Geoscience

Geochronology,Geochemistry and Geological Significance of the Huangcaotan Pluton in the Southern Beishan Orogenic Belt

WANG Jiangtao1, DONG Yunpeng1, ZENG Zhongcheng2 ,YANG Zhao1, SUN Shengsi1,

2016, 30(5): 937-949.

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The Beishan orogenic belt is the transition zone located between the east and west part of southern margin of the Central Asian Orogenic Belt.It is the key area for the study of contact relationship between west and east of the Central Asian Orogenic Belt. The magma information during the orogenetic process was recorded in the granites, as a typical represent of the Huangcaotan pluton in the southern of Beishan, which consists mainly of diorite and granodiorite. Zircon UPb dating yields the crystallization ages of （402±3 )Ma for diorite and （394±7) Ma for granodiorite, respectively. The Huangcaotan pluton displays typical geochemical characteristics of Itype granite: high SiO2 contents （5924%-7154%), high Na2O contents （376%-409%), and aluminumweakly peraluminous affinity（A/CNK=094-111). The relatively lower level of ∑REE, enriched LREE, obvious fractionation of heavy and light rare earth, slightly negative Eu anomaly, together with the highly enriched Rb, Th, U and K in LILE and depleted Nb, P, Hf and Ti in HFSE, indicate subductionrelated geochemical features. The granite may be derived from partial melting of metabasaltic rocks in the middlelower crust caused by underplating of mantlederived magma and contaminated by the mantlederived material. Together with regional geology, it is proposed that the Huangcaotan pluton was formed in volcanic arc on an active continental margin and may be the product of magmation related to the northward subduction of PaleoAsian Ocean in Liuyuan area, representing an important magmatism related to oceanic slab subduction from the Early Devonian in the southern of Beishan orogenic belt.

Geochemisty and Petrogenesis of the Rhyolites from the Baiyingaolao Formation in the Honggeer Area, Central Inner Mongolia

ZHANG Xiangxin, GAO Yongfeng, LEI Shihe

2016, 30(5): 950-960.

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The Baiyingaolao Formation in the Honggeer area of central Inner Mongolia is mainly composed of rhyolites, with minor dacite and latite. The rhyolites are characterized by high SiO2, Al2O3, K2O, and low CaO, MgO. Their high Sr/Y, La/Yb, and low Y, Yb values show an adakitic geochemical affinity. The results of K2O/Na2O and A/CNK reveal that the rhyolites belong to a peraluminous highK calcalkalic type. The rocks are obviously enriched in LILEs such as K, Rb, Th, U, and depleted in HFSEs such as Nb, Ta, Ti and P with obvious negative anomalies. The total of REE content is relatively low, with enrichment in LREE and medium negative Eu anomaly. The SrNdPb isotopic compositions show positive εNd(t)(+088 to +266), and low tDM(t) (5883 to 7164 Ma). The above geochemical characteristics reveal that the rhyolites of the Baiyingaolao Formation in the Honggeer area belong to highK calcalkine and Ctype adakitic rocks, and they were the products of partial melting of the thickened continental crust. The rocks were formed in an intraplate extensional tectonic setting after postorogenic thickened lithospheric gravitational collapse at Early Cretaceous, which was related with the collision after closure of MongolOkhotsk Ocean. Garnet was the residual phase during the partial melting, and fractional crystallization with the removal of plagioclase, ilmenite and apatite played an important role in magma evolution.

The Granite Petrogenesis in the Area of the Gaoerqi LeadZincSilver Deposit, Inner Mongolia: Constraints of Geochemistry, Zircon UPb Geochronology and Hf Isotope

WANG Jichun1，2，3，WANG Yinhong1，ZHANG Mei2,3，LIU Jiajun1，PENG Runmin1，WANG Jianpi

2016, 30(5): 961-980.

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The discovery of Gaoerqi leadzincsilver deposit is not only an important prospecting achievement in ErlianDongwuqi polymetallic metallogenic belt, but also a significant breakthrough for prospecting blind deposits. This paper, based on the study of geochemistry, zircon UPb geochronology and LuHf isotopes of orebearing granites, has provided constraints on petrogenesis, magma source and rockforming tectonic settings and other issues of the orebearing rocks. The orebearing rocks are mainly porphyriticlike mediumcoarse grained monzogranite and mediumfine grained syenogranite. The contents of SiO2, Na2O+K2O and REEs are of higher values, but the contents of P2O5, TiO2, CaO and MgO are of lower values in the orebearing rocks. The contents of SiO2 and Na2O+K2O are 646%-7912% and 559%-1017%, respectively. The Eu element has a characteristic of strong negative anomaly. The orebearing rocks are not only rich in Rb, K and other LILE, but also rich in Zr, Hf and other HFS. The orebearing rocks are with strong depletions in Ba, Sr, P, Ti, Eu, etc. The orebearing rocks are with higher values of εHf(t) between 44 and 140, and have younger crust model ages with values of tDCc between 424 Ma and 1,042 Ma, which reveals that the granites mainly derive from the partial melting of young accreted crust which derives from depleted mantle. The granites are with characteritics of A2type granites, and form in the plate extension phase after collision orogenesis. The LAICPMS UPb isotope ages of zircons are (3068±19) Ma and (3104±23) Ma, respectively, which proves the zircons belong to the products of tectonic magmatism in Late Carboniferous. It reveals that the main collision between North China and Siberian plates has finished in this period, and has entered the postcollision extension phase.

Geochronological, Geochemical Characteristics and Mineralization Potentiality of Late Jurassic Intrusive Rocks in Ar Horqin Banner Area, Inner Mongolia

LU Yanming, ZHUAN Shaopeng, SUO Chengxun, YIN Min

2016, 30(5): 981-993.

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Ar Horqin Banner area is located in the eastern XinganMongolian orogenic belt, and the Mesozoic magmatic rocks are widely distributed. In this paper, zircon UPb geochronological and element geochemical studies were carried out for the Late Jurassic intrusive rocks in Ar Horqin Banner area. The study of petrology indicates that the granitoids are mainly composed of quartz monzobiorite, quartz diorite and biotite granodiorite. Zircon LAICPMS UPb dating of the biotite granodiorite gives a weighted average age of (14379±084) Ma(MSWD=33), indicating that it belongs to the Late Jurassic, and it is during regional MoAuCu metallogenic peak period. Major elemental geochemistry shows that the rocks are quasialuminous calalkaline granites, which is characterized by relatively rich alkali. Trace elements have a similar variation trend of low REE contents and obvious fractionation of light and heavy rare earth, significant negative anomaly of Eu, the enrichment of strong incompatible elements (Rb, Th, U, LREE), depletion of high fieldstrength element (P, Ti, Y and HREE), relative depletion in Nb, Ta and Ba. Main body of the granites belongs to calcalkaline I genetic type. The magmas were the product of partial melting of the basite in the crust, formed in an extensional setting after the collision, which is a favorable metallogenic tectonic evolution stage. SI, K/Rb and Rb/Sr ratios are relatively small, DI values and Fe2O3/FeO ratios are relatively large, which shows that the granites belong to mediumstrong evolution, medium fractionated, oxidation type or magnetiteseries. Their geochemical ore parameters indicate that Cu, Au, Mo mineralization potentiality decreases systematically, consistent with the other mineralization characteristics in the study area.

The LAICPMS Zircon UPb Age of the Qinlingliang Intrusion,Shaanxi Province and Its Geological Significance

SU Qiangwei, ZHANG Jing, WANG Wenbo

2016, 30(5): 994-1003.

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Triassic granite are widespread in the Qinling orogenic belt, which directly records the important information of the evolution process of the Qinling orogenic belt. The Qinlingliang intrusion is located in the north of the ShangDan suture belt, mainly consisting of the quartz monzonite porphyry, with the Kfeldspar as phenocryst (some phenocrysts have a white rim of plagioclase) and mainly quartz (25%), plagioclase (45%), Kfeldspar (10%), biotite (15%) and amphibole (5%) as matrix. The zircons in the Qinlingliang intrusion show the characteristics of magmatic zircon with fine euhedral crystal and zonation. The LAICPMS zircon UPb ages of two samples are (2165±21) Ma and (2194±26) Ma, indicating that the Qinlingliang intruded in the Late Triassic. The age is consistent with the time of the northern subduction of the MianLüe oceanic crust(248-200 Ma), indicating that they have close relationship. The geochemical characteristics of the Qinlingliang quartz monzonite prophyry intrusion suggest that it was the production of the arc magmatic activity under the oceanic crust subduction setting. Comprehensive discussions make it clear that the closing time of the MianLüe ocean and the beginning time of fullscale collision between Yangtze and North China plates should be later than (216-219) Ma.

Geochemical Characteristics and Tectonic Significance of Gabbro from Bashikangkuole in West Part of Eastern Kunlun,China

ZHENG Yong1,YANG Yousheng1,CHEN Bangxue1,ZHU Yanfei2

2016, 30(5): 1004-1013.

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Major and trace element analysis were conducted in this study. The rocks have MgO contents between 578% and 123%, FeO contents between 516% and 104%, Al2O3 contents between 142% and 2156%, which is relatively high in all. The TiO2 contents of the samples range from 018% to 132% (average=077%), which is relatively high and similar to those of the island arc tholeiitic basalts (TiO2=084%). However, the rocks show relatively low contents of K2O (005%-053% with an average of 02%), consistent with those of the ocean ridge tholeiitic basalt (K2O=02%). The REE patterns are characterized by an enrichment of LREEs and a depletion of HREEs. The trace element spidergram shows enrichments for LILEs (except K), Ti and P, and depletions for Nb and Zr. It is suggested that the rocks formed in island Backarc basin. Zircon UPb dating was taken and two groups of age were obtained. The upper intercept age of (501±1) Ma (MSWD=025) indicates the crystallization age of the original rock during the Late Cambrian. The lower intercept age of (451±2) Ma (MSWD=0084) suggests the age of the metamorphism during the early stage of Late Ordovician. Combined with the result of major and trace element and zircon UPb dating, it is concluded that the subduction of oceanic crust began from the Late Cambrian and the subsequent collision happened no later than the Late Ordovician.

Zircon UPb Geochronology of Granite in the Huashandong Tungsten Deposit, Jiangxi Province, China and Its Geological Significance

LUO Gang1,2, QU Hongying2, XIAO Rongge3, MEI Yanxiong2, HUANG Xiubao4

2016, 30(5): 1014-1025.

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Huashandong deposit is a newly found tungsten deposit in northwest Jiangxi Province, China. The exploration report shows that the granite is related to the forming of this deposit.This paper reports LAICPMS zircon UPb age, major and trace elements of the orerelated granite in the Huashandong tungsten deposit. LAICPMS zircon UPb dating yielded the crystallization age of (807±8) Ma for the granite. The granite is calcalkaline, peraluminous and rich in Na,characterized by the SiO2 content from 6823% to 7378%，Al2O3 content from 1441% to 1581%, Na2O+K2O content from 593% to 7%，K2O/Na2O content from 038 to 086，A/CNK＞11.ΣREE is low and there is enrichment of LREE.The fractionation between LREE and HREE is obvious. It is enriched in such LILE as Rb,Tu,U,La,Nd and depleted in HFSE such as Ba,Nb,Ti,Sr,P, with medium anomalies of Eu. In addition to the geological setting of Huanan plate in the Neoproterozoic, it shows that granite was formed in a continental marginal arc setting, and mainly originated from partial melting of crust.The age of Huashandong tungsten deposit is very close to the age of granite,showing that the mineralization is consistent with the differentiation evolution of granite,and the Huashandong tungsten deposit is the product of Jinningian magmatic activities.

Origin and Tectonic Implications of the Early Paleozoic HighSi Granite in the Eastern Baoshan Block, Yunnan

KANG Huan1, LI Dapeng1,2, CHEN Yuelong1, LU Zhen1

2016, 30(5): 1026-1037.

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Integrated mineral chemistry, geochemistry and zircon UPbHf isotopic analyses were carried out on the highSi granite in the eastern Baoshan block.Results show that the highSi granite is Stype and shows calcalkaline, strongly peraluminous features. Zircon UPb isotopic analyses show that the highSi granite emplaced at 454 Ma with 800 to 1,100 Ma inherited zircon grains. Magmatic zircons from the highSi granite in the eastern Baoshan show similar Hf isotope compositions with those from coveal felsic intrusions in the Tibetan Plateau and its southeastern margin, implying their similar magmatic origin. Lines of evidence including mineral chemistry, zircon Hf isotopes, and geochemical simulation show a complex history of the highSi granite in eastern Baoshan: the parental magmas of the highsilica granite originated from partial melting of the regional sedimentary rocks; the melts underwent highdegree differentiation, and then assimilated wallrock during emplacement; some minerals experienced solidstate reequilibration after cooling. Similarities of the highSi granite in eastern Baoshan and the coeval Pinghe batholithin geochemical features imply their parallel processes of their petrogenesis.

Skarn Mineral Characteristics and Their Geological Significance of the Huangshaping Deposit in Hunan Province

ZHAO Fei1, YIN Jingwu1, WANG Mengya1, ZHANG Zhenhua1, SUN Yandong1, ZHANG Piao1,

2016, 30(5): 1038-1050.

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The Huangshaping polymetallic deposit is a skarn deposit, which lies on the northern margin of the middle Nanling tectonic belt. According to the output state of skarn, mineral assemblage and characteristics of petrography, the stage of mineralization is divided into skarn stage, retrograde alteration stage, the early and the late sulfide stage. The skarn minerals are mainly garnet, pyroxene, vesuvianite. Metallic minerals mainly include scheelite, molybdenite, magnetite, galena and sphalerite. The electron microprobe analysis(EPMA)result shows that the garnets forming in the skarn stages are mainly andraditegrossularite series and garnets vary from grossularite to andradite. The andradites commonly have zonal structure which can record the evolutionary process of physicochemical conditions. The andradite and grossularite both contain Sn, but the content of Sn in the former is higher than the latter. The pyroxenes are mainly diopsidehedenbergite series, and the content of Fe and Mn has a rising trend from the internal contact zone to the external contact zone. Mineralogical characteristics and compositional variations suggest that the property of fluid changed with two redox fluctuations at least. Skarn mineralogy characteristics is of important geological implications of W(Sn)MoBi polymetallic mineralization.

Geological Characteristics and S,Pb Isotope Geochemistry of Yuku Zincpolymetallic Deposit in Luanchuan，Western Henan

TIAN Haohao1,2，ZHANG Shouting2，CAO Huawen3,2，HAN Jiangwei4，TANG Li2，PEI Qiuming2

2016, 30(5): 1051-1060.

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The Yuku zincpolymetallic deposit is located in the northwest of YukuChitudian PbZn ore belt, MoWPbZnAg polymetallic concentration area in Luanchuan, western Henan.This deposit is hosted in the carbonate rocks (that interbedded with clastic rocks) from the Sanchuan Formation of Neoproterozoic Luanchuan Group. The orebody occurred in the diopsidegarnet skarn rock with stratoid and lentoid occurrence, which is strictly controlled by the skarn zone. The sulfur isotopic compositions of sulfides from this deposit are relatively stable, and the δ34S values range from 23‰ to 39‰, with an average of 32‰. The sulfur isotopic compositions are similar to the ones of porphyry-skarn type deposits in this region, indicating that these sulfurs originated from deep magma. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of sulfides samples from this orebody vary in ranges of 17781-18455, 15502-15590 and 38232-38624, with the average values of 18043, 15545 and 38438 respectively. The Pb isotopic compositions of ore sulfides are also stable, and these leads are derived from mantle. For this deposit, the mineralization is closely related to the hydrothermal process of tectonic magmatism. The comprehensive analysis mentioned above indicates that Yuku deposit belongs to the skarn deposit with post magmaticepithermal metasomatic activities.

Tectonic and Sedimentary Environment in the Ordovician Period of Central Xing an Block

CHEN Anxia1,2, ZHOU Duo1,2, ZHANG Qingkui1, GUAN Peiyan1，YANG Bin1

2016, 30(5): 1061-1071.

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The tectonic sedimentary environment in the Ordovician Period of central Xing an Block is attracted widespread attention by geologists. On the basis of regional investigation work, the arc and arcback environment of the study area was firstly verified by the clastic rocks in Toudaoqiao area and invasion rocks in Saqitu area. Then the sedimentary environment and its evolution were introduced in detail through a series of sequence stratigraphic correlation in central Xingan Block during Ordovician. The conclusion showed that there was a slope tilted to NE direction and extended to NE direction in the Ordovician period. A series of shoreshallow sea transgressive clastic rocks were found in Halahahe Formation along the slope. The arc volcanic rocks developed extensively in Duobaoshan Formation. The uplift near the island arc contributed to the SWdirection extension parts of the ZhalantunDuobaoshan arc island. The subsidence appeared far from the island arc, and radiolarian cherts were found locally. The island arc progress was over, and the subsidence and clastic rock appeared again during the sedimentation of Luohe Formation. After several times of uplift and subsidence of the crust, the study area was exposed and denuded finally.

Characteristics of Slopebreak Zone and Its Deposition Response in the North Slope of Bonan Low Uplift

YANG Youran1,2，YANG Xianghua1,2，ZHU Hongtao1,2，LI Sen1,2，GUAN Dayong3， WANG Xin3

2016, 30(5): 1072-1084.

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There were several different kinds of sedimentary bodies of E3d2 in the northern Bonan Low Uplift which were closely related to structure and evolution of slopebreak zone. It developed a complete slopebreak zone sedimentary cycle of E3d12 in the northern Bonan Low Uplift. In the early stage of the evolution, (iethe early E3d12 period) some ancient gulchs filled with vermiform, chaotic anomalous bodies and lowlying lands developed in slope with submarginal sedimentation. In the late stage of the evolution, (iethe late E3d12 period) after the peneplanation process, the slopebreak zone became the channel of sedimentary deposited in the sub sag area and a series of highangle foresets were deposited within the channel. The anomalous bodies in the early time of evolvement of slopebreak zone were the rapid proximal sedimentary bodies，mainly distributed in the first slope break zone. And in late stage of the evolution, the anomalous bodies, mainly distributed in the second slope break zone, were the distal sedimentary bodies characterized by hightangle progradation. Above all, there were different kinds of sedimentary bodies developing in the northern Bonan Low Uplift from slope to depression during the whole slopebreak zone sedimentary cycle, making up the complex of slopebreak zone and deposition.

Differential Structural Evolution and Its Influence on the Natural Gas Accumulation of Continental Strata in the Western and Northeastern Sichuan Basin

YU Dongdong1,2, TANG Liangjie1,2, YU Yixin1,2, CHEN Qian1,2

2016, 30(5): 1085-1095.

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The west and northeast of Sichuan Basin, located at the northwestern margin of the Yangtze Platform,both developed typical foldthrust belts and foreland basins, and shared certain similarities in relate to structural characteristics. Based on the interpretation of seismic data and anatomy of typical gas fields and in combination with previous study results, this study analyzed differential structural evolution and its influence on natural gas accumulation characteristics in the west and northeast of Sichuan Basin. Consequently, the western Sichuan Basin was mainly affected by the Longmenshan orogenic belt and the corresponding foreland basin formed from the Middle and Late Indosinian,then mainly influenced by Late Yanshanian and Himalayan tectonic movement; but the northeastern Sichuan Basin from the Early Yanshanian began to develop foreland basin, then was influenced by the combination of Dabashan, Micangshan and Xuefengshan in the Middle and Late Yanshanian, finally formed in the intensive movement of Dabashan orogenic belt in the Himalayan. Above differential structural evolution affected the hydrocarbon accumulation characteristics in the continental strata of the west and northeast of Sichuan Basin respectively, which are reflected mainly in source rocks, pathway system, preservation condition and natural gas accumulation process. The western Sichuan Basin mainly developed Xujiahe Formation source rocks, and its pathway system consisted of NE and SN trending faults and relational fractures and its large faults formed by multiperiod tectonic movements affected the preservation of gas fields in piedmont faultfold zone, experiencing four key accumulation periods, ie Late Indosinian, Middle and Late Yanshanian and Himalayan. The northeastern Sichuan Basin developed two sets of source rocks,ieXujiahe Formation and Lower Jurassic, and its NW trending faults were the main pathway system, and its erosion and large faults caused poor preservation condition of piedmont faultfold belt, experiencing three key accumulation periods, ieMiddle Yanshanian,Late Yanshanian and Himalayan.

Characteristics of the Highresolution Sequence Stratigraphy and the Distribution of Tight Oil Reservoirs in the Salt Lake: A Case from the A Region of Lucaogou Formation, Jimsar Sag

ZHANG Yaqi1,2， MA Shizhong1， GAO Yang2， LI Yingyan2， ZHANG Jing2， WANG Li2， SUN

2016, 30(5): 1096-1104.

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Based on cores，log and welllog data, under the guidance of the theory of the highresolution sequence stratigraphy, evolution of all levels baselevel cycles and highresolution sequence stratigraphic model were analyzed in the A region of Lucaogou Formation of Jimsar Sag. The results show that 1 longterm, 6 middleterm and 44 shortterm baselevel cycles were classified. According to the structural feature, stacking pattern and spatial variation of shortterm baselevel cycle, the authors established A region of Lucaogou Formation highresolution sequence stratigraphic framework. By analyzing the sequence structure, stack style and space variation, suggested that sedimentary facies types and controlling factors of the high quality of tight oil reservoir is obtained by shortterm baselevel cycles; Concluded that the high quality of tight oil reservoir is located at the conversion surface of 2 eustatic cycles and formed a depositional system of carbonate and siltstone sheet from shallow to semideep lake, therefore, the 2 cycles of falling semicycle control the tight reservoir development and the types of microfacies control the position and quality of dense reservoir. This has important significant to guide the high precision stratigraphic subdivision in A region and even the salt lake facies.

Study on the Genetic Mechanism of Immature Oil from Qingdong Sag, Jiyang Depression

GE Haixia1， ZHANG Zhihuan1，MIN Wei2，ZHANG Linpu2， LIU Dong1， ZHANG Chengjin1

2016, 30(5): 1105-1114.

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The source potential of Qingdong sag has not been fully recognized due to low exploration extent. Thus study on the genetic mechanism of immature oil of this sag is important for future exploration. The immature oil of Qingdong sag is mainly discovered on the edges of the sag and the source rocks are believed to be the upper submember of the 4th member of Shahejie Formation. Oilsource correlation shows that immature oil are mainly from immature source rocks of upper submember of the 4th member of Shahejie Formation. On the basis of molecular geochemical and organic petrology analysis, the immature source rocks possesses geological and geochemical condition to generate immature oil, the mechanism of which are as follows: (1) the mudstone/shale of the 4th member of Shahejie Formation has high organic abundance. The organic matters types are sapropelic type(Ⅰ)and sapropelichumic type(Ⅱ1), abundant in hydrogenrich components which are prone to generate hydrocarbons in early period; (2) the symbiotic saline reducing environment of source rocks and evaporates with the strata fluids of high salinity can promote hydrocarbon generating; (3) the soluble organic matters in the source rocks are easy to generate hydrocarbon influenced by low temperature chemical reactions, bacterial activities and catalysis during the early period of evolution. Therefore, more attention should be focused on the immature oil in the future exploration of Qingdong sag.

Feature of Paleofluids and Present Fluids in the Inner Buried Hill of Niutuozhen Uplift, Baxian Sag

LI Fei1， LI Shaolong2， ZENG Jianhui1， LIU Jingwang3， LIU Jia1, GE Daiwei1, WANG

2016, 30(5): 1115-1123.

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The inner buriedhills with low degree of exploration, widely occur in Niutuozhen uplift of Baxian Sag. Vein calcites and host rocks were investigated using petrology, isotope and fluidinclusion to determine the origin, stage and evolution character of paleofluids. Combining the characteristics of present formation water, the influence of fluid flow on petroleum entrapment were summarized. The results show that three types of calcite veins have been found(Cal1, Cal2 and Cal3). The stable isotopes of the earliest calcites (Cal1), formed in the early stage of the Caledonian Orogeny, were equivalent to the host marine carbonates, which indicated that Cal1 were associated with host rocks. The subsequent calcite veins(Cal2) formed in the later stage of the Caledonian Orogeny could be divided into two periods. First, the early calcite veins (Cal21)in the edge of the fissure displayed isotopic compositions similar to those of the host rocks, which suggested that Cal21 were also associated with the host rocks. The late calcite vein (Cal22) in the middle of the fissure displayed similar δ13C, depleted δ18O, and higher 87Sr/86Sr relative to host rocks. The characteristic of fluidinclusion suggested the entrapment temperature was less than 50 ℃, and the saline of fluid inclusions in Cal22 were relative low, ranging from 13wt% to 35wt%NaCl. The outcomes have been interpreted as the result of the mixing of host marine carbonates with atmospheric fresh water. The latest calcite veins(Cal3)with hot homogenization temperature (Th=142 ℃ to 210 ℃)fluid inclusions, formed at the stage of the Es3 to Es4 during the Himalayan Orogeny, displaying depleted δ18O and δ13C, and higher 87Sr/86Sr relative to the host rocks, were derived from magmation. Based on the above data, the fluid flow history could be broken down into three stages which were from host marine carbonates, atmospheric fresh water and magmation, respectively. The evidence of hydrocarbon fluid flow has not been found and the present formation water has a low total dissolved solids(2 to 3 g/L), high rNa/rCl(1 to 12). There are large differences between Niutuozhen uplift and its surrounding hydrocarbon generation subsags in the chemical characteristics of present formation water. These proved that the condition of oil and gas preservation is poor and there is no connection between Niutuozhen uplift and Baxian Sag in dynamic fluid field. Combined comprehensively the evolution of the fluid flow and the chemical characteristics of present formation water, the paper argues that the feature of fluid flow is unsuitable for petroleum entrapment.

Characteristics of Movable Fluids in Different Diagenetic Facies and the Influencing Factors of Lowpermeability Reservoir: Taking Chang 6 Jiyuan Oilfield as An Example

REN Ying, SUN Wei, MING Hongxia, ZHANG Xi, HUO Lei, CAO Lei, CHEN Bin

2016, 30(5): 1124-1133.

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The distribution characteristics and factors of reservoir movable fluid saturation in different diagenetic facies of Chang 6 in Jiyuan oilfield are analyzed by using high pressure mercury injection, constant mercury injection and nuclear magnetic resonance. Results show that: (1) there are three significant types of diagenetic facies in research area, including the chlorite cementationresidual intergranular pore facies, feldspar corrosion facies and kaolinite cementation facies, whose microscopic porethroat structure have remarkable difference, especially in throat. (2) Analyzed from T2 spectrum that the porethroat of cementationresidual intergranular pore facies reservoir is welldistributed, good connectivity, and percent of movable fluid saturation is high. The porethroat of feldspar corrosion facies reservoir is poorer than cementationresidual intergranular pore facies reservoir, and the percent of movable fluid saturation is middle. The porethroat of kaolinite cementation facies reservoir is simplification and small, and the percent of movable fluid saturation is the lowest of all. (3) The main controlling factors of movable fluid saturation in different diagenetic are porethroat radius, mainstream throat radius, porethroat radius ratio, significant porethroat volume, and permeability is one of important factors influencing movable fluid saturation. Another adverse factor is the increase content of kaolinite and illite

Study on Two Dimensional Channeling Distribution of Unconsolidated Sandstone Reservoir

YU Chunlei1,2，WANG Shuoliang2，ZHANG Yuan2,3，WANG Juan2

2016, 30(5): 1134-1140.

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The injection water channeling phenomenon is more serious in most of the high water cut oil fields. The injection water channeling phenomenon has become the main contradiction in the effective development of the oil field. The channeling formation permeability calculation and description method are particularly urgent and important. At present the channeling permeability calculation methods can only calculate the channeling permeability at injection and production well point, cant get the channeling permeability distribution between injection production wells. The calculation method is relatively isolated, and there is no effective combination of the experimental results, the numerical simulation results and the reservoir engineering method results. In this paper, through the longterm water injection experiment, the dynamic formation process of the flow channel is simulated. And the relation formula between the water injection erosion ratio and the permeability of the reservoir is concluded. On the basis of the conventional numerical simulation method, the permeability variation law model is introduced into the numerical simulation calculation, and a new channeling distribution of unconsolidated sandstone reservoir is established, and the two dimensional distribution of permeability in the current state of the oil field is obtained. By comparing the dynamic data method, the probability density model method, the empirical formula method and the tracer test results, the results of this method are proved to be reliable.

Application of Remote Sensing Interpretation on 1∶50,000 Regional Geological Survey of North Bayan Hara Mountain

ZHANG Zhijun, LIU Shihua, KONG Di, QI Wanqiang, XU Dezhong

2016, 30(5): 1141-1149.

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Remote sensing technology is an important means of geological mapping. The efficiency and quality of mapping can be effectively improved through making full use of remote sensing technology. By using remote sensing method, and starting with the lithological and structure interpretation based on the SPOT5 and ETM data of Bayan Hara Mountain, the research obtained information to the greatest degree. The basis of lithology interpretation was carried on the detailed elaboration from four aspects in this research. The visual interpretation key system was established for the research area. And then the formation lithology was delimited through visual interpretation key. The rock section and lithological association were subdivided on each stratum. Various different levels of structural features were identified. New tectonic framework was established, and the tectonic blocks were divided for the research area. A perspective recognition of lithostratigraphic correlation and structure was obtained by painstaking research work. This would provide new materials for regional geological in Bayan Hara Mountain.

Analysis of Characteristics and Reason of Rocky Desertification Occurrence and Evolution in Karst Areas of Southwestern China

AN Guoying1，ZHOU Xuan2，WEN Jing1，TONG Liqiang1

2016, 30(5): 1150-1159.

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Using the rocky desertification data from remote sensing survey，this paper researched rocky desertification distribution and evolution during the past nearly decade from 1999 to 2008 in the karst areas of southwest China, including spatial region, carbonate lithology，karst topography，economic development and so on, and analyzed preliminarily the influencing factors of rocky desertification. The result shows that the distribution of rocky desertification concentrates in Yunnan, Guizhou and Guangxi provinces，and rocky desertification distribution is closely related to the different lithologic compositions and karst geomorphologies; the occurrence rate of rocky desertification is higher in the pure carbonate rock than that in the impure，decreasing with limestone or carbonate becoming smaller; the occurrence rate is the highest in the peak forest and cluster topography which is high terrain elevation and easily occurs rocky desertification, decreasing with the relative height of landscape becoming smaller. And correlations between desertification extent and lithology or landform are diverse, and the proportion of lowextent rocky desertification is higher than the proportion of moderateand severeextent in pure carbonate rocks, but the proportion of moderateand severeextent rocky desertification is higher than the proportion of the low extent in impure carbonate; the proportion of lowextent rocky desertification is higher than that of the moderateand severeextent in peak depression and plain landforms, and the proportion of moderateand severeextent rocky desertification is higher than that of the low extent in hilly terraces and hilly valley, and all those are affected by tectonic environment evolution and human activities. At the same time, from 1999 to 2008, it had become a good trend of rocky desertification evolution to reduce the total area and to relieve the extent, and the trend for worsening occurrence rate or improvement of the evolution process is similar to the distribution of different carbonate lithologies and karst topographies. Besides above all, rocky desertification also affect the living standard of the residents: the rocky desertification area of the severeextent rocky desertification county is negative correlation with farmers average net income or per capita GDP; the area size of countys rocky desertification is the most important factor affecting per capita GDP, as well as farmers per capita income. Therefore, the remote sensing survey of the period of rocky desertification indicates that there is a good trend of rocky desertification in the study area, but governance difficulties still exist.

Geological Disaster Characteristics of Highresolution Digital Orthophoto Images and Its Application in Loess Area：Taking Maiji Sheet in Tianshui，Gansu Province as An Example

TIAN You1,2,3, YANG Weimin3, LIU Ting3, LI Hao3, CHENG Xiaojie3, ZHANG Shuxuan3

2016, 30(5): 1160-1169.

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The vigorous development of domestic highresolution remote sensing make it possible to extract information of geologic hazard like morphological structure and components and composition of elements, and to carry out remote sensing investigation of geological hazards in ruthless area, and so on. In this article the geological disaster was visually interpreted in Maiji sheet based on highresolution Digital Orthophoto Map(DOM). Combined with field surveys, this study proposes the image characteristics of loess landslide, collapse and debris flow. The main interpretation keys of loess landslide are roundbacked armchair landform, shadow and white stripes of slip cliff, and the discontinuity of terrace with same height at the line of landslide limitation. Collapse and debris flow can be interpreted by outline and tone of geological disasters.Results show that DOM is an ideal source of remote sensing data for geological disasters interpretation in loess area; mudslides and landslides can be interpreted with a high accuracy and the accuracy of collapse interpretation is relatively lower; the accuracy of undetected rate is as following, landslides＞mudslides＞collapse. At last a discussion on the reason was carried out.

Causes of Lakes in Taerhu in the Hetao Plain, Inner Mongolia

ZHANG Haoyue1, ZHANG Xujiao2, LI Chenglu2,HE Zexin2, YE Peisheng3,YE Mengni2

2016, 30(5): 1170.

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There are a series of lakes in Taerhu, Wuyuan of Inner Mongolia in the Hetao Plain, which is an obvious comparison to the local arid climate. Researching on the mechanism of lakes is important to hydrogeology and climate changes in Quaternary period. By carrying out chemical tests on the samples along the way from Serteng Mountain to Taerhu lakes and to Yellow River, the results show that Gibbs model projection indicates lakewater samples lie in the transition of evaporation and rock weathering effects, which is far away from the effect of precipitation while groundwater is mainly controlled by rock weathering effects, showing groundwater recharges lake water that suffers extremely evaporation; Piper trilinear diagram reveals hydrochemical types are mainly HCO3—Ca for springs in front of mountains, HCO3—Na and Cl—Na for groundwater, HCO3—Na for Yellow River water and Cl—Na for lake water, which also shows there exists hydraulic relationship between groundwater and lake water that contains great concentration of the salt during the process of being recharged; TDS of the groundwater rapidly increases from the north to the south, varying from 262 mg/l to 2,296 mg/l. The lakes TDS, however, after reaching the maximum value of 1,213 mg/l in the north of Taerhu, decreases and is finally lower than that of groundwater, which shows lake water is recharged by present Yellow River and the change of groundwater conforms to hydrogeology model. The results of Quaternary geological survey show lakes can not only develop upon the riverbed subfacies, but also upon the dam facies in Taerhu. In addition, the distribution features of scattered lakes are not similar to those of oxbow lakes. The two arguments above basically eliminate the possibility that lakes are left by the ancient Yellow River. Alluvial deposit was ever eroded by the wind, which led in occurrence of underlain groundwater. In conclusion, the basins of lakes were formed by wind erosion.

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