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1. Chaijiazhuang pluton in the Tianshui area: petrogenesis and magma mixing | |||
QIN Jiangfeng,SUN Danhui,ZHANG Bo | |||
Earth Science 11 May 2015 | |||
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Abstract:The Chaijiazhuang pluton occurs in the western Qinling orogen, Tianshui area, central China. The pluton contain some magmatic mafic microgranular enclaves, which are fine-grained and contain acicular apatite and plagioclase megacrysts,. The mafic microgranular enclaves have lower SiO2 (60.27% - 60.38%) and higher Mg#=54-55 and Nb/Ta(14.8-16.6), this indicates that they may result from partial melting of the sub-continental lithosphere mantle(SCLM). Geochemically, the host monzonitic granite show some adakitic characteristics with high Sr, Ba, low Y and HREE, high Sr/Y(88-98) and Y/Yb(13-15) ratios, but tend to have a higher concentration of K2O(4.01%~4.53%). The high (La/Yb)N ratios, concave-unward shapes of the HREE and a lack of significant Eu anomalies, high Ba and Sr as well as low aboundances of Y and HREE suggest a feldspar-poor, garnet ± amohibole-rich fractionation mineral assemblage. Coupled with previous studies we propose that the Chaijiazhuang monzonitic granite may be result from partial melting of thickened lower crust, the latter was triggered by underplating mafic magma which was caused by subducting slab breakoff during the late orogenic stage in Western Qinling Orogen. | |||
TO cite this article:QIN Jiangfeng,SUN Danhui,ZHANG Bo. Chaijiazhuang pluton in the Tianshui area: petrogenesis and magma mixing[OL].[11 May 2015] http://en.paper.edu.cn/en_releasepaper/content/4642435 |
2. Mechanism and estimation of the pockmarks in the subaqueous Yellow River delta | |||
LIU Hongjun,WANG Hu | |||
Earth Science 17 December 2013 | |||
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Abstract:The genesis mechanism and estimation method of pockmarks in the subaqueous Yellow River delta are investigated experimentally and theoretically, in which the wave-induced seepage is particularly considered. First of all, laboratory simulation tests were carried out to explore the response of silty seabed under cyclic loads, in which the layers and the saturation of seabed were considered. Excess pore pressure and seepage-related phenomenon was observed. The excess pore pressure was found to decrease more rapidly at the surface layer and the scale of seepage channels would be bigger with bigger amplitude of the cyclic loads and lower saturation of the underlying layer. In addition, the relationship between wave-induced seepage and pockmark was discussed, and the estimation of wave-induced seepage was proposed. Then, Mathematical model to simulate wave-induced excess pore pressure in the seabed was given. The model was then verified and corresponding parameters were calibrated by comparing with the laboratory tests results. Furthermore, the model was applied to the on-site Yellow River delta, in which different wave conditions and different stratifications of the seabed were considered. The genesis mechanism of pockmarks was summarized through the calculated results and the existing in-situ investigations. The wave-induced seepage in the seabed is a direct cause of the pockmarks in the subaqueous Yellow River delta; Extreme storm waves are necessary external factors; The surface hard layer and the underlying unsaturated weak layer would be certain internal factors; Scour and transport that caused by wave and current would be factors that contribute to the late reformation of the pockmarks in the subaqueous Yellow River delta. | |||
TO cite this article:LIU Hongjun,WANG Hu. Mechanism and estimation of the pockmarks in the subaqueous Yellow River delta[OL].[17 December 2013] http://en.paper.edu.cn/en_releasepaper/content/4574705 |
3. Estimation of phytoplankton primary production based on in situ hyperspectral and simulated MERIS data in Taihu Lake, China | |||
LI Yunmei,LE Chengfeng,ZHA Yong,SUN Deyong | |||
Earth Science 15 November 2012 | |||
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Abstract:This study attempts to demonstrate the possibility of hyperspectra reflectance and MERIS data in estimating primary production. Reflectance spectra of waters in shallow Taihu Lake of East China were measured at 50 monitoring stations with an ASD FieldSpec spectroradiometer during 8-22 November of 2007. Primary production at the 50 stations was calculated from the vertically generalized production model. The relationship between primary production and reflectance was established via regression analysis. It was found that strong correlation exists between primary production and reflectance at 443nm and 679nm. The reflectance at these two wavelengths Rrs(443) and Rrs(679) can explain 70% and 65% variance in primary production, respectively. The ratio of two bands is more accurately than a single band in estimating primary production, but the accuracy depends considerably on the range of primary production. Primary production was also estimated from MERIS channels in the vicinity of 443nm (band 2), 555nm (band 5) and 679nm (band 8). These simulated channels can be used to estimate primary production satisfactorily. However, individual bands can achieve more accurate estimates than the ratio of multiple bands. | |||
TO cite this article:LI Yunmei,LE Chengfeng,ZHA Yong, et al. Estimation of phytoplankton primary production based on in situ hyperspectral and simulated MERIS data in Taihu Lake, China[OL].[15 November 2012] http://en.paper.edu.cn/en_releasepaper/content/4495879 |
4. Multistage decompression and high-T exhumation of eclogite from the Luotian dome in the North Dabie complex zone | |||
LIU Yican,DENG Liangpeng,GU Xiaofeng | |||
Earth Science 05 December 2011 | |||
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Abstract:Petrologic investigations of eclogites from the Luotian dome in the North Dabie complex zone (NDZ) suggest that the eclogites underwent ultrahigh-pressure (UHP) metamorphism and recorded a complex multistage evolution history. As a result, they exhibit multiple decompression textures and rare preservation of former UHP metamorphic record. The eclogites are characterized by high-T metamorphism and multiple symplectites that formed by granulite- and amphibolite-facies metamorphism during decompression. Main UHP metamorphic evidences are coesite pseudomorphs, indicated by the occurrence of radial cracks around quartz inclusions and of polycrystalline quartz inclusions in garnet, and relic coesite in zircon. The newly established Ti-in-zircon and Zr-in-rutile thermometers provide a possibility to estimate the peak and post-peak temperatures of the eclogites in the region and the results indicate that the eclogites experienced a long-lived and extended high-T metamorphic evolution from HT/UHP eclogite-facies to UHT/HP granulite-facies stages characterized by near-isothermal decompression during the initial stages of exhumation. UHT metamorphic conditions were inferred by applying Cpx-Opx geothermometry to the hypersthene lamellae and the host clinopyroxene. Therefore, the studied eclogites experienced UHP metamorphism and multiple decompressions during high-T exhumation. This may be one of the major reasons why the coesite and related UHP records are rarely preserved in the NDZ. | |||
TO cite this article:LIU Yican,DENG Liangpeng,GU Xiaofeng. Multistage decompression and high-T exhumation of eclogite from the Luotian dome in the North Dabie complex zone[OL].[ 5 December 2011] http://en.paper.edu.cn/en_releasepaper/content/4453717 |
5. Detection of LNAPL contamination with GPR and resistivity surveys | |||
LU Qi,LIU Cai,FENG Xuan,LI Hongli,LIANG Wenjing,ZOU Lilong | |||
Earth Science 25 November 2011 | |||
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Abstract:This paper presents the effectiveness of electromagnetic (EM) exploration techniques for detecting near-surface soil contaminants. Field work has been done at a former industrial site containing light non-aqueous phase liquid (LNAPL) in soils. The experiment shows that a combination of ground penetrating radar (GPR) and electrical resistivity can provide an effective means of mapping subsurface contamination. Soil cores sampled in the three boreholes clearly indicate that the concentration of total petroleum hydrocarbons (TPH) has an inverse relation to the relative dielectric constant and a direct proportional correlation with the electrical resistivity.GPR data have high spatial resolution and enable us to image the shallow subsurface stratigraphy, although its depth of penetration is greatly limited in a conductive region. The electrical resistivity method is effective to obtain the resistivity structure associated with the subsurface stratigraphy and the contamination zone. Three-dimensional GPR and resistivity images are constructed to map LNAPL contamination which is illustrated by the decreased radar signal amplitude and increased resistivity. | |||
TO cite this article:LU Qi,LIU Cai,FENG Xuan, et al. Detection of LNAPL contamination with GPR and resistivity surveys[OL].[25 November 2011] http://en.paper.edu.cn/en_releasepaper/content/4451870 |
6. Reservoir connectivity evaluation based on the reservoir architecture | |||
Yin Taiju,ZHANG Changmin,GONG Fuhua | |||
Earth Science 15 January 2010 | |||
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Abstract:Reservoir connection is a key factor for water flooding recovery. Ways for connection evaluation is though well test or radioactive injection and its output survey. In fact there are great deference in permeability among different genetic sandbodies. In L3 block the permeability of distributaty channel is 4 to 10 times higher than the other genetic sandbody such as levee, crevasse splay sand. Because of its densely well space, we can get detailed genetic sandbodies distribution for every layer. In the framework it is easy to evaluate the connectivity of every layer among inject wells and output wells based on the genetic sandbodies distribution. Generally wells drilled on the same distributay channel or on the different channel sandbody which superposed together is well connected, while the wells suited on the channel and other genetic sand is poor connected. In L3 fault block, the upper layer is better connected than lower layer. The connectivity evaluation is proved by the output and press data. As a summery we believe it is possible to evaluate the connectivity through reservoir architecture analysis. | |||
TO cite this article:Yin Taiju,ZHANG Changmin,GONG Fuhua. Reservoir connectivity evaluation based on the reservoir architecture[OL].[15 January 2010] http://en.paper.edu.cn/en_releasepaper/content/39035 |
7. A Model for the Wumishan Cycle and Their Vertical Stacking Patterns: Cyclic Sedimentation Genetically Related to Milankovitch Cycles in the Precambrian | |||
Mei Mingxiang,Zhou Hongrui,Du Benming,Luo Zhiqing | |||
Earth Science 19 December 2005 | |||
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Abstract: Carbonate strata of the Meso-Proterozoic Wumishan Formation in the Jixian area near Tianjin are ~3300 m thick and were deposited over some 100 million years (from ~1310±20 Ma to ~1207±10 Ma). Metre-scale cycles (parasequences) dominate the succession. They are generally of the peritidal carbonate type, and mostly show an approximately symmetrical lithofacies succession with thin stromatolite biostromes and small thrombolite bioherms constituting the central part and tidal-flat dolomites forming the upper and lower parts. Lagoonal dolomitic shales with palaeosoil caps make up the topmost layers. The boundaries of the Wumishan cycles are typically exposure surfaces, and there is abundant evidence for fresh-water diagenesis. Widespread 1:4 stacking patterns indicate that the individual Wumishan cycles are sixth-order parasequences, with 4 parasequences constituting one fifth-order parasequence set. Locally, 5-8 seventh-order beds or couplets, can be discerned in some of the cycles. The regular vertical stacking pattern of seventh-order beds within the sixth-order parasequences, forming the fifth-order parasequence sets, are interpreted as the result of environmental fluctuations controlled by Milankovitch rhythms, namely the superimposition of precession, and short and long-eccentricity. The widespread 1:4 stacking pattern in the cyclic succession, as well as the local 1:5-8 stacking patterns of the beds within the cycles, suggest that the Milankovitch rhythms had similar ratios in the Meso-Proterozoic as in the Phanerozoic. Based on the cycle stacking patterns, 26 third-order sequences can be distinguished and these group into 6 second-order, transgressive-regressive megasequences, all reflecting a composite, hierarchical succession of sea-level changes. | |||
TO cite this article:Mei Mingxiang,Zhou Hongrui,Du Benming, et al. A Model for the Wumishan Cycle and Their Vertical Stacking Patterns: Cyclic Sedimentation Genetically Related to Milankovitch Cycles in the Precambrian[OL].[19 December 2005] http://en.paper.edu.cn/en_releasepaper/content/4458 |
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