HCO3?; and (c) Ca2+, Mg2+–HCO3?, Cl?. The hydrochemical facies “a” and “b” dominate within shallow depths in recharge areas under rapid flow conditions, while hydrochemical facies “c” characterizes shallow and mixed groundwater, which dominate intermediate or discharge areas (near Efteni Lake and Büyük Melen River) during low flow conditions and agricultural contamination. Calcium and bicarbonate ions, total hardness and electrical conductivity of total dissolved solids (EC–TDS) values increase along the groundwater flow path; but these parameters remain within the limits specified by the standards set for industrial and agricultural usages.

    • Exploratory Precipitation in North-Central China during the Past Four Centuries

      2010, 84(1):223-229.

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      Abstract:Abstract: Two robust precipitation reconstructions were conducted by combining tree-ring chronologies, dryness/wetness indices from historical documents, and climate data from the global grid. It was found that the recurrent drought history of a region can help us understand the variability of precipitation. Several dry/wet periods during the past four centuries and potential cycles of precipitation variation were determined. Furthermore, the reconstructions are not only consistent well with each other in North-central China, but also in good agreement with variations of precipitation in northeastern Mongolia, the Longxi area in Gangsu Province and the Dulan area of Qinghai Province, and the snow accumulation of the Guliya glacier. These synchronous variations indicate that it is valuable to study various climate records, find common information and determine the driving force of climate change.

    • Late Cenozoic Geomorphology, Geochronology and Physiography of Yuntaishan in Southern Taihang Mountain, North China

      2010, 84(1):230-239.

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      Abstract:Abstract: The late Cenozoic geomorphic features and geochronologic data of the Zhingfang River catchment in the Yuntaishan World Geopark are studied. Several quarternary geochronologic methods, including electron spin resonance (ESR), optically stimulated luminescence (OSL), thermo-luminescence (TL) and U-series are presented in this paper. The results suggest that there are two planation surfaces, named as the Taihang surface which is a peneplain of Taihang stage formed during Oligocene or Oligocene to early-middle Miocene period, and Tang-hien surface which is a mature wide valley of Tang-hien stage formed during late Miocene-Pliocene or Pliocene-early Pleistocene period and probably ended prior to 2.2–2.6 Ma based on ESR dating. After the Tang-hien stage, the incision and aggradation of the river formed six stream terraces with heights of 3–5 m, 8–12 m, 22–24 m, 28–38 m, 50–62 m and 80–85 m above the river bottom, respectively. The dating results of the alluvium sediments suggest that these terraces were formed during Holocene, 20–23 ka B.P., 110–120 ka B.P., 200–240 ka B.P., 840–1200 ka B.P. or ~450 ka B.P. and 1600–1800 ka B.P. or ~1100 ka B.P., respectively. These results indicate that episodic incision of the river, which controls the formation of the scenery in the Yuntaishan World Geopark, was mainly influenced by the periodic dry-wet climate change during late Cenozoic mountain uplift.

Chief Editor:HOU Zengqian

Governing Body:China Association for Science and Technology

Organizer:Geological Society of China

start publication :1922

ISSN:ISSN 1000-9515

CN:CN 11-2001/P

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