Table of Content

07 June 2013, Volume 27 Issue 3

Previous Issue    Next Issue

Engineering Geology and Environmental Geology

Petrological and Geochemical Features of Basalts at 49.6°E and 50.5°E Hydrothermal Fields along the Southwest Indian Ridge

YU Miao, SU Xin, TAO Chun-hui, WU Guang-hai, LI Huai-ming, LOU Han-lin

2013, 27(3):  497-508. 

Asbtract ( 3587 )   PDF (15624KB) ( 1188 )  

Related Articles | Metrics

We analyzed basalt samples from 4 sites at 49.6°E and 50.5°E along the Southwest Indian Ridge, which were collected with television-video guided grab  (TVG ) or dredge  (D ) during 2 hydrothermal expeditions of Chinese vessel “Da Yang Yi Hao” in 2008 and in 2010. These samples are fragments of basaltic pillow lavas and sheet flows. These samples are mainly porphyritic with fine-grained, and euhedral to anhedral phenocrysts of plagioclase, olivine and pyroxene. The matrix contains microcrystalline plagioclase, olivine and pyroxene, in which tabular plagioclase microphenocrysts occur with a radical texture. Whole rock major and rare earth  elements data of these samples show that ratios of K/Ti range from 0.071 to 0.091, and La/Sm from 0.52 to 0.70, suggesting that they are normal mid-ocean ridge basalt (N-MORB). Plagioclase compositions range from An_76-78 to An₆₆, while those of olivine range from Fo₈₆ to Fo₈₄. In comparison of earlier study on basalt samples along SWIR (49°E -70°E), samples in this study are featured with much more depletion in light rare earth elements, Na₈ and K/Ti, but higher Fe₈. These data indicate that mantle melting in the study area occur in higher degree and at deeper depth. Furthermore, petrologic and mineralogic features of basalts at 49.6°E and 50.5°E suggest that magma activity and source in the study area are complex.

Comparison of A-type Granites from Taimushan and Gushan Regions in Fujian Province and Their Geodynamic Significance

LI Liang-lin, ZHOU Han-wen, CHEN Zhi-hua, WANG Jin-rong, CHEN Zheng-hua

2013, 27(3):  509-524. 

Asbtract ( 1505 )   PDF (4415KB) ( 1707 )  

Related Articles | Metrics

Taimushan and Gushan are located in the southeast coastal areas of Fujian. Petrology and petrography studies have shown that Taimushan and Gushan granites belong to aluminous A-type granitoids and alkaline A-type granitoids respectively. Zircon LA-ICP-MS U-Pb dating results indicate that the granites in two regions, whose diagenetic ages were (96.6±1.6) Ma (MSWD=0.65) and(99.4±2.3) Ma (MSWD=0.49) respectively, formed in the earlier of Late Cretaceous. Based on granites of the two regions, we focused on the difference of two types of A-type granites in the eastern coast of China in terms of the petrology, petrography, geochemistry and discrimination diagrams. On the whole,  the AKI values, TFeO/MgO ratio, 10⁴×Ga/Al and (Zr+Nb+Ce+Y) values of the alkaline A-type granites  are higher than those of aluminous A-type granites of the same region, but also there is a range of overlap in above chemical indicators, and the traditional A-type granite discrimination diagrams are not thoroughly applicable to the strong differentiation aluminous A-type granite. Geochemistry shows that the granites in two regions should have a similar source, namely magma originated from the partial melting of crustal material and the process of diagenesis have some mantle material involved in. However, alkaline A-type granites in Gushan region may have more mantle material involved in, showing some characteristics of mantle-derived magmatic origin. Integrated with geochemistry, field geology, regional background and geochronology reveal that petrogenesis of the granites of two regions is closely related to the angle of the subduction of PaleoPacific Plate to the Eurasian Plate, and their tectonic environment belongs to a back-arc tensional tectonic environment.

Zircon U-Pb Age of the Spilite-Keratophyre Sequence of the Dashizhai Formation in Maodeng of Xilinhaote, Inner Mongolia and Its Geological Significance

CHENG Tian-she，YANG Wen-jing，WANG Deng-hong

2013, 27(3):  525-536. 

Asbtract ( 4443 )   PDF (2991KB) ( 1624 )  

Related Articles | Metrics

The spilite-keratophyre sequence is formed of spilite and quartz keratophyre interbeddedly in Dashizhai Formation in Maodeng district of Xilinhaote, Inner Mongolia. The zircon LA-ICP-MS U-Pb gives a weighted average age of (287.4±1.7) Ma (MSWD=0.63). These new data suggest that the protolith age of Dashizhai Formation was about Early Permian. The spilite is characterized by high SiO₂,Al₂O₃(>16%),Na₂O,TiO₂(>1.3%) and low CaO,MgO contents. The contents quartz keratophyre is characterized by high SiO₂,Na₂O and low Al₂O₃,TiO₂,K₂O,CaO contents. The spilite-keratophyre sequence belongs to typical bimodal rock series showed in the classification diagram of Zr/TiO₂-Nb/Y and calc-alkaline rock series showed in the SiO₂-FeO/MgO diagram. Spilite and quartz keratophyre are richer in LILE than in adjacent HFSE and similar in REE curve, which displays the characteristics of island-arc environment.Rock assemblage, rock series and geochemical characteristics prove that the spilite-keratophyre sequence formed in a continental margin-arc and local rifting environment, evoluting from the cognate magma which is from the wedge mantle by fluid metasomatism.

The  Indosinian Crust Uplift-Denudation in Geza Arc of Yunnan Province and Its Geological Significance： Evidence from Biotite Geobarometer

LIU Xue-long, LI Wen-chang , YIN Guang-hou

2013, 27(3):  537-546. 

Asbtract ( 1135 )   PDF (7106KB) ( 1205 )  

Related Articles | Metrics

Regional uplift and denudation is one of the main factors that have effect on the changes and preservation after deposit formation. Mineral geobarometer can quantitatively obtain the initial crystallization pressure of granitic magma, which is also one of the effective methods to reflect granitic intrusion depth and uplift history. In this paper, we apply biotite ^TAl geobarometer to calculate the emplacement depth of typical ore-forming porphyries in Geza magmatic belts in Indosinian and to estimate the crust uplift-denudation rates. Also, we discuss the changes and preservation after deposit formation. The results indicate that the denudation rate of ore-bearing intrusion is rather slow with an average value of 0.018 mm/a, which is favorable to preserve the deposit after its formation. Our study also provides a quantitative reference for the tectonic uplift and denudation of the western Yunnan plateau since Indosinian.

Zircon U-Pb Geochronology for the Stratotype Section of the Neoproterozoic Chengjiang Formation in Central Yunnan and Its Geological Significance

CUI Xiao-zhuang,JIANG Xin-sheng,WANG Jian,ZHUO Jie-wen,XIONG Guo-qing,

2013, 27(3):  547-556. 

Asbtract ( 1293 )   PDF (25229KB) ( 1221 )  

Related Articles | Metrics

The Chengjiang Formation is one of the most important Neoproterozoic stratigraphic units in South China; therefore, its accurate depositional age is significant for establishing and completing the Neoproterozoic regional stratigraphic framework of South China. The tuff interbed from the topmost part of the stratotype section of the Chengjiang Formation in Central Yunnan was dated by SHRIMP zircon U-Pb dating. Three groups of weighted mean 206Pb/238U ages were obtained, which are (819±14) Ma (MSWD=0.15), (781±11) Ma (MSWD=0.24) and (725±11) Ma (MSWD=0.65), respectively. The youngest age ((725±11) Ma) is interpreted as the formation time for the tuff interbed from the topmost part of the Chengjiang Formation, which can represent the top boundary age of the Chengjiang Formation in Central Yunnan. Thus, it is further confirmed that the Chengjiang Formation was deposited between 800 and 725 Ma. Combined with related research data, it is proved that the Chengjiang Formation is equivalent to the Kaijianqiao Formation and Liantuo Formation, and all the three formations should correlate with the upper part of the preglacial Banxi Group, rather than the glacial Chang'an Formation. In addition, it is also inferred that the both groups of zircons with older age might be records of the episodic magmatism related to Neoproterozoic break-up of the Rodinia supercontinent.

Geochemistry of Sandstones from the Middle Jurassic Zhiluo Formation,Dongsheng District, Northeastern Ordos Basin:
Implications for Provenance and Tectonic Setting

WU Zhao-jian, HAN Xiao-zhong, YI Chao, QI Cai-ji, HUI Xiao-chao, WANG Ming-tai

2013, 27(3):  557-567. 

Asbtract ( 4534 )   PDF (5809KB) ( 1280 )  

Related Articles | Metrics

The provenance analysis of sandstones are essential for the distribution and composition of sandbodies, reservoir properties and the sources of uranium, in the uranium deposits exploration. In this paper, detailed petrological and geochemical studies were carried out on the sandstones of Middle Jurassic Zhiluo Formation from 8 drilling cores in the northeastern Ordos Basin, in order to determine their provenance and tectonic setting. The samples are coarse greywacke with moderate to high SiO₂ content  and Al₂O₃/SiO₂ ratio, a high content of K₂O and a low content of Fe₂O₃, MgO and TiO₂, which implies that these sandstones are in felsic，lacking of mafic materials. The rocks are enriched in large ion lithophile elements (LILEs, such as K, Rb, Sr and Ba), and depleted in high field strength elements (HFSEs, such as Nb, Ta, Ti and P). These features indicate that the source region have affinity of subductionrelated tectonic setting. Similarly, other discrimination diagrams, such as (TFe₂O₃+MgO)-TiO₂,  (TFe₂O₃+MgO)-Al₂O₃/SiO₂, Th-Sc-Zr/10, Th-Co-Zr/10, further suggest that the Zhiluo Formation sandstones were deposited as detritus from a continental island arc or active continental margin. Together with other characteristics, such as enrichment LREE, relatively flat HREE patterns, without or slightly Eu anomalies, flat patterns with positive Eu anomalies in the PAAS-normalized rare element plots, allowed us to conclude that the rocks are strongely related to the Phanerozoic granitoids from the northern margin of North China craton.

Gravel Fabric Characteristics of the Upper Cretaceous Hekou Formation in Fuzhou-Chongren Basin, Jiangxi and the Geological Significance

CHEN Liu-qin, GUO Fu-sheng, LIANG Wei, JIANG Xing-bo

2013, 27(3):  568-576. 

Asbtract ( 1013 )   PDF (3407KB) ( 1308 )  

Related Articles | Metrics

Continental basins of the Late Cretaceous in southeast China are characterized by red coarse terrestrial clastic rocks. Fabric analysis of gravels was carried out at 19 outcrops of the Upper Cretaceous Hekou Formation of Fuzhou-Chongren basin in western Gan-Hang tectonic belt, and the composition, particle size, shape and preferred orientations of gravels were also studied in detail. As a whole, the gravel deposits are featured by complex composition, poor sorting, subangular to subrounded particles and low degree of weathering. Combined with lithologic features of bedrocks, the source, genesis and formation conditions of gravels at different areas are analyzed and discussed. The research result shows that the gravels of the Late Cretaceous Hekou Formation were the products of alluvial fan and braided river facies in a semiarid to arid climate condition with multi-source and rapid accumulation. The composition assemblages of gravels from different areas of the basin are obviously different, reflecting complex provenance condition around the basin. Based on the  characteristics of bedrock strata and the rose diagrams of the maximum flat planes (ab-planes) of gravels, the sediment source was inferred to come mainly from northeastern, northern, northwestern and southeastern parts of the basin during the sedimentation period of Hekou Formation.

Re-Os Dating for Derni Cu(Zn-Co) Ore Deposit in Qinghai Province, China and Its Geological Implication

JIAO Jian-gang, LU Hao, SUN Ya-li, HUANG Xi-feng, DUAN Jun

2013, 27(3):  577-584. 

Asbtract ( 3215 )   PDF (3059KB) ( 1628 )  

Related Articles | Metrics

Derni massive sulfide Cu(Zn-Co) deposit is mainly wrapped by ophiolite in East Kunlun Mountains, and 8 massive sulfide ores give an isochronal age of (295.5±7.2)Ma by Re-Os isotope, which is a little later than zircon U-Pb age (308.2±4.9) Ma of the basalt in the mining area. The diagenesis and metallogenic epoch is between Late Carboniferous and Early Permian. It is older than the Indo-Chinese epoch granite in the north side of the mining area, suggesting no direct genesis relationship between granite and Derni Cu(Zn-Co) ore deposit. According to the texture and structure of the ores, mineral compositions and various geochemistry data, the genesis of Derni Cu(Zn-Co) ore deposit can be summarized as submarine exhalation-sedimentary mineralization and experienced later hydrothermal superimposition, which is similar to Cyprus-type VMS deposit by tectonic setting and mineral compositions. From mapping and borehole logging, the main ore bodies of Derni Cu(Zn-Co) ore deposit lay in brecciaous serpentinite or between brecciaous serpentinite and carbonaceous Fe-Si rock, which is different from any other VMS deposits in the world, and the special phenomenon may be caused by quick spreading of Late Paleozoic Tethyan middle ocean ridge, lack of enough mafic magma replenishment, accompanied by rapid ascending of meta-peridotite.

A Correlation Study of Au-polymetallic Mineralization and Granite-Porphyry Magmatism in the Xinping Mining Area of
the Dayaoshan Metallogenic Belt, Eastern Guangxi Province

WANG Xin-yu, LIU Ming-chao, ZHOU Guo-fa, HUANG Xi-qiang, WANG Rui-hu

2013, 27(3):  585-592. 

Asbtract ( 1196 )   PDF (1849KB) ( 1523 )  

Related Articles | Metrics

The Xinping granite-porphyry occurring in the Xinping gold mining area is located in the middle part of the Dayaoshan Au metallogenic belt, eastern Guangxi Province. During our recent field geological survey, a gold deposit was found in contact zone between the porphyry and its wall rocks, whereas quartz-vein-typed molybdenum orebody and mineralized spot were also firstly recognized inside of the intrusion. These suggest that the Au-Mo-polymetallic mineralization is closely related to the granitic igneous activity. Zircons of the granitic porphyry are analyzed using LA-ICP-MS U-Pb isotopic method, which gives a weighted mean 206Pb/238U age of (462.9 ± 6.4) Ma. It reveals a midOrdovican magmatic timing, providing a lower constraint for the mineralization age. The Xinping porphyry samples show REE characteristics akin to those of the granite-porphyries occurring in nearby Gupao, Yuanzhuding and Dali minging areas, indicative of similar nature of source rocks and petrogenesis. Thus, a further potential is predicted by this study in exploring porphyry-related gold and molybdenum deposits in the Xinping gold field.

Geological and Geochemical Characteristics of Manganese-bearing Rock Series of Yangjiawan Manganese Deposit, Songtao County, Guizhou Province

HE Zhi-wei,YANG Rui-dong,GAO Jun-bo,CHENG Wei,HUANG Jian-guo

2013, 27(3):  593-602. 

Asbtract ( 3157 )   PDF (2503KB) ( 1811 )  

Related Articles | Metrics

“Datangpo type” manganese deposits of Nanhua System studied in this paper are located in Songtao County of Guizhou Province. Based on years of exploration and research, there are three superficial deposits of Xixibao manganese deposit, Yangjiawan manganese deposit, Lijiawan manganese deposit, making up a new pattern of “Manganese Triangle”, in which Yangjiawan manganese deposit is a medium-large one. Geological and geochemical characteristics of manganese-bearing rock series of Yangjiawan manganese deposit indicate that in manganesebearing rock series exists volcanic material such as tuff, and mineral association of pyrite, barite and calcimangite, which shows a hydrothermal origin. Besides, this manganese ore falls on the hydrothermal deposition region according to illustrated diagrams of Fe-Mn-(Ni+Co+Cu)×10 and P₂O₅-Y, and contents of As, Sb, Ga, Ag, Ba, Zn, Co, Bi, W and Pb are higher than those of normal sedimentary rocks, moreover, ratios of Co/Ni, Y/Ho and Nb/Ta all show similar characteristics to hot fluid of ocean-floor black chimney. The overall content of rare earth elements of this manganese deposit is relatively high, and the differentiation of light and heavy rare earth are obvious, and distribution pattern is smooth, slightly lean to the right. In addition, δEu (0.49-0.71), δCe(0.94-1.25) and Ce/La-La/Yb diagrams also show features of hydrothermal participation. Besides,  δ¹³C_PDB and δ¹⁸O_PDB of the manganese deposit range from -3.80‰ to -4.17‰ and from -6.95‰ to 8.78‰, respectively; therefore,  the mineralization temperatures are estimated from 54.2 to 65.7 ℃, belonging to the low and medium temperature hydrothermal condition. In conclusion, the authors consider that Yangjiawan manganese deposit is of hydrothermal genesis.

Study of the Sedimentary Environment of Heqing Manganese Deposit, Yunnan，China

CHANG Hai-liang，WEN Xing-ping，REN Tao，WANG Hong-wei，LIU Can

2013, 27(3):  603-611. 

Asbtract ( 1467 )   PDF (7863KB) ( 1061 )  

Related Articles | Metrics

Heqing manganese deposit in Yunnan is located in the southwestern margin of the Yangtze platform, adjoining the Sanjiang geosyncline in the west. The deposit formed in the transition zone of the two tectonic units. Ore minerals are mainly psilomelane, rhodochrosite, manganite and hausmannite, containing a small amount of pyrolusite and nsutite. There is metal mineral zonation in space：minerals from No.17 exploration line to the west are mainly psilomelane and pyrolusite, from No.10 to No.15 exploration lines are mainly manganite and rhodochrosite, and from No.7 to No.10 exploration lines are mainly hausmannite and rhodochrosite. The δ¹³C values of the limestone samples range from -3.0‰ to 2.9‰ with a mean value of 0.6‰ and the δ¹⁸O varies between -9.9‰ and -5.5‰, averaging at -7.7‰; the δ¹³C values of the ore samples range from -46.3‰ to -9.8‰ with a mean value of -24.2‰ and the δ¹⁸O values vary from -16.5‰ to -3.1‰, averaging at -8.6‰. Comprehensive studies support that Heqing manganese deposit formed in a restricted shallow water environment. Ore minerals deposited in media property zone (from acid to alkaline and from reduction to oxidation), and isotope studies support that the biogenic methane might participate in mineralization.

Characteristics of Carbon and Oxygen Isotope in Heqing Manganese Deposit,Yunnan, China

WANG Hong-wei , WEN Xing-ping, CHANG Hai-liang, LIU Can, LI Lin-qiang

2013, 27(3):  612-620. 

Asbtract ( 1413 )   PDF (4790KB) ( 1006 )  

Related Articles | Metrics

Heqing manganese deposit is located in the southwestern margin of Yangtze platform in Yunnan Province, China. Carbon and oxygen isotopes indicate that Songgui Formation which is the main ore bearing stratum experienced one transgression and another long-term regression. The paleotemperature derived from oxygen isotopes are higher due to the exchange of oxygen isotope between biological (algae) metabolites and seawater, changes in paleoclimate and sea depth. The paleosalinity show normal marine sediments and there are good correlation between the paleosalinity and the value of δ¹³C. δ¹⁸O values from cores are higher mainly owing to the variation of paleosalinity, which are good correlation with δ¹³C value. With the sea level falling, the possibility of buried organic was decreased, which led to negative values of δ¹³C. Through a comprehensive analysis of carbon and oxygen isotopes, it is concluded that the depositional environment was at least a semi-enclosed shallow or near continental basin. With uplifting of Yangze platform continuously and climate changing from humid, hot into arid gradually, the manganese ores were formed accompanied by falls in sea level.

Geochemial Characteristics on Salt Springs and Potash Perspective in Dogai Coring Area of Qiangtang Basin

NIU Xin-sheng，CHEN Wen-xi，LIU Xi-fang

2013, 27(3):  621-628. 

Asbtract ( 1134 )   PDF (1550KB) ( 1348 )  

Related Articles | Metrics

Multi-layers and a large amount of gypsum and lithofacies paleogeographic data from predecessors indicate that Jurassic marine layers of Qiangtang basin have good saline condition. There is a series of Ca-chloride springs in Jurassic layers of Dogai Coring area. For this study 30 salt springs water samples were collected from field. Then, chemical composition, δ¹⁸O and δD of water samples were determined in laboratory. Geochemical analysis demonstates that salt springs have high concentration of Na⁺,Cl^-,Ca²⁺,K⁺, Li, Rb and poor concentration of Br, B. In addition, geochemical coefficients of water samples have obvious anomaly of potash mineral. δ¹⁸O and δD of salt springs reveal that springs water came from atmospheric precitation. When meteoric water entered into stratum and became groundwater, saline minerals of stratum were dissolved and  lixiviation brine have been generated as groundwater. This is consistent with the result of coefficients of geochemistry analysis. In sum, potash perspective of south bank of Dogai Coring Lake is the best one of four sampling locations, whose salt springs have high salinity and concentration of K⁺ and might lixiviate potash-halite and potash stratum. Northwest side of Wananhu, Yuanquanhe and Dongwenquan take a second place of potash perspective. They have relatively lower salinity and anomaly of potash mineral.

Study of Geochemical Ore-forming Anomaly Identification Based on the Theory of Blind Source Separation

CHEN Ling, GUO Ke, LIU Bing-li

2013, 27(3):  629-636. 

Asbtract ( 1572 )   PDF (2474KB) ( 1543 )  

Related Articles | Metrics

The paper first attempts to use blind source separation technique for geochemical field, and uses FastICA algorithm in the theory of blind source separation for the study of ore-forming anomaly identification of 1∶10,000 soil geochemical survey data in Dong Gapu copper exploration area,Tibet. First, we established the anti-combination model of the evolution of geochemical data elements based on blind source separation algorithm in order to determine the geochemistry of combined ore-forming elements. Then, we determined the single-element geochemical anomalies and elemental composition of the lower limit, the delineation of abnormal concentration centers using fractal method, and determine the abnormal zonation. Finally, we combined the elemental characteristics of the study area with geological features, compare  single-element anomaly map and the combination of anomaly, and explain the anomaly classification and anomaly evaluation of geochemical elements of the study area. Division of four anomalous areas in the latter part of the validation project achieved good results.

Global Distribution of Phanerozoic Carbonates and Controlling Factors

JIN Zhen-kui, YU Kuan-hong, PAN Yi, ZHAO Dong-feng, LU Yan-xia

2013, 27(3):  637-643. 

Asbtract ( 1789 )   PDF (10092KB) ( 1680 )  

Related Articles | Metrics

About 60% oil and gas of the world is produced from carbonate rocks. Where and when are carbonate rocks most developed in the world? What are the controlling factors? To figure out these questions is not only important to selection of strategic exploration areas abroad, but also important to understanding of global paleogeography. Based on various data from 179 carbonate basins in the world，global distribution of Phanerozoic carbonates and the controlling factors were studied in this paper. Carbonates occur in every geological period, but the degree of development is different. In the Devonian, Cretaceous and Paleogene, carbonates were widely spread, while in the Silurian, Permian, Triassic and Jurassic, distribution of carbonates  was limited. In different geological periods, carbonates are developed in different areas. From the Cambrian to Ordovician, carbonates mainly occurred in Russia, China, North America and Australia. After the Triassic, carbonates mainly occurred in the Middle East, South Europe, North Africa and South America. In the Cenozoic, carbonates mainly occurred in the Middle East, North Africa and South Asia. Continental drifts and sea level change controlled distribution of carbonates. In the Paleozoic, the Laurasia (current Eurasia and North America), Siberia, South China and Australia were in low latitudes, where the sea was warm and carbonates were developed. But the Gondwana continent (current Africa and South America) were in high latitudes, where the sea was cold and not favorable for carbonate deposition. In the Mesozoic, the Laurasia drifted to high latitudes and thus little carbonates were deposited, while the Gondwana broke up and drifted to low latitudes and abundant carbonates were developed in South America and North Africa. In the Cenozoic, the Middle East and South Asia were in low latitudes and carbonates were developed. Thus carbonates distribution is well correlated with continental drift. Fluctuation of sea level is another important factor controlling the distribution of carbonates. When sea level rises, continental seas are widely formed, providing favorable sites for deposition of carbonates.When sea level falls, continent marginal seas are developed, which are not favorable for deposition of carbonates.

Reef-beach Reservoir Features of Changxing Formation and Its Controlling Factors in Tieshan-Longhui of Northeastern Sichuan

TANG Hong,WU Bin,ZHANG Ting,CAO Gang，LUO Ren

2013, 27(3):  644-652. 

Asbtract ( 935 )   PDF (7889KB) ( 1734 )  

Related Articles | Metrics

Changxing Formation reef-beach reservoir features are studied with core, thin section observation and logging explanation.It turns out that the main reservoir rocks are reef dolomites and reef limestone, and the reservoir space is mainly secondary pore with poor reservoir property.The reservoir types are mostly fracture-pore and pore-fracture with low-porosity and low-permeability.Changxing Formation has obvious electric response.The reef shows low gamma value, box-shaped resistivity and positive difference of deep & shallow double laterologging.The non-reef shows finger-like logging curve, low gamma, positive difference of laterologging, no significant fluctuation of three porosity log curve and its flow is affected by fissures.Relative change of sea level controls the scale of reef and beach, which gives a foundation of good reservoir.And the sedimentary setting determines the distribution of sedimentary facies which has effects on reservoir property.Uplifted side of rift trough and palaeogeomorphology highland dominate the distribution of reef and beach in the platform margin, which is the basis of the development of excellent reservoir facies belts.Moreover, dolomitization and solution promoted the property of reservoir and provided advantages for the formation of secondary pores.

Characteristics and Processes of Deep Water Unidirectionally-migrating Channel-levee System

LI Hua，WANG Ying-min，XU Qiang，HAN Zi-liang，XU Yan-xia

2013, 27(3):  653-661. 

Asbtract ( 1169 )   PDF (4283KB) ( 1447 )  

Related Articles | Metrics

Unidirectionally-migrational channel-levee system well develops in the deep area of Baiyun of the Pearl River Mouth Basin，the South China Sea and in Lower Congo Basin，west Africa，which consists of thalweg deposits，laterally migrating deposits，slump deposits/mass transport complex deposits and levee deposits with terraces. The channel shows obviously migrating characteristic，which results from interaction between gravity flow and contour current. Furthermore，migrating direction of channel corresponds to the direction of contour current. It is likely to be controlled by relatively energy of gravity flow and contour current，sediment supply，fluctuated sealevel，climate，morphology，Coriolis force，width of shelf and so on. There are three geneses of terraces: (1) gravity flow incised the laterally migrating deposits;(2) sediment unbalance or fault lead to slump or slide; and (3) various incision of gravity flow in channel. Work on unidirectionally-migrating channel-levee system not only is helpful to improve knowledge of deep water deposits，but also provides a new prospect for oil and gas exploration.

Combining Several Modeling Methods to Build 3D Architecture Model of Alluvial Fan: A Case Study on Lower Karamay Formation,
Liuzhong Dong Area, Karamay Oilfield

LI Jun, LI Shao-hua, ZHANG Min, XU Chang-fu, WU Xiao-jun

2013, 27(3):  662-668. 

Asbtract ( 1337 )   PDF (6152KB) ( 1520 )  

Related Articles | Metrics

This paper is a case study on the Lower Karamay Formation. By analyzing  eight sealed coring wells with small distance and the architecture characteristics of twenty-four wells around, a 3D architecture model of target formation of the study area is built. Different architecture modeling methods practical to fans with different subfacies were derived. Fan head is extensive connecting body mainly composed of sheet-flow sandstone bodies, and the distribution areas of the architecture of different levels are small, so Object-based modeling method is used. The main architecture units of mid-fan are fine sheet-flow grains, braided channel and sheet-flow sandstone body.The braided channel and sheet-flow sandstone bodies have obvious contact belt. So Truncate Gauss Simulation method is used. The main architecture unit of the fan-margin is fine sheet-flow grains, as well as a small number of through-flow and sheet-flow sandstone bodies, so Sequence Indicator Simulation and Object-based modeling method are applicable. The 3D architecture model built can well embody the distribution areas and the contact relations of the architecture units of different levels in both horizontal and vertical directions, which can provide an evidence for the remaining oil prediction, as well as well-pattern adjustment and remaining oil tapping.

Sedimentary Characteristics and Model of the Alluvial Fan in Kuche Formation of Neogene in Kuqa Depression

LI Xin, ZHONG Da-kang, LI Yong, LEI Gang-lin, YANG Xian-zhang, LI Wei

2013, 27(3):  669-680. 

Asbtract ( 1500 )   PDF (11359KB) ( 1153 )  

Related Articles | Metrics

According to outcrop investigation and well-logging identification, the sedimentary characteristics and distribution law of the alluvial fan in Kuche Formation of Neogene in Kuqa Depression were systematically studied with seismic and 3D electric method data, and the sedimentary models of the alluvial fan were obtained. The alluvial fan is dominated by the yellow or yellow-red conglomerates and coarse-grained sandstones, and there exist flush-filling structures, cross beddings and parallel beddings in conglomerates. The well-logging curves of the alluvial fan are in the characteristics of low GR and high resistance, and manifest themselves as box-like, infundibuliform and campaniform shapes. The seismic facies are dominated by clutter and foreset facies. In the areas lacking wells, the data of 3D electric method were also used to improve the research precision. The results of comprehensive research reveal that the scales of alluvial fans in the western region nearby well Bz1 and well Db1 are larger than those in the eastern region, and the tectonic movement is the main controlling factor; it experienced strong tectonic movements during the depositional period of Kuqa Depression, and the uplift caused lakes to shrink quickly to the south，and mountain blocks rose and suffered from erosion, providing sediment sources for alluvial fans; the scale and distribution of alluvial fans in the area nearby well Bz1 were expanding continuously; due to tectonic uplift, the alluvial fan in the area nearby well Db1 has the feature of multiple provenances. It is considered that there are two models of alluvial fans in Kuqa Depression, i.e. a model of single provenance of conglomerate, which reveals a long-term, stable and successional depositional process, and a model of multiple provenances of conglomerate, which is controlled by local structures.

Structural Evolution of Paleogene and Its Affect on Lithologic Reservoir in Qikou Sag

WANG Zhi-yao, HOU Su-ying, LIU Zhi-ying

2013, 27(3):  681-687. 

Asbtract ( 1493 )   PDF (4150KB) ( 1030 )  

Related Articles | Metrics

The analyses of the mode of structural evolution in Qikou sag showed that，graben faulting of Paleogene generate complex half graben-like framework on NW-SE orientation and complex duplex fault graben on N-S orientation in Qikou sag. The tectonic framework of the convex, concave and concave-uplift alternately formed in Qikou sag，which created favorability for the formation of the lithologic reservoir. The high-quality source rocks developed in the sedimentary center were material foundation of the development of the lithologic oil reservoirs. Synsedimentary fault and its configuration decided the characters of gullies controlling sources，transform zones controlling fans and faulted slopes controlling sands，and that the middle of subaqueous fan，delta front and infralittoral subaqueous fan were the most favorable hydrocarbon accumulation zones. The development of the faults make the deep oil-gas accumulation more favorable，which provided effective reservoir space for the development of the lithologic oil reservoir. Tectonic activity and sedimentary evolution formed the optimal configuration relationships of the source-reservoir-cap，which created favorable conditions for the formation of multi-types lithologic oil reservoirs. According to the lithologic oil reservoir types，spatial distribution characteristics and oil accumulation characters in Tanan sag，four kinds of lithologic oil reservoir forming modes are summarized，including the fault terrace-steep slope-break belt，fault terrace-gentle slope-break belt，cliff-steep slope-break belt and inner basin slope, break belt reservoir forming mode of Qikou sag, combining the geological structure characters. In Qikou sag, 4 types of oil-gas accumulation modes are formed：accumulation of shelving, accumulation of actic region, accumulation of fault flight of stairs, accumulation of break in slope of Qikou sag.

Fault Migration Capability and Evolution of Fault-Lithologic Reservoirs of  Dainan Formation in Gaoyou Depression

DONG Cai-yuan, LIU Zhen, LIU Qi-dong, LUO Bei-wei, LI Chu-hua, WANG Wei-jun

2013, 27(3):  688-694. 

Asbtract ( 2737 )   PDF (4559KB) ( 1243 )  

Related Articles | Metrics

Fault sealing evolution is analyzed based on normal stress calculation, and combined with migration pathway pattern division, and favorable areas of fault-lithologic reservoirs of Dainan Formation are predicted in Gaoyou depression. It is concluded that the critical value of fault sealing is 13.8 MPa. Most of the reservoir faults are open in the accumulation period and closed now. However, there is one reservoir fault sealing all the time, which is Shaoshen 1 reservoir of own source type. Two types of migration pathway patterns were divided in theory which are the high-efficient and the low-efficient types respectively. The high-efficient type developed with bottom sand, while the low-efficient without bottom sand. East Lian 12 oil-west Yong 22 oil and east Shao 14 oil are the most favorable areas of fault-lithologic reservoirs of Dainan Formation in Gaoyou depression. Deep Shaobo sub-sag to the northwest of Shaoshen 1 reservoir is the secondary favorable area.

Application of the Reservoir Geophysics Technology to LS Oilfield of Daqing Changyuan

LI Zhan-dong,LIU Yi-kun,HAI Dong-ming

2013, 27(3):  695-702. 

Asbtract ( 1117 )   PDF (8997KB) ( 822 )  

Related Articles | Metrics

According to the problem of using reservoir geophysical techniques in potential tapping of residual oil becoming hard in Daqing Changyuan, this article systematically expounds well-to-seismic integration structure research and reservoir prediction. Well-to-seismic integration technique makes micro structure interpretation successful in the practice.(1) Hierarchical structural interpretation is carried out, and structural interpretation of small-scale geologic body is established;(2)On low grade faults identification and combination, well log data are used to guide and to verify seismic faults interpretation, combined with the techniques concluding coherent body inclination positioning, 3D visualization, etc; (3)On micro-amplitude structure, well point hierarchical data grid mapping are adopted, assisted by hand recognition, trend surface analysis, coherence cube, to implement the structure one by one. The practice of reservoir application proves that the popularity of using seismic attribute to predict reservoir is very limited, but in predicting ‘bit balling sand’  sand body, it is successful. The accuracy of seismic reconstruction inversion technique in reservoir prediction proves to be very high. It not only reflects sand bodies contact relationship well, but also predicts sand body horizontal boundary. By the method of ‘well determine facies, slice assemble shape’, using the characteristics of well log shape difference and height difference etc, assisted by inversion slice in river course vertical evolution research, finally multi-period river classification is achieved.

Reservoir Prediction Based on Seismic Data Within Wide Well Space Area of Qikou 18-1 Block

GUO Tai-xian，ZHAO Chun-ming

2013, 27(3):  703-709. 

Asbtract ( 1122 )   PDF (10378KB) ( 1055 )  

Related Articles | Metrics

Shahejie Formation reservoir in Qikou 18-1 Block belongs to fan delta facies, with rapidly changed sand body, and the sparse well data in the block is not enough for the reservoir study of high accuracy. According to this complicated geological feature and limited well data, high quality reservoir sandstone distribution of the block is predicted with 3D seismic data by the method of seismic attributes analysis and seismic inversion controlled with well logs.  On the basis of lithologic calibration with well data, optimum selecting seismic attributes extracted from 3D seismic data, especially RMS, is able to discriminate the thick sandstone from the mudstone, and as a result, the scope of fan delta, which is the favorable sedimentary facies of the block, can be determined with the sandstone distribution. Afterwards, high quality reservoir sandstones within fan delta and its internal architecture can be determined by seismic inversion controlled with well logs, which provides the geological  evidence to make or to adjust the development plan of the block. Practically, it is proved that this set of reservoir prediction technology is comparatively fit for determination of favorable target in offshore oilfield with sparse well net and is useful for risk reduction in development.

Movable Fluid Study of Low Permeability Reservoir with Nuclear Magnetic Resonance Technology

ZHENG Ke, XU Huai-min, CHEN Jian-wen, WANG Yong-hong

2013, 27(3):  710-718. 

Asbtract ( 2987 )   PDF (4673KB) ( 1556 )  

Related Articles | Metrics

The movable fluid evaluation was conducted based on a total of 277 matrix block samples from three typical domestic lowpermeability reservoirs of different lithologies, mainly using nuclear magnetic resonance(NMR) core analysis technique of low magnetic field and supplemented by other routine test means including rock thin section, environment scanning electron microscopy(ESEM), high-resolution computed tomography(CT) and imaging logging. The distribution law and influencing factors of reservoir movable fluid were analyzed, and the cutoff value for T₂ and porethroat radius of movable fluid were calculated. The results show that the movable fluid parameters of low permeability reservoirs have wide range. The relation of the movable fluid parameters and the permeability gets better with the increase of permeability. The correlation among percentage of movable fluid, porosity, permeability is better in sandstone reservoirs. The values calculated by nonlinear optimization method well agreed with the measured values. Micropore structures, such as development degree of micro-fracture, pore size distribution, clay mineral and the filling degree, determine the distribution of movable fluids in low permeability reservoirs.

Risk Evaluation and Comprehensive Geological Prediction Based on Fuzzy Wavelet Neural Network during Tunneling in Karst Area

LI Zhi-lin, WANG Xing-hua, XIE Li-zhao

2013, 27(3):  719-726. 

Asbtract ( 1343 )   PDF (7898KB) ( 673 )  

Related Articles | Metrics

Focused on the uncertainty and complexity of risk assessment of karst tunnels and limitation of current methods, the artificial neural network (ANN), wavelet analysis and fuzzy mathematics were integrated. A model of risk assessment of karst tunnels based on fuzzy wavelet neural network (FWNN) was established. According to the advantages and disadvantages of various geophysical methods and the sensitivity of forecasting karst water, and with the method and principle of the comprehensive geological prediction, this study proposed the geological prediction program combined with geological analysis, risk classification, grading prediction and geological disasters approaching alarm technology.In the implementation of risk evaluation on Qiyue Mountain karst tunnel, the karst water is successfully forecasted, and the scientificity and feasibility of the program are proved to be validated.

Analysis on the Characteristics and Mechanism of Debris Flow in Nabao Gully of Wangmo，Guizhou

WANG Tao, YU Bin, QI Xing, ZHU Yuan, CHEN Yuan-jing

2013, 27(3):  727-732. 

Asbtract ( 1308 )   PDF (1528KB) ( 1270 )  

Related Articles | Metrics

A heavy rainfall was triggered in Wangmo County, Guizhou Province on June 5-6, 2011. A debris flow was broken out in Nabao gully in this area, and caused plenty of damage. This study analyzed the source, topography and rainfall conditions of debris flow, and revealed that the large intensity of rainfalls and the large proportion of slopes in the range of 30°-40° were the triggering reason of shallow landslides, and the landslides provided the solid sources of debris flow. The characteristics and dynamic parameters of the debris flow are concluded as follows: the debris flow is one of the less viscous debris flow; the peak discharge is 25 m³/s, and the total volume of debris flow is about 6,100 m³. The debris flow in Nabao gully was induced by shallow landslide. In the light of the characteristics of Nabao gully, the local government and resident should attach great importance to these and take the corresponding biological and engineering measures to prevent debris flow.

Multi-time Scale Analysis of Annual Sediment Yield of the Jiangjiagou Debris Flow in Dongchuan of Yunnan Based on Empirical Model Decomposition

LIN Wei， XIE Hong， ZHANG Jin-shan

2013, 27(3):  733-737. 

Asbtract ( 1204 )   PDF (715KB) ( 1103 )  

Related Articles | Metrics

Empirical Model Decomposition (EMD) was used to study the multitime scale analysis for the time series of the annual sediment yield of the Jiangjiagou debris flow between 1965 and 2004 in Dongchuan, Yunnan Province. The result shows that this annual sediment yield can be decomposed into three IMF components and one Res trend component. The analysis shows that the annual sediment yield of the Jiangjiagou debris flow reveals cyclical fluctuations, and there are fluctuations at 2-4 years, 6-10 years and 17-21 years time scale. Through the analysis of these components，we found that the amplitude of the fluctuations became larger after 1985, which indicated that the annual sediment yield of the Jiangjiagou debris flow varied greatly. And the rainfall affects the annual sediment yield of the Jiangjiagou debris flow and its cyclical fluctuations to some degree. The human activities have changed the local environment, providing the solid material for Jiangjiagou debris flow,thus make the cyclical fluctuations of the annual sediment discharge of debris flow in Jiangjiagou become more complex.

Preliminary Research on the Relationship Between Microscopic Structure and Shear Strength of Red-bed Soft Rocks

WANG Ying-chun， CHEN Jian

2013, 27(3):  738-742. 

Asbtract ( 1012 )   PDF (1591KB) ( 1109 )  

Related Articles | Metrics

Red-bed soft rocks belong to the layers which are susceptible to landslide and collapse. The micro-structural characteristics of the rock have an important impact on its macroscopic mechanical strength. In this paper, the micro-structural observation with scanning electron microscopy (SEM) and the angle-changed shear strength test of the Jurassic red-bed sandstone, siltstone and mudstone samples which were collected from Pingshan County in Sichuan Province and Suijiang County in Yunnan Province were conducted. A large number of microstructures of red-bed sandstone, siltstone and mudstone were analyzed and the shear strength values of the red-bed soft rocks were obtained. The microstructure parameters, i.e.porosity, particle roundness, particle orientation and the quantized value of Euler number of the red-bed sandstone, siltstone and mudstone were extracted based on MATLAB digital image processing techniques. Then the quantitative relationship between the above parameters and the shear strength were analyzed. The results show that the shear strength and porosity of the red-bed soft rock have a negative exponential relationship; the shear strength and particle roundness and particle orientation have a negative linear relationship; the shear strength and the Euler number have positively correlated linear relationship.

Determination of the REV for Fractured Rock Mass of the Low Ductility

ZHANG Li-li, WANG Yun, ZHANG Xin, WANG Yun, YU Qing-chun

2013, 27(3):  743-749. 

Asbtract ( 1016 )   PDF (1442KB) ( 1519 )  

Related Articles | Metrics

The FractureToKarst software which is a main analysis tool in this paper and developed by the listed authors, is a DFN (Discrete Fracture Network) software. According to the Standard of Rock Fracture Classification established by ISRM in 1978, this paper discussed the existence and sizes of representative elementary volume (REV) of low-ductility fractured rock masses using the FractureToKarst and proposed a general method to determine the existence of REV. Combined with the existing study of the fractured-rock flow, the major results are concluded as follows: (1)in the rock masses when their average spacing is less than 0.6 m, the REV exists; (2)when their average spacing is more than 0.6 m, the REV does not exist.

Application of Infrared Thermal Imaging on Seepage Probing of Fengxian Temple in Longmen Grottoes

FANG Yun, ZHANG Jun-jian, XIA Guo-zheng，ZHOU Wei-qiang, SU Mei-liang

2013, 27(3):  750-754. 

Asbtract ( 980 )   PDF (6809KB) ( 1041 )  

Related Articles | Metrics

Longmen Grottoes is one of key cultural relic units under the state-level protection, which were carved in the carbonate rocks, and Fengxian Temple is one of the representative works of Longmen Grottoes. Because of the long-term impact of natural environment and human activities, Fengxian Temple has generated a variety of serious geological diseases, including seepage which can induced other diseases and had been threaten the integrity of the rock and the sculpture for a very long time. According to continuous observation, the seepage of Fengxian Temple has increased year by year. So it is very important to control the seepage. Detecting the parts of water seepage and seepage sources accurately is the base of designing the later period controlling programs of water disaster. In this paper, the seepage of Fengxian Temple had been detected under different conditions by means of infrared thermal imaging. And the results show that using thermal imaging devices can detect the seepage of the cliff rock site accurately and effectively, and what's more, the source of water seepage, the distribution and activity patterns of the seepage can be determined too. Compared with previous human observation, infrared thermal imaging has obvious advantages. Also, this technology can be used in probing the seepage of other caves in Longmen Grottoes.